True diversity would consist of a diplex transmission scheme (that's
'diplex' not 'duplex'). The sending station would transmit on two different
frequencies simultaneously, say 80M and 160M; the receiving station would
receive on both frequencies. Of course, separate antennas, transmitters,
receivers, et cetera, would be required. This technique helps to overcome
fading, QRM, QRN. We used this in the military with RTTY transmissions.
Another version of diversity (CW) reception was presented in one of the
ham radio magazines -- a stereo-type audio device was added to one's
receiver that would give the listener left and right channels in his
headphones. The article described how the received signal would
be separated into two sidebands on either side of the center frequency.
I'll see if I can find this fascinating article. The author of the article
said that once you copied CW in this manner, you'd never go back to mono
reception!
73, Jeff KH6O
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