| Communications Toolbox | |
This example illustrates the basic format of the analog modulation and demodulation functions. Although the example uses phase modulation, most elements of this example apply to other analog modulation techniques as well.
The example samples an analog signal and modulates it. Then it simulates an additive white Gaussian noise (AWGN) channel, demodulates the received signal, and plots the original and demodulated signals.
% Prepare to sample a signal for two seconds,
% at a rate of 100 samples per second.
Fs = 100; % Sampling rate
t = [0:2*Fs+1]'/Fs; % Time points for sampling
% Create the signal, a sum of sinusoids.
x = sin(2*pi*t) + sin(4*pi*t);
Fc = 10; % Carrier frequency in modulation
phasedev = pi/2; % Phase deviation for phase modulation
y = pmmod(x,Fc,Fs,phasedev); % Modulate.
y = awgn(y,10,'measured',103); % Add noise.
z = pmdemod(y,Fc,Fs,phasedev); % Demodulate.
% Plot the original and recovered signals.
figure; plot(t,x,'k-',t,z,'g-');
legend('Original signal','Recovered signal');
Other examples using analog modulation functions appear in the online reference pages for ammod, amdemod, ssbdemod, and fmmod.
| | Analog Modulation | Digital Modulation | |
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