All nations’ university collegeP. O. Box kf-1908, koforidua, Ghana

DEPARTMENT

OF

ELECTRONICS AND COMMUNICATION ENGINEERING

DIGITAL COMMUNICATION LABORATORY OBSERVATION

MANUAL

BY

LINUS ANTONIO OFORI AGYEKUM

linusntn59@gmail.com

All nations’ university college

P. O. Box kf-1908, koforidua, Ghana

DEPARTMENT

OF

ELECTRONICS AND COMMUNICATION ENGINEERING

Certified that this is the bonafide record of the work done by

Mr./Miss..…………………………………………………………………………………………….of the

…………….…………………………..level/semester in ELECTRONICS AND COMMUNICATION

ENGINEERING of this college, in the ..………………………………….. Laboratory during the year

…………………….………………,in partial fulfillment of the requirements of the B.E Degree of the

All Nations University College, Koforidua.

Lab-in-charge Head of Department

INDEX NO: …………………………….

End of Semester Examination held in the month of …………………………

NO TITLEEXPERIMENT

DATESUBMISION

DATEMARK

LABORATORY OBSERVATION

Experiment One

Amplitude Mudualation

AIM

To perform Amplitude Modulation using Matlab programming and Simulink.

APPARATUS/SOFTWARE

Matlab

ALGORITHM

1. Create the vector “t”- time that varies from zero to two or three cycles with intervals 1/1000.

2. Create a message signal with single sine amplitude EmSin(2πfmt).3. Create a carrier signal, EcSin(2πfct).4. Create the modulated signal using the AM equation.5. Simulate for input and output graphs.

PROGRAM

clc;clear all;close all;t=0:0.001:2; % time generationEc=10; % carrier signal voltageEm=5; % message signal voltagefm=2; % message signal frequencyfc=15; % carrier signal frequencyec=Ec*sin(2*pi*fc*t); %carrier Signalem=Em*sin(2*pi*fm*t); %Modulating Signalecm=(Ec+em);am=ecm.*sin(2*pi*fc*t); % amplitude modulated signalsubplot(311);plot(t,ec);gridxlabel('time-->');ylabel('amplitude-->');title('CARRIER SIGNAL');subplot(312);plot(t,em);gridxlabel('time-->');ylabel('amplitude-->');title('MESSAGE SIGNAL');subplot(313);plot(t,am);gridxlabel('time-->');ylabel('amplitude-->');title('MODULATION');

GRAPHICAL OUTPUT

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-10

0

10

time-->

ampli

tude--

>CARRIER SIGNAL

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-5

0

5

time-->

ampli

tude--

>

MESSAGE SIGNAL

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-20

0

20

time-->

ampli

tude--

>

MODULATION

Figure 1: Amplitude Modulation

SIMULINK BLOCK OF AMPLITUDE MODULATION

Scope

Product

1

Constant

Carrier Signal

BaseBand Signal

Add

GRAPHICAL OUTPUT

RESULTS

Amplitude Modulation was successfully simulated using matlab and simulink.

Experiment Two

Frequency Modulation

AIM

To perform Frequency Modulation using Matlab programming and Simulink.

APPARATUS/SOFTWARE

Matlab

ALGORITHM

1. Create the vector “t”- time that varies from zero to two or three cycles with intervals 1/1000.

2. Create a message signal with single sine frequency. All the frequency used in the message should be less that the carrier frequency likewise amplitude of message signal should be less than carrier amplitude. [AmSin(2πfmt)].

3. Create a carrier signal, [AcCos(2πfct)].4. Create the modulated signal using the FM equation. AcCos(2πfct)

+BSin(2πfmt). B stands for modulation index. Chose value more than 1.

5. Simulate for input and output graphs.

PROGRAM

clc;clear all;close all;t=0:0.001:1; % creation of timeAm=10; % message signal voltageAc=5; % carrier signal voltage B=2; % modulation indexfm=2; % message signal frequencyfc=10; % carrier signal frequencyfa=Am*sin(2*pi*fm*t); % message signalfb=Ac*cos(2*pi*fc*t); % carrier signalFM=Ac*cos(2*pi*fc*t+B*sin(2*pi*fm*t)); % modulated output signalsubplot(3,1,1);plot(t,fa);gridxlabel('time-->');ylabel('amplitude-->');title('MESSAGE SIGNAL');

subplot(3,1,2);plot(t,fb);gridxlabel('time-->');ylabel('amplitude-->');title('CARRIER SIGNAL');subplot(3,1,3);plot(t,FM);gridxlabel('time-->');ylabel('amplitude-->');title('MODULATED SIGNAL');

GRAPHICAL OUTPUT

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-10

0

10

time-->

ampli

tude

-->MESSAGE SIGNAL

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-5

0

5

time-->

ampli

tude

-->

CARRIER SIGNAL

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-5

0

5

time-->

ampli

tude

-->

MODULATED SIGNAL

Figure 2: Frequency Modulation

SIMULINK BLOCK OF FREQUENCY MODULATION

Sine Wave Scope

FM

FMModulatorPassband

GRAPHICAL OUTPUT

RESULTS

Frequency Modulation was successfully simulated using matlab and simulink.

Experiment Three

Amplitude Shift Keying

AIM

To perform Amplitude Shift Keying using Matlab programming and Simulink.

APPARATUS/SOFTWARE

Matlab

ALGORITHM

1. Create the vector “t”- time that varies from zero to two or three cycles with intervals 1/100.

2. Create a message signal using bit streams of 0s and 1s.3. Create a carrier signal, [Sin(2πft)].4. Create the modulated signal using the matlab programming involving

for, if, else and elseif statements.5. Simulate for input and output graphs.

