Re: Re[Discuss-gnuradio] sampling precision

[Martin Braun]

On Fri, Jul 04, 2008 at 07:52:56AM -0700, irene159 wrote:
> Can someone give me more informations on the "rational_bw" parameter?

I apologise for not answering the actual question. This parameter
controls how wide the transition band for the interpolation filter can
be and depends on the oversampling of your original signal.

Say you are resampling by factor 2/3 (i.e. your sampling rate becomes
smaller in the process). Say your signal is fairly narrow band, and even
with 2/3 the sampling rate, the highest available frequency is only 1/4
of your sampling frequency. Then you can have a fairly wide transition
width (rational_bw = 0.25). If you don't know anything about your
signal, you must set rational_bw close to 0.5 to allow as many frequencies
as possible, but that results in higher filter complexity.


> Are there any files using resampling function that I can take a look at?

Sure, loads. Just search through the examples.

-- 
Martin Braun
Institut fuer Nachrichtentechnik
Universitaet Karlsruhe

http://www.int.uni-karlsruhe.de

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