Plotting the convolution of two signals

Dennis (view profile)

on 23 Oct 2014
Latest activity Commented on by Celeste MacNeil

on 14 Oct 2018

Rick Rosson (view profile)

I am given two functions x(t) =5[u(t+1)-u(t-1)] and h(t)=u(t-1)-u(t-7). I am asked to convolve these two signals and plot the result in the range -3 to 10. Here is the code that I wrote:
t=-3:0.1:10; t_c=-3:0.05:10; h_t=heaviside(t-1)-heaviside(t-7); x_t1=5.*(heaviside(t+1)-heaviside(t-1)); c_x_h=conv(x_t1,h_t); figure(1) plot(t_c,c_x_h)
However, since this is a simple convolution I verified it by hand and it does not look like the plot i get in MATLAB. The max value should be 10 but in MATLAB i get 100. Also, the duration of the function should be 8 but i get 4 with MATLAB. Please help.

Rick Rosson (view profile)

on 23 Oct 2014

t_c = -6:0.1:20;
and:
dt = t(2) - t(1);
c_x_h = dt*conv(x_t1,h_t);

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Baiyu Zhang

Baiyu Zhang (view profile)

on 28 Jun 2018
What is dt = t(2)-t(1)? What does it mean?
Celeste MacNeil

Celeste MacNeil (view profile)

on 14 Oct 2018
What do you mean dt = t(2)-t(1)?
Celeste MacNeil

Celeste MacNeil (view profile)

on 14 Oct 2018
I assume you just mean the step?

IKRAM jebali (view profile)

on 31 Mar 2017

Hello! Thank you. I'had the same problem. Me too amnclear as to why the dt is needed though and why t_c needed to be extended to -6 to 20. I use it but i don't know why? There is any answer please. Thank you.

1 Comment

Aswin Farzana Mohamed Ansar

Aswin Farzana Mohamed Ansar (view profile)

on 20 Oct 2017
Because the length of the convolution of two matrices of ,length m and n will be m+n-1. inorder to get the same vector size, you need to do this.