[h=3]Code:[/h]close all; clear all;clc;
%************************************************%
% Amplitude Modulation %
%************************************************%
%********************Variables******************%
fs=input('Enter sampling frequency= '); % sampling frequency
fm=2; % Modulatig Signal Frequency
fc=50; % Carrier Frequency
Am=1; % Modulatig Signal Amplitude
Ac=1; % Carrier Signal Amplitude
%*********************Signals*******************%
Wc=2*pi*fc;
Wm=2*pi*fm;
t=0:1/(fs):1;
choice = questdlg('Choose input for AM','Input','Sine','square', 'Sawtooth', '');
switch choice
case 'Sine'
Modulating_Signal=Am*sin(Wm*t);
case 'square'
Modulating_Signal=Am*square(Wm*t);
case 'Sawtooth'
Modulating_Signal=Am*sawtooth(Wm*t);
end
carrier_Signal = Ac*sin(Wc*t);
%********************MODULATION*****************%
AM_time= Modulating_Signal.*carrier_Signal;
AM_Freq=fftshift(abs(fft(AM_time)));
%**********************Plot*********************%
figure(1);subplot(321);plot(t,carrier_Signal);
title('AM carrier signal');xlabel('time'),ylabel('amplitude');grid on;
car_Sig_freq=fftshift(abs(fft(carrier_Signal)));
axiss=-fs/2:fs/(length(car_Sig_freq)-1):fs/2
figure(1);subplot(322);plot(axiss,car_Sig_freq);axis([-1000 1000 0 6000])
title('Carrier signal FREQ');xlabel('Frequency'), ylabel('amplitude');grid on;
figure(1);subplot(323);plot(t,Modulating_Signal);
title('AM modulating signal');
xlabel('time'), ylabel('amplitude');grid on;
Mod_Sig_freq=fftshift(abs(fft(Modulating_Signal)));
axiss=-fs/2:fs/(length(Mod_Sig_freq)-1):fs/2
figure(1);subplot(324);plot(axiss,Mod_Sig_freq);axis([-1000 1000 0 6000])
title('Modulating signal FREQ');
xlabel('Frequency'), ylabel('amplitude');grid on;
figure(1);subplot(325);plot(t,AM_time);
title('AM time-domain');
xlabel('time'), ylabel('amplitude');grid on;
axiss=-fs/2:fs/(length(AM_Freq)-1):fs/2;
figure(1);subplot(326);plot(axiss,AM_Freq);axis([-1000 1000 0 6000])
title('AM frequency-domain');xlabel('frequency'), ylabel('amplitude');grid on;
%********************DEMODULATION****************%
AM_DM_time=AM_time.*carrier_Signal;
AM_DM_Freq=fftshift(abs(fft(AM_DM_time)));
filter=fir1(200,fm/fs,'low');
orignal_t_Signal=conv(filter,AM_DM_time);
orignal_f_Signal=fftshift(abs(fft(orignal_t_Signal)));
figure(2);subplot(221);plot(t,AM_DM_time);
title('Demodulated Signal time-domain');xlabel('time'), ylabel('amplitude');grid on;
axiss=-fs/2:fs/(length(AM_DM_Freq)-1):fs/2;
figure(2);subplot(222);plot(axiss,AM_DM_Freq);axis([-1000 1000 0 6000])
title('Demodulated Signal freq-domain');xlabel('frequency'), ylabel('amplitude');grid on;
t1=0:1/(length(orignal_t_Signal)-1):1
figure(2);subplot(223);plot(t1,orignal_t_Signal);
title('Filterd Signal time-domain');xlabel('time'), ylabel('amplitude');grid on;
axiss=-fs/2:fs/(length(orignal_f_Signal)-1):fs/2;
figure(2);subplot(224);plot(axiss,orignal_f_Signal);axis([-1000 1000 0 6000])
title('Filterd Signal freq-domain');
xlabel('frequency'), ylabel('amplitude');grid on;clear all;
%************************************************%
% Frequency Modulation %
%************************************************%
%***************Variables************************%
Ac=1; %carrier signal amplitude
Am=1; %Modulation signal amplitude
fm=2; %Modulating signal frequncy
fc=50; %carrier signal frequncy
m=10; % index of FM
%********************Signal********************%
fs=10000;
Wc=2*pi*fc;
Wm=2*pi*fm;
t=0:1/(fs-1):1;
choice1 = questdlg('Choose input for FM','Input','Sine','cosine', '');
switch choice1
case 'Sine'
Modulating_Signal=Am*sin(Wm*t);
case 'cosine'
Modulating_Signal=Am*cos(Wm*t);
end
Carrier_Signal_fm = Ac*cos(Wc*t);
%********************Modulation****************%
m=10; %modulating index
FM_time= Ac*cos((Wc*t)+m*Modulating_Signal);
FM_Freq=fftshift(abs(fft(FM_time)));
%Demodulation
FM_DEM_T= 100*demod(FM_time,fc,fs,'fm'); %Hilbert transform gives 90 phase shift
FM_DEM_F=fftshift(abs(fft(FM_DEM_T)));
axisx=-fs/2:fs/(length(FM_DEM_F)-1):fs/2
%*****************Plot*************************%
figure(3);subplot(221);plot(t, Modulating_Signal);
title('FM modulating signal');
mod_Sig_fre=fftshift(abs(fft(Modulating_Signal)));
axiss=-fs/2:fs/(length(mod_Sig_fre)-1):fs/2
figure(3);subplot(222);plot(axiss,mod_Sig_fre);axis([-1000 1000 0 6000])
title('Mod signal Freq');xlabel('Frequncy'), ylabel('amplitude');grid on;
figure(3);subplot(223);plot(t, Carrier_Signal_fm);
title('FM Carrier signal');
Carrier_Signal_freq=fftshift(abs(fft( Carrier_Signal_fm)));
axiss=-fs/2:fs/(length( Carrier_Signal_freq)-1):fs/2
figure(3);subplot(224);plot(axiss,Carrier_Signal_freq);axis([-1000 1000 0 6000])
title('Carrier signal Freq');xlabel('Frequency'), ylabel('amplitude');grid on;
figure(4);subplot(221);plot(t,FM_time);
xlabel('time(second)'),ylabel('amplitude');title('FM Modulated time-domain');grid on;
FM_Sig_freq=fftshift(abs(fft(FM_time)));
axiss=-fs/2:fs/(length(FM_Sig_freq)-1):fs/2
figure(4);subplot(222);plot(axiss, FM_Sig_freq);
title('FM signal Freq');xlabel('Frequncy'), ylabel('amplitude');grid on;
figure(4);subplot(223);plot(t,FM_DEM_T);
title('FM DEmodulated signal Time');
figure(4);subplot(224);plot(axiss,FM_DEM_F);
title('FM DEmodulated signal Freq');
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