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Re: [Discuss-gnuradio] Filter delays and direction of time.
From: |
Achilleas Anastasopoulos |
Subject: |
Re: [Discuss-gnuradio] Filter delays and direction of time. |
Date: |
Thu, 20 Jan 2005 22:59:42 -0500 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) |
> Yes this is correct. If you're using a non-symmetric filter, you must
> reverse the taps before handing them to gr_fir_filter. For common
> cases, it doesn't matter because the taps are symmetric.
>
Eric,
I am not sure if tap reversal solves the problem:
suppose I want to implement a simple
filter that performes a delay by 2 samples.
The correct coefficients are [0,0,1].
However, gnuradio will return
y[k]=x[k+2]
which is not what i want.
If I reverse the coefficients, I get [1,0,0]
which when used in gnuradio will return
y[k]=x[k]
which is not what we want either.
Achilleas