Re: questions on FFT
- From: "Andor" <andor.bariska@xxxxxxxxx>
- Date: 30 Mar 2006 10:41:05 -0800
jeffxia wrote:
....
3. Suppose I have N samples in time domain and the time interval is t. I
want to remove its low frequency components. So I desigh a K order FIR
highpass filter. The length of the resulting signal is N+K-1. Does the
time interval is still meaningful in the resulting signal? What if I still
want to keep N samples of the resulting data?
Let's say you have two polynomials, one with degree N and the other
with degree K. You multiply them together, the new polynomial has
degree N+K. Can you throw away some terms to make it have degree N?
Obviously, if N is the number of samples on a CD, and K is a
third-order difference filter, then you won't lose too much information
if you truncate the filtered output back to N samples.
If you have to, make sure that you throw away the right part of the
output signal (this depends on whether your FIR is linear- or
minimum-phase or none of the above).
Regards,
Andor
.
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