Raised Cosine Filter in Matlab

We are designing a raised cosine filter in Matlab. I have developed most of the logic for BPSK Transmitter but I could use a little help with finishing it out. Not really sure how to plot this in stem or in scatterplot.

close all; clear all;
% Design BPSK transmitter with the random data bits. 
M =  5;           % Modulation levels (Binary PSK)
k = log2(M);     % number of bits per symbol
N = 2e3;         % total number of random bits
sps = 4;         % number of samples per symbol
EbN0 = 10;       % Eb/N0 level in dB
iBits = rand(N, 1) > 0.5;     % generate random bits
bits = 2*iBits - 1;    % convert modulation symbols
% plot first fifty bits.
figure;
stem(    ); grid on; 
title('Random bits'); xlabel('samples'); ylabel('amplitude');
% Attach the plot here…
 
% plot constellation diagram
scatterplot(  ,1,0,'*r');grid on; 
% Attach the plot here…

[Walter Roberson]

bits50 = bits(1:50);
stem(bits50)

Answer 1

[Sriram Tadavarty]

Hi Nathan,

Access the vector bits from 1 to 50 elements and pass as the first argument of stem function.

Then, pass the bits directly to scatterplot.

So, the above code will be as below:

close all; clear all;
% Design BPSK transmitter with the random data bits. 
M =  5;           % Modulation levels (Binary PSK)
k = log2(M);     % number of bits per symbol
N = 2e3;         % total number of random bits
sps = 4;         % number of samples per symbol
EbN0 = 10;       % Eb/N0 level in dB
iBits = rand(N, 1) > 0.5;     % generate random bits
bits = 2*iBits - 1;    % convert modulation symbols
% plot first fifty bits.
figure;
stem(bits(1:50)); grid on; 
title('Random bits'); xlabel('samples'); ylabel('amplitude');
% Attach the plot here…
 
% plot constellation diagram
scatterplot( bits ,1,0,'*r');grid on; 
% Attach the plot here…

For more reference about usage of stem and scatterplot functions, go through these links:

https://www.mathworks.com/help/matlab/ref/stem.html

https://www.mathworks.com/help/comm/ref/scatterplot.html

Hope this helps.

Regards,

Sriram