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Re: [Discuss-gnuradio] gr_firdes cutoff frequency
From: |
Martin Braun |
Subject: |
Re: [Discuss-gnuradio] gr_firdes cutoff frequency |
Date: |
Mon, 12 Dec 2011 11:48:32 +0100 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
Hi Songsong,
the cutoff frequency is relative to the given sampling rate, whatever
that is. The firdes stuff doesn't know about the "true" sampling rate.
It's not uncommon to set the sampling rate to 1 and then have cutoff
somewhere in between 0 and 1.
MB
On Mon, Dec 12, 2011 at 02:53:07PM +0900, Songsong Gee wrote:
> I'm looking benchmark program and now found use of gr.firdes.low_pass:
>
>
> chan_coeffs = gr.firdes.low_pass (1.0, # gain
>
> sw_decim *
> self.samples_per_symbol(),
> # sampling rate
>
> 1.0, # cutoff
> frequency: midpoint of trans. band
>
> 0.5, # width of
> trans. band
>
> gr.firdes.WIN_HANN) # filter type
>
>
> I checked that low pass function in doxygen, and it says cutoff frequency has
> unit measure [Hz].
>
> Recalling above expression, it says that cutoff frequency is 1.0 Hz
>
> Is it right? Or is it a factor that is normalized to the sampling frequency?
>
>
> I'm asking about it because I want to use band_pass filter and I have no idea
> what value I have to choose for low/high cutoff frequency
>
>
> --
>
> Seokseong Jeon, PhD Candidate
>
> Communication & Networks Lab
>
> IT Convergence Engineering (ITCE), POSTECH, Korea
>
> +82 10 8338 1229, gee.songsong at gmail . com
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
--
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Dipl.-Ing. Martin Braun
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KIT -- University of the State of Baden-Württemberg and
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