Course Code

E C E 4 0 7 Course Title

Unified electronics lab V

Pre-requisitesNACourse Contents

1 Use slotted line1 To determine unknown frequency2 To find SWVR and Reflection coefficient

2 1 To investigate the properties of a system comprising a dipole and a parasitic element

2 Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo 3 To know the form of a YAGI antenna and examine multi element yagi 4 To see how gain and directivity increase as element numbers

increase 3 To study the effect of thickness of conductors upon the bandwidth of dipole4 Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas

1 To investigate stacked and bayed yagi antennas 2 To compare their performance with a single yagi

5 Implementation of Time Division Multiplexing system using matlabsimulink6 Implementation of pulse code modulation and demodulation using

matlabsimulink MTE

7 Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulink

8 Implementation of pulse data coding techniques for various formats using matlabsimulink

9 Implementation of Data decoding techniques for various formats using matlabsimulink

10 Implementation of amplitude shift keying modulator and demodulator using matlabsimulink

11 Implementation of frequency shift keying modulator and demodulator using matlabsimulink

12 Implementation of phase shift keying modulator and demodulator using matlabsimulink

Textbook Lab Manual ECE407 Additional Readings

1 Microwave Devices And Circuits Third Edition By Samuel Y Liao

2 Contemporary Communication System using matlab by John G Proakis Masoud Salehi

3 Modern Digital and Communication Systems by BP Lathi Zhi Ding

4 Analog Communication by V Chandra Sekhar

L T P Credit(or Max Marks)

0 0 4 4

Experiment No 1OBJECT By the use of the slotted line

a) To determine the unknown frequency b) To determine the Voltage Standing Wave Ratio (VSWR) and Reflection Coefficient

APPARATUS Transmitter Mod MW-TX One slotted line MW-5 Loads of different values (OCSC75Ω50Ω100Ω) RF cable (Zo=75Ω) Voltmeter THEORY When power is applied to transmission line voltage amp current appear If ZL=ZO load absorbs all power amp none is reflected If ZLneZO some power is absorbed amp rest is reflected We have one set of Voltage amp Current waves traveling towards load amp a reflected set traveling back to generator These sets of traveling waves in opposite directions set up an interference pattern called Standing Waves Maxima (antinodes) amp minima (node) of Voltage amp Current occur at fixed positions The slotted line is used to measure voltage and current directly on the various sections of a coaxial line as by the slot you can enter the electrical and magnetic fields between the two connectors constituting the coaxial line In presence of standing wave the voltage (or current) maximum and minimum value can bee seen the distance between a maximum and the adjacent minimum is equal to one fourth the wave length the speed factor of the line is equal to1 because the dielectric is air Once the speed factor is known by measuring the distance between two minima and multiplying it by two it is possible to obtain the frequency of the signal applied to the slotted line if this is unknown The standing wave ratio (SWR) is equal to the ratio to the maximum to the minimum value in fact on the maximum the direct and reflected wave value (of voltage and current) are added and on the minimum are subtracted If the reflected wave does not exist voltage and current keep constant along all the line and their ratio is equal to the characteristic impedance Zo the SWR is equal to 1 Such a line is called a flat line The output power of the generator tuned to the lowest frequencies (for example 7015 MHz) must be regulated to the maximum connect the output of the generator to the

slotted line with 75 Ω cable 1 m long connect 75 Ω to the other end of the slotted line the line is thus terminated on its characteristic impedance If the machining is perfect by moving the probes along the slotted line the signal amplitude will keep almost constant any way there may be variations which are due to the connectors or to slight variation of the probes alignment Change the termination of 75 Ω with a 50 Ω and measure the voltage along the line it has stronger minimum and maximum values than the last ones Check if the distance between minimum and maximum is equal to frac14 the wavelength in other words by varying the frequency and repeating measurement you can observe how the distance between max an min is longer or shorter if you decrease or increase the frequency repeat the exercise with termination of 100 ohm

Note that with the help of slotted line you can distinguish if the load is greater or smaller than the characteristic impedance of the line In fact with 100 ohm the voltage minimum is at frac14 wave length from the load while on the load there is a maximum with 50 ohm the voltage minimum is on the load

PROCEDURE 1 Connect the generator (transmitter) to the slotted line through RF cable 2 Terminate the line by attaching a load (ZL) on other end of line 3 Insert probes of voltmeter in the slots provided on the trailer of the slotted line 4 Turn on the generator and excite the cable with RF waves 5 Move the trailer on the slotted line Positions of maximum amp minimum voltage appear

alternately on the slotted line 6 Note down the max amp min values of voltage 7 Also note down the positions of the voltage minima and voltage maxima on the scale 8 Determine VSWR by the following formula

Measured VSWR= V max V min

9 Determine the calculated VSWR by the formula

VSWR = 1 + Г 1 - Г where Г= Z L ndash Z 0 ZL + Z0

10 Calculate the unknown frequency with the help of the following formula λ 2 =distance between consecutive V maxima or minima

f = c λ 11 Repeat same procedure for different loads (ZL)

OBSERVATIONS Frequency of incident wave =

CALCULATIONS

RESULT

PRACTICAL NO 2

OBJECT bull To investigate the properties of a system comprising a dipole and a parasitic element bull Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo bull To know the form of a YAGI antenna and examine multi element yagi bull To see how gain and directivity increase as element numbers increase

APPARATUS Antenna Lab hardware Discovery Software Dipole elements

Yagi boom THEORY Antenna An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves In other words antennas convert radio frequency electrical currents into electromagnetic waves and vice versa Antennas are used in systems such as radio and television broadcasting point-to-point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rocks at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Simple Dipole Antenna The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically with one end of each wire connected to the radio and the other end hanging free in space This is the simplest practical antenna and it is also used as reference model for other antennas Generally the dipole is considered to be omni-directional in the plane perpendicular to the axis of the antenna but it has deep nulls in the directions of the axis Yagi Uda Antenna An antenna with a driven element and one or more parasitic element is generally know as a ldquoyagirdquo after on of its inventors (Mssrs Yagi and Uda) With the length of the second dipole (the un-driven or ldquoparasiticrdquo element) shorter then the driven dipole (the driven element) the direction of maximum radiation is from the driven element towards the parasitic element In this case the parasitic element is called the |rdquodirectorrdquo With the length of the second dipole longer than the driven dipole the direction of maximum radiation is from the parasitic element towards the driven element In the case the parasitic element is called the ldquoreflectorrdquo

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

Experiment No 1OBJECT By the use of the slotted line

a) To determine the unknown frequency b) To determine the Voltage Standing Wave Ratio (VSWR) and Reflection Coefficient

APPARATUS Transmitter Mod MW-TX One slotted line MW-5 Loads of different values (OCSC75Ω50Ω100Ω) RF cable (Zo=75Ω) Voltmeter THEORY When power is applied to transmission line voltage amp current appear If ZL=ZO load absorbs all power amp none is reflected If ZLneZO some power is absorbed amp rest is reflected We have one set of Voltage amp Current waves traveling towards load amp a reflected set traveling back to generator These sets of traveling waves in opposite directions set up an interference pattern called Standing Waves Maxima (antinodes) amp minima (node) of Voltage amp Current occur at fixed positions The slotted line is used to measure voltage and current directly on the various sections of a coaxial line as by the slot you can enter the electrical and magnetic fields between the two connectors constituting the coaxial line In presence of standing wave the voltage (or current) maximum and minimum value can bee seen the distance between a maximum and the adjacent minimum is equal to one fourth the wave length the speed factor of the line is equal to1 because the dielectric is air Once the speed factor is known by measuring the distance between two minima and multiplying it by two it is possible to obtain the frequency of the signal applied to the slotted line if this is unknown The standing wave ratio (SWR) is equal to the ratio to the maximum to the minimum value in fact on the maximum the direct and reflected wave value (of voltage and current) are added and on the minimum are subtracted If the reflected wave does not exist voltage and current keep constant along all the line and their ratio is equal to the characteristic impedance Zo the SWR is equal to 1 Such a line is called a flat line The output power of the generator tuned to the lowest frequencies (for example 7015 MHz) must be regulated to the maximum connect the output of the generator to the

slotted line with 75 Ω cable 1 m long connect 75 Ω to the other end of the slotted line the line is thus terminated on its characteristic impedance If the machining is perfect by moving the probes along the slotted line the signal amplitude will keep almost constant any way there may be variations which are due to the connectors or to slight variation of the probes alignment Change the termination of 75 Ω with a 50 Ω and measure the voltage along the line it has stronger minimum and maximum values than the last ones Check if the distance between minimum and maximum is equal to frac14 the wavelength in other words by varying the frequency and repeating measurement you can observe how the distance between max an min is longer or shorter if you decrease or increase the frequency repeat the exercise with termination of 100 ohm

Note that with the help of slotted line you can distinguish if the load is greater or smaller than the characteristic impedance of the line In fact with 100 ohm the voltage minimum is at frac14 wave length from the load while on the load there is a maximum with 50 ohm the voltage minimum is on the load

PROCEDURE 1 Connect the generator (transmitter) to the slotted line through RF cable 2 Terminate the line by attaching a load (ZL) on other end of line 3 Insert probes of voltmeter in the slots provided on the trailer of the slotted line 4 Turn on the generator and excite the cable with RF waves 5 Move the trailer on the slotted line Positions of maximum amp minimum voltage appear

alternately on the slotted line 6 Note down the max amp min values of voltage 7 Also note down the positions of the voltage minima and voltage maxima on the scale 8 Determine VSWR by the following formula

Measured VSWR= V max V min

9 Determine the calculated VSWR by the formula

VSWR = 1 + Г 1 - Г where Г= Z L ndash Z 0 ZL + Z0

10 Calculate the unknown frequency with the help of the following formula λ 2 =distance between consecutive V maxima or minima

f = c λ 11 Repeat same procedure for different loads (ZL)

OBSERVATIONS Frequency of incident wave =

CALCULATIONS

RESULT

PRACTICAL NO 2

OBJECT bull To investigate the properties of a system comprising a dipole and a parasitic element bull Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo bull To know the form of a YAGI antenna and examine multi element yagi bull To see how gain and directivity increase as element numbers increase

APPARATUS Antenna Lab hardware Discovery Software Dipole elements

Yagi boom THEORY Antenna An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves In other words antennas convert radio frequency electrical currents into electromagnetic waves and vice versa Antennas are used in systems such as radio and television broadcasting point-to-point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rocks at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Simple Dipole Antenna The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically with one end of each wire connected to the radio and the other end hanging free in space This is the simplest practical antenna and it is also used as reference model for other antennas Generally the dipole is considered to be omni-directional in the plane perpendicular to the axis of the antenna but it has deep nulls in the directions of the axis Yagi Uda Antenna An antenna with a driven element and one or more parasitic element is generally know as a ldquoyagirdquo after on of its inventors (Mssrs Yagi and Uda) With the length of the second dipole (the un-driven or ldquoparasiticrdquo element) shorter then the driven dipole (the driven element) the direction of maximum radiation is from the driven element towards the parasitic element In this case the parasitic element is called the |rdquodirectorrdquo With the length of the second dipole longer than the driven dipole the direction of maximum radiation is from the parasitic element towards the driven element In the case the parasitic element is called the ldquoreflectorrdquo

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

slotted line with 75 Ω cable 1 m long connect 75 Ω to the other end of the slotted line the line is thus terminated on its characteristic impedance If the machining is perfect by moving the probes along the slotted line the signal amplitude will keep almost constant any way there may be variations which are due to the connectors or to slight variation of the probes alignment Change the termination of 75 Ω with a 50 Ω and measure the voltage along the line it has stronger minimum and maximum values than the last ones Check if the distance between minimum and maximum is equal to frac14 the wavelength in other words by varying the frequency and repeating measurement you can observe how the distance between max an min is longer or shorter if you decrease or increase the frequency repeat the exercise with termination of 100 ohm

Note that with the help of slotted line you can distinguish if the load is greater or smaller than the characteristic impedance of the line In fact with 100 ohm the voltage minimum is at frac14 wave length from the load while on the load there is a maximum with 50 ohm the voltage minimum is on the load

PROCEDURE 1 Connect the generator (transmitter) to the slotted line through RF cable 2 Terminate the line by attaching a load (ZL) on other end of line 3 Insert probes of voltmeter in the slots provided on the trailer of the slotted line 4 Turn on the generator and excite the cable with RF waves 5 Move the trailer on the slotted line Positions of maximum amp minimum voltage appear

alternately on the slotted line 6 Note down the max amp min values of voltage 7 Also note down the positions of the voltage minima and voltage maxima on the scale 8 Determine VSWR by the following formula

Measured VSWR= V max V min

9 Determine the calculated VSWR by the formula

VSWR = 1 + Г 1 - Г where Г= Z L ndash Z 0 ZL + Z0

10 Calculate the unknown frequency with the help of the following formula λ 2 =distance between consecutive V maxima or minima

f = c λ 11 Repeat same procedure for different loads (ZL)

OBSERVATIONS Frequency of incident wave =

CALCULATIONS

RESULT

PRACTICAL NO 2

OBJECT bull To investigate the properties of a system comprising a dipole and a parasitic element bull Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo bull To know the form of a YAGI antenna and examine multi element yagi bull To see how gain and directivity increase as element numbers increase

APPARATUS Antenna Lab hardware Discovery Software Dipole elements

Yagi boom THEORY Antenna An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves In other words antennas convert radio frequency electrical currents into electromagnetic waves and vice versa Antennas are used in systems such as radio and television broadcasting point-to-point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rocks at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Simple Dipole Antenna The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically with one end of each wire connected to the radio and the other end hanging free in space This is the simplest practical antenna and it is also used as reference model for other antennas Generally the dipole is considered to be omni-directional in the plane perpendicular to the axis of the antenna but it has deep nulls in the directions of the axis Yagi Uda Antenna An antenna with a driven element and one or more parasitic element is generally know as a ldquoyagirdquo after on of its inventors (Mssrs Yagi and Uda) With the length of the second dipole (the un-driven or ldquoparasiticrdquo element) shorter then the driven dipole (the driven element) the direction of maximum radiation is from the driven element towards the parasitic element In this case the parasitic element is called the |rdquodirectorrdquo With the length of the second dipole longer than the driven dipole the direction of maximum radiation is from the parasitic element towards the driven element In the case the parasitic element is called the ldquoreflectorrdquo

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

VSWR = 1 + Г 1 - Г where Г= Z L ndash Z 0 ZL + Z0

10 Calculate the unknown frequency with the help of the following formula λ 2 =distance between consecutive V maxima or minima

f = c λ 11 Repeat same procedure for different loads (ZL)

OBSERVATIONS Frequency of incident wave =

CALCULATIONS

RESULT

PRACTICAL NO 2

OBJECT bull To investigate the properties of a system comprising a dipole and a parasitic element bull Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo bull To know the form of a YAGI antenna and examine multi element yagi bull To see how gain and directivity increase as element numbers increase

APPARATUS Antenna Lab hardware Discovery Software Dipole elements

Yagi boom THEORY Antenna An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves In other words antennas convert radio frequency electrical currents into electromagnetic waves and vice versa Antennas are used in systems such as radio and television broadcasting point-to-point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rocks at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Simple Dipole Antenna The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically with one end of each wire connected to the radio and the other end hanging free in space This is the simplest practical antenna and it is also used as reference model for other antennas Generally the dipole is considered to be omni-directional in the plane perpendicular to the axis of the antenna but it has deep nulls in the directions of the axis Yagi Uda Antenna An antenna with a driven element and one or more parasitic element is generally know as a ldquoyagirdquo after on of its inventors (Mssrs Yagi and Uda) With the length of the second dipole (the un-driven or ldquoparasiticrdquo element) shorter then the driven dipole (the driven element) the direction of maximum radiation is from the driven element towards the parasitic element In this case the parasitic element is called the |rdquodirectorrdquo With the length of the second dipole longer than the driven dipole the direction of maximum radiation is from the parasitic element towards the driven element In the case the parasitic element is called the ldquoreflectorrdquo

