Your ideas are pretty good Bruce, but maybe i wasnt clear enough, this frequencies can apper at the same time. And there can even be more components in the signal, like voice.

Consider DTMF detection with uC but with these other frequencies, in fact these are the frequencies of multifrequency signaling. My guess is that this conventional procedures wouldn´t be as close to real as in your experiment. or Maybe not? i will anyway try.

Thanks