Skip to main content

Analog Communications lab MATLAB Programs

%% Amplitude Modulation And Demodulation
% Name:
%
% R.No:
%% closing and clearing commands
close all
clear all
clc
%% Initialization
fs=8000; % sampling frequency
fm=20; % message signal frequency
fc=500; % carrier signal frequency
t=[0:.1*fs]/fs; % time index
%% Message signal Generation
Am=1; % message signal amplitude
m=Am*cos(2*pi*fm*t); % message signal
subplot(4,3,1:3);
plot(t,m);
xlabel('time-->'), ylabel('amplitude')
title('Modulating or Message signal(fm=20Hz)');
%% Carrier signal Generation
Ac=1; % carrier signal amplitude
c=Ac*cos(2*pi*fc*t); % carrier signal
subplot(4,3,4:6);
plot(t,c);
xlabel('time-->'), ylabel('amplitude')
title('Carrier signal(fc=500Hz)');
%% Under Modulation
ka=0.5; % modulation sensitivity
u=ka*Am; % modulation Index
s1=Ac*(1+u*cos(2*pi*fm*t)).*cos(2*pi*fc*t);%AM
subplot(4,3,7);
plot(t,s1);
xlabel('time-->'), ylabel('amplitude')
title('Under Modulated signal(ka.Am=0.5)');
%% Critically Modulated signal
Am=2; % message signal amplitude
ka=0.5; % modulation sensitivity
u=ka*Am; % modulation index
s2=Ac*(1+u*cos(2*pi*fm*t)).*cos(2*pi*fc*t);
subplot(4,3,8);
plot(t,s2);
xlabel('time-->'), ylabel('amplitude')
title('Critically Modulated signal(ka.Am=1)');
%% Over Modulated signal
Am=5; % message signal amplitude
ka=0.5; % modulation sensitivity
u=ka*Am; % modulation index
s3=Ac*(1+u*cos(2*pi*fm*t)).*cos(2*pi*fc*t);
subplot(4,3,9);
plot(t,s3);
xlabel('time-->'), ylabel('amplitude')
title('Over Modulated signal(ka.Am=2.5)');
%% Demodulation
% for under modulated signal
r1= s1.*c; %detection
[b a] = butter(1,0.01);% LPF design
mr1= filter(b,a,r1);% demodulation
subplot(4,3,10);
plot(t,mr1);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal')

% for critically modulated signal
r2= s2.*c;%detection
[b a] = butter(1,0.01);% LPF design
mr2= filter(b,a,r2);% demodulation
subplot(4,3,11);
plot(t,mr2);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal')

% for overmodulated signal
r3= s3.*c;%detection
[b a] = butter(1,0.01);% LPF design
mr3= filter(b,a,r3);% demodulation
subplot(4,3,12);
plot(t,mr3);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal')


%% Pre emphasis and De emphasis
% Name:
%
% R.No:
%% closing and clearing commands
close all
clear all
clc
%% Initialization
f1=10;

for f=1:50
x(f)=(1/sqrt(1+(f1/f)^2));
f2(f)=f;
end
subplot(2,1,1);
plot(f2,x);
title('pre-emphasis filter response');

for f=1:50
y(f)=(1/sqrt(1+(f/f1)^2));
f3(f)=f;
end
subplot(2,1,2);
plot(f3,y);
title('de-emphasis filter response');


%% Time Division Multiplexing
% Name:
%
% R.No:
%% closing and clearing commands
close all;
clear all;
clc
%% Signal generation
x=0:.5:4*pi;     % signal taken upto 4pi
sig1=8*sin(x); % generate 1st sinusoidal signal
l=length(sig1);
sig2=8*triang(l);% Generate 2nd traingularSignal

%% 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');
ylabel('Amplitude--->');
xlabel('Time--->');

subplot(2,2,3);
stem(sig1);
title('Sampled Sinusoidal Signal');
ylabel('Amplitude--->');
xlabel('Time--->');

subplot(2,2,4);
stem(sig2);
title('Sampled Triangular Signal');
ylabel('Amplitude--->');
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
 % TDM of both quantize signal
tdmsig=reshape(sig,1,2*l1);              
% Display of TDM Signal
figure
stem(tdmsig);
title('TDM Signal');
ylabel('Amplitude--->');
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)
xlabel('Time--->');
%Display of Both Sampled Signal
plot(sig3);
title('Recovered Sinusoidal Signal');
ylabel('Amplitude--->');
xlabel('Time--->');
subplot(2,1,2)
plot(sig4);
title('Recovered Triangular Signal');
ylabel('Amplitude--->');
xlabel('Time--->');


%% DSBSC Modulation And Demodulation% Name:
%
% R.No:
%% closing and clearing commands
close all
clear all
clc
%% Initialization
Vm= 1; % message signal amplitude
Vc= 1; % carrier signal amplitude
fm = 20;%message signal frequency
fc= 500; %carrier signal frequency
fs=2*fc; % sampling frequency
t =0:inv(fs):2*pi; %time index
m_t = Vm*sin(2*pi*(fm/fs)*t);% message signal
subplot(4,1,1);
plot(t,m_t);
xlabel('time-->'), ylabel('amplitude')
title('message signal')
c_t = Vc*sin(2*pi*(fc/fs)*t); % carrier signal
subplot(4,1,2);
plot(t,c_t);
xlabel('time-->'), ylabel('amplitude')
title('carrier signal')
s_t = m_t.*c_t; %DSB-SC signal
subplot(4,1,3);
hold on;
plot(t,s_t);
plot(t,m_t,'r:');
plot(t,-m_t,'r:');
hold off;
xlabel('time-->'), ylabel('amplitude')
title('DSB-SC modulated signal')
%% Demodulated signal
r = s_t.*c_t;% detection
[b a] = butter(1,0.01);%LPF design
mr= filter(b,a,r);%demodulation
subplot(4,1,4);
plot(t,mr);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal')

 %% SSB-SC Modulation And Demodulation
% Name:
%
% R.No:
%% closing and clearing commands
close all
clear all
clc
%% Initialization
fs=8000; % sampling frequency
fm=20;%message signal frequency
fc=50;%carrier signal frequency
Am=1;% message signal amplitude
Ac=1;% carrier signal amplitude
t=[0:.1*fs]/fs;%time index
%% message signal generation
m1=Am*cos(2*pi*fm*t);% message signal 1
subplot(4,2,1);
plot(t,m1);
xlabel('time-->'), ylabel('amplitude')
title('Message Signal 1');

m2=Am*sin(2*pi*fm*t);% Message signal 2
subplot(4,2,2)
plot(t,m2);
xlabel('time-->'), ylabel('amplitude')
title('Message Signal 2');
%% carrier signal generation
c1=Ac*cos(2*pi*fc*t);% carrier signal 1
subplot(4,2,3)
plot(t,c1)
xlabel('time-->'), ylabel('amplitude')
title('Carrier Signal 1');

c2=Ac*sin(2*pi*fc*t);% carrier signal 2
subplot(4,2,4)
plot(t,c2)
xlabel('time-->'), ylabel('amplitude')
title('Carrier Signal 2');
%% SSB-SC generation
Susb=0.5*m1.*c1-0.5*m2.*c2;
subplot(4,2,5);
plot(t,Susb);
xlabel('time-->'), ylabel('amplitude')
title('SSB-SC Signal with USB');

Slsb=0.5*m1.*c1+0.5*m2.*c2;
subplot(426)
plot(t,Slsb);
xlabel('time-->'), ylabel('amplitude')
title('SSB-SC Signal with LSB');
%% Demodulation
r1 = Susb.*c1;% Detection
[b a] = butter(1,0.0001,'low');%LPF design
mr1= filter(b,a,r1);% demodulation
subplot(4,2,7);plot(t,mr1);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal 1')

r2 = Slsb.*c2;% Detection
[b a] = butter(1,0.0001,'low');%LPF design
mr2= filter(b,a,r2);% demodulation
subplot(4,2,8);plot(t,mr2);
xlabel('time-->'), ylabel('amplitude')
title('Demodulated signal 2')


