Tried your matlab code. Looks like fine QPSK symbols to me. The absolute
phase reference is not zero but that should not affect DQPSK demodulation
since the last symbol is the phase reference for the current symbol.
Maybe you need to adjust phase based on pilot bins?
I would proceed to demodulating the bins to see if the data you recover
makes sense. There must be some regular structure to the data stream that
you can identify.
-Clark
From: Jens Elsner <[EMAIL PROTECTED]>
To: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] OFDM / DAB demodulation
Date: Sat, 1 Apr 2006 18:30:33 +0200
You are absolutely right - the matlab code is attached.
You can get my sample data (local radio station, 3 MBytes) from
http://www.1c3.de/dab_ml.dat.bz2.
Jens
On Sat, Apr 01, 2006 at 10:27:57AM -0500, Robert McGwier wrote:
> Why don't you allow us to provide you with help based on the reality as
> opposed to conjecture. Post your matlab scripts. This "remote viewing"
> exercise is inefficient.
>
>
> Bob
>
>
>
> Jens Elsner wrote:
> >I resampled all the data to do a proof-of-concept. The frames are only
a
> >small part
> >of the "chunk" variable. What I am getting is a fairly nice pi/4 DPSK.
> >Only that
> >in between OFDM Symbols (there are 76 in a frame) there is some sort of
> >random
> >phase jitter. And I am clueless what it could be. Frequency offset is
> >compensated,
> >the channel doesnt vary that fast.
> >
> >Jens
> >
> >
>
>
> --
> AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
> NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
> Laziness is the number one inspiration for ingenuity. Guilty as
charged!
>
<< dabtest_ml.m >>
<< prs.m >>
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