Sine wave signal stop time

Hi all,

I am generating a sine wave as shown below:

     Fs = 8000;                 
     dt = 1/Fs;                  
     t = 0: dt: 3;

     Fc = 320;                   % hertz
     x1 = sin(2*pi*Fc*t);

     plot(t,x1);

How can I make the sine wave stop after 2 seconds please?

[Geoff Hayes]

John - please clarify what you mean by wanting to make the sine wave stop after 2 seconds. Do you only want to show 2 seconds of data, and if so, then just initialize t as

 t = 0:dt:2-dt;

[John Smith]

Thanks for the reply. I want the graph to show a time period of 3 seconds but the sine wave to start from 0sec and stop at 2 sec. How can I achieve this please?

Answer 1

[Geoff Hayes]

John - just do as before but specify t as

 t = 0: dt: 2-dt;

Once you have called

 plot(t,x1);

you will see data from 0 to 2 seconds. To extend this to 3 seconds, just change the x-axis limits using

 xlim([0 3])

You will now have a time period from 0 to 3 seconds, but data for just 0 to 2.

[John Smith]

Thanks for the reply.

Answer 2

[KL]

     Fs = 8000;                 
     dt = 1/Fs;                  
     t1 = 0: dt: 2;
     t2 = 0*(2: dt : 3);
     t = [t1 t2];
     Fc = 320;                   % hertz
     x1 = sin(2*pi*Fc*t);
     plot(t,x1);

is this what you want?