[GreenKeys] Space diversity receive antenna

[Richard Knoppow]

    There is a good deal of information in the technical literature. 
Space diversity and polarity diversity was very widely used in HF 
communications. Also, many microwave links used polarity diversity. The 
problem is that antennas are large.

On 1/4/2025 9:29 AM, Harold Hallikainen via GreenKeys wrote:
> 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
> 
> 
> 
> 
> 

-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998