[BC] Noise Free Radio

[Cowboy]

On Saturday 06 October 2007 12:52 pm, Dale Adkins-WINI wrote:
>  I've forgotten the details, but twenty or twenty-five years ago
>  George Yazell was promoting a project he called "Noise Free Radio"
>  in which you would frequency modulate  your AM carrier.
>  Can somebody relate what ever happened to the proposal?  

 For some reason, it died on the vine.
 ( too early, I suspect )

 'Twas a simple concept.
 FM the AM carrier some miniscule deviation.
 Transmitting is easy.

 At the receiver, multiply the AM carrier up by some large
 factor, such that the deviation was now about 75 khz, then mix
 that to produce an IF of 10.7 Mhz, and feed it into the normal
 FM if strip.
 Receiving, not so easy.

 Then, the whole idea has some challenges.
 What happens when the modulating frequency exceeds the deviation ?
 Part of the concept involved modulating FM an AM carrier with 15 Khz
 audio, but deviation of the carrier was something like 5 hz.

 To this day, methinks it could be done, but the technology for detecting
 the instantaneous rate of change of the rate of change of the instantaneous
 carrier phase just didn't exist with any reliability to function in the real world.

-- 
Cowboy