Part2_BPSK.m

function errorRate = Part2_BPSK(SNR, showFigures)

% To run function type in the following commands in command prompt
% Part2_BPSK(5, 0) => Provides error rate for OOK with SNR 5 without figures
% Part2_BPSK(5, 1) => Provides error rate for OOK with SNR 5 with figures

SIZE = 1024; %Number of bits to be transmitted
originalData= randi([0 1],1,SIZE); % This generates an array of random binary numbers

Fc = 10000; %Carrier Frequency
Fs = Fc * 4; %Sampling Frequency
index = 1:500; %Output Range

dataRate = 1000; %Number of bits transfered per second
numberOfSamplesPerBit =  round(Fs/dataRate); %Number of samples per bit
totalNumberOfSamples = round(Fs*SIZE/dataRate); %Total Number of samples to be modulated

if(showFigures)
    figure();
    noOfData = ceil(length(index)/numberOfSamplesPerBit);
    stairs(originalData(1:noOfData));
    title('Data Wave Form');
    ylim([-2 2]);
    xlim([1 noOfData]); 
end

%Signal (-1,1) generated from random original signal (0,1)
signal = DataToSignalGeneration(originalData, SIZE);

%Initialization of Carrier Signal with an array of zeros
carrierSignal = zeros(1,totalNumberOfSamples);
Loop = 1;

%Loop to obtain sampled cosined values as carrier signal
while(Loop<=totalNumberOfSamples)
    carrierSignal(Loop) = 2*pi*(Fc/Fs)*(Loop-1) + pi/2;
    Loop = Loop+1;
end


%Multiplication of carrier signal with input signal
replicatedData = repelem(originalData,numberOfSamplesPerBit);
additionalPhase = pi*(replicatedData+1);
modulatedSignal = cos(carrierSignal + additionalPhase);

%disp(modulatedSignal);

if(showFigures)
    figure();
    plot(index,modulatedSignal(index));
    title('Modulated Signal');
end

%To generate artificial noise to be added with the modulated signal
noisySignal = NoisySignalGeneration(modulatedSignal, totalNumberOfSamples, SNR);

if(showFigures)
    figure();
    plot(index,noisySignal(index));
    title('Receieved Signal');
end

%To Obtain demodulated signal by multiplying with twice the carrier signal
demodulatedSignal = (2*cos(carrierSignal)).*noisySignal;

if(showFigures)
    figure();
    plot(index,demodulatedSignal(index));
    title('Demodulated Signal');
end

%To generate a low pass butterworth 6th order filter and obtain filtered signal with
%cutoff frequecy of 0.2
[b,a] = butter(6,0.2);
filteredSignal = filtfilt(b,a,demodulatedSignal);

if(showFigures)
    figure();
    plot(index,filteredSignal(index));
    title('Filtered Signal')
end

%Obtain midpoints from recieved filtered signal
receivedData = filteredSignal(numberOfSamplesPerBit/2:numberOfSamplesPerBit:totalNumberOfSamples);

%Use threshold logic to decode the received signal by setting threshold to 0.5
decodedData = DataDecoding(receivedData, SIZE, 0,[-1,1]);

if(showFigures)
    figure();
    noOfData = ceil(length(index)/numberOfSamplesPerBit);
    stairs(decodedData(1:noOfData));
    title("Decoded Data");
    ylim([-2 2]);
    xlim([1 noOfData]); 
end

%Calculate the bit error rate
errorRate = ErrorRate(signal,decodedData, SIZE);

end