Adc Lab Matlab

8/15/2019 Adc Lab Matlab

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Analog And Digital Communication Systems

Dept of ECE,MITS

DIGITAL

COMMUNICATION USING

MATLAB


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Dept of ECE,MITS

1.Time division multiplexing and demultiplexing

Aim: To generate and demodulate frequency shift keyed (FSK) signal using MATLAB

Appartus:computer with matlab software

Block diagram:

Program:

clc;

close all;

clear all;

% Signal generation

x=0:.5:4*pi; % siganal taken upto 4pi

sig1=8*sin(x); % generate 1st sinusoidal signal

l=length(sig1);

sig2=8*triang(l); % Generate 2nd traingular Sigal


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Dept of ECE,MITS

% Display of Both Signal

subplot(2,2,1);

plot(sig1);

title('Sinusoidal Signal');

ylabel('Amplitude--->');

xlabel('Time--->');

subplot(2,2,2);

plot(sig2);

title('Triangular Signal');


xlabel('Time--->');

% Display of Both Sampled Signal

subplot(2,2,3);

stem(sig1);

title('Sampled Sinusoidal Signal');


xlabel('Time--->');subplot(2,2,4);

stem(sig2);

title('Sampled Triangular Signal');


xlabel('Time--->');

l1=length(sig1);

l2=length(sig2);

for i=1:l1

sig(1,i)=sig1(i); % Making Both row vector to a matrix

sig(2,i)=sig2(i);

end


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Dept of ECE,MITS

% TDM of both quantize signal

tdmsig=reshape(sig,1,2*l1);

% Display of TDM Signal

figure

stem(tdmsig);

title('TDM Signal');


xlabel('Time--->');

% Demultiplexing of TDM Signal

demux=reshape(tdmsig,2,l1);

for i=1:l1

sig3(i)=demux(1,i); % Converting The matrix into row vectors

sig4(i)=demux(2,i);

end

% display of demultiplexed signal

figure

subplot(2,1,1) plot(sig3);

title('Recovered Sinusoidal Signal');


xlabel('Time--->');

subplot(2,1,2)

plot(sig4);

title('Recovered Triangular Signal');


xlabel('Time--->');


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Dept of ECE,MITS

model waveforms:

Result:


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Dept of ECE,MITS

2.Pulse code modulation and demodulation

Aim: To generate and Pulse code modulation demodulate signal using MATLAB


Block diagram:

Program:

cl c;

cl ose al l ;

cl ear al l ;

a=1;

f =2;

t =0: 0. 01: 1;

x=a*si n( 2*pi *f *t ) +a;

f i gure(1)

pl ot ( t , x) ;

f i gure(2)

st em( t , x) ;

par t =[ 0: 0. 1: 2*a];

code=[ 0: 0. 1: ( ( 2*a)+0. 1) ]

[ i nd, d] =quant i z( x, par t , code) ;

f i gur e( 3)

s tai r s ( t , d)

pcm=dec2bi n(d) ;

di spl ay( pcm) ;


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Dept of ECE,MITS

deco=bi n2dec( pcm) ;

[ b, a] =but t er ( 3, 0. 1, ' l ow' ) ;

r ecover ed=f i l t er ( b, a, deco) ;

f i gur e( 4)

pl ot ( t , r ecover ed) ;

model waveforms:

Result:


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Dept of ECE,MITS

3.Delta modulation and demodulation

Aim: generate and demodulate delta modulation signal using MATLAB

Appartus: computer with matlab software

Block diagram:

Program:

clc;

clear all;

close all;

a=2;

t=0:2*pi/50:2*pi;

x=a*sin(t);

l=length(x);

plot(x,'r');

delta=0.2;

hold on

xn=0;

for i=1:l;

if x(i)>xn(i)

d(i)=1;


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Dept of ECE,MITS

xn(i+1)=xn(i)+delta;

else

d(i)=0; xn(i+1)=xn(i)-delta;

end

end

stairs(xn)

hold on

for i=1:d

if d(i)>xn(i)

d(i)=0;

xn(i+1)=xn(i)-delta;

else

d(i)=1; xn(i+1)=xn(i)+delta;

end

end

plot(xn,'c');

legend('Analog signal','Delta modulation','Demodulation')

title('DELTA MODULATION / DEMODULATION ')

model waveforms:


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Dept of ECE,MITS

Result:


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Dept of ECE,MITS

4.FREQUENCY SHIFT KEYING

Aim: To generate and demodulate frequency shift keyed (FSK) signal using MATLAB


Block diagram:

Algorithm:

FSK modulation

Generate two carriers signal.

1. Generate binary data, message signal and inverted message signal

2. Start FOR loop

3. Multiply carrier 1 with message signal and carrier 2 with inverted message signal

4.

Perform addition to get the FSK modulated signal

5. Plot message signal and FSK modulated signal.

6. End FOR loop.

7. Plot the binary data and carriers.

FSK demodulation

1. Start FOR loop

2. Perform correlation of FSK modulated signal with carrier 1 and carrier 2 to get two decision

variables x1 and x2.


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Dept of ECE,MITS

3. Make decisionon x = x1-x2 to get demodulated binary data. If x>0, choose ‘1’ else choose

‘0’.

