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Re: [Discuss-gnuradio] some results about D8PSK (problems)


From: Stefan Brüns
Subject: Re: [Discuss-gnuradio] some results about D8PSK (problems)
Date: Thu, 19 Mar 2009 12:18:28 +0100
User-agent: KMail/1.9.9

Hi Bill,

I mentioned some problems with carrier offsets between different USRPs (or 
daughterboards, for RFX non-MIMO boards) when you reported on DBPSK. I found 
that error rate vastly improved when I factored the offset directly into the 
frequency arguments of the benchmark_{rx,tx}.py programs.

Although the costas loop should be able to deal with carrier offsets, as long 
as these stay in the allowed range, there is a bug in the mpsk receiver 
block, which leads to bad performance for larger offsets. Can you try the 
attached patch? (Lacking time to test it myself atm ...)

Stefan

On Wednesday 18 March 2009 22:19:50 Bill Stevenson wrote:
> ________________________________
> From: Bill Stevenson <address@hidden>
> To: Bill Stevenson <address@hidden>
> Sent: Wednesday, March 18, 2009 5:16:26 PM
> Subject: Re: [Discuss-gnuradio] some results about D8PSK (problems)
>
>
> Hello,
>
> I have searched the mailing list for the questions about D8PSK and also
> reviewed the README file for the benchmark_tx.py and benchmark_rx.py, it
> seemed that D8PSK could not work in a decent way like DQPSK or DBPSK on
> USRP now. Is that right? I have tried to find out the most appropriate
> values for --costas-loop and --gain-mu, but still found that 0.05 for the
> gain of loop filter and 0..001 for the gaim-mu  could make the PDR reach
> 100% with two USRPs seperated with very short distance. Other values for
> these two arguments would ruin the communication seriously. So the D8PSK
> could not work well on USRP???
>
> Thanks.
>
> Bill 




-- 
Stefan Brüns  /  Bergstraße 21  /  52062 Aachen
mailto:lurch at gmx.li  http://www.kawo1.rwth-aachen.de/~lurchi/
   phone: +49 241 53809034     mobile: +49 151 50412019

Attachment: mpsk_receiver_phase_jump.patch
Description: Text Data


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