Plot the signals y(t)=sin(8πt) and g(t)=sin(18πt). Then sample both with a sampling period of 1/13s. Sketch the discrete signals. What do you observe?

I was given this problem and so far, this is what I've done

t = [0:0.1:13]
y = sin(8*pi*t);
g = sin(18*pi*t)
plot(t,y,'color','r'); hold on;
plot(t,g,'color','b');

What I'm really confused on is the sampling period and sketching the discrete signals. Did I implement the sampling time correctly in t? Is there a way to create a discrete signal?

Thank you.

Answer 1

[J. Webster]

Since t is an array, and you want y and g to be arrays, you need to use the . notation for operations...

so for example, replace

18*pi*t 
with
18.*pi.*t

Answer 2

[Star Strider]

The ‘1/13s’ I believe should be the step in your ‘t’ vector.

This is how I interpret the problem:

tlim = 1;
tc = linspace(0, tlim, 250);
t = [0:(1/13):tlim];
y = @(t) sin(8*pi*t);
g = @(t) sin(18*pi*t);

figure(1)
subplot(2,1,1)
plot(tc,y(tc),'-r',  tc,g(tc),'-b'); 
grid

subplot(2,1,2)
plot(t,y(t),'-r',  t,g(t),'-b');
grid

That’s an impressive illustration of the phenomenon the problem is asking you to observe. (I made ‘y’ and ‘g’ anonymous functions for convenience.)

Answer 3

[Azzi Abdelmalek]

Use stem function instead plot function