MATLAB Code for Pulse Amplitude Modulation (PAM) and Demodulation

• 📘 Overview & Theory of Pulse Amplitude Moduation (PAM)
• 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Analog Signal and Digital Signal
• 🧮 Simulation results for comparison of PAM, PWM, PPM, DM, and PCM
• 📚 Further Reading

• 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of an Analog Signal (2)
• 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Digital data
• 🧮 Other Pulse Modulation Techniques (e.g., PWM, PPM, DM, and PCM)

 

Pulse Amplitude Modulation (PAM) & Demodulation of an Analog Message Signal

MATLAB Script

clc;

clear all;

close all;

fm= 10; % frequency of the message signal

fc= 100; % frequency of the carrier signal

fs=1000*fm; % (=100KHz) sampling frequency (where 1000 is the upsampling factor)

t=0:1/fs:1; % sampling rate of (1/fs = 100 kHz)

m=1*cos(2*pi*fm*t); % Message signal with period 2*pi*fm (sinusoidal wave signal)

c=0.5*square(2*pi*fc*t)+0.5; % square wave with period 2*pi*fc

s=m.*c; % modulated signal (multiplication of element by element)

subplot(4,1,1);

plot(t,m);

title('Message signal');

xlabel ('Time');

ylabel('Amplitude');

subplot(4,1,2);

plot(t,c);

title('Carrier signal');

xlabel('Time');

ylabel('Amplitude');

subplot(4,1,3);

plot(t,s);

title('Modulated signal');

xlabel('Time');

ylabel('Amplitude');

%demdulated

d=s.*c; % At receiver, received signal is multiplied by carrier signal

filter=fir1(200,fm/fs,'low'); % low-pass FIR filter which order is 200

% here fm is the cut-off frequency and the fs is the sampling frequency

original_t_signal=conv(filter,d); % convolution of demodulated signal with filter %coefficient

t1=0:1/(length(original_t_signal)-1):1;

subplot(4,1,4);

plot(t1,original_t_signal);

title('demodulated signal');

xlabel('time');

ylabel('amplitude');

web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

 Output

 

Copy the code from here

 

% The code is written by SalimWireless.Com clc; clear all; close all; fm= 10; % frequency of the message signal fc= 100; % frequency of the carrier signal fs=1000*fm; % (=100KHz) sampling frequency (where 1000 is the upsampling factor) t=0:1/fs:1; % sampling rate of (1/fs = 100 kHz) m=1*cos(2*pi*fm*t); % Message signal with period 2*pi*fm (sinusoidal wave signal) c=0.5*square(2*pi*fc*t)+0.5; % square wave with period 2*pi*fc s=m.*c; % modulated signal (multiplication of element by element) subplot(4,1,1); plot(t,m); title('Message signal'); xlabel ('Time'); ylabel('Amplitude'); subplot(4,1,2); plot(t,c); title('Carrier signal'); xlabel('Time'); ylabel('Amplitude'); subplot(4,1,3); plot(t,s); title('Modulated signal'); xlabel('Time'); ylabel('Amplitude'); %demdulated d=s.*c; % At receiver, received signal is multiplied by carrier signal filter=fir1(200,fm/fs,'low'); % low-pass FIR filter which order is 200 % here fm is the cut-off frequency and the fs is the sampling frequency original_t_signal=conv(filter,d); % convolution of demodulated signal with filter %coefficient t1=0:1/(length(original_t_signal)-1):1; subplot(4,1,4); plot(t1,original_t_signal); title('demodulated signal'); xlabel('time'); ylabel('amplitude'); web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

Another Code for Pulse Amplitude Modulation and Demodulation of an Analog Message Signal 

MATLAB Script

 clc;
clear;
close all;

% Parameters
messageFrequency = 2;   % Message frequency in Hz
carrierFrequency = 20;  % Carrier frequency in Hz
samplingFrequency = 1000; % Sampling frequency in Hz
duration = 1;           % Signal duration in seconds
A = 1;                  % Amplitude of the signals

% Time vector
t = 0:1/samplingFrequency:duration;

% Message signal (sinusoidal)
messageSignal = A * sin(2 * pi * messageFrequency * t);

% Carrier signal (square wave)
carrierSignal = A * square(2 * pi * carrierFrequency * t);

% PAM signal
pamSignal = messageSignal .* (carrierSignal > 0);

% Plotting
figure;
subplot(3,1,1);
plot(t, messageSignal);
title('Message Signal');
xlabel('Time (s)');
ylabel('Amplitude');

subplot(3,1,2);
plot(t, carrierSignal);
title('Carrier Signal');
xlabel('Time (s)');
ylabel('Amplitude');

subplot(3,1,3);
plot(t, pamSignal);
title('PAM Signal');
xlabel('Time (s)');
ylabel('Amplitude');
web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

Copy the Code from here

% The code is written by SalimWireless.Com clc; clc; clear; close all; % Parameters messageFrequency = 2; % Message frequency in Hz carrierFrequency = 20; % Carrier frequency in Hz samplingFrequency = 1000; % Sampling frequency in Hz duration = 1; % Signal duration in seconds A = 1; % Amplitude of the signals % Time vector t = 0:1/samplingFrequency:duration; % Message signal (sinusoidal) messageSignal = A * sin(2 * pi * messageFrequency * t); % Carrier signal (square wave) carrierSignal = A * square(2 * pi * carrierFrequency * t); % PAM signal pamSignal = messageSignal .* (carrierSignal > 0); % Plotting figure; subplot(3,1,1); plot(t, messageSignal); title('Message Signal'); xlabel('Time (s)'); ylabel('Amplitude'); subplot(3,1,2); plot(t, carrierSignal); title('Carrier Signal'); xlabel('Time (s)'); ylabel('Amplitude'); subplot(3,1,3); plot(t, pamSignal); title('PAM Signal'); xlabel('Time (s)'); ylabel('Amplitude'); web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

