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[Discuss-gnuradio] Re: FSK now (really) working at 100kbit/sec

From: Deqiang chen
Subject: [Discuss-gnuradio] Re: FSK now (really) working at 100kbit/sec
Date: Fri, 15 Apr 2005 15:37:27 +0000

hello, Eric,

I remembered there is an annoucement that FSK can work at 100kbps.
So I dig it out and take a look at the source code for the FSK ( fsk_rx.py) . I am a little surprised that there are no time recovery there. My understanding is that for fsk, if you
use noncoherent demodulation, you would not need the phase information.
However, you still need to know the timing in order to correctly sampling
the output of correlator or matched filter.
Could you give a hint of what is going on here ?


Re: [Discuss-gnuradio] Re: FSK now (really) working at 100kbit/sec
From:   Eric Blossom
Subject:        Re: [Discuss-gnuradio] Re: FSK now (really) working at 
Date:   Tue, 1 Mar 2005 14:34:21 -0800
User-agent:     Mutt/1.5.6i

On Tue, Mar 01, 2005 at 10:53:10PM +0100, Stephane Fillod wrote:
On Mon, Feb 28, 2005 at 03:59:00AM -0800, Eric Blossom wrote:

> The primary bottleneck is in the rx path and is in the generic (C++)
> implemenation of gr_fir_ccf.   We could use a SIMD version
> of this filter primitive (and/or a smarter demod implementation).

gr_fir_ccf with SIMD is an easy one. Basically, it's like a FCC
but with input and taps swapped at the dotprod level. IOW, the SIMD
assembly is written already, and we just need the API glue and qa stuff.
If nobody does it, I'll look at it once I get the usrp going on

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