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

OBJECT bull To investigate the properties of a system comprising a dipole and a parasitic element bull Understand the terms lsquodriven elementrsquo lsquoreflectorrsquo lsquodirectorrsquo bull To know the form of a YAGI antenna and examine multi element yagi bull To see how gain and directivity increase as element numbers increase

APPARATUS Antenna Lab hardware Discovery Software Dipole elements

Yagi boom THEORY Antenna An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves In other words antennas convert radio frequency electrical currents into electromagnetic waves and vice versa Antennas are used in systems such as radio and television broadcasting point-to-point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rocks at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Simple Dipole Antenna The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically with one end of each wire connected to the radio and the other end hanging free in space This is the simplest practical antenna and it is also used as reference model for other antennas Generally the dipole is considered to be omni-directional in the plane perpendicular to the axis of the antenna but it has deep nulls in the directions of the axis Yagi Uda Antenna An antenna with a driven element and one or more parasitic element is generally know as a ldquoyagirdquo after on of its inventors (Mssrs Yagi and Uda) With the length of the second dipole (the un-driven or ldquoparasiticrdquo element) shorter then the driven dipole (the driven element) the direction of maximum radiation is from the driven element towards the parasitic element In this case the parasitic element is called the |rdquodirectorrdquo With the length of the second dipole longer than the driven dipole the direction of maximum radiation is from the parasitic element towards the driven element In the case the parasitic element is called the ldquoreflectorrdquo

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

PROCEDURE 1 Identify one of the Yagi Boom Assemblies and mount it on top of the Generator

Tower 2 Ensure that all of the elements are removed except for the dipole 3 Ensure that the Motor Enable switch is off and then switch on the trainer 4 Launch a signal strength vs angle 2D polar graph and immediately switch on the

motor enable 5 Ensure that the Receiver and Generator antennas are aligned with each other and that

the spacing between them is about one meter 6 Set the dipole length to 10cm 7 Acquire a new plot at 1500MHz 8 Observe the polar plot 9 Identify one of the other undriven dipole antenna element 10 move the driven dipole forward on the boom by about 25 cm and mount a second

undriven dipole element behind the first at a spacing of about 5 cm 11 set the undriven length to 10 cm 12 acquire a second new plot at 1500 MHz

Has the polar pattern changed by adding the second element _____________________________________________________________________

13 change the spacing to 25cm and acquire a third new plot at 1500 MHz

What changes has the alteration in spacing made to the gain and directivity _____________________________________________________________________

CHANGING THE LENGTH OF THE PARASITIC ELEMENT 14 Launch a new signal strength vs angle 2D polar graph window 15 Acquire a new plot at 1500 MHz 16 Extend the length of the un-driven element to 11cm 17 Acquire a second new plot at 1500 MHz 18 Reduce the length of the un-driven element to 8cm 19 Acquire a third new plot at 1500MHz

What changes has the alteration in length made to the gain and directivity __________________________________________________________________________________________________________________________________________ ADDING A SECOND REFLECTOR

20 Mount the driven dipole on the boom forward from the axis of rotation by about 25cm and mount a second un-driven dipole element behind the first at a spacing of about 5cm

21 Set the dipole length to 10cm and the un-driven dipole length to 11cm 22 Acquire a new plot at 1500MHz 23 Observe the polar plot 24 Mount a second parasitic element about 5cm from the first parasitic reflector and

adjust its length to 11cm 25 Acquire a second new plot at 1500MHz 26 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

27 Change the spacing between the two reflectors and acquire a third new plot at 1500MHz

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

Is there any significant difference between the plots now _____________________________________________________________________You will find that the addition of a second reflector has little effect on the gain and directivity of the antenna irrespective of the spacing between the two reflectors

ADDING DIRECTORS 28 Remove the second reflector element from the boom 29 Launch a new signal strength vs angle 2D polar graph window 30 Acquire a new plot at 1500 MHz 31 Observe the polar plot 32 Mount a parasitic element about 5cm in front of the driven 33 element and adjust its length to 85cm 34 Acquire a second new plot at 1500 MHz 35 Observe the polar plot

Is there any significant difference between the two plots _____________________________________________________________________

36 Move the director to about 25 cm in front of the driven element 37 Acquire a third new plot at 1500 MHz 38 Observe the polar plot

How does the new plot compare with the previous two ____________________________________________________________________

39 Launch another new signal strength vs angle 2d polar graph window 40 Acquire a new plot at 1500 MHz 41 Add a second director 5 cm in front of the second 42 Acquire a second new plot at 1500 MHz 43 Add a third director 5 cm in front of the second 44 Acquire a third new plot at 1500 MHz 45 Add a fourth director 5 cm in front of the third 46 Acquire a fourth new plot at 1500 MHz

How do the gains and directivities compare _____________________________________________________________________

47 Launch another new signal strength vs angle 2D polar graph window 48 Acquire a new plot at 1500 MHz 49 Move the reflector to 25 cm behind the driven element Acquire a second new plot at

1500 MHz

Does the driven element ndash reflector spacing have much effect on the gain or directivity of the antenna _____________________________________________________________________ RESULT The addition of a second parasitic dipole element close to the driven dipole gives rise to a change in directivity and an increase in gain in a preferred direction It also showed that the length of the parasitic element had an effect on the direction of maximum gain If the parasitic element is the same length or longer than the driven element the gain is in a direction from parasitic element to driven element The parasitic element acts as a reflector If the parasitic element is shorter than the driven element the gain is in a direction from driven element to parasitic element The parasitic element acts as a director

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

PRACTICAL NO 3 OBJECT To study the effect of thickness of conductors upon the bandwidth of dipole APPARATUS Electronica Veneta (turntable) with stand Field meter SFM 1 EV Microwave generator 75ohm coaxial cable Basic dipole antenna short thick conductors (8mm) Basic dipole antenna Short Thin dipole (3mm) THEORY Dipole It consists of two poles that are oppositely charged Dipole antenna The simple dipole is one of the basic antennas It is an antenna with a center-fed driven element for transmitting or receiving radio frequency energy This is the directed antenna ie radiations take place only forward or backward Its characteristic impedance is 73Ω Half wave dipole Half wave dipole is an antenna formed by two conductors whose total length is half the wave length In general radio engineering the term dipole usually means a half-wave dipole (center-fed) Thin and thick dipole Theortically the dipole length must be half wave this is true if the wavelengthconductorrsquos dia ratio is infinite Usually there is a shortening coefficient K (ranging from 09-099)according to which the half wavelength in free space must be multiplied by K in order to have the half wave dipole length once the diameter of the conductor to be used is known(refer fig) Bandwidth The range of frequencies in which maximum reception is achieved Effect of thickness By increasing the conductor diameter in respect to the wavelength the dipole characteristic impedance will increase too in respect to the value of 73Ω On the other hand outside the center frequency range the antenna reactance varies more slowly in a thick than in a thick antenna This means with the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

PROCEDURE 1 Construct a dipole with arms of 3mm diameter (short) and mount on the central support of

the tuntable 2 Set the antenna and instruments as shown in figure 3 Set the generator to a determinate output level and to the center frequency of the antenna

under test 7015 MHz for measurements with short (thick or thin dipole) 4 Adjust the dipole length and sensitivity of the meter to obtain the maximum reading (10 th

LED glowing) 5 Now decrease the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f2 6 Now increase the frequency up to the value such that the 10 th LED keeps on glowing Note

the value as f1 7 Note down the difference between these two frequencies this will be the bandwidth

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

8 Calculate the wavelength for the resonance frequency of around 700 MHz for short dipole using the formula fc=λ 9 The ratio used for calculating the shortening coefficient is 2λ

where d=dia of conductor 11 From graph obtain a shortening coefficient K 12 Calculate the physical length of Dipole and compare with the measured length

Physical length of half wavelength dipole= x K 13 Construct a dipole with arms of 8mm diameter (short) 14 Repeat the same procedure for thick dipole

OBSERVATIONS amp CALCULATIONS Resonant frequency= MHz fc=λ= 300 = cm Measured length of short dipole thin= 220mm Measured length of short thick dipole=195mm THIIN dipole d= The ratio used for calculating the shortening coefficient is (with a dia of 3mm) =d2λK= From graph we obtain a coefficient of 0960 for the thin dipole Physical length of half wavelength dipole= x K=

THICK dipole d= The ratio used for calculating the shortening coefficient is with a diameter of 8mm =d2λK=

From graph we obtain a coefficient of 0947 for thick dipole Calculated physical length of half wavelength dipole= x K= (These values refer to a dipole in air Actually the dipole under consideration is not totally in air because for mechanical reasons its internal part is in a dielectric This slightly increases the resonance frequency) RESULT With the same shifting in respect to the center frequency the impedance of an antenna with larger diameter is more constant and consequently the SWR assumes lower values Practically the BANDWIDTH is wider In other words increasing the thickness of conductor has an effect upon the bandwidth of the dipole Thicker the conductor larger would be the bandwidth

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

PRACTICAL NO 4 OBJECT

1048707Understand the terms lsquobayingrsquo and lsquostackingrsquo as applied to antennas 1048707To investigate stacked and bayed yagi antennas 1048707To compare their performance with a single yagi

THEORY Yagi antennas may be used side-by-side or one on top of another to give greater gain or directivity This is referred to as baying or stacking the antennas respectively

PROCEDURE (A)Baying Two Yagis

1 Connected up the hardware of AntennaLab 2 Loaded the Discovery software 3 Loaded the NEC-Win software 4 Ensure that a Yagi Boom Assembly is mounted on the Generator Tower 5 Building up a 6 element yagi The dimensions of this are

Length Spacing Reflector 11 cm 5cm behind driven

element Driven Element 10 cm Zero (reference) Director 1 85 cm 25 cm in front of

DE Director 2 85 cm 5 cm in front of D1 Director 3 85 cm 5 cm in front of D2 Director 4 85 cm 5 cm in front of D3

6 Plot the polar response at 1500 MHz 7 Without disturbing the elements too much remove the antenna from the Generator Tower 8 Identify the Yagi Bay base assembly (the broad grey plastic strip with tapped holes) and

mount this centrally on the Generator Tower

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

9 Mount the 6 element yagi onto the Yagi Bay base assembly at three holes from the centre 10 Assemble an identical 6 element yagi on the other Yagi Boom Assembly and mount this

on the Yagi Bay base assembly at three hole the other side of the centre ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

11 Identify the 2-Way Combiner and the two 183mm cables 12 Connect the two 183mm cables to the adjacent connectors on the Combiner and their

other ends to the two 6 element yagis 13 Connect the cable from the Generator Tower to the remaining connector on the

Combiner 14 Acquire a new plot for the two bayed antennas onto the same graph as that for the single

6 element yagi 15 Reverse the driven element on one of the yagis and acquire a third plot OBSERVATIONS Does reversing the driven element make much difference to the polar pattern for the two bayed yagis ___________________________________________________________________________ How does the directivity of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ How does the forward gain of the two bayed yagis compare with the single yagi plot (with the driven element the correct way round) ___________________________________________________________________________ Now move the two yagis to the outer sets of holes on the Yagi Bay base assembly Ensure that you keep the driven elements the same way round as you had before to give the correct phasing Superimpose a plot for this assembly How do the directivity and forward gain of the wider spaced yagis compare with the close spaced yagis ___________________________________________________________________________

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

(B) Stacking Two Yagis

1 Identify the Yagi Stack base assembly (the narrow grey plastic strip with tapped holes) and mount this on the side of the Generator Tower

2 Mount the 6 element yagi onto the Yagi Stack base assembly at one set of holes above the centre

3 Plot the polar response at 1500 MHz 4 Mount the other 6 element yagi on the Yagi Stack base assembly at the uppermost set of

holes ensuring that the two yagis are pointing in the same direction (towards the Receiver Tower)

5 Identify the 2-Way Combiner and the two 183mm coaxial cables 6 Connect the two 183mm cables to the adjacent connectors on the Combiner and their other

ends to the two 6 element yagis 7 Connect the cable from the Generator Tower to the remaining connector on the Combiner 8 Superimpose the polar plot for the two stacked antennas onto that for the single 6 element

yagi 9 Reverse the driven element on one of the yagis and superimpose a third plot 10 Change the position of the lower yagi to the bottom set of holes on the Yagi Stack base

assembly Ensure that the driven elements are correctly phased and superimpose a fourth polar plot

OBSERVATIONS How does the directivity of the different configurations compare ___________________________________________________________________________ How does the forward gain of the stacked yagis compare with the single yagi ___________________________________________________________________________ How does the forward gain of the stacked yagis change when the driven element phasing is incorrect ___________________________________________________________________________ RESULT

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

PRACTICAL NO 5OBJECT Implementation of Time Division Multiplexing system using matlabsimulink THEORY Time-division multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel but are physically taking turns on the channel The time domain is divided into several recurrent timeslots of fixed length one for each sub-channel A sample byte or data block of sub-channel 1 is transmitted during timeslot 1 sub-channel 2 during timeslot 2 etc One TDM frame consists of one timeslot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization After the last sub-channel error correction and synchronization the cycle starts all over again with a new frame starting with the second sample byte or data block from sub-channel 1 etcFor multiple signals to share one medium the medium must somehow be divided giving each signal a portion of the total bandwidth The current techniques that can accomplish this include

Frequency division multiplexing (FDM) Time division multiplexing (TDM)-Synchronous vs statistical1 Wavelength division multiplexing (WDM) Code division multiplexing (CDM)

MultiplexingTwo or more simultaneous transmissions on a single circuit

Figure 5 MultiplexingMultiplexor (MUX)Demultiplexor (DEMUX)

Time Division MultiplexingSharing of the signal is accomplished by dividing available transmission time on a medium among usersDigital signaling is used exclusively Time division multiplexing comes in two basic forms1 Synchronous time division multiplexing and2 Statistical or asynchronous time division multiplexing

Synchronous Time Division MultiplexingThe original time division multiplexing the multiplexor accepts input from attached devices in a round-robin fashion and transmits the data in a never ending patternT-1 and ISDN telephone lines are common examples of synchronous time division multiplexingIf one device generates data at a faster rate than other devices then the multiplexor must either sample the incoming data stream from that device more often than it samples the other devices or buffer the faster incoming streamIf a device has nothing to transmit the multiplexor must still insert a piece of data from that device into the multiplexed stream So that the receiver may stay synchronized with the incoming data stream the transmitting multiplexor can insert alternating 1s and 0s into the data streamThree types popular today of Synchronous Time Division Multiplexing

bull T-1 multiplexing (the classic)bull ISDN multiplexingbull SONET (Synchronous Optical NETwork)

The T1 (154 Mbps) multiplexor stream is a continuous series of frames of both digitized data and voice channelsThe ISDN multiplexor stream is also a continuous stream of frames Each frame contains various control and sync infoSONET ndash massive data ratesStatistical Time Division MultiplexingA statistical multiplexor transmits only the data from active workstations (or why works when you donrsquot have to) If a workstation is not active no space is wasted on the multiplexed stream A statistical multiplexor accepts the incoming data streams and creates a frame containing only the data to be transmittedTo identify each piece of data an address is included If the data is of variable size a length is also included More precisely the transmitted frame contains a collection of data groupsA statistical multiplexor does not require a line over as high a speed line as synchronous time division multiplexing since STDM does not assume all sources will transmit all of the timeGood for low bandwidth lines (used for LANs)Much more efficient use of bandwidth