PROGRAM

clc;clear all;close all;m=[1 0 1 0 1 0 1 0]; %initialize the messagem_len=length(m); %initialize the length of mt=0:0.01:0.99; %initialize the timex=length(t); %initialize the length of tone=sin(2*pi*t); %carrier signalzero=zeros([1,x]); %generation of zeros to the length of task=0;subplot(3,1,1);plot(t,one);grid xlabel('time-->');ylabel('amplitude-->');title('CARRIER SIGNAL');subplot(3,1,2);stem(m);gridxlabel('time-->');ylabel('amplitude-->');title('MESSAGE SIGNAL');for i=1:1:m_len if(m(i)==1) %modulating signal ask=[ask one]; elseif(m(i)==0)

ask=[ask zero]; endendsubplot(3,1,3);plot(ask);gridxlabel('time-->');ylabel('amplitude-->');title('MODULATED SIGNAL');

GRAPHICAL OUTPUT

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-1

0

1

time-->

ampli

tude

-->

CARRIER SIGNAL

1 2 3 4 5 6 7 80

0.5

1

time-->

ampli

tude

-->

MESSAGE SIGNAL

0 100 200 300 400 500 600 700 800 900-1

0

1

time-->

ampli

tude

-->

MODULATED SIGNAL

Figure 3: Amplitude Shift Keying

SIMULINK BLOCK OF AMPLITUDE SHIFT KEYING

Switch

Sine Wave

Scope

BernoulliBinary

Bernoulli BinaryGenerator

GRAPHICAL OUTPUT

RESULTS

Amplitude Shift Keying was successfully simulated using matlab and simulink.

Experiment Four

Frequency Shift Keying

AIM

To perform Frequency Shift Keying using Matlab programming.

APPARATUS/SOFTWARE

Matlab

ALGORITHM

1. Create the vector “t”- time that varies from zero to two or three cycles with intervals 1/100.

2. Create a message signal using bit streams of 0s and 1s.3. Create a carrier signals, [Sin(2πft)] and [Sin(4πft)].4. Create the modulated signal using the matlab programming involving

for, if, else and elseif statements.5. Simulate for input and output graphs.

PROGRAM

clear all;close all;m=[1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0]; % initialize the message signalm_len=length(m); % initialize the length of mt=0:0.01:0.99; % initialize timex=length(t); % initialize the length of tf1=sin(4*pi*t); % carrier signal1f2=sin(2*pi*t); % carrier signal2fsk=0;for i=1:m_len if(m(i)==0) %start the modulation fsk=[fsk,f1]; elseif(m(i)==1) fsk=[fsk,f2]; endend

subplot(3,1,1);stem(m);xlabel('time-->');ylabel('amplitude-->');title('MESSAGE SIGNAL');subplot(3,1,2);plot(t,f1,t,f2);xlabel('time-->');ylabel('amplitude-->');title('CARRIER SIGNAL');subplot(3,1,3);plot(fsk); % plot the fskxlabel('time-->');ylabel('amplitude-->');title('MODULATED SIGNAL');

GRAPHICAL OUTPUT

0 5 10 15 20 25 300

0.5

1

time-->

ampl

itude

-->

MESSAGE SIGNAL

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-1

0

1

time-->

ampl

itude

-->

CARRIER SIGNAL

0 500 1000 1500 2000 2500 3000-1

0

1

time-->

ampl

itude

-->

MODULATED SIGNAL

Figure 4: Frequency Shift Keying

RESULTS

Frequency Shift Keying was successfully simulated using matlab.

Experiment Five

Phase Shift Keying

AIM

To perform Phase Shift Keying using Matlab programming.

APPARATUS/SOFTWARE

Matlab

ALGORITHM

1. Create the vector “t”- time that varies from zero to two or three cycles with intervals 1/100.

2. Create a message signal using bit streams of 0s and 1s.3. Create a carrier signals, [Sin(2πft)] and [Sin(4πft)+pi].4. Create the modulated signal using the matlab programming involving

for, if, else and elseif statements.5. Simulate for input and output graphs.

PROGRAM

clc;clc;clear all;close all;m=[1 0 1 1 0 1 0 1]; %initialize message signalm_len=length(m); %initialize the length of mt=0:0.01:0.99; %initialize timex=length(t); %initialize length of tone=sin(2*pi*t); %carrier signal 1zero=sin((2*pi*t)+pi); %carrier sinal 2psk=0;for i=1:m_len if(m(i)==1) %start modulation psk=[psk,one]; elseif(m(i)==0)

psk=[psk,zero]; endendsubplot(3,1,1);plot(t,one,t,zero);xlabel('time-->');ylabel('amplitude-->');title('CARRIER SIGNAL');subplot(3,1,2);stem(m);xlabel('time-->');ylabel('amplitude-->');title('MESSAGE SIGNAL');subplot(3,1,3);plot(psk); %plot the pskxlabel('time-->');ylabel('amplitude-->');title('MODULATED SIGNAL');

GRAPHICAL OUTPUT

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-1

0

1

time-->

ampl

itude

-->

CARRIER SIGNAL

1 2 3 4 5 6 7 80

0.5

1

time-->

ampl

itude

-->

MESSAGE SIGNAL

0 100 200 300 400 500 600 700 800 900-1

0

1

time-->

ampl

itude

-->

MODULATED SIGNAL

Figure 5: Phase Shift Keying

RESULTS

Phase Shift Keying was successfully simulated using matlab.