# How to draw a pulse train

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Sadiq Akbar on 15 Mar 2022
Commented: Scott MacKenzie on 17 Mar 2022
I want to draw a pulse train in Matlab like the one shown blue in attached picture. The duration of each pulse is Tp and there are M=199 zeros in between two consective pulses. The PRI of the pulse train is 200Tp. Then I want to decompose each pulse into 7 small pulses of amplitude +1 and -1 (i.e., 1Tp=7Tc where Tc=28ns is the duration of small pulse) like shown white in the attached picture. Sadiq Akbar on 16 Mar 2022
I write a code that draws a square train. The code is as below:
clear all
clc
fy=100;
wy=2*pi*fy;
duy=0.02;
fs=20000;
dt=1/fs;
t=-(duy-dt):dt:(duy-dt);
A=1.5;
y=A*square(wy*t);
plot(t,y,'k')
axis([-duy duy -2.5 2.5])
xlabel('Seconds')
title('Square signal')
Now I want to replace each -ve pulse with M=199 zeros. Can anyboy help me how to do that?

Scott MacKenzie on 16 Mar 2022
Edited: Scott MacKenzie on 17 Mar 2022
It seems you want to replace the negative portion of the pulse with zeros. Like this, perhaps:
fy=100;
wy=2*pi*fy;
duy=0.02;
fs=20000;
dt=1/fs;
t=-(duy-dt):dt:(duy-dt);
A=1.5;
y=A*square(wy*t);
subplot(1,2,1);
plot(t,y,'k')
axis([-duy duy -2.5 2.5])
xlabel('Seconds')
title('Square signal')
subplot(1,2,2);
y(y<0)=0;
plot(t,y,'k')
axis([-duy duy -2.5 2.5])
xlabel('Seconds')
title('Square signal') Scott MacKenzie on 17 Mar 2022
You're welcome. Good luck.