Matlab code for TDM Matlab code for Time Division Multiplexing clcclose allclear all Signal generationx=054pi siganal taken upto 4pisig1=8sin(x) generate 1st sinusoidal signall=length(sig1)sig2=8triang(l) Generate 2nd traingular Sigal Display of Both Signalsubplot(221) plot(sig1)title(Sinusoidal Signal)ylabel(Amplitude---gt)xlabel(Time---gt)subplot(222)plot(sig2)title(Triangular Signal)ylabel(Amplitude---gt)xlabel(Time---gt)

Display of Both Sampled Signalsubplot(223)stem(sig1)title(Sampled Sinusoidal Signal)ylabel(Amplitude---gt)xlabel(Time---gt)subplot(224)stem(sig2)title(Sampled Triangular Signal)ylabel(Amplitude---gt)xlabel(Time---gt)l1=length(sig1)l2=length(sig2) for i=1l1 sig(1i)=sig1(i) Making Both row vector to a matrix sig(2i)=sig2(i) end TDM of both quantize signaltdmsig=reshape(sig12l1) Display of TDM Signalfigure

stem(tdmsig)title(TDM Signal)ylabel(Amplitude---gt)xlabel(Time---gt) Demultiplexing of TDM Signal demux=reshape(tdmsig2l1) for i=1l1 sig3(i)=demux(1i) Converting The matrix into row vectors sig4(i)=demux(2i) end display of demultiplexed signal figure subplot(211) plot(sig3) title(Recovered Sinusoidal Signal) ylabel(Amplitude---gt) xlabel(Time---gt) subplot(212) plot(sig4) title(Recovered Triangular Signal) ylabel(Amplitude---gt) xlabel(Time---gt) Results

0 10 20 30-10

-5

0

5

10Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt0 10 20 30

0

2

4

6

8Triangular Signal

Am

plitu

de--

-gt

Time---gt

0 10 20 30-10

-5

0

5

10Sampled Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt0 10 20 30

0

2

4

6

8Sampled Triangular Signal

Am

plitu

de--

-gt

Time---gt

0 10 20 30 40 50 60-8

-6

-4

-2

0

2

4

6

8TDM Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 30-10

-5

0

5

10Recovered Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 300

2

4

6

8Recovered Triangular Signal

Am

plitu

de--

-gt

Time---gt

PRACTICAL NO 6OBJECT Implementation of pulse code modulation and demodulation using matlabsimulinkTHEORY ANALOG-TO-DIGITAL CONVERSIONA digital signal is superior to an analog signal because it is more robust to noise and can easily be recovered corrected and amplified For this reason the tendency today is to change an analog signal to digital data In this section we describe two techniques pulse code modulation and delta modulationPulse code Modulation (PCM)Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals which was invented by Alec Reeves in 1937 It is the standard form for digital audio in computers and various Blu-ray Compact Disc and DVD formats as well as other uses such as digital telephone systems A PCM stream is a digital representation of an analog signal in which the magnitude of the analogue signal is sampled regularly at uniform intervals with each sample being quantized to the nearest value within a range of digital stepsPCM consists of three steps to digitize an analog signal

1 Sampling2 Quantization3 Binary encoding

Before we sample we have to filter the signal to limit the maximum frequency of the signal as it affects the sampling rate

Filtering should ensure that we do not distort the signal ie remove high frequency components that affect the signal shape

Figure 61 Components of PCM encoder

Sampling Analog signal is sampled every TS secs Ts is referred to as the sampling interval fs = 1Ts is called the sampling rate or sampling frequency There are 3 sampling methods

ndash Ideal - an impulse at each sampling instantndash Natural - a pulse of short width with varying amplitudendash Flattop - sample and hold like natural but with single amplitude value

The process is referred to as pulse amplitude modulation PAM and the outcome is a signal with analog (non integer) values

stem(tdmsig)title(TDM Signal)ylabel(Amplitude---gt)xlabel(Time---gt) Demultiplexing of TDM Signal demux=reshape(tdmsig2l1) for i=1l1 sig3(i)=demux(1i) Converting The matrix into row vectors sig4(i)=demux(2i) end display of demultiplexed signal figure subplot(211) plot(sig3) title(Recovered Sinusoidal Signal) ylabel(Amplitude---gt) xlabel(Time---gt) subplot(212) plot(sig4) title(Recovered Triangular Signal) ylabel(Amplitude---gt) xlabel(Time---gt) Results

0 10 20 30-10

-5

0

5

10Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt0 10 20 30

0

2

4

6

8Triangular Signal

Am

plitu

de--

-gt

Time---gt

0 10 20 30-10

-5

0

5

10Sampled Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt0 10 20 30

0

2

4

6

8Sampled Triangular Signal

Am

plitu

de--

-gt

Time---gt

0 10 20 30 40 50 60-8

-6

-4

-2

0

2

4

6

8TDM Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 30-10

-5

0

5

10Recovered Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 300

2

4

6

8Recovered Triangular Signal

Am

plitu

de--

-gt

Time---gt

PRACTICAL NO 6OBJECT Implementation of pulse code modulation and demodulation using matlabsimulinkTHEORY ANALOG-TO-DIGITAL CONVERSIONA digital signal is superior to an analog signal because it is more robust to noise and can easily be recovered corrected and amplified For this reason the tendency today is to change an analog signal to digital data In this section we describe two techniques pulse code modulation and delta modulationPulse code Modulation (PCM)Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals which was invented by Alec Reeves in 1937 It is the standard form for digital audio in computers and various Blu-ray Compact Disc and DVD formats as well as other uses such as digital telephone systems A PCM stream is a digital representation of an analog signal in which the magnitude of the analogue signal is sampled regularly at uniform intervals with each sample being quantized to the nearest value within a range of digital stepsPCM consists of three steps to digitize an analog signal

1 Sampling2 Quantization3 Binary encoding

Before we sample we have to filter the signal to limit the maximum frequency of the signal as it affects the sampling rate

Filtering should ensure that we do not distort the signal ie remove high frequency components that affect the signal shape

Figure 61 Components of PCM encoder

Sampling Analog signal is sampled every TS secs Ts is referred to as the sampling interval fs = 1Ts is called the sampling rate or sampling frequency There are 3 sampling methods

ndash Ideal - an impulse at each sampling instantndash Natural - a pulse of short width with varying amplitudendash Flattop - sample and hold like natural but with single amplitude value

The process is referred to as pulse amplitude modulation PAM and the outcome is a signal with analog (non integer) values

0 10 20 30 40 50 60-8

-6

-4

-2

0

2

4

6

8TDM Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 30-10

-5

0

5

10Recovered Sinusoidal Signal

Am

plitu

de--

-gt

Time---gt

0 5 10 15 20 25 300

2

4

6

8Recovered Triangular Signal

Am

plitu

de--

-gt

Time---gt

PRACTICAL NO 6OBJECT Implementation of pulse code modulation and demodulation using matlabsimulinkTHEORY ANALOG-TO-DIGITAL CONVERSIONA digital signal is superior to an analog signal because it is more robust to noise and can easily be recovered corrected and amplified For this reason the tendency today is to change an analog signal to digital data In this section we describe two techniques pulse code modulation and delta modulationPulse code Modulation (PCM)Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals which was invented by Alec Reeves in 1937 It is the standard form for digital audio in computers and various Blu-ray Compact Disc and DVD formats as well as other uses such as digital telephone systems A PCM stream is a digital representation of an analog signal in which the magnitude of the analogue signal is sampled regularly at uniform intervals with each sample being quantized to the nearest value within a range of digital stepsPCM consists of three steps to digitize an analog signal

1 Sampling2 Quantization3 Binary encoding

Before we sample we have to filter the signal to limit the maximum frequency of the signal as it affects the sampling rate

Filtering should ensure that we do not distort the signal ie remove high frequency components that affect the signal shape

Figure 61 Components of PCM encoder

Sampling Analog signal is sampled every TS secs Ts is referred to as the sampling interval fs = 1Ts is called the sampling rate or sampling frequency There are 3 sampling methods

ndash Ideal - an impulse at each sampling instantndash Natural - a pulse of short width with varying amplitudendash Flattop - sample and hold like natural but with single amplitude value

The process is referred to as pulse amplitude modulation PAM and the outcome is a signal with analog (non integer) values

PRACTICAL NO 6OBJECT Implementation of pulse code modulation and demodulation using matlabsimulinkTHEORY ANALOG-TO-DIGITAL CONVERSIONA digital signal is superior to an analog signal because it is more robust to noise and can easily be recovered corrected and amplified For this reason the tendency today is to change an analog signal to digital data In this section we describe two techniques pulse code modulation and delta modulationPulse code Modulation (PCM)Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals which was invented by Alec Reeves in 1937 It is the standard form for digital audio in computers and various Blu-ray Compact Disc and DVD formats as well as other uses such as digital telephone systems A PCM stream is a digital representation of an analog signal in which the magnitude of the analogue signal is sampled regularly at uniform intervals with each sample being quantized to the nearest value within a range of digital stepsPCM consists of three steps to digitize an analog signal

1 Sampling2 Quantization3 Binary encoding

Before we sample we have to filter the signal to limit the maximum frequency of the signal as it affects the sampling rate

Filtering should ensure that we do not distort the signal ie remove high frequency components that affect the signal shape

Figure 61 Components of PCM encoder

Sampling Analog signal is sampled every TS secs Ts is referred to as the sampling interval fs = 1Ts is called the sampling rate or sampling frequency There are 3 sampling methods

ndash Ideal - an impulse at each sampling instantndash Natural - a pulse of short width with varying amplitudendash Flattop - sample and hold like natural but with single amplitude value

The process is referred to as pulse amplitude modulation PAM and the outcome is a signal with analog (non integer) values

According to the Nyquist theorem the sampling rate must be at least 2 times the highest frequency contained in the signal

Quantization Sampling results in a series of pulses of varying amplitude values ranging between two

limits a min and a max The amplitude values are infinite between the two limits We need to map the infinite amplitude values onto a finite set of known values This is achieved by dividing the distance between min and max into L zones each of

height D D = (max - min)LQuantization Levels

The midpoint of each zone is assigned a value from 0 to L-1 (resulting in L values) Each sample falling in a zone is then approximated to the value of the midpoint

Quantization Error When a signal is quantized we introduce an error - the coded signal is an approximation

of the actual amplitude value The difference between actual and coded value (midpoint) is referred to as the

quantization error The more zones the smaller D which results in smaller errors BUT the more zones the more bits required to encode the samples -gt higher bit rate

Quantization Error and SNQR Signals with lower amplitude values will suffer more from quantization error as the error

range D2 is fixed for all signal levels Non linear quantization is used to alleviate this problem Goal is to keep SNQR fixed for

all sample values Two approaches

The quantization levels follow a logarithmic curve Smaller Drsquos at lower amplitudes and larger Drsquos at higher amplitudes

Companding The sample values are compressed at the sender into logarithmic zones and then expanded at the receiver The zones are fixed in height

Bit rate and bandwidth requirements of PCM The bit rate of a PCM signal can be calculated form the number of bits per sample x the

sampling rate Bit rate = nb x fs The bandwidth required to transmit this signal depends on the type of line encoding used

Refer to previous section for discussion and formulas A digitized signal will always need more bandwidth than the original analog signal Price

we pay for robustness and other features of digital transmission

PCM Decoder To recover an analog signal from a digitized signal we follow the following steps

We use a hold circuit that holds the amplitude value of a pulse till the next pulse arrives

We pass this signal through a low pass filter with a cutoff frequency that is equal to the highest frequency in the pre-sampled signal

The higher the value of L the less distorted a signal is recovered

Matlab code of PCMPCMthe uniform quantization of an analog signal using L quantizaton levelsimplemented by uniquanm function of matlab(uniquanm)function [q_outDeltaSQNR]=uniquan(sig_inL)usage [q_outDelta SQNR]=uniquan(sig_inL) L-number ofuniform quantization levels sig_in-input signalvector function output q_out-quantized output Delta-quantization interval SQNR- actual signal to quantization ratiosig_pmax=max(sig_in) finding the +ve peaksig_nmax=min(sig_in) finding the -ve peakDelta=(sig_pmax-sig_nmax)L quantization intervalq_level=sig_nmax+Delta2Deltasig_pmax-Delta2 define Q-levelsL_sig=length(sig_in) find signal lengthsigp=(sig_in-sig_nmax)Delta+12 convert int to 12 to L+12 rangeqindex=round(sigp) round to 12L levelsqindex=min(qindexL) eliminate L+1 as a rare possibilityq_out=q_level(qindex) use index vector to generate outputSQNR=20log10(norm(sig_in)norm(sig_in-q_out)) actual SQNR valueend

sampandquantm function executes both sampling and uniform quantization

sampandquantmfunction [s_outsq_outsqh_outDeltaSQNR]=sampandquant(sig_inLtdts) usage [s_outsq_outsqh_outDeltaSQNR]=sampandquant(sig_inLtdts) L-no of uniform quantization levels sig_in-input signal vector td-original signal sampling period of sig_in ts- new sampling period NOTE tdfs must be +ve integef function outputs

s_out-sampled output sq_out-sample and quantized output sqh_out-sample quantized and hold output Delta- quantization interval SQNR-actual signal to quantization ratioif rem(tstd1)==0 nfac=round(tstd) p_zoh=ones(1nfac) s_out=downsample(sig_innfac) [sq_outDeltaSQNR]=uniquan(s_outL) s_out=upsample(s_outnfac) sqh_out=upsample(sq_outnfac)else warning(Error tstd is not an integer) s_out=[] sq_out=[] sqh_out=[] Delta=[] SQNR=[]endend

generation of PCM clcclearclftd=0002 original sampling rate rate 500 hzt=[0td1] time interval of 1 secxsig=sin(2pit)-sin(6pit) n1hz +3 hz sinusoidalsLsig=length(xsig)Lfft=2^ceil(log2(Lsig)+1)Xsig=fftshift(fft(xsigLfft))Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)ts=002 new sampling rate =50 hzNfact=tstd send the signal through a 16-level uniform quantiser[s_outsq_outsqh_out1DeltaSQRN]=sampandquant(xsig16tdts) obtaind the signal which is - sampledquantiserand zero-order hold signal sqh_out plot the original signal and PCM signal in time domain figrue(1)figure(1)subplot(211)sfig1=plot(txsigktsqh_out1(1Lsig)b)set(sfig1Linewidth2)title(Signal it g(it t) and its 16 level PCM signal)xlabel(time(sec))

send the signal through a 16-level unifrom quantiser[s_outsq_outsqh_out2DeltaSQNR]=sampandquant(xsig4tdts) obtained the PCM signal which is - sampledquantiserand zero_order hold signal sqh_out plot the original signal and the PCM signal in time domainsubplot(212)sfig2=plot(txsigktsqh_out2(1Lsig)b)set(sfig2Linewidth2)title(Signal it g(it t) and its 4 level PCM signal)xlabel(time(sec))Lfft=2^ceil(log2(Lsig)+1)Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)SQH1=fftshift(fft(sqh_out1Lfft))

