Question

I need the code written in Matlab software to send a number of bits using the Pulse Shape Modulation, and demodulate the signal using the correlation coefficient. The part that i need to modified is the part that is in Bold. The two functions are : function [outSignals,time] = modulation(inBits) and function [outBits] = demodulation(inSignals).

%% Main Function

function runComm_code()

    clear;clc;

  SNRdB = 0:0.5:26;

    nBits = 1e6;

    SNRdBLength = length(SNRdB);

    Pe = ones(1,SNRdBLength);

    clc; disp('Simulation running: 0.0% completed.');

    for i = 1:SNRdBLength

        Pe(i) = transmitReceive(nBits,SNRdB(i));

        clc;fprintf('%s: %.1f%% completed','Simulation running',i/SNRdBLength*100);

    end

    hold on; semilogy(SNRdB,Pe); grid on;

    clc; disp('Simulation finished.');

return

%% Bit Transmission Function

function [Perror,nErrors,TxBits,RxBits] = transmitReceive(nBits,SNRdB)

%     TxBits = [0 1 1 0 1 0 0 1 1 1];

    nBitsMax = 100000;

    nBitsOrig = nBits;

    TxBits = [];

    RxBits =[];

    if(nBits > nBitsMax)

        n = ceil(nBits/nBitsMax);

        nErrorsArr = zeros(1,n);

        for i = 1:n

            if(nBits < nBitsMax)

                [~,nErrorsArr(i),TxBitsTmp,RxBitsTmp] = transmitReceive(nBits,SNRdB);

                TxBits = [TxBits,TxBitsTmp];

                RxBits = [RxBits,RxBitsTmp];

                break;

            else

                [~,nErrorsArr(i),TxBitsTmp,RxBitsTmp] = transmitReceive(nBitsMax,SNRdB);

                TxBits = [TxBits,TxBitsTmp];

                RxBits = [RxBits,RxBitsTmp];

                nBits = nBits - nBitsMax;

            end           

        end

        nErrors = sum(nErrorsArr);

        Perror = nErrors/nBitsOrig;

        return;

    end

       

    TxBits = round(rand(1,nBits));

    TxSignals = modulation(TxBits);

    [RxSignals] = addAWGNoise(TxSignals,SNRdB);

    RxBits = demodulation(RxSignals);

    errorBits = TxBits ~= RxBits;

    nErrors = sum(errorBits);   

    Perror = nErrors/nBits;

   

return

%% Modulation and Demodulation Functions

function [outSignals,time] = modulation(inBits)

    % This code is for On-Off Keying (OOK) modulation

    % You need to substitute this with your own Matlab code according

    % to your assigned modulation scheme.

    pulseWidth = 1e-9;

    timeWindow = 10.5e-9;

    carrierFreq = 4e9;

   

    signalBW = 1.5/pulseWidth;

    osFactor = 1 + carrierFreq/signalBW;

   

   [signal1,time] = pulseSignal(pulseWidth,timeWindow,osFactor);

    signal1 = signal1.*squareSignal(time,carrierFreq);

    signalLength = length(signal1);

    signal0 = zeros(signalLength,1);

   

    inBits = inBits(:)';

    nBits = length(inBits);

    outSignals = zeros(signalLength,nBits);

    col0 = inBits == 0;

    col1 = inBits == 1;

    outSignals(:,col0) = repmat(signal0,1,sum(col0));

    outSignals(:,col1) = repmat(signal1,1,sum(col1));

return

function [outBits] = demodulation(inSignals)

   

    % This code is for On-Off Keying (OOK) modulation

    % You need to substitute this with your own Matlab code according

    % to your assigned modulation scheme.

    SNRmin = 10^(12/10);

    Ps = sum(modulation(1).^2);

    Po = Ps./SNRmin;

   

    Psignals = sum(inSignals.^2);

    outBits = Psignals > Po;   

return

%% Noise Adding Function

function [outSignals,noiseSignals] = addAWGNoise(signals,SNRdB)

    signalsSize = size(signals);

    SNR = 10^(SNRdB/10);

    Ps = max(sum(signals.^2));

    Po = Ps./SNR;

    noiseSignals = sqrt(Po/2).*randn(signalsSize(1),signalsSize(2));

    outSignals = signals+noiseSignals;

return

%% Signal Creation Functions

function [outSignal,time] = pulseSignal(Tp,Tw,osFactor)

    if(nargin == 2), osFactor = 1; end

    if(osFactor < 1), osFactor = 1; end

    B = 1.5/Tp;

    fs = osFactor*2*B;

    Nw = ceil(fs*Tw);

    Np = ceil(fs*Tp);

    outSignal = [0; ones(Np,1); zeros(Nw-Np-1,1)];

    outSignal(end)=0;

    time = (0:length(outSignal)-1)'/fs;

return

function [outSignal] = squareSignal(time,freq)

    tsample = time(2)-time(1);

    tperiod = 1/freq;

    n = ceil(tperiod/tsample);

    npos = ceil(n/2);

    nneg = n - npos;

    Nperiods = ceil(time(end)*freq);

    signalTmp = [ones(npos,1); -1*ones(nneg,1)];

    outSignal = repmat(signalTmp,Nperiods+1,1);

    outSignal = [ 0; outSignal(1:length(time)-1) ];

return

Answer 1

function [y Bitrate MSE Stepsize QNoise]=pcm(A,fm,fs,n)
	%A=amplitute of cosine signal
	%fm=frequency of cosine signal
	%fs=sampling frequency
	%n= number of bits per sample
	%MSE=Mean Squar error, QNoise=Quantization Noise
	%Example [y Bitrate MSE Stepsize QNoise]=pcm(2,3,20,3)
	%If you have any problem or feedback please contact me @
	%%===============================================
	% NIKESH BAJAJ
	% Asst. Prof., Lovely Professional University, India
	% Almameter: Aligarh Muslim University, India
	%%===============================================
	t=0:1/(100*fm):1;
	x=A*cos(2*pi*fm*t);
	%---Sampling-----
	ts=0:1/fs:1;
	xs=A*cos(2*pi*fm*ts);
	%xs Sampled signal
	%--Quantization---
	x1=xs+A;
	x1=x1/(2*A);
	L=(-1+2^n); % Levels
	x1=L*x1;
	xq=round(x1);
	r=xq/L;
	r=2*A*r;
	r=r-A;
	%r quantized signal
	%----Encoding---
	y=[];
	for i=1:length(xq)
	d=dec2bin(xq(i),n);
	y=[y double(d)-48];
	end
	%Calculations
	MSE=sum((xs-r).^2)/length(x);
	Bitrate=n*fs;
	Stepsize=2*A/L;
	QNoise=((Stepsize)^2)/12;
	figure(1)
	plot(t,x,'linewidth',2)
	title('Sampling')
	ylabel('Amplitute')
	xlabel('Time t(in sec)')
	hold on
	stem(ts,xs,'r','linewidth',2)
	hold off
	legend('Original Signal','Sampled Signal');
	figure(2)
	stem(ts,x1,'linewidth',2)
	title('Quantization')
	ylabel('Levels L')
	hold on
	stem(ts,xq,'r','linewidth',2)
	plot(ts,xq,'--r')
	plot(t,(x+A)*L/(2*A),'--b')
	grid
	hold off
	legend('Sampled Signal','Quantized Signal');
	figure(3)
	stairs([y y(length(y))],'linewidth',2)
	title('Encoding')
	ylabel('Binary Signal')
	xlabel('bits')
	axis([0 length(y) -1 2])
	grid