# AM Stereo TX? (Motorola C-QUAM) **URL:** \ **Category:** GNU Radio\ **Created:** [March 25, 2014, 1:00am UTC](https://www.ruby-forum.com/t/am-stereo-tx-motorola-c-quam/240021 "2014-03-25T01:00:48Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [March 25, 2014, 1:00am UTC](https://www.ruby-forum.com/t/am-stereo-tx-motorola-c-quam/240021/1 "2014-03-25T01:00:48Z")
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. 🙂 ---
**Author:** ![jowijo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e95f7d/32.png) [@jowijo](https://www.ruby-forum.com/u/jowijo)\ **Post date:** [March 25, 2014, 1:13am UTC](https://www.ruby-forum.com/t/am-stereo-tx-motorola-c-quam/240021/2 "2014-03-25T01:13:40Z")
On 03/24/2014 07:59 PM, Jordan J. wrote: > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) > 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. ---
**Author:** ![jowijo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e95f7d/32.png) [@jowijo](https://www.ruby-forum.com/u/jowijo)\ **Post date:** [March 25, 2014, 2:34am UTC](https://www.ruby-forum.com/t/am-stereo-tx-motorola-c-quam/240021/3 "2014-03-25T02:34:15Z")
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://jsgil.mylinuxisp.com/AM-Stereo/QuadMod-4Way.gif) [http://www.morpheustechnology.com/ebooks/Wireless/03%20Amplitude%20Modulation.htm](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 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) To: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) 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 J. 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. 🙂 * * * Discuss-gnuradio mailing list [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) 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 L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami.