introduction in telecommunication (121009) chris roeloffzen

1 2007

Introduction in Telecommunication(121009)

Chris Roeloffzen

Chair: Telecommunication engineering (EWI)Floor 8 HOGEKAMP EL/TN building (north)Telephone 489 2804E-mail: [email protected]

2 2007

Contents of the course

Book: Electronic Communications Systems W. Tomasi. Prentice Hall, 5th edition, 2004ISBN: 0-13-049492-5

For up-to-date information see: www.el.utwente.nl/tel/education/

3 2007

Contents of the courseLecture 1 - 3: Introduction

Chapter 1: Introduction to Electronic CommunicationsChapter 2: Signal Analysis and Mixing

Lecture 4 - 7: CW modulationChapter 4: Amplitude modulation, TransmissionChapter 5: Amplitude modulation, ReceptionChapter 6: Single-side banded Communication SystemsChapter 7: Angle Modulation TransmissionChapter 8: Angle Modulation Receivers

Lecture 8 - 11: MediaChapter 12: Metallic Transmission LinesChapter 14: Electromagnetic Wave PropagationChapter 15: AntennasChapter 13: Optical Fibers

Lecture 12 - 14: Digital CommunicationChapter 9: Digital ModulationChapter 10: Digital Transmission

Lecture 15 & 16: ?????????????????For specific information see: www.el.utwente.nl/te/education/education.htm

4 2007

Today: Lecture 1

Chapter 1:

Introduction to Electronic Communications

5 2007

Chapter 1

• What is Telecommunication?

• Transmission and Networks

• Milestones

• Signal transmission and Media

• Modulation and Demodulation

• The Electromagnetic Frequency Spectrum

• Bandwidth and Information Capacity

• Noise Analysis

6 2007

Introduction

What is Telecommunication ??????

What are the three main components in a communication system?

Give some information signals

Any transmission, emission, or reception of signs, signals, writing, images and sound or intelligence of any nature by wire, radio, optical or other electromagnetic systems.

ITU-1989

7 2007

Communication Networks

Point to point

Mesh network

8 2007

Milestones

Samuel Morse:1837 telegraph

9 2007

Samuel Morse: 1837 telegraph

Alexander Bell:1876 telephone

Milestones

10 2007

Samuel Morse: 1837 telegraphAlexander Bell:1876 telephone

Marconi: 1895 wireless telegraphnot the inventor ofRadio

Nikola Tesla <1895: Inventor of Radio

Milestones

11 2007

Samuel Morse: 1837 telegraphAlexander Bell:1876 telephoneMarconi: 1895 wireless telegraph

not the inventor ofRadio

Nikola Tesla <1895: Inventor of Radio

Lee De Forest 1907: triode vacuum tube ‘Audion’

(amplifier)

Milestones

12 2007



Nikola Tesla <1895: Inventor of RadioLee De Forest 1907: triode vacuum tube

1920: Commercial AM radio broadcast

Milestones

13 2007



Nikola Tesla <1895: Inventor of RadioLee De Forest 1907: triode vacuum tube1920: Commercial AM radio broadcast

1939: First FM radio broadcast ‘Alphine New Jersey by Edwin Armstrong

Milestones

14 2007

( ) 1010log outP dB

in

PA

P

Pin Pout

V

I

R

V I R

P V I

2VP

R

2

( ) 10 10210log 20log ,

out

out outP dB in out

in in

in

V

R VA R R

V VR

What is the advantage of using dB ????????????????

Power Measurements (dB, dBm)

15 2007

( ) 1010log0.001 W

outout dBm

PP

Pin Pout

Power Measurements (dB, dBm)

16 2007

Signal transmission (1)

Information source

(intelligence)

Transmitter Receiver

Received Information

System noise and interference

Transmission mediumor

Communications channel

Copper cable (coax, UTP)

Optical fiber cable

Free space (Radio)

17 2007

Signal transmission (2)

Low-frequency source information (analog or digital)

Modulator and frequency up-

converter

Transmission medium

(channel)

High-frequency oscillator

Amplifier

Frequency down-

converter

High-frequency local oscillator

Power amplifier

Filter

Transmitter Receiver

18 2007

Transmission media and products

19 2007

Adaptation to the media

Reasons are a.o.

