Simulating transfer functions in MATLAB?

Greetings again!

Another feat I am trying to accomplish is to simulate a simple transfer function design given one signal that over samples another. Is there any way to do this is MATLAB? If so, how can this be done, and what information needs to be known before I start?

Thanks!

Answer 1

[Fangjun Jiang]

Not sure what is "given one signal that over samples another". Use tf() to define a transfer function, use step() to see the step response. From help tf and help step, you'll find many other functions through "See also".

[Andreas Goser]

Plus have a look into Simulink...

[Jesse]

Fangjun and Andreas, thanks for the reply.

I don't know if this is possible, but is there a way to construct a transfer function from a few columns of data from a data file?

Could you still use the tf function?

[Jesse]

Let me add to that last comment. Here's what I'm trying to do. I have 2 line plots from a data file on a single figure in MATLAB (Fangjun, we were discussing this yesterday). I'm trying to match one of the lines to the other via a transfer function. Is there a way to do that in MATLAB at all?

[Fangjun Jiang]

No! You can try-and-error, which means you guess a transfer function, plot its output to see if it matches and then you re-fine your guess. But there is no built-in function that can help you. The remotely related topic is the System Identification Toolbox. But that still requires you have a rough idea what the transfer function is like. The toolbox can help you to figure out the coefficients.

Answer 2

[Sean]

Hello Jesse,

Are the lines you are looking at linear? If they are sampled at different intervals/points, you could still do a linear regression to get the equations for each line. Then you could divide the equations to get a linear transfer function.

If they aren't linear, I think you could still do it, but it would be a lot more ornery. :)