Single Side Band (SSB) Modulation and Demodulation using MATLAB

Single sideband (SSB) modulation might be a sort of modulation used to send data, which includes an audio signal. Amplitude modulation produces an output signal in which the bandwidth is two times the most frequency of the original baseband signal. SSB modulation neglects this bandwidth increase, and also the power wasted on a carrier, at the price of more device complexity and tougher tuning at the receiver side.

Figure: Block Diagram of Modulation

Figure: Spectrum 

The Expression for Single Side Band with Upper Side Band : 

here, 
m is the cosine wave with time duration of ‘t’, 
fc is the carrier frequency, 
t is the time duration and 
mh s the Hilbert transform of baseband.
Example: 

MATLAB

% MATLAB code for modulation
% carrier frequency
fc = 200;

% baseband frequency
fm = 30;

% sampling frequency
fs= 4000;

% time duration
t = (0 : 1 / fs :1 );
t = linspace(0, 1, 1000);

% cosine wave with time duration of 't'
m = cos(2 * pi * fm * t);

% Hilbert transform of baseband
mh = imag(hilbert(m));

% Single Side Band with Upper Side Band
sb = m .* cos(2 * pi * fc * t) - mh .* sin(2 * pi * fc * t);

%Demodulation by Synchronous method
em = sb.*m;

%Filtering High Frequemcies
[ n,w ] = buttord(2/1000,4/1000, .5, 5);
[ a,b ] = butter(n,w,'low');
dem = filter(a,b,em);

% displaying the modulation
figure;
plot(t, sb);
title('Single SideBand Modulation');
xlabel('Time(sec)');
ylabel('Amplitude');

% displaying the demodulation
figure;
plot(t, em);
title('Single SideBand Demodulation');
xlabel('Time(sec)');
ylabel('Amplitude');

% displaying the filtered signal
figure;
plot(t, dem);
title('Filtered Signal');
xlabel('Time(sec)');
ylabel('Amplitude');

Output:

Demodulated Signal

Filtered Signal