SQH2=fftshift(fft(sqh_out2Lfft)) Now use LPF to filter the two PCM signalBW=10 Bandwidth is no larger than 10HzH_lpf=zeros(1Lfft)H_lpf(Lfft2-BWLfft2+BW-1)=1 ideal LPF S1_recv=SQH1H_lpfs_recv1=real(ifft(fftshift(S1_recv)))s_recv1=s_recv1(1Lsig)S2_recv=SQH2H_lpfs_recv2=real(ifft(fftshift(S2_recv)))s_recv2=s_recv2(1Lsig) plot the filtered signal against the original signalfigure(2)subplot(211)sfig3=plot(txsigb-ts_recv1b-)legend(originalrecovered)set(sfig3Linewidth2)title(signalit g(it t) and filtered 16-level PCM signal)xlabel(time(sec))subplot(212)sfig4=plot(txsigb-ts_recv2(1Lsig)b)legend(originalrecovered)set(sfig1Linewidth2)title(signalit g(it t) and filtered 4-level PCM signal)xlabel(time(sec))

Results

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal it g(it t) and its 16 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal g( t) and its 4 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 16-level PCM signal

original

recovered

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 4-level PCM signal

original

recovered

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

Matlab code of PCMPCMthe uniform quantization of an analog signal using L quantizaton levelsimplemented by uniquanm function of matlab(uniquanm)function [q_outDeltaSQNR]=uniquan(sig_inL)usage [q_outDelta SQNR]=uniquan(sig_inL) L-number ofuniform quantization levels sig_in-input signalvector function output q_out-quantized output Delta-quantization interval SQNR- actual signal to quantization ratiosig_pmax=max(sig_in) finding the +ve peaksig_nmax=min(sig_in) finding the -ve peakDelta=(sig_pmax-sig_nmax)L quantization intervalq_level=sig_nmax+Delta2Deltasig_pmax-Delta2 define Q-levelsL_sig=length(sig_in) find signal lengthsigp=(sig_in-sig_nmax)Delta+12 convert int to 12 to L+12 rangeqindex=round(sigp) round to 12L levelsqindex=min(qindexL) eliminate L+1 as a rare possibilityq_out=q_level(qindex) use index vector to generate outputSQNR=20log10(norm(sig_in)norm(sig_in-q_out)) actual SQNR valueend

sampandquantm function executes both sampling and uniform quantization

sampandquantmfunction [s_outsq_outsqh_outDeltaSQNR]=sampandquant(sig_inLtdts) usage [s_outsq_outsqh_outDeltaSQNR]=sampandquant(sig_inLtdts) L-no of uniform quantization levels sig_in-input signal vector td-original signal sampling period of sig_in ts- new sampling period NOTE tdfs must be +ve integef function outputs

s_out-sampled output sq_out-sample and quantized output sqh_out-sample quantized and hold output Delta- quantization interval SQNR-actual signal to quantization ratioif rem(tstd1)==0 nfac=round(tstd) p_zoh=ones(1nfac) s_out=downsample(sig_innfac) [sq_outDeltaSQNR]=uniquan(s_outL) s_out=upsample(s_outnfac) sqh_out=upsample(sq_outnfac)else warning(Error tstd is not an integer) s_out=[] sq_out=[] sqh_out=[] Delta=[] SQNR=[]endend

generation of PCM clcclearclftd=0002 original sampling rate rate 500 hzt=[0td1] time interval of 1 secxsig=sin(2pit)-sin(6pit) n1hz +3 hz sinusoidalsLsig=length(xsig)Lfft=2^ceil(log2(Lsig)+1)Xsig=fftshift(fft(xsigLfft))Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)ts=002 new sampling rate =50 hzNfact=tstd send the signal through a 16-level uniform quantiser[s_outsq_outsqh_out1DeltaSQRN]=sampandquant(xsig16tdts) obtaind the signal which is - sampledquantiserand zero-order hold signal sqh_out plot the original signal and PCM signal in time domain figrue(1)figure(1)subplot(211)sfig1=plot(txsigktsqh_out1(1Lsig)b)set(sfig1Linewidth2)title(Signal it g(it t) and its 16 level PCM signal)xlabel(time(sec))

send the signal through a 16-level unifrom quantiser[s_outsq_outsqh_out2DeltaSQNR]=sampandquant(xsig4tdts) obtained the PCM signal which is - sampledquantiserand zero_order hold signal sqh_out plot the original signal and the PCM signal in time domainsubplot(212)sfig2=plot(txsigktsqh_out2(1Lsig)b)set(sfig2Linewidth2)title(Signal it g(it t) and its 4 level PCM signal)xlabel(time(sec))Lfft=2^ceil(log2(Lsig)+1)Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)SQH1=fftshift(fft(sqh_out1Lfft))

SQH2=fftshift(fft(sqh_out2Lfft)) Now use LPF to filter the two PCM signalBW=10 Bandwidth is no larger than 10HzH_lpf=zeros(1Lfft)H_lpf(Lfft2-BWLfft2+BW-1)=1 ideal LPF S1_recv=SQH1H_lpfs_recv1=real(ifft(fftshift(S1_recv)))s_recv1=s_recv1(1Lsig)S2_recv=SQH2H_lpfs_recv2=real(ifft(fftshift(S2_recv)))s_recv2=s_recv2(1Lsig) plot the filtered signal against the original signalfigure(2)subplot(211)sfig3=plot(txsigb-ts_recv1b-)legend(originalrecovered)set(sfig3Linewidth2)title(signalit g(it t) and filtered 16-level PCM signal)xlabel(time(sec))subplot(212)sfig4=plot(txsigb-ts_recv2(1Lsig)b)legend(originalrecovered)set(sfig1Linewidth2)title(signalit g(it t) and filtered 4-level PCM signal)xlabel(time(sec))

Results

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal it g(it t) and its 16 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal g( t) and its 4 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 16-level PCM signal

original

recovered

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 4-level PCM signal

original

recovered

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

s_out-sampled output sq_out-sample and quantized output sqh_out-sample quantized and hold output Delta- quantization interval SQNR-actual signal to quantization ratioif rem(tstd1)==0 nfac=round(tstd) p_zoh=ones(1nfac) s_out=downsample(sig_innfac) [sq_outDeltaSQNR]=uniquan(s_outL) s_out=upsample(s_outnfac) sqh_out=upsample(sq_outnfac)else warning(Error tstd is not an integer) s_out=[] sq_out=[] sqh_out=[] Delta=[] SQNR=[]endend

generation of PCM clcclearclftd=0002 original sampling rate rate 500 hzt=[0td1] time interval of 1 secxsig=sin(2pit)-sin(6pit) n1hz +3 hz sinusoidalsLsig=length(xsig)Lfft=2^ceil(log2(Lsig)+1)Xsig=fftshift(fft(xsigLfft))Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)ts=002 new sampling rate =50 hzNfact=tstd send the signal through a 16-level uniform quantiser[s_outsq_outsqh_out1DeltaSQRN]=sampandquant(xsig16tdts) obtaind the signal which is - sampledquantiserand zero-order hold signal sqh_out plot the original signal and PCM signal in time domain figrue(1)figure(1)subplot(211)sfig1=plot(txsigktsqh_out1(1Lsig)b)set(sfig1Linewidth2)title(Signal it g(it t) and its 16 level PCM signal)xlabel(time(sec))

send the signal through a 16-level unifrom quantiser[s_outsq_outsqh_out2DeltaSQNR]=sampandquant(xsig4tdts) obtained the PCM signal which is - sampledquantiserand zero_order hold signal sqh_out plot the original signal and the PCM signal in time domainsubplot(212)sfig2=plot(txsigktsqh_out2(1Lsig)b)set(sfig2Linewidth2)title(Signal it g(it t) and its 4 level PCM signal)xlabel(time(sec))Lfft=2^ceil(log2(Lsig)+1)Fmax=1(2td)Faxis=linspace(-FmaxFmaxLfft)SQH1=fftshift(fft(sqh_out1Lfft))

SQH2=fftshift(fft(sqh_out2Lfft)) Now use LPF to filter the two PCM signalBW=10 Bandwidth is no larger than 10HzH_lpf=zeros(1Lfft)H_lpf(Lfft2-BWLfft2+BW-1)=1 ideal LPF S1_recv=SQH1H_lpfs_recv1=real(ifft(fftshift(S1_recv)))s_recv1=s_recv1(1Lsig)S2_recv=SQH2H_lpfs_recv2=real(ifft(fftshift(S2_recv)))s_recv2=s_recv2(1Lsig) plot the filtered signal against the original signalfigure(2)subplot(211)sfig3=plot(txsigb-ts_recv1b-)legend(originalrecovered)set(sfig3Linewidth2)title(signalit g(it t) and filtered 16-level PCM signal)xlabel(time(sec))subplot(212)sfig4=plot(txsigb-ts_recv2(1Lsig)b)legend(originalrecovered)set(sfig1Linewidth2)title(signalit g(it t) and filtered 4-level PCM signal)xlabel(time(sec))

Results

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal it g(it t) and its 16 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal g( t) and its 4 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 16-level PCM signal

original

recovered

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 4-level PCM signal

original

recovered

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

SQH2=fftshift(fft(sqh_out2Lfft)) Now use LPF to filter the two PCM signalBW=10 Bandwidth is no larger than 10HzH_lpf=zeros(1Lfft)H_lpf(Lfft2-BWLfft2+BW-1)=1 ideal LPF S1_recv=SQH1H_lpfs_recv1=real(ifft(fftshift(S1_recv)))s_recv1=s_recv1(1Lsig)S2_recv=SQH2H_lpfs_recv2=real(ifft(fftshift(S2_recv)))s_recv2=s_recv2(1Lsig) plot the filtered signal against the original signalfigure(2)subplot(211)sfig3=plot(txsigb-ts_recv1b-)legend(originalrecovered)set(sfig3Linewidth2)title(signalit g(it t) and filtered 16-level PCM signal)xlabel(time(sec))subplot(212)sfig4=plot(txsigb-ts_recv2(1Lsig)b)legend(originalrecovered)set(sfig1Linewidth2)title(signalit g(it t) and filtered 4-level PCM signal)xlabel(time(sec))

Results

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal it g(it t) and its 16 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2Signal g( t) and its 4 level PCM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 16-level PCM signal

original

recovered

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 4-level PCM signal

original

recovered

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 16-level PCM signal

original

recovered

0 01 02 03 04 05 06 07 08 09 1-2

-1

0

1

2

time(sec)

signal g(it t) and filtered 4-level PCM signal

original

recovered

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

PRACTICAL NO 7 OBJECT Implementation of delta modulation and demodulation and observe effect of slope Overload using matlabsimulinkTHEORY Delta ModulationDelta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance DM is the simplest form of differential pulse-code modulation (DPCM) where the difference between successive samples is encoded into n-bit data streams In delta modulation the transmitted data is reduced to a 1-bit data stream

This scheme sends only the difference between pulses if the pulse at time tn+1 is higher in amplitude value than the pulse at time tn then a single bit say a ldquo1rdquo is used to indicate the positive value

If the pulse is lower in value resulting in a negative value a ldquo0rdquo is used This scheme works well for small changes in signal values between samples If changes in amplitude are large this will result in large errors

Figure 11 the process of delta modulation

Figure 12 Delta modulation components

Figure 13 Delta demodulation components

Mtalb Code

Function for Delta Modulation (deltamodm)function s_DMout=deltamod(sig_inDeltatdts) usage s_DMout=deltamod(xsigDeltatdts) Delta-step size sig_in-input signal vector td-original signal sampling period of sig_in NOTE tdfs must be a positive integer S_DMout -DM sampled output ts-new sampling periodif (rem(tstd1)==0) nfac=round(tstd) p_zoh=ones(1nfac) s_down=downsample(sig_innfac) Num_it=length(s_down) s_DMout(1)=Delta2 for k=2Num_it xvar=s_DMout(k-1) s_DMout(k)=xvar+Deltasign(s_down(k-1)-xvar) end s_DMout=kron(s_DMoutp_zoh)else warning(Error tst is not an integer) s_DMout=[]endend

Delta Modulation togenerate DM signals with different step sizes Delta1=02Delta2=Delta1Delta3=Delta4clcclearclftd=0002 original sampling rate rate 500 hzt=[0td1] time interval of 1 secxsig=sin(2pit)-sin(6pit) 1hz +3 hz sinusoidalsLsig=length(xsig)ts=002 new sampling rate =50 hzNfact=tstd send the signal through a 16-level uniform quantiserDelta1=02s_DMout1=deltamod(xsigDelta1tdts) obtaind the DM signal plot the original signal and DM signal in time domain figrue(1)figure(1)subplot(311)sfig1=plot(txsigkts_DMout1(1Lsig)b)set(sfig1Linewidth2)title(Signal it g(it t) and its DM signal)xlabel(time(sec))axis([0 1 -22 22]) Apply DM again by doubling the DeltaDelta2=2Delta1s_DMout2=deltamod(xsigDelta2tdts)subplot(312)sfig2=plot(txsigkts_DMout2(1Lsig)b)set(sfig2Linewidth2)

title(Signal it g(it t) and DM signal with doubled stepsize)xlabel(time(sec))axis([0 1 -22 22])Delta3=2Delta2s_DMout3=deltamod(xsigDelta3tdts)subplot(313)sfig3=plot(txsigkts_DMout3(1Lsig)b)set(sfig3Linewidth2)title(Signal it g(it t) and DM signal with quadrupled stepsize)xlabel(time(sec))axis([0 1 -22 22])

Results

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal it g(it t) and its DM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal g( t) and DM signal with doubled stepsize

time(sec)

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal g( t) and DM signal with quadrupled stepsize

time(sec)

PRACTICAL NO 8OBJECT Implementation of pulse data coding techniques for various formats using matlabsimulink

THEORY Data Encoding MethodsWe can roughly divide line coding schemes into five broad categories as shown in figure 21

Figure 21 line coding scheme

Non-Return to Zero (NRZ)

Figure 22 NRZbull It is called NRZ because the signal does not return to zero at the middle of the bitbull NRZ is the simplest representation of digital signalsbull One bit of data is transmitted per clock cyclebull Bit values of 1and 0 are represented by high and low voltage signals respectively

NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert)

Figure 23 NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert) In NRZ-L the level of the voltage determines the value of the bit In NRZ-I the inversion or the lack of inversion determines the value of the bit

Polar RZ Return-to-Zero scheme

Polar biphase Manchester and differential Manchester schemes

In Manchester and differential Manchester encoding the transition at the middle of the bit is used for synchronization

The minimum bandwidth of Manchester and differential Manchester is 2 times that of NRZ

Bipolar Schemes sometimes called multilevel binary Three voltage levels positive negative and zero Two variations of bipolar encoding

o AMI (alternate mark inversion) 0 neutral zero voltage 1 alternating positive and negative voltages

o Pseudoternary 1 neutral zero voltage 0 alternating positive and negative voltages

bull AMI (alternate mark inversion)ndash The work mark comes from telegraphy and means 1ndash AMI means alternate 1 inversionndash The neutral zero voltage represents binary 0ndash Binary 1s are represented by alternating positive and negative voltages

bull Pesudotenary ndash Same as AMI but 1 bit is encoded as a zero voltage and the 0 bit is encoded as

alternating positive and negative voltages

Multilevel Schemesbull The desire to increase the data speed or decrease the required bandwidth has resulted in

the creation of many schemesbull The goal is to increase the number of bits per baud by encoding a pattern of m data

elements into a pattern of n signal elementsbull Different types of signal elements can be allowing different signal levelsbull If we have L different levels then we can produce Ln combinations of signal patternsbull The data element and signal element relation isbull mBnL coding where m is the length of the binary pattern B means binary data n is the

length of the signal pattern and L is the number of levels in the signalingbull B (binary L=2) T (tenary L=3) and Q (quaternary L=4) bull In mBnL schemes a pattern of m data elements is encoded as a pattern of n signal

elements in which 2m le Ln

2B1Q (two binary one quaternary)ndash m=2 n=1 and L=4ndash The signal rate (baud rate)

