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Re: [Discuss-gnuradio] Amateur television ATV

From: Lamar Owen
Subject: Re: [Discuss-gnuradio] Amateur television ATV
Date: Wed, 26 Apr 2006 16:14:01 -0400
User-agent: KMail/1.9.1

On Wednesday 26 April 2006 14:03, Matt Ettus wrote:
> Matteo Campanella wrote:
> > hello, In the case of atv, as I believe the passband of the signal is
> > way too large for the throughput of usrp usb, are there any special
> > techniques/tricks to achieve some sort of result?
> I believe that most ATV is AM (almost 12 MHz) instead of VSB (6 MHz).
> If that is true, then you could do an AM demodulation in the FPGA pretty
> easily.  You would tune the picture carrier to the center of the
> passband.  Of course, the TVRX filters are only 6 MHz wide, so you'd
> lost the high frequency content of the signal, and probably the sound
> carrier.

If it's true DSB AM, then just tune to one side, filtering out one sideband, 
and treat it as single sideband.  Would want to watch out for aliasing, of 
course, from the rejected sideband.  Unless you're real good, and set it so 
that the aliased sideband folds into the passband perfectly... :-)  the 
sidebands are, after all, identical in AM.
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772

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