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The purpose of this project is to simulate the basic components of an analog communication system using
MATLAB programming. Specifically, an AM modulator and a corresponding super-heterodyne receiver
will be simulated using radio-station generated signals.
Contents
Audio Signals : audio signals that used during testing
Screens : output figures
Source Code : MATLAB file
Project Requirements
MATLAB program recommended version 2021
Block Diagram
Result Figures
Removing RF stage
%%%%%%%%%% comment this part if you want to demodulate without RF stage %%%%%%%%%%% sum_signals_BPF = sum_signals;
band_pass_filter =fdesign.bandpass(F_stop1, F_pass1, F_pass2, F_stop2, A_stop1, A_pass, A_stop2, 15*Fs);
band_pass_filter = design(band_pass_filter, 'equiripple');
sum_signals_BPF = filter(band_pass_filter, sum_signals);
SUM_SIGNALS_BPF = fftshift(fft(sum_signals_BPF));
f_MODULATED_SIGNAL = (-length(SUM_SIGNALS_BPF) /2:1:length(SUM_SIGNALS_BPF) /2-1)';
subplot(2, 1, 2)
plot(f_MODULATED_SIGNAL*Fs_carrier/ length(SUM_SIGNALS_BPF), abs(SUM_SIGNALS_BPF), 'r')
title("RF stage after BPF for audio "+choose_signal)
xlabel("Frequency (Hz)")
ylabel("Magnitude")
gridon
Offset in Receiver Oscillator frequency
%%%%%%%%%% the receiver oscillator offset [0, 0.1k, 1k] %%%%%%%%%%
offset =0;
IF =25000+offset; % If frequency 25 KHz
Run Program
by running code, user required to choose which audio he want to hear as in the following figure