[amsat-bb] SO-50 & frequency stability as of late

Alan wa4sca at gmail.com
Mon Sep 8 16:30:47 UTC 2014


I have been watching it shift 5-10 KHz or so on some passes, though 3-5 KHz is more common.  Watching
it with a DSP rig allows you to compensate.

The more interesting question is what, if anything, the uplink is doing?  I got up for a 0200 L pass
to experiment, and there was nobody else on.  I thought I had it figured out, and suddenly the
downlink shifted.  Then, my uplink data seemed wrong, as if it also shifted.   ;(  Will try again the
next time I have some insomnia.




<-----Original Message-----
<From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Clayton Coleman
<Sent: Monday, September 08, 2014 10:54 AM
<Subject: [amsat-bb] SO-50 & frequency stability as of late
<I have been noticing some irregular shifts in SO-50's downlink
<frequency the past several days.  I noticed it in the past but it's
<been a while since this occurred.  Several others are reporting it as
<At my AOS today (15:12 UTC, orbit # 62976), SatPC32 had predicted the
<downlink to be near 436.801 MHz, when in fact I was receiving the bird
<at 436.793.  It proceeded to jump up to 436.795 at my TCA before
<making it's way down to 436.780 near my LOS.
<This seems to be posing some issues for people using full computer
<control and also those who stick to pre-programmed memory channels to
<make frequency adjustments during a pass.
<Considering this recent frequency instability, I would recommend you
<manually tune for the strongest downlink frequency.  This would help
<eliminate some issues with stepping on stations engaged in existing
<QSO's.  An alternative would be to try using RIT if you insist on
<computer control.
<The old rule applies -- if you can't hear, don't transmit.
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