Re: [Scilab-users] Plotting properties of digital audio filters

[fred_audio_dsp]

Hi Rafael, 

Would you mind sharing the code that produced these plots, or hinting at the
method? 

Regards 



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Re: [Scilab-users] Plotting properties of digital audio filters

[fred_audio_dsp]

Hi,

By making the FFT size of the form 2*2^x, I managed to get more of an
expected result.

Still the phase response of the filters I analyze drops off to -180°
unexpectedly, as illustrated in the plot below (without frequency vector
applied because I'm just testing). This is a peak filter, -3dB@500Hz, Q=1.
Note that any kind of phase unwrapping did not produce any different result.

 

I have included a zip file of the captured impulse response.
response.zip   

Regards,

Frederik



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Re: [Scilab-users] Plotting properties of digital audio filters

[fred_audio_dsp]

Hi Rafael,

Thank you very kindly for your assistance so far!

If I understand correctly, the unwrap() macro quoted in your message has
been part of Scilab since somewhere in 2014, am I wrong?

Using scilab's phasemag() macro as suggested, I get the exact same output as
when plotting the phase with the code posted in my first message:

phi=(atan(imag(A),real(A)))*180/%pi


Kind regards,

Frederik



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Re: [Scilab-users] Plotting properties of digital audio filters

[fred_audio_dsp]

Hi Rafael,

Thank you for your reply. I have tried unwrapping the phase for the 24dB/oct
low pass filter at 1kHz with scilab's unwrap() function. Plots included
below; I scaled the frequency axis linearily to better show what's going on.

without unwrap()
 

with unwrap()
 

Kind regards,

Frederik



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