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 _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
