Effacer les filtres
Effacer les filtres

How to design an arbitrary phase flat magnitude FIR filter?

10 vues (au cours des 30 derniers jours)
Nathan Lively
Nathan Lively le 17 Fév 2022
I need to design an FIR filter with flat magnitude, but arbitrary phase. This seems like a pretty straight forward request, but I have searched through all of the FIR functions and cannot find anyting that will work. I most recently experimented with fdesign.arbmagnphase, but the results did not look correct. Plus, it gives me a design object when what I want are the FIR filter coefficients that I can export to a CSV file and load into a DSP.
If you'd like to try running the code, here's a link to download the phase variable below.
Fs = 192000;
magnitudeFlat = zeros(height(Fs),1);
phase = phaseA - phaseB; % The phase specification is based on the difference of two other responses.
% convert to complex vector
complexVector = @(mag_dB,phase_radians) [10.^(mag_dB/20) .* exp(1j*(phase_radians))];
Z = complex(magnitudeFlat,phaseDiff);
% design FIR filter
n = 2^12;
Nyq = Fs/2;
f = frequencyHz(1:Nyq) / Nyq; f(end)=1; % Normalize the last row to 1 since it's off by a tiny amount.
b = fir2(n,f,Z(1:Nyq)); % So far, this is the only FIR function I have found that will take in a complex array.
% plot filter kernel
semilogx(abs(fft(b))*2) % The resulting plot does not have flat magnitude.

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Nathan Lively
Nathan Lively le 19 Fév 2022
User error. I created use function complexVector, but was calling complex. ¯\_(ツ)_/¯

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