Generate the following signals in Simulink

Good evening Matlab community. I am a bit new to simulink. I would like to know how to plot the function x(t)= 5*cos(30*pi*t+0.25*pi) using blocks. My attempt is below: but the output is all wrong. How do I plot this function? Am I supposed to use a constant source? the contents of my function block is in the other pic. I want a clear xy plot in the scope. Or do I use the xy plot block? I would appreciate any guidance thank you!

[Purushottama Rao]

Are u intended to use sine wave as the input for the function?? I feel that you are looking for a some kind of sine func defined by y. In that case 'u' should be time and a linearly increasing. Use a clock instead of a sine wave as the input to the function.

[Aaron Connell]

I see that worked thank you! How can I reduce the frequency of the output? is it a clock parameter or something that I set int he function block?

[Aaron Connell]

cause it cycles far too many times per second than I would like. I would want one cycle per second

[Aaron Connell]

I figured out how to zoom, but now the maximas and minimas look jagged or blocky...assuming this is numerical approximation? How can I smoth them?

[Purushottama Rao]

you can go for more sampling time by discretizing the model. Use a power gui block to do so.

[Aaron Connell]

Unsure how to do that. Would adding a zero order hold help?

[Purushottama Rao]

Include a powergui block in your model from library. In the powergui parameters, change the model to dicrete model and enter the sampling time such as 5e-5 or so.

[Aaron Connell]

didn't work, did I do it right?

[Purushottama Rao]

can u attach ur model??

[Aaron Connell]

it wont let me attach a .slx file

[Aaron Connell]

hold on let me dropbox it with a url

[Aaron Connell]

It is question 2 specifically, same issue for those two signals

http://www.filedropper.com/laba_1

[Purushottama Rao]

I was trying to replicate your model here. One trick for your problem is to use a gain block with unit gain in front of the function and Set the sampling time to the value entered in powergui.

[Aaron Connell]

okay let me try it out hold on, and thank you so much for your help!

[Aaron Connell]

added the gain block, so set the sampling time in which block?

[Purushottama Rao]

set the sampling time in the gin block parmeter.

[Aaron Connell]

ahh! My gain block does not have a sampling section underneath multiplication

[Purushottama Rao]

You can also use a zero order hold block in the same way. Dont forget to change the sampling time.

[Aaron Connell]

That did it! Thank you!!!!!

Answer 1

[Purushottama Rao]

Use a clock as an input in place of sine wave. To reduce the number of cycles you need to modify the function y. If you are looking for 1 cycle/second then use a function similar to y= 5*cos(2*pi*u+0.25*pi)