[amsat-bb] AO-85 Downlink Frequency Shifted Down 2.5Khz ?

[Alan]

High temperatures depress the downlink frequencies.  AO-85 has just finished an 11 day period of continuous illumination which normally increases the temperature 30-35 C.  Low battery voltage is also a factor.  It is still seeing very short eclipses, but that will return to normal over the next few days.

73,

Alan
WA4SCA


<-----Original Message-----
<From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Hasan
<al-Basri via AMSAT-BB
<Sent: Sunday, November 03, 2019 05:19 AM
<To: James Pierce <james at thirdglance.com>
<Cc: AMSAT-BB <amsat-bb at amsat.org>
<Subject: Re: [amsat-bb] AO-85 Downlink Frequency Shifted Down 2.5Khz ?
<
<Yes it is off freq (often) and by the amount you mentioned. I'm guessing it
<is thermal.
<73, N0AN
<
<Hasan
<
<On Sun, Nov 3, 2019, 1:43 AM James Pierce via AMSAT-BB <amsat-
<bb at amsat.org>
<wrote:
<
<> The last couple of passes I’ve chased AO-85 over Australia the downlink is
<> appearing about 2.5Khz lower than expected.
<>
<> I am uplinking at 435.170 and was expecting the downlink at 145.978.6 …
<> however it seems the return is arriving at more like 145.976.1- The signal
<> coming back is excellent once tuned, especially while the bird is higher in
<> the pass.  And yes, for anyone wondering, I use macdoppler for full doppler
<> tuning through the whole pass.
<>
<> Can anyone shed any light as to what may be happening? I’ve always found
<> AO-85 to be a very quiet bird over Australia, and I wonder if this may be
<> part of the reason.
<>
<> James - VK3VJP
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