2B1Q is used in DSL (digital subscriber line) technology to provide a high-speed connection to the Internet by using subscriber telephone lines

8B6Tbull Eight binary six ternary (8B6T)

ndash This code is used with 100BASE-4T cablendash Encode a pattern of 8 bits as a pattern of 6 signal elements where the signal has

three levels (ternary)

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

title(Signal it g(it t) and DM signal with doubled stepsize)xlabel(time(sec))axis([0 1 -22 22])Delta3=2Delta2s_DMout3=deltamod(xsigDelta3tdts)subplot(313)sfig3=plot(txsigkts_DMout3(1Lsig)b)set(sfig3Linewidth2)title(Signal it g(it t) and DM signal with quadrupled stepsize)xlabel(time(sec))axis([0 1 -22 22])

Results

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal it g(it t) and its DM signal

time(sec)

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal g( t) and DM signal with doubled stepsize

time(sec)

0 01 02 03 04 05 06 07 08 09 1

-2

-1

0

1

2

Signal g( t) and DM signal with quadrupled stepsize

time(sec)

PRACTICAL NO 8OBJECT Implementation of pulse data coding techniques for various formats using matlabsimulink

THEORY Data Encoding MethodsWe can roughly divide line coding schemes into five broad categories as shown in figure 21

Figure 21 line coding scheme

Non-Return to Zero (NRZ)

Figure 22 NRZbull It is called NRZ because the signal does not return to zero at the middle of the bitbull NRZ is the simplest representation of digital signalsbull One bit of data is transmitted per clock cyclebull Bit values of 1and 0 are represented by high and low voltage signals respectively

NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert)

Figure 23 NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert) In NRZ-L the level of the voltage determines the value of the bit In NRZ-I the inversion or the lack of inversion determines the value of the bit

Polar RZ Return-to-Zero scheme

Polar biphase Manchester and differential Manchester schemes

In Manchester and differential Manchester encoding the transition at the middle of the bit is used for synchronization

The minimum bandwidth of Manchester and differential Manchester is 2 times that of NRZ

Bipolar Schemes sometimes called multilevel binary Three voltage levels positive negative and zero Two variations of bipolar encoding

o AMI (alternate mark inversion) 0 neutral zero voltage 1 alternating positive and negative voltages

o Pseudoternary 1 neutral zero voltage 0 alternating positive and negative voltages

bull AMI (alternate mark inversion)ndash The work mark comes from telegraphy and means 1ndash AMI means alternate 1 inversionndash The neutral zero voltage represents binary 0ndash Binary 1s are represented by alternating positive and negative voltages

bull Pesudotenary ndash Same as AMI but 1 bit is encoded as a zero voltage and the 0 bit is encoded as

alternating positive and negative voltages

Multilevel Schemesbull The desire to increase the data speed or decrease the required bandwidth has resulted in

the creation of many schemesbull The goal is to increase the number of bits per baud by encoding a pattern of m data

elements into a pattern of n signal elementsbull Different types of signal elements can be allowing different signal levelsbull If we have L different levels then we can produce Ln combinations of signal patternsbull The data element and signal element relation isbull mBnL coding where m is the length of the binary pattern B means binary data n is the

length of the signal pattern and L is the number of levels in the signalingbull B (binary L=2) T (tenary L=3) and Q (quaternary L=4) bull In mBnL schemes a pattern of m data elements is encoded as a pattern of n signal

elements in which 2m le Ln

2B1Q (two binary one quaternary)ndash m=2 n=1 and L=4ndash The signal rate (baud rate)

2B1Q is used in DSL (digital subscriber line) technology to provide a high-speed connection to the Internet by using subscriber telephone lines

8B6Tbull Eight binary six ternary (8B6T)

ndash This code is used with 100BASE-4T cablendash Encode a pattern of 8 bits as a pattern of 6 signal elements where the signal has

three levels (ternary)

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

PRACTICAL NO 8OBJECT Implementation of pulse data coding techniques for various formats using matlabsimulink

THEORY Data Encoding MethodsWe can roughly divide line coding schemes into five broad categories as shown in figure 21

Figure 21 line coding scheme

Non-Return to Zero (NRZ)

Figure 22 NRZbull It is called NRZ because the signal does not return to zero at the middle of the bitbull NRZ is the simplest representation of digital signalsbull One bit of data is transmitted per clock cyclebull Bit values of 1and 0 are represented by high and low voltage signals respectively

NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert)

Figure 23 NRZ-L (NRZ-Level) NRZ-I (NRZ-Invert) In NRZ-L the level of the voltage determines the value of the bit In NRZ-I the inversion or the lack of inversion determines the value of the bit

Polar RZ Return-to-Zero scheme

Polar biphase Manchester and differential Manchester schemes

In Manchester and differential Manchester encoding the transition at the middle of the bit is used for synchronization

The minimum bandwidth of Manchester and differential Manchester is 2 times that of NRZ

Bipolar Schemes sometimes called multilevel binary Three voltage levels positive negative and zero Two variations of bipolar encoding

o AMI (alternate mark inversion) 0 neutral zero voltage 1 alternating positive and negative voltages

o Pseudoternary 1 neutral zero voltage 0 alternating positive and negative voltages

bull AMI (alternate mark inversion)ndash The work mark comes from telegraphy and means 1ndash AMI means alternate 1 inversionndash The neutral zero voltage represents binary 0ndash Binary 1s are represented by alternating positive and negative voltages

bull Pesudotenary ndash Same as AMI but 1 bit is encoded as a zero voltage and the 0 bit is encoded as

alternating positive and negative voltages

Multilevel Schemesbull The desire to increase the data speed or decrease the required bandwidth has resulted in

the creation of many schemesbull The goal is to increase the number of bits per baud by encoding a pattern of m data

elements into a pattern of n signal elementsbull Different types of signal elements can be allowing different signal levelsbull If we have L different levels then we can produce Ln combinations of signal patternsbull The data element and signal element relation isbull mBnL coding where m is the length of the binary pattern B means binary data n is the

length of the signal pattern and L is the number of levels in the signalingbull B (binary L=2) T (tenary L=3) and Q (quaternary L=4) bull In mBnL schemes a pattern of m data elements is encoded as a pattern of n signal

elements in which 2m le Ln

2B1Q (two binary one quaternary)ndash m=2 n=1 and L=4ndash The signal rate (baud rate)

2B1Q is used in DSL (digital subscriber line) technology to provide a high-speed connection to the Internet by using subscriber telephone lines

8B6Tbull Eight binary six ternary (8B6T)

ndash This code is used with 100BASE-4T cablendash Encode a pattern of 8 bits as a pattern of 6 signal elements where the signal has

three levels (ternary)

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

Polar RZ Return-to-Zero scheme

Polar biphase Manchester and differential Manchester schemes

In Manchester and differential Manchester encoding the transition at the middle of the bit is used for synchronization

The minimum bandwidth of Manchester and differential Manchester is 2 times that of NRZ

Bipolar Schemes sometimes called multilevel binary Three voltage levels positive negative and zero Two variations of bipolar encoding

o AMI (alternate mark inversion) 0 neutral zero voltage 1 alternating positive and negative voltages

o Pseudoternary 1 neutral zero voltage 0 alternating positive and negative voltages

bull AMI (alternate mark inversion)ndash The work mark comes from telegraphy and means 1ndash AMI means alternate 1 inversionndash The neutral zero voltage represents binary 0ndash Binary 1s are represented by alternating positive and negative voltages

bull Pesudotenary ndash Same as AMI but 1 bit is encoded as a zero voltage and the 0 bit is encoded as

alternating positive and negative voltages

Multilevel Schemesbull The desire to increase the data speed or decrease the required bandwidth has resulted in

the creation of many schemesbull The goal is to increase the number of bits per baud by encoding a pattern of m data

elements into a pattern of n signal elementsbull Different types of signal elements can be allowing different signal levelsbull If we have L different levels then we can produce Ln combinations of signal patternsbull The data element and signal element relation isbull mBnL coding where m is the length of the binary pattern B means binary data n is the

length of the signal pattern and L is the number of levels in the signalingbull B (binary L=2) T (tenary L=3) and Q (quaternary L=4) bull In mBnL schemes a pattern of m data elements is encoded as a pattern of n signal

elements in which 2m le Ln

2B1Q (two binary one quaternary)ndash m=2 n=1 and L=4ndash The signal rate (baud rate)

2B1Q is used in DSL (digital subscriber line) technology to provide a high-speed connection to the Internet by using subscriber telephone lines

8B6Tbull Eight binary six ternary (8B6T)

ndash This code is used with 100BASE-4T cablendash Encode a pattern of 8 bits as a pattern of 6 signal elements where the signal has

three levels (ternary)

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

Multilevel Schemesbull The desire to increase the data speed or decrease the required bandwidth has resulted in

the creation of many schemesbull The goal is to increase the number of bits per baud by encoding a pattern of m data

elements into a pattern of n signal elementsbull Different types of signal elements can be allowing different signal levelsbull If we have L different levels then we can produce Ln combinations of signal patternsbull The data element and signal element relation isbull mBnL coding where m is the length of the binary pattern B means binary data n is the

length of the signal pattern and L is the number of levels in the signalingbull B (binary L=2) T (tenary L=3) and Q (quaternary L=4) bull In mBnL schemes a pattern of m data elements is encoded as a pattern of n signal

elements in which 2m le Ln

2B1Q (two binary one quaternary)ndash m=2 n=1 and L=4ndash The signal rate (baud rate)

2B1Q is used in DSL (digital subscriber line) technology to provide a high-speed connection to the Internet by using subscriber telephone lines

8B6Tbull Eight binary six ternary (8B6T)

ndash This code is used with 100BASE-4T cablendash Encode a pattern of 8 bits as a pattern of 6 signal elements where the signal has

three levels (ternary)

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

ndash 28=256 different data patterns and 36=478 different signal patterns (The mapping is shown in Appendix D)

ndash There are 478-256=222 redundant signal elements that provide synchronization and error detection

ndash Part of the redundancy is also used to provide DC (direct-current) balancebull + (positive signal) - (negative signal) and 0 (lack of signal) notationbull To make whole stream DC-balanced the sender keeps track of the weight

4D-PAM5 bull Four-dimensional five-level pulse amplitude modulation (4D-PAM5)

ndash 4D means that data is sent over four wires at the same timendash It uses five voltage levels such as -2 -1 0 1 and 2ndash The level 0 is used only for forward error detectionndash If we assume that the code is just one-dimensional the four levels create

something similar to 8B4Qndash The worst signal rate for this imaginary one-dimensional version is Nx48 or N2ndash 4D-PAM5 sends data over four channels (four wires) This means the signal rate

can be reduced to N8ndash All 8 bits can be fed into a wire simultaneously and sent by using one signal

elementndash Gigabit Ethernet use this technique to send 1-Gbps data over four copper cables

that can handle 1Gbps8 = 125Mbaudndash

Multiline Transmission MLT-3bull The multiline transmission three level (MLT-3)bull Three levels (+V 0 and ndashV) and three transition rules to move the levels

ndash If the next bit is 0 there is no transitionndash If the next bit is 1 and the current level is not 0 the next level is 0ndash If the next bit is 1 and the current level is 0 the next level is the opposite of the

last nonzero levelbull Why do we need to use MLT-3

ndash The signal rate for MLT-3 is one-fourth the bit rate (N4)

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

ndash This makes MLT-3 a suitable choice when we need to send 100 Mbps on a copper wire that cannot support more than 32 MHz (frequencies above this level create electromagnetic emission)

ndash

Summary of line coding schemes

Matlab codefunction [U P B M S]=nrz(a) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formatting UnipolarU=an= length(a)POLARP=afor k=1n if a(k)==0 P(k)=-1

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

endend Bipolar B=a f = -1 for k=1n if B(k)==1 if f==-1 B(k)=1 f=1 else B(k)=-1 f=-1 end end end Mark M(1)=1 for k=1n M(k+1)=xor(M(k) a(k)) end Space S(1)=1 for k=1n S(k+1)=not(xor(S(k) a(k))) endPlotting Waves subplot(5 1 1) stairs(U) axis([1 n+2 -2 2]) title(Unipolar NRZ) grid on subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ) grid on subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ) grid on subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark) grid on subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space) grid on

Inputa=[1 0 0 1 1]

a =

1 0 0 1 1[U P B M S]=nrz(a)

Output wavform

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

1 2 3 4 5 6 7-202

Unipolar NRZ

1 2 3 4 5 6 7-202

Polar NRZ

1 2 3 4 5 6 7-202

Bipolar NRZ

1 2 3 4 5 6 7-202

NRZ-Mark

1 2 3 4 5 6 7-202

NRZ-Space

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

RACTICAL NO 9OBJECT Implementation of Data decoding techniques for various formats using matlabsimulinkMatlab Codefunction [Ur Pr Br Mr Sr]=nrzRx(UPBMS) a is input data sequence U = Unipolar P=Polar B=Bipolar M=Mark and S=SpaceWave formattingUnipolarUr=Un= length(P)POLARPr=Pl=find(Prlt0)Pr(l)=0 Bipolarn= length(B) Br=B l=find(Brlt0)Br(l)=1 Mark n= length(M) for k=1n-1 Mr(k)=xor(M(k) M(k+1)) end Space n= length(S) S(1)=1 for k=1n-1 Sr(k)=not(xor(S(k) S(k+1))) endPlotting Waves n= length(Ur) subplot(5 1 1) stairs(Ur) axis([1 n+2 -2 2]) title(Unipolar NRZ Decoded) grid on n= length(P) subplot(5 1 2) stairs(P) axis([1 n+2 -2 2]) title(Polar NRZ Decoded) grid on n= length(Br) subplot(5 1 3) stairs(B) axis([1 n+2 -2 2]) title(Bipolar NRZ Decoded) grid on n= length(Mr) subplot(5 1 4) stairs(M) axis([1 n+2 -2 2]) title(NRZ-Mark Decoded) grid on n= length(Sr) subplot(5 1 5) stairs(S) axis([1 n+2 -2 2]) title(NRZ-Space Decoded) grid onend

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

InputU =

1 0 0 1 1

P =

1 -1 -1 1 1

B =

1 0 0 -1 1

M =

1 0 0 0 1 0

S =

1 1 0 1 1 1

Call [Ur Pr Br Mr Sr]=nrzRx(UPBMS)

Output Pr =

1 0 0 1 1

Ur =

1 0 0 1 1

Pr =

1 0 0 1 1

Br =

1 0 0 1 1

Mr =

1 0 0 1 1

Sr =

1 0 0 1 1

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

PRACTICAL NO 10OBJECT Implementation of amplitude shift keying modulator and demodulator using matlabsimulinkTHEORY ASK (amplitude shift keying) modulatorAmplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier waveThe amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal) keeping frequency and phase constant The level of amplitude can be used to represent binary logic 0s and 1s We can think of a carrier signal as an ON or OFF switch In the modulated signal logic 0 is represented by the absence of a carrier thus giving OFFON keying operation and hence the name given

ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal

For example a digital ldquo1rdquo could not affect the signal whereas a digital ldquo0rdquo would by making it zero

The line encoding will determine the values of the analog waveform to reflect the digital data being carried

Fig 41 Ask modulator

Fig 41 Ask signal

Matlab Code

program for amplitude shift keying clcclear allclose alls= [1 0 1 0]f1=20a=length (s)for i=1a f=f1s (1i) for t=(i-1)100+1i100x(t)=sin(2pift1000)endendplot(x)xlabel(time in secs)ylabel(amplitude in volts)title(ASK)grid on

Results

0 50 100 150 200 250 300 350 400-1

-08

-06

-04

-02

0

02

04

06

08

1

time in secs

am

plitu

de in v

olts

ASK

PRACTICAL NO 11

OBJECT Implementation of frequency shift keying modulator and demodulator using matlabsimulink

THEORYFSK (frequency shift keying) modulatorFrequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave The simplest FSK is binary FSK (BFSK) BFSK literally implies using a pair of discrete frequencies to transmit binary (0s and 1s) information

ApplicationsMost early telephone-line modems used audio frequency-shift keying to send and receive data up to rates of about 300 bits per second

Matlab CodeFSKclcclear allclose alls= [1 0 1 0]f1=10f2=50a=length (s)for i=1a if s(1i)==1 freq=f1s(1i) for t= (i-1)100+1i100 x(t)= sin(2pifreqt1000)endelseif s(1i)==0 b=(2s(1i))+1 freq=f2b for t=(i-1)100+1i100 x(t)= sin(2pifreqt1000) endendendplot(x)xlabel(title in secs)ylabel(amplitude in volts)title (FSK)grid on

Results

OBJECT Implementation of frequency shift keying modulator and demodulator using matlabsimulink

THEORYFSK (frequency shift keying) modulatorFrequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave The simplest FSK is binary FSK (BFSK) BFSK literally implies using a pair of discrete frequencies to transmit binary (0s and 1s) information

ApplicationsMost early telephone-line modems used audio frequency-shift keying to send and receive data up to rates of about 300 bits per second

Matlab CodeFSKclcclear allclose alls= [1 0 1 0]f1=10f2=50a=length (s)for i=1a if s(1i)==1 freq=f1s(1i) for t= (i-1)100+1i100 x(t)= sin(2pifreqt1000)endelseif s(1i)==0 b=(2s(1i))+1 freq=f2b for t=(i-1)100+1i100 x(t)= sin(2pifreqt1000) endendendplot(x)xlabel(title in secs)ylabel(amplitude in volts)title (FSK)grid on

Results

0 50 100 150 200 250 300 350 400-1

-08

-06

-04

-02

0

02

04

06

08

1

title in secs

am

plit

ude in v

olts

FSK

PRACTICAL NO 12OBJECT Implementation of phase shift keying modulator and demodulator using matlabsimulink

THEORY PSK (phase shift keying) modulator

Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing or modulating the phase of a reference signal (the carrier wave)

Any digital modulation scheme uses a finite number of distinct signals to represent digital data PSK uses a finite number of phases each assigned a unique pattern of binary digits Usually each phase encodes an equal number of bits Each pattern of bits forms the symbol that is represented by the particular phase The demodulator which is designed specifically for the symbol-set used by the modulator determines the phase of the received signal and maps it back to the symbol it represents thus recovering the original data This requires the receiver to be able to compare the phase of the received signal to a reference signal mdash such a system is termed coherent (and referred to as CPSK)

Alternatively instead of using the bit patterns to set the phase of the wave it can instead be used to change it by a specified amount The demodulator then determines the changes in the phase of the received signal rather than the phase itself Since this scheme depends on the difference between successive phases it is termed differential phase-shift keying (DPSK) DPSK can be significantly simpler to implement than ordinary PSK since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non-coherent scheme) In exchange it produces more erroneous demodulations The exact requirements of the particular scenario under consideration determine which scheme is used

Matlab CodeInitializing VariablesThe first step is to initialize variables for number of samples per symbol number of symbols to simulate alphabet size (M) and the signal to noise ratio The last line seeds the random number generators

nSamp = 8 numSymb = 100M = 4 SNR = 14seed = [12345 54321]rand(state seed(1)) randn(state seed(2))

Generating Random Information Symbols Next use RANDSRC to generate random information symbols from 0 to M-1 Since the simulation is of QPSK the symbols are 0 through 3 The first 10 data points are plotted

numPlot = 10rand(state seed(1))

PRACTICAL NO 12OBJECT Implementation of phase shift keying modulator and demodulator using matlabsimulink

THEORY PSK (phase shift keying) modulator

Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing or modulating the phase of a reference signal (the carrier wave)

Any digital modulation scheme uses a finite number of distinct signals to represent digital data PSK uses a finite number of phases each assigned a unique pattern of binary digits Usually each phase encodes an equal number of bits Each pattern of bits forms the symbol that is represented by the particular phase The demodulator which is designed specifically for the symbol-set used by the modulator determines the phase of the received signal and maps it back to the symbol it represents thus recovering the original data This requires the receiver to be able to compare the phase of the received signal to a reference signal mdash such a system is termed coherent (and referred to as CPSK)

Alternatively instead of using the bit patterns to set the phase of the wave it can instead be used to change it by a specified amount The demodulator then determines the changes in the phase of the received signal rather than the phase itself Since this scheme depends on the difference between successive phases it is termed differential phase-shift keying (DPSK) DPSK can be significantly simpler to implement than ordinary PSK since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non-coherent scheme) In exchange it produces more erroneous demodulations The exact requirements of the particular scenario under consideration determine which scheme is used

Matlab CodeInitializing VariablesThe first step is to initialize variables for number of samples per symbol number of symbols to simulate alphabet size (M) and the signal to noise ratio The last line seeds the random number generators

nSamp = 8 numSymb = 100M = 4 SNR = 14seed = [12345 54321]rand(state seed(1)) randn(state seed(2))

Generating Random Information Symbols Next use RANDSRC to generate random information symbols from 0 to M-1 Since the simulation is of QPSK the symbols are 0 through 3 The first 10 data points are plotted

numPlot = 10rand(state seed(1))

msg_orig = randsrc(numSymb 1 0M-1)stem(0numPlot-1 msg_orig(1numPlot) bx)xlabel(Time) ylabel(Amplitude)

Phase Modulating the Data

Use MODEMPSKMOD object to phase modulate the data and RECTPULSE to upsample to a sampling rate 8 times the carrier frequency Use SCATTERPLOT to see the signal constellation

grayencod = bitxor(0M-1 floor((0M-1)2))msg_gr_orig = grayencod(msg_orig+1)msg_tx = modulate(modempskmod(M) msg_gr_orig)msg_tx = rectpulse(msg_txnSamp)h1 = scatterplot(msg_tx)

Creating the Noisy SignalThen use AWGN to add noise to the transmitted signal to create the noisy signal at the receiver Use the measured option to add noise that is 14 dB below the average signal power (SNR = 14 dB) Plot the constellation of the received signal

randn(state seed(2))msg_rx = awgn(msg_tx SNR measured [] dB)h2 = scatterplot(msg_rx)

Recovering Information from the Transmitted SignalUse INTDUMP to downsample to the original information rate Then use MODEMPSKDEMOD object to demodulate the signal and detect the transmitted symbols The detected symbols are plotted in red stems with circles and the transmitted symbols are plotted in blue stems with xs The blue stems of the transmitted signal are shadowed by the red stems of the received signal Therefore comparing the blue xs with the red circles indicates that the received signal is identical to the transmitted signal

close(h1(ishandle(h1)) h2(ishandle(h2)))msg_rx_down = intdump(msg_rxnSamp)msg_gr_demod = demodulate(modempskdemod(M) msg_rx_down)[dummy graydecod] = sort(grayencod) graydecod = graydecod - 1msg_demod = graydecod(msg_gr_demod+1)stem(0numPlot-1 msg_orig(1numPlot) bx) hold onstem(0numPlot-1 msg_demod(1numPlot) ro) hold offaxis([ 0 numPlot -02 32]) xlabel(Time) ylabel(Amplitude)

PRACTICAL NO 13OBJECT Study of microwave components and instruments THEORYMicrowave Components

Connecting Devicesndash Waveguide

bull Rectangularbull Circular

ndash Microstrip linendash Strip line

Junctionsndash E planendash H planendash EH plane or magic tee (hybride line)ndash Hybride ring

Microwave Sourcendash Multicavity klystronndash Reflex klystronndash Magnetronndash Travelling Wave Tube (TWT)ndash Crossed Field Amplifier (CFA)ndash Backward oscillator

Semiconductor Sourcendash Gunn Diodendash IMPATT IMPATT TRAPATTndash Tunnel Diode

Microwave Amplifierndash Multicavity klystron ndash Travelling Wave Tube (TWT)ndash Gunn Diodendash Parametric Amplifier

Switches ndash PIN Diode

WaveguidesA waveguide is a structure which guides waves such as electromagnetic waves or sound waves There are different types of waveguide for each type of wave The original and most common meaning is a hollow conductive metal pipe used to carry high frequency radio waves particularly microwaves Waveguides differ in their geometry which can confine energy in one dimension such as in slab waveguides or two dimensions as in fiber or channel waveguides In addition different waveguides are needed to guide different frequencies an optical fiber guiding light (high frequency) will not guide microwaves (which have a much lower frequency) As a rule of thumb the width of a waveguide needs to be of the same order of magnitude as the wavelength of the guided wave

Principal of operationWaves in open space propagate in all directions as spherical waves In this way they lose their power proportionally to the square of the distance that is at a distance R from the source the power is the source power divided by R2 The waveguide confines the wave to propagation in one dimension so that (under ideal conditions) the wave loses no power while propagatingWaves are confined inside the waveguide due to total reflection from the waveguide wall so that the propagation inside the waveguide can be described approximately as a zigzag between the walls This description is exact for electromagnetic waves in a rectangular or circular hollow metal tube

Rectangular WaveguideIt consists of a rectangular hollow metallic conductor

randn(state seed(2))msg_rx = awgn(msg_tx SNR measured [] dB)h2 = scatterplot(msg_rx)

Recovering Information from the Transmitted SignalUse INTDUMP to downsample to the original information rate Then use MODEMPSKDEMOD object to demodulate the signal and detect the transmitted symbols The detected symbols are plotted in red stems with circles and the transmitted symbols are plotted in blue stems with xs The blue stems of the transmitted signal are shadowed by the red stems of the received signal Therefore comparing the blue xs with the red circles indicates that the received signal is identical to the transmitted signal

close(h1(ishandle(h1)) h2(ishandle(h2)))msg_rx_down = intdump(msg_rxnSamp)msg_gr_demod = demodulate(modempskdemod(M) msg_rx_down)[dummy graydecod] = sort(grayencod) graydecod = graydecod - 1msg_demod = graydecod(msg_gr_demod+1)stem(0numPlot-1 msg_orig(1numPlot) bx) hold onstem(0numPlot-1 msg_demod(1numPlot) ro) hold offaxis([ 0 numPlot -02 32]) xlabel(Time) ylabel(Amplitude)

PRACTICAL NO 13OBJECT Study of microwave components and instruments THEORYMicrowave Components

Connecting Devicesndash Waveguide

bull Rectangularbull Circular

ndash Microstrip linendash Strip line

Junctionsndash E planendash H planendash EH plane or magic tee (hybride line)ndash Hybride ring

Microwave Sourcendash Multicavity klystronndash Reflex klystronndash Magnetronndash Travelling Wave Tube (TWT)ndash Crossed Field Amplifier (CFA)ndash Backward oscillator

Semiconductor Sourcendash Gunn Diodendash IMPATT IMPATT TRAPATTndash Tunnel Diode

Microwave Amplifierndash Multicavity klystron ndash Travelling Wave Tube (TWT)ndash Gunn Diodendash Parametric Amplifier

Switches ndash PIN Diode

WaveguidesA waveguide is a structure which guides waves such as electromagnetic waves or sound waves There are different types of waveguide for each type of wave The original and most common meaning is a hollow conductive metal pipe used to carry high frequency radio waves particularly microwaves Waveguides differ in their geometry which can confine energy in one dimension such as in slab waveguides or two dimensions as in fiber or channel waveguides In addition different waveguides are needed to guide different frequencies an optical fiber guiding light (high frequency) will not guide microwaves (which have a much lower frequency) As a rule of thumb the width of a waveguide needs to be of the same order of magnitude as the wavelength of the guided wave

Principal of operationWaves in open space propagate in all directions as spherical waves In this way they lose their power proportionally to the square of the distance that is at a distance R from the source the power is the source power divided by R2 The waveguide confines the wave to propagation in one dimension so that (under ideal conditions) the wave loses no power while propagatingWaves are confined inside the waveguide due to total reflection from the waveguide wall so that the propagation inside the waveguide can be described approximately as a zigzag between the walls This description is exact for electromagnetic waves in a rectangular or circular hollow metal tube

Rectangular WaveguideIt consists of a rectangular hollow metallic conductor

PRACTICAL NO 13OBJECT Study of microwave components and instruments THEORYMicrowave Components

Connecting Devicesndash Waveguide

bull Rectangularbull Circular

ndash Microstrip linendash Strip line

Junctionsndash E planendash H planendash EH plane or magic tee (hybride line)ndash Hybride ring

Microwave Sourcendash Multicavity klystronndash Reflex klystronndash Magnetronndash Travelling Wave Tube (TWT)ndash Crossed Field Amplifier (CFA)ndash Backward oscillator

Semiconductor Sourcendash Gunn Diodendash IMPATT IMPATT TRAPATTndash Tunnel Diode

Microwave Amplifierndash Multicavity klystron ndash Travelling Wave Tube (TWT)ndash Gunn Diodendash Parametric Amplifier

Switches ndash PIN Diode

WaveguidesA waveguide is a structure which guides waves such as electromagnetic waves or sound waves There are different types of waveguide for each type of wave The original and most common meaning is a hollow conductive metal pipe used to carry high frequency radio waves particularly microwaves Waveguides differ in their geometry which can confine energy in one dimension such as in slab waveguides or two dimensions as in fiber or channel waveguides In addition different waveguides are needed to guide different frequencies an optical fiber guiding light (high frequency) will not guide microwaves (which have a much lower frequency) As a rule of thumb the width of a waveguide needs to be of the same order of magnitude as the wavelength of the guided wave

Principal of operationWaves in open space propagate in all directions as spherical waves In this way they lose their power proportionally to the square of the distance that is at a distance R from the source the power is the source power divided by R2 The waveguide confines the wave to propagation in one dimension so that (under ideal conditions) the wave loses no power while propagatingWaves are confined inside the waveguide due to total reflection from the waveguide wall so that the propagation inside the waveguide can be described approximately as a zigzag between the walls This description is exact for electromagnetic waves in a rectangular or circular hollow metal tube

Rectangular WaveguideIt consists of a rectangular hollow metallic conductor

The electromagnetic waves in (metal-pipe) waveguide may be imagined as travelling down the guide in a zig-zag path being repeatedly reflected between opposite walls of the guide

Need to find the fields components of the em wave inside the waveguide

ndash Ez Hz Ex Hx Ey Hy Wersquoll find that waveguides donrsquot support TEM waves

Modes of propagation TEM (Ez=Hz=0) canrsquot propagate TE (Ez=0) transverse electric

ndash In TE mode the electric lines of flux are perpendicular to the axis of the waveguide

ndash TM (Hz=0) transverse magnetic Ez existsndash In TM mode the magnetic lines of flux are perpendicular to the axis of the

waveguidendash HE hybrid modes in which all components exists

The cutoff frequency occurs when

Dominant mode- T10

Circular waveguideIt consists of a circular hollow metallic conductorFor same cutoff frequency the cylindrical waveguide longer then rectangular waveguide in cross-sectional area so it is more bulkyDominant mode- T11

Microstrip LineMicrostrip is a type of electrical transmission line which can be fabricated using printed circuit board [PCB] technology and is used to convey microwave-frequency signals It consists of a conducting strip separated from a ground plane by a dielectric layer known as the substrate Microwave components such as antennas couplers filters power dividers etc can be formed from microstrip the entire device existing as the pattern of metallization on the substrate Microstrip is thus much less expensive than traditional waveguide technology as well as being far lighter and more compact

Cross-section of microstrip geometry Conductor (A) is separated from ground

plane (D) by dielectric substrate (C) Upper dielectric (B) is typically air

The disadvantages of microstrip compared with waveguide are the generally lower power handling capacity and higher losses Also unlike waveguide microstrip is not enclosed and is therefore susceptible to cross-talk and unintentional radiationIt is behave as a parallel wire

Strip lineA stripline circuit uses a flat strip of metal which is sandwiched between two parallel ground planes The insulating material of the substrate forms a dielectric The width of the strip the thickness of the substrate and the relative permittivity of the substrate determine the characteristic impedance of the strip which is a transmission line As shown in the diagram the central conductor need not be equally spaced between the ground planes In the general case the dielectric material may be different above and below the central conductorTo prevent the propagation of unwanted modes the two ground planes must be shorted together This is commonly achieved by a row of vias running parallel to the strip on each sideLike coaxial cable strip line is non-dispersive and has no cut off frequency Good isolation between adjacent traces can be achieved more easily than with microstrip

Cross-section diagram of strip line geometry Central conductor (A) is sandwiched between ground planes (B and D) Structure is supported by dielectric (C)

Waveguide Junction

E-type waveguide junction

It is called an E-type T junction because the junction arm ie the top of the T extends from the main waveguide in the same direction as the E field It is characterized by the fact that the outputs of this form of waveguide junction are 180deg out of phase with each other

Waveguide E-type junctionThe basic construction of the waveguide junction shows the three port waveguide device Although it may be assumed that the input is the single port and the two outputs are those on the top section of the T actually any port can be used as the input the other two being outputs

To see how the waveguide junction operates and how the 180deg phase shift occurs it is necessary to look at the electric field The magnetic field is omitted from the diagram for simplicity

Waveguide E-type junction E fieldsIt can be seen from the electric field that when it approaches the T junction itself the electric field lines become distorted and bend They split so that the positive end of the line remains with the top side of the right hand section in the diagram but the negative end of the field lines remain with the top side of the left hand section In this way the signals appearing at either section of the T are out of phaseThese phase relationships are preserved if signals enter from either of the other ports

H-type waveguide junctionThis type of waveguide junction is called an H-type T junction because the long axis of the main top of the T arm is parallel to the plane of the magnetic lines of force in the waveguide It is characterized by the fact that the two outputs from the top of the T section in the waveguide are in phase with each other

Waveguide H-type junctionTo see how the waveguide junction operates the diagram below shows the electric field lines Like the previous diagram only the electric field lines are shown The electric field lines are shown using the traditional notation - a cross indicates a line coming out of the screen whereas a dot indicates an electric field line going into the screen

Waveguide H-type junction electric fieldsIt can be seen from the diagram that the signals at all ports are in phase Although it is easiest to consider signals entering from the lower section of the T any port can actually be used - the phase relationships are preserved whatever entry port is ised

Magic T hybrid waveguide junction

The magic-T is a combination of the H-type and E-type T junctions The most common application of this type of junction is as the mixer section for microwave radar receivers

Magic T waveguide junctionThe diagram above depicts a simplified version of the Magic T waveguide junction with its four portsTo look at the operation of the Magic T waveguide junction take the example of whan a signal is applied into the E plane arm It will divide into two out of phase components as it passes into the leg consisting of the a and b arms However no signal will enter the E plane arm as a result of the fact that a zero potential exists there - this occurs because of the conditions needed to create the signals in the a and b arms In this way when a signal is applied to the H plane arm no signal appears at the E plane arm and the two signals appearing at the a and b arms are 180deg out of phase with each other

Magic T waveguide junction signal directionsWhen a signal enters the a or b arm of the magic t waveguide junction then a signal appears at the E and H plane ports but not at the other b or a arm as shownOne of the disadvantages of the Magic-T waveguide junction are that reflections arise from the impedance mismatches that naturally occur within it These reflections not only give rise to power loss but at the voltage peak points they can give rise to arcing when sued with high power transmitters The reflections can be reduced by using matching techniques Normally posts or screws are used within the E-plane and H-plane ports While these solutions improve the impedance matches and hence the reflections they still reduce the power handling capacity

Hybrid ring waveguide junction

This form of waveguide junction overcomes the power limitation of the magic-T waveguide junctionA hybrid ring waveguide junction is a further development of the magic T It is constructed from a circular ring of rectangular waveguide - a bit like an annulus The ports are then joined to the annulus at the required points Again if signal enters one port it does not appear at allt he others

The hybrid ring is used primarily in high-power radar and communications systems where it acts as a duplexer - allowing the same antenna to be used for transmit and receive functionsDuring the transmit period the hybrid ring waveguide junction couples microwave energy from the transmitter to the antenna while blocking energy from the receiver input Then as the receive cycle starts the hybrid ring waveguide junction couples energy from the antenna to the receiver During this period it prevents energy from reaching the transmitter

Multicavity klystronGain of about 10-20 dB are typical with two cavity tubes A higher overall gain can be achieved by connecting several two cavity tubes in cascade feeding the output of each of the tubes to the input of the succeeding one With four cavities power gains of around 50 dB cab be easily achieved The cavities are tuned the same frequency

Reflex klystron

In the reflex klystron (also known as a Sutton klystron after its inventor) the electron beam passes through a single resonant cavity The electrons are fired into one end of the tube by an electron gun After passing through the resonant cavity they are reflected by a negatively charged reflector electrode for another pass through the cavity where they are then collected The electron beam is velocity modulated when it first passes through the cavity The formation of electron bunches takes place in the drift space between the reflector and the cavity Thevoltage on the reflector must be adjusted so that the bunching is at a maximum as the electron beam re-enters the resonant cavity thus ensuring a maximum of energy is transferred from the electron beam to the RFoscillations in the cavity The voltage should always be switched on before providing the input to the reflex klystron as the whole function of the reflex klystron would be destroyed if the supply is provided after the input The reflector voltage may be varied slightly from the optimum value which results in some loss of output power but also in a variation in frequency This effect is used to good advantage for automatic frequency control in receivers and in frequency modulation for transmitters The level of modulation applied for transmission is small enough that the power output essentially remains constant At regions far from the optimum voltage no oscillations are obtained at all This tube is called a reflex klystron because it repels the input supply or performs the opposite function of a klystron

Magnetron

Magic T hybrid waveguide junction

The magic-T is a combination of the H-type and E-type T junctions The most common application of this type of junction is as the mixer section for microwave radar receivers

Magic T waveguide junctionThe diagram above depicts a simplified version of the Magic T waveguide junction with its four portsTo look at the operation of the Magic T waveguide junction take the example of whan a signal is applied into the E plane arm It will divide into two out of phase components as it passes into the leg consisting of the a and b arms However no signal will enter the E plane arm as a result of the fact that a zero potential exists there - this occurs because of the conditions needed to create the signals in the a and b arms In this way when a signal is applied to the H plane arm no signal appears at the E plane arm and the two signals appearing at the a and b arms are 180deg out of phase with each other

Magic T waveguide junction signal directionsWhen a signal enters the a or b arm of the magic t waveguide junction then a signal appears at the E and H plane ports but not at the other b or a arm as shownOne of the disadvantages of the Magic-T waveguide junction are that reflections arise from the impedance mismatches that naturally occur within it These reflections not only give rise to power loss but at the voltage peak points they can give rise to arcing when sued with high power transmitters The reflections can be reduced by using matching techniques Normally posts or screws are used within the E-plane and H-plane ports While these solutions improve the impedance matches and hence the reflections they still reduce the power handling capacity

Hybrid ring waveguide junction

This form of waveguide junction overcomes the power limitation of the magic-T waveguide junctionA hybrid ring waveguide junction is a further development of the magic T It is constructed from a circular ring of rectangular waveguide - a bit like an annulus The ports are then joined to the annulus at the required points Again if signal enters one port it does not appear at allt he others

The hybrid ring is used primarily in high-power radar and communications systems where it acts as a duplexer - allowing the same antenna to be used for transmit and receive functionsDuring the transmit period the hybrid ring waveguide junction couples microwave energy from the transmitter to the antenna while blocking energy from the receiver input Then as the receive cycle starts the hybrid ring waveguide junction couples energy from the antenna to the receiver During this period it prevents energy from reaching the transmitter

Multicavity klystronGain of about 10-20 dB are typical with two cavity tubes A higher overall gain can be achieved by connecting several two cavity tubes in cascade feeding the output of each of the tubes to the input of the succeeding one With four cavities power gains of around 50 dB cab be easily achieved The cavities are tuned the same frequency

Reflex klystron

In the reflex klystron (also known as a Sutton klystron after its inventor) the electron beam passes through a single resonant cavity The electrons are fired into one end of the tube by an electron gun After passing through the resonant cavity they are reflected by a negatively charged reflector electrode for another pass through the cavity where they are then collected The electron beam is velocity modulated when it first passes through the cavity The formation of electron bunches takes place in the drift space between the reflector and the cavity Thevoltage on the reflector must be adjusted so that the bunching is at a maximum as the electron beam re-enters the resonant cavity thus ensuring a maximum of energy is transferred from the electron beam to the RFoscillations in the cavity The voltage should always be switched on before providing the input to the reflex klystron as the whole function of the reflex klystron would be destroyed if the supply is provided after the input The reflector voltage may be varied slightly from the optimum value which results in some loss of output power but also in a variation in frequency This effect is used to good advantage for automatic frequency control in receivers and in frequency modulation for transmitters The level of modulation applied for transmission is small enough that the power output essentially remains constant At regions far from the optimum voltage no oscillations are obtained at all This tube is called a reflex klystron because it repels the input supply or performs the opposite function of a klystron

Magnetron

The hybrid ring is used primarily in high-power radar and communications systems where it acts as a duplexer - allowing the same antenna to be used for transmit and receive functionsDuring the transmit period the hybrid ring waveguide junction couples microwave energy from the transmitter to the antenna while blocking energy from the receiver input Then as the receive cycle starts the hybrid ring waveguide junction couples energy from the antenna to the receiver During this period it prevents energy from reaching the transmitter

Multicavity klystronGain of about 10-20 dB are typical with two cavity tubes A higher overall gain can be achieved by connecting several two cavity tubes in cascade feeding the output of each of the tubes to the input of the succeeding one With four cavities power gains of around 50 dB cab be easily achieved The cavities are tuned the same frequency

Reflex klystron

In the reflex klystron (also known as a Sutton klystron after its inventor) the electron beam passes through a single resonant cavity The electrons are fired into one end of the tube by an electron gun After passing through the resonant cavity they are reflected by a negatively charged reflector electrode for another pass through the cavity where they are then collected The electron beam is velocity modulated when it first passes through the cavity The formation of electron bunches takes place in the drift space between the reflector and the cavity Thevoltage on the reflector must be adjusted so that the bunching is at a maximum as the electron beam re-enters the resonant cavity thus ensuring a maximum of energy is transferred from the electron beam to the RFoscillations in the cavity The voltage should always be switched on before providing the input to the reflex klystron as the whole function of the reflex klystron would be destroyed if the supply is provided after the input The reflector voltage may be varied slightly from the optimum value which results in some loss of output power but also in a variation in frequency This effect is used to good advantage for automatic frequency control in receivers and in frequency modulation for transmitters The level of modulation applied for transmission is small enough that the power output essentially remains constant At regions far from the optimum voltage no oscillations are obtained at all This tube is called a reflex klystron because it repels the input supply or performs the opposite function of a klystron

Magnetron

A cross-sectional diagram of a resonant cavity magnetron Magnetic lines of force are parallel to the geometric axis of this structure

All cavity magnetrons consist of a hot cathode with a high (continuous or pulsed) negative potential by a high-voltage direct-current power supply The cathode is built into the center of an evacuated lobed circular chamber A magnetic field parallel to the filament is imposed by a permanent magnet The magnetic field causes the electrons attracted to the (relatively) positive outer part of the chamber to spiral outward in a circular path rather than moving directly to this a node Spaced around the rim of the chamber are cylindrical cavities The cavities are open along their length and connect the common cavity space As electrons sweep past these openings they induce a resonant high-frequency radio field in the cavity which in turn causes the electrons to bunch into groups A portion of this field is extracted with a short antenna that is connected to a waveguide (a metal tube usually of rectangular cross section) The waveguide directs the extracted RF energy to the load which may be a cooking chamber in a microwave oven or a high-gain antenna in the case of radar

Travelling Wave Tube (TWT)A traveling-wave tube (TWT) is an electronic device used to amplify radio frequency signals to high power usually in an electronic assembly known as a traveling-wave tube amplifier (TWTA)

Cutaway view of a TWT (1) Electron gun (2) RF input (3) Magnets (4) Attenuator (5) Helix coil (6) RF output (7) Vacuum tube (8) Collector

Crossed Field Amplifier (CFA)A crossed-field amplifier (CFA) is a specialized vacuum tube first introduced in the mid-1950s and frequently used as a microwave amplifier in very-high-power transmitters A CFA has lower gain and bandwidth than other microwave amplifier tubes (such as klystrons or traveling-wave tubes) but it is more efficient and capable of much higher output power Peak output powers of many megawatts and average power levels of tens of kilowatts can be achieved with efficiency ratings in excess of 70 percent

Backward oscillator A backward wave oscillator (BWO) also called carcinotron (a trade name for tubes manufactured by CSF now Thales) or backward wave tube is a vacuum tubethat is used to generate microwaves up to the terahertz range It belongs to the traveling-wave tube family It is an oscillator with a wide electronic tuning rangeAn electron gun generates an electron beam that is interacting with a slow-wave structure It sustains the oscillations by propagating a traveling wave backwards against the beam The generated electromagnetic wave power has its group velocity directed oppositely to the direction of motion of the electrons The output power is coupled out near the electron gun

It has two main subtypes the M-type the most powerful (M-BWO) and the O-type (O-BWO) The O-type delivers typically power in the range of 1 mW at 1000 GHz to 50 mW at 200 GHz Carcinotrons are used as powerful and stable microwave sources Due to the good quality wavefront they produce they find use as illuminators in terahertz imaging

Gunn DiodeA Gunn diode also known as a transferred electron device (TED) is a form of diode used in high-frequency electronics It is somewhat unusual in that it consists only of N-doped semiconductor material whereas most diodes consist of both P and N-doped regions In the Gunn diode three regions exist two of them are heavily N-doped on each terminal with a thin layer of lightly doped material in between When a voltage is applied to the device the electrical gradient will be largest across the thin middle layer Conduction will take place as in any conductive material with current being proportional to the applied voltage Eventually at higher field values the conductive properties of the middle layer will be altered increasing its resistivity and reducing the gradient across it preventing further conduction and current actually starts to fall down In practice this means a Gunn diode has a region of negative differential resistance The negative differential resistance combined with the timing properties of the intermediate layer allows construction of an RF relaxation oscillator simply by applying a suitable direct current through the device In effect the negative differential resistance created by the diode will negate the real and positive resistance of an actual load and thus create a zero resistance circuit which will sustain oscillations indefinitely The oscillation frequency is determined partly by the properties of the thin middle layer but can be tuned by external factors

