[amsat-bb] SO-50 & frequency stability as of late
dave at druidnetworks.com
Mon Sep 8 18:18:21 UTC 2014
Twice during the 1655Z pass just now I actually had to shift UP in
frequency to hold the downlink. Right at AOS I picked up the signal at
.795, made a contact, and about 30 seconds later I heard a very
noticeable 'shift' in the noise where it was basically unreadable. I
shifted down, it got worse, so I went up and picked it back up at .800
clear as a bell. About 6 minutes later, near my apex, I had followed the
doppler down normally to about .780, and it jumped back up again by
about another 5 or so. Each time it did this, it was in the middle of
someone else's transmission and there was an abrupt 'shift' that didn't
sound anything like the gradual worsening that I normally hear with
Just my observations from a sat-noob. Also first post on amsat-bb... o/
73, Dave, KG5CCI
On 9/8/2014 11:30 AM, Alan wrote:
> 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
> <To: AMSAT-BB
> <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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> <are solely those of the author, and do not reflect the official views
> of AMSAT-NA.
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