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From: | Landsman, Arik |
Subject: | Re: [Discuss-gnuradio] non-diff QPSK symbol sync, improper alignemnt/errors using real msg |
Date: | Thu, 18 Feb 2016 20:19:27 +0000 |
Hi Rich,
Thank you for your reply. Let me mention right away that the problem here was embarrassingly simple: I had endinannes set to LSB, changing to MSB fixed the issue.. But to answer your question, while in debug mode the mod is directly connected to the demod. So no phase error, hence I unplugged costas for the time being. In a real case, which worked ok in 3.6.x with a psudo-random stream and N210's, I had the following: rx in -- power squelch -- agc -- FLL -- PPCS -- CMA equalizer -- Costas -- demod -- filesink This does not fix the costas phase ambiguity, but certain corrected most channel offsets. so I am still at odds as to how to correct sudden constel rotations. maybe a short training symbol, adjusting costas output in pi/2 increments (qpsk). in fact the data is there, just needs to be decoded again with the right phase rotation. I'll post in a separate thread once I poke a bit more. And any ideas are welcome of course... Thanks, Arik From: Richard Bell address@hidden
Sent: Thursday, February 18, 2016 12:58 PM To: Landsman, Arik Cc: address@hidden Subject: Re: [Discuss-gnuradio] non-diff QPSK symbol sync, improper alignemnt/errors using real msg What are you doing to handle the phase ambiguity that diff encoding is intended to fix?
RichOn Wed, Feb 17, 2016 at 2:35 PM, Landsman, Arik
<address@hidden> wrote:
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