Marcus,
Here's what I found, with a google image search, there are some interesting
images and discussions of the modulation techniques there with both block and
flow diagrams.
This one seems very interesting and probably makes it similar to what might
have to be done with gnuradio.
http://jsgil.mylinuxisp.com/AM-Stereo/QuadMod-4Way.gif
http://www.morpheustechnology.com/ebooks/Wireless/03%20Amplitude%20Modulation.htm
The basic idea behind the C-Quam modulator is actually quite simple. The output
stage is an ordinary AM modulator however; the carrier signal has been replaced
by an amplitude limited vector modulator. Therefore, the limiter output is
really a phase-modulated signal.
A standard AM receiver will detect the amplitude variations as L+R. A stereo
receiver will also detect the phase variations and to extract L‑R. It will then
process these signals to separate the left and right channels.
To enable the stereo decoder, a 25 Hz pilot tone is added to the L‑R channel.
Hope this helps.
Bruce
________________________________
From: Marcus D. Leech <mle...@ripnet.com>
To: discuss-gnuradio@gnu.org
Sent: Monday, March 24, 2014 5:11 PM
Subject: Re: [Discuss-gnuradio] AM Stereo TX? (Motorola C-QUAM)
On 03/24/2014 07:59 PM, Jordan Johnson wrote:
I have been Googling a good deal and have not come up with much. I have done
numerous projects with GNURadio, but while I can throw together a wideband AM
transmitter, I cannot figure out the stereo portion. Based on what I know; it
is some kind of phase-modulated information.
>
>
Anyone know how to get started on a flowgraph, or maybe some code examples?
>
>Thanks. :)
>
>
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I don't think I've ever heard of anyone making this query before. You should
probably start with whatever public documents describe the
Motorola system, and go from there.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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