Curve fitting: Arbitrary frequency response using DSP

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Hi,

For DSP (ADAU1701 or Jriver) that can implement IIR filters, how does one convert arbitrary frequency response curves into corresponding IIR filters? Is there any open source tool that can convert between the IIR filter and frequency response and vice versa?

Thanks and Regards,
WA
 
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I don't know the answer for IIR filters, but with a FIR you can just take the inverse DFT of the response you like to get and taper it off. For phase-linear FIR filters you can use a program Parks and McClellan published in the early 1970's. I can send you the FORTRAN code if you like, modified to work under gfortran.
 
If you're using SigmaStudio look at the Auto-EQ control. You can import your measured FR or IR and and then create your own target response or pick from a list of crossover slopes (ie "Target from Filters" option). They are IIR filters, although SigmaStudio does have a FIR control too (haven't used that one).
 
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