main.m

clc;
clear;
close all;

% Start simulation
savepath = 'Assets/';

% Define signal properties
F = 1 * 10^3;
Fs = 40 * 10^3;
tStart = 0;
tStop = 0.01;
sigSNR = 20;
x_range = [-5 5];

% Define channel properties
SNR = 0 : 30;
record_SNR = 20;

% Define PCM properties
nBits = 1 : 48;
record_nBits = 8;

% Initialize the average error power matrix
y_avgerr_an = zeros(length(SNR), length(nBits));
y_avgerr_dg = zeros(length(SNR), length(nBits));

% Run for all SNR and nBits
for iSNR = 1 : length(SNR)
	for inBits = 1 : length(nBits)

		% Get the original signal
		[x_sig, t] = sig_lab1(F, Fs, sigSNR, tStart, tStop);
		
		% Pass it through AWGN channel to reciever side
		y_arcv = awgn(x_sig, SNR(iSNR));
		
		% Get the error power
		y_aerr = (y_arcv - x_sig) .^ 2;
		
		% Get the average error power
		y_avgerr_an(iSNR, inBits) = sum(y_aerr) / length(y_aerr);
		
		% Quantize the original signal
		x_qua = sig_quantize(x_sig, x_range, 2^nBits(inBits));
		
		% Encode the quantized signal
		x_enc = sig_encode(x_qua, nBits(inBits));
		
		% Pass the encoded signal through AWGN channel to reciever side
		y_drcv = awgn(x_enc, SNR(iSNR));
		
		% Decode the recieved signal
		y_dec = sig_decode(y_drcv, nBits(inBits));
		
		% Dequantize the recieved signal
		y_deq = sig_dequantize(y_dec, x_range, 2^nBits(inBits));
		
		% Get the error power
		y_derr = (y_deq - x_sig) .^ 2;
		
		% Get the average error power
		y_avgerr_dg(iSNR, inBits) = sum(y_derr) / length(y_derr);
		if(record_SNR == SNR(iSNR) && record_nBits == nBits(inBits))
			
			% Draw the original signal
			figure;
			
			% Get the time-domain plot of input signal
			subplot(2, 2, 1);
			plot(t, x_sig);
			xlim([tStart tStop]);
			ylim(x_range);
			title('Input Signal - x_sig(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% Get the frequency spectrum of input signal
			[Y_sigf, YF] = sig_freq(x_sig, Fs);
			subplot(2, 2, 2);
			plot(YF, abs(Y_sigf));
			title('Frequency spectrum of Input Signal - x_sig(t)');
			xlabel('Frequency (Hz)');
			ylabel('Amplitude');
			
			% Plot the recieved signal
			% The recieved signal
			subplot(2, 2, 3);
			plot(t, y_arcv);
			xlim([tStart tStop]);
			ylim(x_range);
			title('Recieved analog Signal - y_arcv(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% The error power signal
			subplot(2, 2, 4);
			plot(t, y_aerr);
			xlim([tStart tStop]);
			title('Error power for analog - y_aerr(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% Plot the pcm encoding signals
			figure;
			% The quantized signal
			subplot(2, 2, 1);
			plot(t, x_qua);
			xlim([tStart tStop]);
			ylim([-1 2^nBits(inBits)]);
			title('Quantized PCM Signal - x_qua(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% The encoded signal
			subplot(2, 2, 2);
			plot(x_enc);
			ylim([-1 2]);
			title('Encoded PCM Signal - x_enc(t)');
			xlabel('Bit sample number');
			ylabel('Bit Value');
			
			% The recieved signal
			subplot(2, 2, 3);
			plot(y_drcv);
			title('Recieved PCM Signal - y_drcv(t)');
			xlabel('Bit sample number');
			ylabel('Bit Value');
			
			% The decoded signal
			subplot(2, 2, 4);
			plot(t, y_dec);
			ylim([-1 2^nBits(inBits)]);
			title('Decoded PCM Signal - y_dec(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% Contd recieveing figure
			figure;
			% Get the quantized signal
			subplot(2, 1, 1);
			plot(t, y_deq);
			xlim([tStart tStop]);
			ylim(x_range);
			title('Dequantized PCM Signal - y_deq(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			
			% Get the error signal
			subplot(2, 1, 2);
			plot(t, y_derr);
			title('Error power for PCM - y_derr(t)');
			xlabel('Time (s)');
			ylabel('Amplitude');
			xlim([tStart tStop]);
			drawnow;
		end
	end
end

fig = figure;
for i = 1 : size(y_avgerr_an, 2)
	semilogy(SNR, y_avgerr_an(:, i), 'r');
	hold on;
	semilogy(SNR, y_avgerr_dg(:, i), 'b');
	ttl = sprintf('Bits - Variation of avg. error power (%f bits)', nBits(i));
	title(ttl);
	xlabel('SNR');
	ylabel('Avg. error power - log10');
	xlim([SNR(1) SNR(end)]);
	saveas(fig, [savepath ttl '.jpg']);
	clf(fig);
end

for i = 1 : size(y_avgerr_an, 1)
	semilogy(nBits, y_avgerr_an(i, :), 'r');
	hold on;
	semilogy(nBits, y_avgerr_dg(i, :), 'b');
	ttl = sprintf('SNR - Variation of avg. error power (%f SNR)', SNR(i));
	title(ttl);
	xlabel('No. of Bits');
	ylabel('Avg. error power - log10');
	xlim([nBits(1) nBits(end)]);
	saveas(fig, [savepath ttl '.jpg']);
	clf(fig);
end
close(fig);

figure;
surf(log10(y_avgerr_an), zeros(size(y_avgerr_an)));
hold on;
surf(log10(y_avgerr_dg), ones(size(y_avgerr_dg)));
ttl = 'Variation of avg. error power';
title(ttl);
ylabel('SNR');
xlabel('No. of bits');
zlabel('Avg. error power - log10');