[amsat-bb] Polarization (attitude mostly)

Robert Bruninga bruninga at usna.edu
Wed Jun 1 16:11:01 UTC 2016

Having the RHCP/LHCP switch is better than not having it since it gives
you one more ace in the hole.  Sure, it might only  provide true value for
a few seconds due to all the other variables, but when it occurs, it is
nice to have for such high visibility events (especially if someone else
is buying the hardware)...  but for me personally, I'd probably not bother
with the complexity for just a few more seconds of null avoidance...

Just an opinion.

Bob, Wb4aPR

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Daniel
Sent: Wednesday, June 01, 2016 5:00 AM
Subject: Re: [amsat-bb] Polarization (attitude mostly)

> I pushed back on that requirement
> due to cost and availability issues, but went ahead and installed the
> polarity switch on our CP antennas.  With certainty I can tell you
> that at random times it made a huge difference in downlink signal level.

There was discussion on the ARISS OPs mailing list as to what to recommend
to schools and what would give best "bang for buck" I am still not 100%
convinced that a RHCP/LHCP switch is indeed necessary for ARISS contacts.
The only way to confirm would be one station with both RHCP and LHCP both
receiving at the exact same time and logging or recording the results.
Most/all stations that have said the switch helped have not compared in
real time not switching. Over time the ISS signal can vary wildly, in
particular the solar panels can totally block the signal completely from
time to time. There is a couple of stations with dual VHF circular systems
(mostly ARISS tele-bridge ground stations) and I have asked them to help.
Until we have real world comparisons at least in the case of the ISS, I am
not sure a switch is needed. Can someone do tests to check?
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