%% Frequency Modulation And Demodulation
% Name:
%
% R.No:
%% closing and clearing commands
close all
clear all
clc
%% Initialization
%fm=35HZ,fc=500HZ,Am=1V,Ac=1V,B=10
fs=10000; % sampling frequency
Ac=1;% carrier signal amplitude
Am=1;% message signal amplitude
fm=35;%message signal frequency
fc=500;%carrier signal frequency
B=10;
t=(0:.1*fs)/fs;%time index
%% MESSAGE SIGNAL GENERATION
m_t=Am*cos(2*pi*fm*t);
subplot(4,1,1);
plot(t,m_t);
title('Modulating or Message signal(fm=35Hz)');
%% carrier signal generation
c_t=Ac*cos(2*pi*fc*t);
subplot(4,1,2);
plot(t,c_t);
title('Carrier signal(fm=500Hz)');
%% Frequency modulated signal generation
s_t=Ac*cos(2*pi*fc*t+B*sin(2*pi*fm*t));
subplot(4,1,3);
plot(t,s_t);
title('Frequency Modulated signal');
%% Demodulated signal generation
d=demod(s_t,fc,fs,'fm');
subplot(4,1,4);
plot(t,d);
title('demodulated signal');

%% Pulse Amplitude Moulation And Demodulation
% Name:
%
% R.No:
%% ALGORITHM:
% STEP1:    Start
% STEP2:    define modulating and carrier frequency.
% STEP3:    define time axis
% STEP4:    define modulating signal and carrier signal
% STEP5:    modulate the signals using FFT Algorithm to get PAM signal
% STEP6:    demodulate the signal using IFFT Algorithm to get back the original signal.
% STEP7: Stop
%% PROGRAM:
%% clearing and closing commands
close all
close all
clc
%% Initialization
t=0:1/6000:((10/1000)-(1/6000));% time index
xa=sin(2*pi*100*abs(t));
subplot(3,1,1)
plot(xa);
grid

Ts=32;
x=sin(2*pi*600*(Ts*t));

X=fft(xa,abs(x));
subplot(3,1,2);
stem(t, abs(X));
grid

Y=ifft(xa,X);
subplot(3,1,3)
plot(t,abs(Y))


%% PPM Generation And Demodulation
% Name:
%
% R.No:
%    Choose the sampling frequency fs and modulating frequency f1 such that Nyquist criteria are satisfied.
%    Generate the message signal using f1 andfs .
%    Modulate the message signal using the carrier frequency.
%    FFT is applied to the modulated signal to get frequency spectrum.
%    Demodulate the modulated signal using the same carrier frequency.
%    Plot the graphs for the original message signal, modulated, frequency spectrum and demodulated signal.
%% clearing and closing commands
close all;   
clear all
clc
%% Initialization
fc=100; % carrier signal frequency
fs=1000; % sampling frequency
        f1=80;%f2=300
t=0:1/fs:((2/f1)-(1/fs));
x1=0.4*cos(2*pi*f1*t)+0.5;
        %x2=0.2*(cos(2*pi*f1*t)+cos(2*pi*f2*t))+0.5 ;
subplot(4,2,1)
plot(x1)
title('original msg signal')
       y1=modulate(x1,fc,fs,'ppm')
subplot(4,2,2)
plot(y1)
axis([0 50 -0.2 1.2])
title('ppm one of f1,fc=1000,f1=80 ')
       fx1=abs(fft(y1,1024))
       fx1=[fx1(512:1024) fx1(1:513)]
       f=[(511*fs/1024):(fs/1024):(512*fs/1024)]
subplot(4,2,3)
plot(fx1)
title('freq des ppm signal tone,fc=1000')
       x1_recov = demod(y1,fc,fs,'ppm')
subplot(4,2,4)
plot(x1_recov)
title('time domain recovered signal')


