Max Power wrote:
AM radio multiplexing question: transmitting SSB in sync with AM (numbers
stations, clandestine broadcasting)

I understand that it is possible to multiplex SSB transmissions on top of AM
transmissions, especially on SW.
The AM transmission is decoded by the envelope or PLL coherer, the SSB
transmission is ignored.

On a properly tuned SSB receiver, the AM transmission only partially
interferes with the SSB transmission.

Doesn't make sense to me. The SSB signal *will* be decoded by the AM
detector, even if it isn't intelligible. There will be mutual interference.

A common multiplexing technique is to use an AM signal where the upper
and lower sidebands carry different modulation. On a regular AM
receiver you'll hear a mix of both programs, but if you use an
appropriate filter (commonly found in SSB receivers) you can select
either program without interference.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com