[amsat-bb] Re: AO-51 (2158Z) Mid Atlantic pass.
Alan P. Biddle
APBIDDLE at UNITED.NET
Wed Jul 11 05:53:20 PDT 2007
The first couple of morning NS passes yesterday, I found that everything
worked fine, though there seemed to be a bit more QSB on the audio.
Downlink signals were good, though suffering from relatively low elevation
geometry. On the uplink, as I saw before on LU, it required power for full
quieting ranging from 80 watts out of the brick on the horizon, to what must
have been a watt at most at TCA. There is a very detectable threshold,
unsurprisingly with FM, though things are not normally quiet enough on mode
VU to experiment and find it. On the previous mode LU operation, I was able
to use that threshold, and of course the sparse number of operators, to net
in my uplink frequency, BTW.
Last night, I had a "down the throat" SN pass around 0110 UTC. Signals were
excellent, and at TCA, my S-meter was absolutely pinned, even with the 10 db
attenuator switched on. AO-51 is LOUD on mode S. What I did find, and
N8BBQ made a similar comment, was that there was much less QSB on the
evening pass. AOS to LOS, it was really like a terrestrial repeater. (Plug
for SATPC32. It handles the rapid Doppler perfectly!) I did notice a bit
of noise, which for lack of a better term I will say sounded a bit _like_
terrestrial intermod. It was very low level, but I want to look for that on
some future passes. I also need to get WA4SXM's book out and look at the
antenna locations, as there is definitely a difference in performance
depending on aspect, much more so than on VU.
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