IMPATT Diode An IMPATT diode (IMPact ionization Avalanche Transit-Time) is a form of high power diode used in high-frequency electronics and microwave devices They are typically made with silicon carbide owing to their high breakdown fieldsThey operate at frequencies between about 3 and 100 GHz or more A main advantage is their high power capability These diodes are used in a variety of applications from low power radar systems to alarms A major drawback of using IMPATT diodes is the high level of phase noise they generate This results from the statistical nature of the avalanche process Nevertheless these diodes make excellent microwave generators for many applications

Tunnel DiodeA tunnel diode or Esaki diode is a type of semiconductor diode which is capable of very fast operation well into the microwave frequency region by using quantum mechanical effectsIt was invented in August 1957 by Leo Esaki when he was with Tokyo Tsushin Kogyo now known as Sony In 1973 he received the Nobel Prize in Physics jointly with Brian Josephson for discovering the electron tunneling effect used in these diodes Robert Noyce independently came up with the idea of a tunnel diode while working for William Shockley but was discouraged from pursuing it

These diodes have a heavily doped pndashn junction only some 10 nm (100 Aring) wide The heavy doping results in a broken bandgap where conduction band electron states on the n-side are more or less aligned with valence band hole states on the p-sideTunnel diodes were manufactured by Sony for the first time in 1957 followed by General Electric and other companies from about 1960 and are still made in low volume today Tunnel diodes are usually made from germanium but can also be made in gallium arsenide and silicon materials They can be used as oscillators amplifiers frequency

PIN Diode

A PIN diode is a diode with a wide lightly doped near intrinsic semiconductor region between a p-type semiconductor and an n-type semiconductor region The p-type and n-type regions are typically heavily doped because they are used for ohmic contactsThe wide intrinsic region is in contrast to an ordinary PN diode The wide intrinsic region makes the PIN diode an inferior rectifier (the normal function of a diode) but it makes the PIN diode suitable for attenuators fast switches photodetectors and high voltage power electronics applications

Microwave instrumentsPower DividersCombiners IsolatorsCirculators Attenuators Couplers Terminations Power Amplifiers Hybrids Oscillators Switches Power DividersCombiners

Strip line Power Dividers and Combiners Lumped Element Power Dividers and Combiners

Strip line Power Dividers and Combiners

2-Way Power Divider and Combiner (SMA) (PS2 Series)2-Way Power Divider and Combiner (Type-N) (PS2-NF Series)

3-Way Power Divider and Combiner (SMA) (PS3 Series)3-Way Power Divider and Combiner (Type-N) (PS3-NF Series)

4 Way Power Divider and Combiner (SMA) (PS4 Series)

4-Way Power Divider and Combiner (Type-N) (PS4-NF Series)

5-Way Power Divider and Combiner (PS5 Series) 6-Way Power Divider and Combiner (PS6 Series)

8-Way Power Divider and Combiner (SMA) (PS8 Series)8-Way Power Divider and Combiner (Type-N) (PS8-NF Series)

91112-Way Power Divider and Combiner (PS9 PS11 and PS12 Series)

10-Way Power Divider and Combiner (PS10 Series)

16-Way Power Divider and Combiner (PS16 Series) 32-Way Power Divider and Combiner (PS32 Series)

Lumped Element Power Dividers and Combiners

2-Way Lumped Element Power Divider and Combiner (PL2 Series)

3-Way Lumped Element Power Divider and Combiner (PL3 Series)

4-Way Lumped Element Power Divider and Combiner (PL4 Series)

56-Way Lumped Element Power Divider and Combiner (PL5 and PL6 Series)

8-Way Lumped Element Power Divider and Combiner (PL8 and PM8 Series)

10111216-Way Lumped Element Power Divider and Combiner (PL10 PL11 PL12 and PL16 Series)

Connectorized-Broadband - 2-port Isolator and 3-port Circulator

Connectorized-Broadband Double Junction Isolator and Circulator

Connectorized-Narrow Band Isolators and Circulators

Attenuators

Drop-In Isolator and Circulator (DI Series)

Continuously Variable Attenuator Fixed Coaxial Attenuator

Pin-Diode Attenuator (Linearized Voltage Controlled) Power Coaxial Attenuators

Directional Couplers

Directional Coupler Broadband Model SMA (CB Series) Directional Coupler Octave Model-NF (C-NF

Series)

Directional Coupler Octave Model-SMA (C Series) Dual Directional Coupler - Stripline (DC Series)

High Power Directional Coupler (HC Series) High Power Dual Directional Coupler (HD Series)

High Power Dual Directional Coupler (HDL-Series) Lumped Element Directional Coupler (CL Series)

Terminations

Coaxial TerminationsPower Coaxial Terminations

Amplifiers

Amplifiers

Hybrids

180 Degree- 4 Port Hybrid - Lumped Element 180 Degree Hybrid Coupler - SMA

90 Degree Hybrid - 10 Bandwidth - Lumped Element 90 Degree Hybrid - Stripline

Oscillators

Dielectric Resonator Oscillator (PLDR Series) Free Run Dielectric Resonator Oscillator

Pin Diode Switches

SP1T Octave and Broadband Pin Diode Switches SP2T Octave and Broadband Pin Diode Switches

SP3T Octave and Broadband Pin Diode Switches SP4T Octave and Broadband Pin Diode Switches

SP5T Octave and Broadband Pin Diode Switches SP6T Octave and Broadband Pin Diode Switches

Connectors and Adapters

Connectors (MC Series) Adapters (ADS- ADN-ADT-ADB-ADX-ADZ-ADC- and ADD Series)

Directional Detectors

Directional Detectors (DD Series)

Filters

Combline Bandpass Filter Interdigital Bandpass Filter

PRACTICAL NO 14OBJECT Measurement of klystron characteristics and Measurement of VSWR THEORYMeasurement of klystron characteristicsKlystronA Klystron is a vacuum tube that can be used either as a generator or as an amplifier of power at microwave frequencies

Two Cavity Klystron

Two Cavity Klystron Amplifier A two cavity klystron amplifier is basically a velocity modulated tube The electron beam accelerated by a positive potential is constrained to travel through a cylindrical drift tube in a straight path While passing through the first cavity the electron beam is velocity modulated by the weak RF signal In the moving frame of the electron beam the velocity modulation is equivalent to a plasma oscillation Plasma oscillations are rapid oscillations of the electron density in conducting media such as plasmas or metals So in a quarter of one period of the plasma frequency the velocity modulation is converted to density modulation ie bunches of electrons As the bunched electrons enter the second chamber they induce standing waves at the same frequency as the input signal The signal induced in the second chamber is much stronger than that in the firstPerformance Characteristics

ndash Frequency250Mhz to 100GHzndash Power 10kw-500kw (CW) 30 MW (Pulsed)ndash Power gain 15 dB to 70 dB (60 dB nominal )ndash Bandwidth 10 ndash 60 MHz-generally used in fixed frequency applicationsndash Noise Figure 15-20dBndash Theoretical efficiency 58 (30-40 )

Multicavity KlystronGain of about 10-20 dB are typical with two cavity tubes A higher overall gain can be achieved by connecting several two cavity tubes in cascade feeding the output of each of the tubes to the input of the succeeding one With four cavities power gains of around 50 dB cab be easily achieved The cavities are tuned the same frequency

Two Cavity Klystron Oscillator

A klystron amplifier can be converted into an oscillator be feeding back a part of the catcher output in to the buncher in proper phase

Measurement of VSWR (voltage standing wave ratio)In telecommunications standing wave ratio (SWR) is the ratio of the amplitude of a partial standing wave at an antinode (maximum) to the amplitude at an adjacentnode (minimum) in an electrical transmission lineThe SWR is usually defined as a voltage ratio called the VSWR for voltage standing wave ratio For example the VSWR value 121 denotes a maximum standing wave amplitude that is 12 times greater than the minimum standing wave value It is also possible to define the SWR in terms of current resulting in the ISWR which has the same numerical value The power standing wave ratio (PSWR) is defined as the square of the VSWRSWR is used as a efficiency measure for transmission lines electrical cables that conduct radio frequency signals used for purposes such as connecting radio transmitters and receivers with their antennas and distributing cable television signals A problem with transmission lines is that impedance mismatches in the cable tend to reflect the radio waves back toward the source end of the cable preventing all the power from reaching the destination end SWR measures the relative size of these reflections An ideal transmission line would have an SWR of 11 with all the power reaching the destination and no reflected power An infinite SWR represents complete reflection with all the power reflected back down the cable SWR meters are available which can measure the SWR of a transmission line and checking the SWR is a standard part of installing and maintaining transmission lines

The voltage component of a standing wave in a uniform transmission line consists of the forward wave (with amplitude Vf) superimposed on the reflected wave (with amplitude Vr)Reflections occur as a result of discontinuities such as an imperfection in an otherwise uniform transmission line or when a transmission line is terminated with other than its characteristic impedance The reflection coefficient Γ is defined thus

Γ is a complex number that describes both the magnitude and the phase shift of the reflection The simplest cases when the imaginary part of Γ is zero are Γ = minus 1 maximum negative reflection when the line is short-circuited Γ = 0 no reflection when the line is perfectly matched Γ = + 1 maximum positive reflection when the line is open-circuitedFor the calculation of VSWR only the magnitude of Γ denoted by ρ is of interest Therefore we define

ρ = | Γ | At some points along the line the two waves interfere constructively and the resulting amplitude Vmax is the sum of their amplitudes

At other points the waves interfere destructively and the resulting amplitude Vmin is the difference between their amplitudes

The voltage standing wave ratio is then equal to

As ρ the magnitude of Γ always falls in the range [01] the VSWR is always ge +1The SWR can also be defined as the ratio of the maximum amplitude of the electric field strength to its minimum amplitude ie Emax Emin

PRACTICAL NO 15OBJECT Measurement of Directivity and coupling coefficient of a directional couplerTHEORYDirectional couplerOne specific class of power divider is the directional coupler This is a four port device that samples the power flowing into port 1 coupled in to port 3 (the coupled port) with the remainder of the power delivered to port 2 (the through port) and no power delivered to the isolated port

Usually the isolated port is terminated within the coupler casing In such case the coupler appears to be a three port device In ideal case no power is delivered to port 4 (the isolated port)Directional couplers are described by three specifications

bull Coupling (C) - The ratio of input power to the couple powerbull Directivity (D)- The ratio of coupled power to the power at the isolated portbull Isolation (I) ndash The ratio of input power to power out of the isolated port

Ideally Directivity should be infinite but is mostly between 30-35 dBIf all ports matched (S11=S22=S33= S44=0) symmetry and S14=S23=0 to be satisfied The equations reduce to 6 equations

By comparing these equations yield

By comparing these equations yield

Results

SN P1 P2 P3 P4 C D I

PRACTICAL NO 10OBJECT To determination of the phase-shift of a phase shifter

THEORY

Phase shifterA phase shifter is a microwave network which provides a controllable phase shift of the RF signal Phase shifters are used in phased arraysPhase shifters are devices in which the phase of an electromagnetic wave of a given frequency propagating through a transmission line can be shifted A phase shift circuit is designed to shift the phase of an input signal on the basis of the phase shift characteristics of the circuit and output the resultant signal

A microwave (6 to 18 GHz) Phase Shifter and Frequency Translator

The theory of operation is to divide the input signal into two equal signals 90 degrees apart I (in-phase) and Q (Quadrature) This allows the magnitude of each signal to be re-located along its vectors axis The two signals are then combined Using The Pythagorean Theorem the sum of the vectors produces the resultant output signal

Digital phase shifterThe circuit for this digital phase shifter consists of a 3 dB 90 degree Quadrature Hybrid two Variable Attenuators capable of a 180 degree phase shift an In-Phase Power Combiner and drive circuits to control the variable attenuators The key component is a 3 dB 90 degree Quadrature Hybrid The hybrid is used nine times The input signal is processed by the first hybrid It equally divides the amplitude with a 90 degree phase shift to the Quadrature path and the two signals are isolated This places the I amp Q Vectors on their respective axis The balances of the hybrids are divided in the I amp Q channels for the Variable Attenuators Each attenuator controls the magnitude with 180 phase shift allowing four quadrant operations The final stage is the In-Phase Power Combiner which combines the signals in vector addition to the output In the RF design of a digital phase shifter the preferred media is microstrip Traditional hybrids are designed in stripline Whether incorporating the hybrid as part of the circuit or as a discrete component like hybrids for microstrip configurations the result is the microwave fields of propagation are excited This creates a discontinuity within the transmission line of the device Techniques can be employed to minimize the discontinuity but with nine 4 port hybrids this event occurs directly or in-directly 36 times To this end changing media alters fringing fields thus creating adverse effects and degrading performance

Phase shifterA phase shifter is a microwave network which provides a controllable phase shift of the RF signal Phase shifters are used in phased arraysPhase shifters are devices in which the phase of an electromagnetic wave of a given frequency propagating through a transmission line can be shifted A phase shift circuit is designed to shift the phase of an input signal on the basis of the phase shift characteristics of the circuit and output the resultant signal

A microwave (6 to 18 GHz) Phase Shifter and Frequency Translator

The theory of operation is to divide the input signal into two equal signals 90 degrees apart I (in-phase) and Q (Quadrature) This allows the magnitude of each signal to be re-located along its vectors axis The two signals are then combined Using The Pythagorean Theorem the sum of the vectors produces the resultant output signal

Digital phase shifterThe circuit for this digital phase shifter consists of a 3 dB 90 degree Quadrature Hybrid two Variable Attenuators capable of a 180 degree phase shift an In-Phase Power Combiner and drive circuits to control the variable attenuators The key component is a 3 dB 90 degree Quadrature Hybrid The hybrid is used nine times The input signal is processed by the first hybrid It equally divides the amplitude with a 90 degree phase shift to the Quadrature path and the two signals are isolated This places the I amp Q Vectors on their respective axis The balances of the hybrids are divided in the I amp Q channels for the Variable Attenuators Each attenuator controls the magnitude with 180 phase shift allowing four quadrant operations The final stage is the In-Phase Power Combiner which combines the signals in vector addition to the output In the RF design of a digital phase shifter the preferred media is microstrip Traditional hybrids are designed in stripline Whether incorporating the hybrid as part of the circuit or as a discrete component like hybrids for microstrip configurations the result is the microwave fields of propagation are excited This creates a discontinuity within the transmission line of the device Techniques can be employed to minimize the discontinuity but with nine 4 port hybrids this event occurs directly or in-directly 36 times To this end changing media alters fringing fields thus creating adverse effects and degrading performance

Active versus passive Active phase shifters provide gain while passive phase shifters are lossy

Activendash Applications active electronically scanned array (AESA)ndash Gain The phase shifter amplifies while phase shiftingndash Noise figure (NF)ndash Reciprocity not reciprocal

Passivendash Applications passive electronically scanned array (PESA)ndash Loss the phase shifter attenuates while phase shiftingndash NF NF = lossndash Reciprocity reciprocal

Analog versus digital Analog phase shifters provide a continuously variable phase shift or time delay Digital phase shifters provide a discrete set of phase shifts or time delays Discretization

leads to quantization errors Digital phase shifters require parallel bus control

Observation

Results