%% PWM MODULATION AND DEMODULATION
% Name:
%
% R.no:
%% clearing and closing commands
clear all
close all
clc
%% Initialization
fc=1000; % carrier signal frequency
fs=10000; % sampling frequency
f1=200;
t=0:1/fs:((2/f1)-(1/fs));

x1=0.4*cos(2*pi*f1*t)+0.5;
subplot(421);
plot(x1);
title('original signal tone mesage,f1=500,fs=10000')
%% modulation
y1=modulate(x1,fc,fs,'pwm');
subplot(422);
plot(y1);
axis([0 500 -0.2 1.2]);
title('PWM')
%% demodulation
x1_recov=demod(y1,fc,fs,'pwm');
subplot(423);
plot(x1_recov);
title('time domain recoverd signal tone,f1=200')
Labels:

Comments

Post a Comment

Popular posts from this blog

NSG 2.1 Tcl/OTcl Script Generator

Are you a beginner for ns2 network simulator? Are you afraid of Tcl/oTcl script generation? Then there is a tcl script generator, named NSG 2.1 NSG - Network Simulation Generator NSG 2.1 is a java .jar file.  So, this application can run on all platforms (windows/linux/mac os). It deserves the java installed in you pc, prior to working with NSG 2.1. Java must be installed to run NSG2.1. So, initially, java must be installed. How to install java in Windows/ubuntu/mint/debian linux/ OS X ? Step 1 : Go to Terminal and run  java -version   to check the java version installed in your machine. Step 2 :  For Windows, click here  to download the java installer. Then, it is a typical next-next windows executable installation. For ubuntu/mint/debian linux operating systems, run the following commands in that terminal: sudo apt-get install default-jre sudo apt-get install default-jdk sudo apt-get install openjdk-7-jre sudo apt-get install...
Post a Comment
Read more

List of Websites to get free e-books

Here follows the list of websites to download e-books for free. 1. www.bookfi.org 2. www.bookzz.org  These two websites offer 4 to 5 free downloads per day. Best advantage is that we need not go for any sign-in process or clicking on an advertisement. 3. http://manybooks.net      In this website, apart from downloading in pdf format, one can download in many other e-book formats. 4. www.ebookee.org 5. www.bookboon.com 6. www.gutenberg.org 7. www.books123.me   8. www.brupt.com This website provides file in word (.doc), powerpoint (.ppt) and pdf file formats. 9. www.pdfoxy.com This website provides books in pdf format, but we should wait for 12-15 seconds and enter a Captcha code. But no need to sign-in. 10. www.docstoc.com This is another decent website of downloading ebooks in .pdf format, with no advertisement and no signing in. 11. www.freecomputerbooks.com This is one of the best websites for downloading technical and profession...
Post a Comment
Read more

SUMO installation in linux (Debian/Ubuntu/Mint)

SUMO - S imulation of U rban Mo bility SUMO an open source, portal, microscopic, multi-modal road traffic simulation. It allows for intermodal simulation including pedestrians and comes with a large set of tools for scenario creation.  It allows to simulate as to how a given traffic demand which consists of single vehicles moves through a given road network. The simulator allows to address a large set of traffic management topics. It is purely microscopic: each vehicle is modeled explicitly, has an own route, and moves individually through the network. SUMO Installation Procedure: Installation in Linux and mac OS Step I: Install two pre-requisite packages to build SUMO with GUI. Go to terminal and run: $ sudo apt-get install libgdal1-dev proj libxerces-c2-dev $ sudo apt-get install libfox-1.6-dev libgl1-mesa-dev libglu1-mesa-dev Step II: If you are using Unbuntu 12.04 or older versions, as it doesn't ship with libgdal package, create a symbolic link: $ sudo ln -s /usr/l...
1 comment
Read more