Thanks Jamie. It seems to me, the 15 or 20 khz tone can be imperfect, as long as it has no low-frequency component, right? There would certainly be harmonics and combinations with the audio signal but they would all be above this “carrier” frequency… right? so I’d be looking around the ham radio lists, etc., to build a little oscillator, with a low-cut filter…
I guess I’ll just try it and see. Even if this stupid thing creates some noise, it could hardly be worse than the roar of hyper-amplified background noise caused by the AGC. I’m not doing music or professional, paid productions. I am recording lectures and political speeches, where the audio is pretty lousy anyway.
