On Mon,8/3/2015 8:41 PM, Edward R Cole wrote:
However it is not always bad for the two diversity channels to be combined for best signal. The example is digital signals which the human brain cannot process. The example was given of using two antennas of differing polarity for HF.
Combining, yes -- into different inputs of the analysis system. Again, when signals combine IN THE SAME SIGNAL CHANNEL (emphasis added) differences in the time/phase response of the two signal paths can cause destructive interference which degrades decoding.
OTOH, in a sophisticated decoding system, there's certainly nothing wrong with bring both signals in on separate inputs, then combining them, or choosing the best signal, or even processing the signals to enhance readability. But ONLY combining them on a single electrical channel is a bad idea.
One of my neighbors (near Santa Cruz) has a VERY interesting UHF repeater system. It's multi-site(five sites going on six),voted (meaning that the RX with the best signal is transmitted), and simulcast (all sites transmit at the same time). To make this work, Bboth audio and RF are synchronized to the Hz using a GPS reference and some really innovative use of low cost audio and networking gear. If you're interested, look at wb6ece.org, especially the Technical Info page, where there's video and audio of a talk that KA6SQG did at Pacificon about his system (WB6ECE is his dad's call). The audio is not well recorded, so you'll need headphones for good copy.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
