% QPSK
M = 8;
k = log2(M); % Bits per symbol
EbNoVec = (5:15); % Eb/No values (dB)
numSymPerFrame = 1000; % Number of PSK symbols per frame
berEst = zeros(size(EbNoVec));
for n = 1:length(EbNoVec)
% Convert Eb/No to SNR
snrdB = EbNoVec(n) + 10*log10(k);
% Reset the error and bit counters
numErrs = 0;
numBits = 0;
while numErrs < 200 && numBits < 1e7
% Generate binary data and convert to symbols
data_in = randi([0 1],numSymPerFrame*k,1);
%----------------------------------------------------------------
% Your modulator here:
modSig = pskmod(data_in,M,InputType='bit'); % PSK Modulation
% Pass through AWGN channel:
rxSig = awgn(modSig, snrdB); % Additive White Gaussian Noise with
% increasing snrdB
% Your demodulator here:
data_out = pskdemod(rxSig,M,OutputType='bit'); % PSK Demodulation
%----------------------------------------------------------------
% Calculate the number of bit errors
nErrors = biterr(data_in,data_out);
numErrs = numErrs + nErrors;
numBits = numBits + numSymPerFrame*k;
end
% Estimate the BER
berEst(n) = numErrs/numBits;
fprintf("snrdB: %.6f berEst: %.6f " + ...
" \n \t numErrs: %d numBits: %d\n\n", snrdB, berEst(n), numErrs, numBits);
end
fitEbN0 = EbNoVec(1):0.25:EbNoVec(end); % Interpolation values
figure
yyaxis left
berfit(EbNoVec,berEst,fitEbN0);
yyaxis right
semilogy(EbNoVec, EbNoVec,'g-+')
figure
berfit(EbNoVec,berEst,fitEbN0);
hlgd = findobj(gcf, 'Type','legend');
hlgd.AutoUpdate = 'on';
hold on;
semilogy(EbNoVec, EbNoVec,'g-+', 'DisplayName','EbNoVec')
hold off;
ylim([min([berEst EbNoVec]) max([berEst EbNoVec])] .* [0.1 10])
get(hlgd) % Show Changed Legend Properties
To plot them on the same axes without using yyaxis, set the ylim limits to accommodate both sets of data. (There must be something about the berfit function that does not allow this to be the default.)
EDIT — (2 Mar 2024 at 14:47)
Added second plot and explanation.
EDIT — (2 Mar 2024 at 15:47)
Changed legend.
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