I use diversity (vertically and horizontally polarized antennas) on CW a
lot, and there's more to it than just selecting the louder signal. I
can't put my finger on the precise mechanism, but it seems that CW
characters are less prone to being damaged by bursts of QRN in diversity
mode.
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/
On 4 Aug 2015 07:32, Jim Brown wrote:
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
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