Necessity: transmission frequency rangeEfficiency: multiplexingQuality: e.g. due to noise, interference

Example: Microwave transmission of AM Radio

frequency

pow

er500 kHz

pow

er

frequency

Modulation

20 2007

Change parameters of a carrier

Information signal: Ac(t)fc(t)(t)

Ac(t) : amplitude modulation AM ASKfc(t) : frequency modulation FM FSK(t) : phase modulation PM PSK

Ac(t) and (t) QAM (Digital)

mod cos 2 cc cv t tfA

Modulation principle

DigitalAnalog

21 2007

Demodulation principle

Recovering of information signal from the received modulated transmission signal

Example:

AM: transmitted signal

Demodulation: multiply with in the receiver

cos 2am m cv t v t f t

cos 2 cf t

2

cos 2 cos 2

cos 2

11 cos 2 2

21 1

cos 2 22 2

dem m c c

m c

m c

m m c

v t v t f t f t

v t f t

v t f t

v t v t f t

22 2007

Electromagnetic Frequency Spectrum

Frequency : f [Hertz]Wavelength: [m]

c : velocity of light: 3 108 m/sec

f 1 kHz 3 105 m100 kHz 3 103 m10 MHz 3 101 m = 30 m1 GHz 3 10-1 m = 30 cm

c

f

23 2007

Electromagnetic Frequency Spectrum

24 2007

25 2007

Bandwidth and information capacity (1)

Hartleys law 1920

I = amount of information

B = system bandwidth (Hertz)

t = transmission time (seconds)

The book is wrong!!!!!!

I B t

26 2007

Shannon limit for information capacity

I = information capacity (bits per second)

B = system bandwidth (Hertz)

S/N = signal-to-noise power ratio (dimensionless)

Bandwidth and information capacity (2)

2 10log 1 3.32 log 1S S

I B BN N

27 2007

Example:

Standard telephony

B = 2,7 kHz

1000 (30 dB)S

N

?I

Bandwidth and information capacity

2 10log 1 3.32 log 1S S

I B BN N

28 2007

Example:

Standard telephony

B = 2,7 kHz

1000 (30 dB)S

N

22700log 1 1000 26.9 kbit/secI

Bandwidth and information capacity

2 10log 1 3.32 log 1S S

I B BN N

29 2007

Noise

S/N = signal-to-noise power ratio (dimensionless)

With a given bandwidth a system has a larger capacity if the S/N ratio is larger

In a practical system noise is always present

Noise - internal (generated within the device)- external (generated outside the device)

2 10log 1 3.32 log 1S S

I B BN N

30 2007

Noise

Correlated noise: Related to signal

Uncorrelated noise: Not related to signal

31 2007

NoiseCorrelated noise

Nonlinear distortionHarmonic distortionIntermodulation distortion

Uncorrelated noiseExternal

AtmosphericExtraterrestrialSolarCosmicMan-madeImpulseInterference

InternalThermal noise (random movement of electrons)Shot (random arrival of carriers)Transient time

32 2007

Thermal Noise (white noise)

N KTBN = noise power (watts)B = bandwidth (hertz)K = Boltzmann’s proportionality constant

(1.38 10-23 Joules per kelvin)T = absolute temperature (kelvin)

10log 10log 10log0.001 0.001dBm

KTB KTN B

@ 290k 174 dBm 10logdBmN B

- Random- Continuous spectral density- Additive- Present in all devices

33 2007

Noise voltage

2

224

4

N

NN

VV

N KTB V RKTBR R

2VP VI

R

V IR

34 2007

Signal-to-Noise Ratio

s

n

PS

N P

Ps = signal power (watts)Pn = noise power (watts)

10log s

n

PSdB

N P

Or expressed in decibel

35 2007

Ideal amplifier

Ap

Nonideal amplifier

Ap, Nd

i

i

S

Np i i

p i i

A S S

A N N

i

i

S

N

p i i

p i d i d p

A S S

A N N N N A

Noise in Amplifier

36 2007

Noise Factor and Noise Figure

in

in out outin

out in out p in

out

SS N NN

FS N S A NN

F = noise factor (no dimension)

10logNF F NF = noise figure (dB)

total output noise

that part of the output noise due to the source resistanceF

1F

0NF

37 2007

?TF

FT = total noise factor (dimensionless)

10logT TNF F

NFT = total noise figure (dB)

Noise Factor and Noise Figure of Cascade

38 2007

321

1 1 2 1 2 1

1 11...... n

Tn

F FFF F

A A A A A A

FT = total noise factor (dimensionless)

10logT TNF F

NFT = total noise figure (dB)

Noise Factor and Noise Figure of Cascade

39 2007

Noise Temperature

N

N KTB TKB

T = environmental temperature (290 Kelvin)N = noise power (watts)K = Boltzmann’s constant (1.38 10-23 J/K)B = total noise factor (hertz)

1eT T F

Te = equivalent noise temperatureT = environmental temperature (290 Kelvin)F = noise factor (dimensionless)

1 eTF

T

1F

introduction in telecommunication (121009) chris roeloffzen

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