[Numpy-discussion] Q: Use of scipy.signal.bilinear

R Schumacher rays at blue-cove.com
Tue Dec 8 11:30:44 EST 2015


We have a function which describes a frequency response correction to 
piezo devices we use. To flatten the FFT, it is similar to:
Cdis_t = .5
N = 8192
for n in range(8192):
   B3 = n * 2560 / N
   Fc(n) = 1 / ((B3/((1/(Cdis_t*2*pi))**2+B3**2)**0.5)*(-0.01*log(B3) 
+ 1.04145))

In practice it really only matters for low frequencies.

I suggested that we might be able to do a time domain correction as a 
forward-reverse FFT filter using the function, but another said it 
can also be applied in the time domain using a bilinear transform.
So, can one use
http://docs.scipy.org/doc/scipy-0.16.0/reference/generated/scipy.signal.bilinear.html
and, how does one generate b,a from the given Fourrier domain 
flattening function?

I'd guess someone here has done this...

- Ray




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