4. Plot the demodulated binary data.

Program:

clc;

clear all;

close all;

%GENERATE CARRIER SIGNAL

Tb=1; fc1=2;fc2=5;

t=0:(Tb/100):Tb;

c1=sqrt(2/Tb)*sin(2*pi*fc1*t);

c2=sqrt(2/Tb)*sin(2*pi*fc2*t);

figure(1)

plot(t,c1);

figure(2)

plot(t,c2);

%generate message signal

N=8;

m=rand(1,N);

t1=0;t2=Tb

for i=1:N

t=[t1:(Tb/100):t2]

if m(i)>0.5

m(i)=1;

m_s=ones(1,length(t));

invm_s=zeros(1,length(t));else

m(i)=0;

m_s=zeros(1,length(t));

invm_s=ones(1,length(t));

end


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Dept of ECE,MITS

message(i,:)=m_s;

%Multiplier

fsk_sig1(i,:)=c1.*m_s;

fsk_sig2(i,:)=c2.*invm_s;

fsk=fsk_sig1+fsk_sig2;

%plotting the message signal and the modulated signal

% subplot(3,2,2);axis([0 N -2 2]);

figure(3)

plot(t,message(i,:),'r');

title('message signal');xlabel('t---->');ylabel('m(t)');grid on;hold on;

figure(4)

% subplot(3,2,5);

plot(t,fsk(i,:));

title('FSK signal');xlabel('t---->');ylabel('s(t)');grid on;hold on;

t1=t1+(Tb+.01); t2=t2+(Tb+.01);

end

hold off

%Plotting binary data bits and carrier signal

% subplot(3,2,1);stem(m);figure(5)

stem(m)

title('binary data');xlabel('n---->'); ylabel('b(n)');grid on;

% subplot(3,2,3);plot(t,c1);

figure(6)

plot(t,c1)

title('carrier signal-1');xlabel('t---->');ylabel('c1(t)');grid on;

figure(7)

plot(t,c2);



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Dept of ECE,MITS

% FSK Demodulation

t1=0;t2=Tb

for i=1:N

t=[t1:(Tb/100):t2]

%correlator

x1=sum(c1.*fsk_sig1(i,:));

x2=sum(c2.*fsk_sig2(i,:));

x=x1-x2;

%decision device

if x>0

demod(i)=1;

else

demod(i)=0;

end

t1=t1+(Tb+.01);

t2=t2+(Tb+.01);

end

%Plotting the demodulated data bits

% subplot(3,2,6);figure(8)

stem(demod);

title(' demodulated data');xlabel('n---->');ylabel('b(n)'); grid on;


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Dept of ECE,MITS

Model graph:

Result:


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Dept of ECE,MITS

5. QUADRATURE PHASE SHIFT KEYING

Aim: To generate and demodulate quadrature phase shifted (QPSK) signal using MATLAB


Block diagram:

transmiter

Reciver


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Dept of ECE,MITS

Algorithm

QPSK modulation

1. Generate quadrature carriers.

2. Start FOR loop

3. Generate binary data, message signal(bipolar form)

4. Multiply carrier 1 with odd bits of message signal and carrier 2 with even bits of message

signal

5. Perform addition of odd and even modulated signals to get the QPSK modulated signal

6. Plot QPSK modulated signal.

7. End FOR loop.

8. Plot the binary data and carriers.

QPSK demodulation

1. Start FOR loop

2. Perform correlation of QPSK modulated signal with quadrature carriers to get two decision

variables x1 and x2.

3. Make decision on x1 and x2 and multiplex to get demodulated binary data.

If x1>0and x2>0, choose ‘11’. If x1>0and x2


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Dept of ECE,MITS

%generate message signal

N=8;m=rand(1,N);

t1=0;t2=Tb

for i=1:2:(N-1)

t=[t1:(Tb/100):t2]

if m(i)>0.5

m(i)=1;


else

m(i)=0;

m_s=-1*ones(1,length(t));

end

%odd bits modulated signal

odd_sig(i,:)=c1.*m_s;

if m(i+1)>0.5 18

m(i+1)=1;


else

m(i+1)=0;m_s=-1*ones(1,length(t));

end

%even bits modulated signal

even_sig(i,:)=c2.*m_s;

%qpsk signal

qpsk=odd_sig+even_sig;

%Plot the QPSK modulated signal

subplot(3,2,4);plot(t,qpsk(i,:));

title('QPSK signal');xlabel('t---->');ylabel('s(t)');grid on; hold on;

t1=t1+(Tb+.01); t2=t2+(Tb+.01);

end

hold off


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Dept of ECE,MITS

%Plot the binary data bits and carrier signal

subplot(3,2,1);stem(m);

title('binary data bits');xlabel('n---->');ylabel('b(n)');grid on;

subplot(3,2,2);plot(t,c1);


subplot(3,2,3);plot(t,c2);


% QPSK Demodulation

t1=0;t2=Tb

for i=1:N-1

t=[t1:(Tb/100):t2]

%correlator

x1=sum(c1.*qpsk(i,:));

x2=sum(c2.*qpsk(i,:));

%decision device

if (x1>0&&x2>0)

demod(i)=1;

demod(i+1)=1;

elseif (x1>0&&x2


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title('qpsk demodulated bits');xlabel('n---->');ylabel('b(n)');grid on;

Result:


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Dept of ECE,MITS

6. DIFFERENTIAL PHASE SHIFT KEYING

Aim: To study the various steps involved in generating differential phase shift keyed signal

at the modulator end and recovering the binary signal from the received DPSK signal.


PROGRAM:

cl c; cl ear al l ; cl ose al l ; m=1; n=8; b=r andi nt ( m, n) ; f i gure(1) s tai r s (b) ; k=1; f or i =1: n- 1;

f ( 1) =xor ( k, B( 1, 1) ) ; f ( i +1) =xor ( not ( f ( i ) , b( 1, i +1) ) ;

end i f f ( i )>0

m( i ) =0 el se

m( i ) =1;


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Dept of ECE,MITS

end end f i gure(2) st ai r s(m) ; f or i =1: n

i f m( i ) >0 phase( i ) =pi

el se phase( i ) =0

Result:

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Adc Lab Matlab