Re: [Discuss-gnuradio] OFDM / DAB demodulation

[Clark Pope]

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 <address@hidden>
> To: address@hidden
> 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 >>


> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/