 

Pulse Amplitude Modulation (PAM) & Demodulation for Digital Data

% The code is written by SalimWireless.Com
clc;
clear;
close all;


% PAM Modulation and Demodulation Example


% Parameters
M = 8; % PAM order (8-PAM)
numSymbols = 100; % Number of symbols to transmit
Fs = 1000; % Sampling frequency
T = 1; % Symbol duration


% Generate random data
data = randi([0 M-1], 1, numSymbols); % Random data symbols


% PAM Modulation
% Map the data symbols to PAM levels
pamLevels = linspace(-M + 1, M - 1, M); % PAM levels
modulatedSignal = pamLevels(data + 1); % Map data to PAM levels


% Create a time vector
t = 0:1/Fs:T*numSymbols-1/Fs;


% Upsample and create PAM signal
upsampledSignal = zeros(1, length(t));
for i = 1:numSymbols
upsampledSignal((i-1)*Fs+1:i*Fs) = modulatedSignal(i);
end


% Add some noise
snr = 20; % Signal-to-noise ratio
noisySignal = awgn(upsampledSignal, snr, 'measured');


% PAM Demodulation
% Sample the noisy signal at symbol rate
receivedSymbols = noisySignal(1:Fs:end);


% Map received symbols to nearest PAM level
demodulatedData = zeros(1, numSymbols);
for i = 1:numSymbols
[~, demodulatedData(i)] = min(abs(receivedSymbols(i) - pamLevels));
end


% Plotting
figure;
subplot(4,1,1);
stem(data);
title('Original Data');
xlabel('Time (s)');
ylabel('Amplitude');


subplot(4,1,2);
plot(t, upsampledSignal);
title('Transmitted PAM Signal');
xlabel('Time (s)');
ylabel('Amplitude');


subplot(4,1,3);
plot(t, noisySignal);
title('Received Noisy PAM Signal');
xlabel('Time (s)');
ylabel('Amplitude');


subplot(4,1,4);
stem(demodulatedData);
title('Demodulated Data');
xlabel('Symbol Index');
ylabel('PAM Level');
grid on;


% Display results
disp('Original Data:');
disp(data);
disp('Demodulated Data:');
disp(demodulatedData);

web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

Output

Copy the MATLAB Code from here

% The code is written by SalimWireless.Com % The code is written by SalimWireless.Com clc; clear; close all; % PAM Modulation and Demodulation Example % Parameters M = 8; % PAM order (8-PAM) numSymbols = 100; % Number of symbols to transmit Fs = 1000; % Sampling frequency T = 1; % Symbol duration % Generate random data data = randi([0 M-1], 1, numSymbols); % Random data symbols % PAM Modulation % Map the data symbols to PAM levels pamLevels = linspace(-M + 1, M - 1, M); % PAM levels modulatedSignal = pamLevels(data + 1); % Map data to PAM levels % Create a time vector t = 0:1/Fs:T*numSymbols-1/Fs; % Upsample and create PAM signal upsampledSignal = zeros(1, length(t)); for i = 1:numSymbols upsampledSignal((i-1)*Fs+1:i*Fs) = modulatedSignal(i); end % Add some noise snr = 20; % Signal-to-noise ratio noisySignal = awgn(upsampledSignal, snr, 'measured'); % PAM Demodulation % Sample the noisy signal at symbol rate receivedSymbols = noisySignal(1:Fs:end); % Map received symbols to nearest PAM level demodulatedData = zeros(1, numSymbols); for i = 1:numSymbols [~, demodulatedData(i)] = min(abs(receivedSymbols(i) - pamLevels)); end % Plotting figure; subplot(4,1,1); stem(data); title('Original Data'); xlabel('Time (s)'); ylabel('Amplitude'); subplot(4,1,2); plot(t, upsampledSignal); title('Transmitted PAM Signal'); xlabel('Time (s)'); ylabel('Amplitude'); subplot(4,1,3); plot(t, noisySignal); title('Received Noisy PAM Signal'); xlabel('Time (s)'); ylabel('Amplitude'); subplot(4,1,4); stem(demodulatedData); title('Demodulated Data'); xlabel('Symbol Index'); ylabel('PAM Level'); grid on; % Display results disp('Original Data:'); disp(data); disp('Demodulated Data:'); disp(demodulatedData); web('https://www.salimwireless.com/search?q=pulse%20amplitude%20modulation', '-browser');

Simulation Results for comparison of PAM, PWM, PPM, DM, and PCM

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 PWM | PPM | DM | Quantization | PCM

Explore Signal Processing Simulations

Further Reading

1. Pulse Amplitude Modulation and Demodulation theory
2. Is PAM a Digital Modulation Technique ?
3. Pulse Width Modulation (PWM) and Demodulation
4. Pulse Position Modulation (PPM) and Demodulation
5. Delta Modulation and demodulation
6. Pulse Code Modulation (PCM)
7. Quantization Signal to Noise Ration (Q-SNR)
8. MATLAB Code for Pulse Width Modulation and Demodulation
9. MATLAB Code for Pulse Position Modulation (PPM) and Demodulation
10. MATLAB Code for Pulse Code Modulation (PCM) and demodulation