[GreenKeys] Space diversity receive antenna

[Harold Hallikainen]

I'm really having a problem with QSB. A received signal (20 meters) goes
from great to down in the noise over several seconds. As an experiment, I
transmitted both mark and space tones from here in Tucson AZ and received
them on the KFS SDR in Half Moon Bay CA. I then ran the recorded audio
into the DSP TU and output the levels of the mark and space filters. The
results are at
https://w6iwi.org/script/csvgraph.html?CsvUrl=https%3A%2F%2Fw6iwi.org%2Frtty%2FTuNotes%2Fms220517a.csv
.

This reminds me of a TV station where I lived in San Luis Obispo CA that
had a long microwave feed. They put two receive dishes on their tower and
had a carrier operated relay in the receiver start a slow astable
multivibrator that switched the receiver input between the two receive
dishes. The switching would stop when a good signal became present.

So, how about applying this to RTTY? I am using a 30 foot vertical for
transmit and receive. I could put up a 20 meters dipole about 50 feet
away. During receive, I could switch between these two antennae.

Is this worth trying? I could use signal strength indicated by the
receiver. Or I could use something from the terminal unit (such as switch
during mark hold).

Is anyone using space diversity? Comments?

Thanks!

Harold
https://w6iwi.org





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