I'm Andrea and this is my first post on DSPRelated.
I have a trouble that I can't solve.
I have a generic system whose output, in the frequency domain, has a module
proportional to the fourth power of angular frequency [ |.| proportional to w.^4
I have to build a FIR filter that compensates this phenomena. So the filter is a
sort of lowpass filter decaying with an inverse fourth power law.
I build up such a filter with the frequency sampling method (manual, not fir2),
but filtering the signal (sampled at 44100 Hz) I encounter some problems:
- filter's numer of taps must be a multiple of 1024 to have linear phase
- filtering the signal (with filter command) I obtain some unwanted zeros in the
frequency domain corresponding to the secondary lobes. But I can see these
secondary lobes only with a very high resolution FFT or FREQZ
- fir2 doesn't work (the ideal freq. response is very different from the
What I can do to solve?
Thank you very much,