# Raised Cosine Filter in Matlab

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Nathan Jaqua on 15 Mar 2020
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…

#### 1 Comment

Walter Roberson on 15 Mar 2020
bits50 = bits(1:50);
stem(bits50)

Sriram Tadavarty on 15 Mar 2020
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:
Hope this helps.
Regards,
Sriram