How to build a filter from frequency response

Hi, I have measurements of a system that is frequency selective (it has several cascaded filters). I would like to build an IIR (FIR is also possible) that has similar frequency response as the measurements. I don't have the group delay or phase information, however I know that there are few simple analog filters in the chain. Thanks, Alecs

Answer 1

[Honglei Chen]

You can use fdesign.arbmag to do this. The reference page has several examples.

http://www.mathworks.com/help/signal/ref/fdesign.arbmag.html

Answer 2

[Alecsander Eitan]

Thank you. It works but only for symmetric magnitude. I have shifted the filter to be around 0.5 and increased Fs by 2. It enabled asymmetric BPF. The only drawback I have is that since I use IIR filter, it is not possible to shift the filter back to 0, I have to shift the signal up and down. Bottom line: it works!