Re: low-pass filter question
Re: low-pass filter question
- Subject: Re: low-pass filter question
- From: Todd Lipcon <email@hidden>
- Date: Tue, 10 Jan 2006 16:56:58 -0500 (EST)
On Tue, 10 Jan 2006, Dan Morgan wrote:
The problem is that the Apple low-pass filter has a response that is anything
but sharp. I set up a little test program that injected sine waves of
different frequencies and found that frequencies of half the cutoff were
being significantly attenuated and frequencies of double the cutoff had a
significant fraction passed. This is not acceptable behavior for the
intended application.
I'm not very familiar with the Apple low-pass filter, but this is pretty
usual for most audio low passes, rather than a brick wall DSP sort of LPF.
If you want the brick wall kind of filter, I'd look into doing an FFT,
setting the unwanted frequencies to 0, and then doing an IFFT to restore
to the time domain.
Hope that helps
-Todd
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