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Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver
From: |
Marcus D. Leech |
Subject: |
Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver |
Date: |
Sun, 11 Mar 2012 23:11:36 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
On 11/03/12 10:54 PM, Johnathan Corgan wrote:
> This is where I've run into a lot of issues. Too much gain, the lower
> end of the dynamic range is filled with IMD. Too little gain, the
> noise figure is too high. It's hard to get even 12 bits of ADC
> dynamic range in the presence of strong signals.
>
>
It's the "dirty little secret" of SDR--analog considerations continue to
be important. Although I suppose
with a direct-sampled 28-bit ADC running at a few Gsps, you'd have
enough dynamic range and oversampling
to cope with anything--as long as whatever gain stages you had in
front of the ADC would remain nice and
linear :-)
Some broadcast FM receivers (even analog ones) have a tracking filter in
the front end, to eliminate the
IMD problem before it becomes a problem. That eliminates the "broad
as a barn door" front-end issues.
I'm using the TVRX2, which uses the TDA18272 chip, which has a built-in
4-band band-select filter, so that
may improve things quite a bit in terms of keeping subsequent stages
linear.
--
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
- [Discuss-gnuradio] Sample audio from my FM stereo receiver, Marcus D. Leech, 2012/03/11
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Andrew Davis, 2012/03/11
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Marcus D. Leech, 2012/03/11
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Rafael Diniz, 2012/03/12
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, mleech, 2012/03/12
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Marcus D. Leech, 2012/03/12
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Marcus D. Leech, 2012/03/12
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Andrew Davis, 2012/03/12
- Re: [Discuss-gnuradio] Sample audio from my FM stereo receiver, Marcus D. Leech, 2012/03/12