On Tue, 7 Oct 2008 07:13:45 -0700 (PDT), move <liubenyuan@[EMAIL PROTECTED]
>
wrote:
>Hi all:
>
>I want to implemnt the filter spec below using CIC + CICCOMP filter
>
>FS=5MHz, fp=9k, fst=10k, ap=0.1, ast=100, decimator=100
>
>I am using a Differential delay=50 and Number of sections=5 CIC filter
>and cascading a ciccomp filter which provide an extra 2 decimator. but
>the cic compensate filter
>
>fs=100k, fp=9k, fst=10k,ap=0.1,ast=100 D=2
>
>will take 404 taps to implement using equiripple method, the taps is
>too long for input data block which is only 200 samples a frame, so
>before next frame is coming, the filter is still full of unprocessed
>last frame data, this will cause the output of nextframe filter in-
>accurate.
>
>any suggestions?
>
>savor
Hi,
If you can get your hands on a copy, perhaps
the paper:
Kwentus, A., et al, "Application of Filter Sharpening to Cascaded
Integrator-comb Decimation Filters. IEEE Transactions on Signal
Processing, Vol. 45, Feb. 1997, pp. 457-467.
will help you flatten the passband of your CIC filter
so that you don't need so many taps in your
compensation filter.
You can learn about "filter sharpening" at:
http://www.dsprelated.com/showabstract/62.php
which is Chapter 1 of the
book "Streamlining Digital Signal Processing, a Tricks
of the Trade Guidebook" (published by Wiley & Sons and
the IEEE).
Just a thought.
Good Luck,
[-Rick-]
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