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Re: Doppler lesson



I'm using the doppler correction feature in WiSP during telemetry collection
and still get a residual drift of a few kHz. The direction correlates nicely
with the time of day so think my downconverter LO is drifting about 1 ppm as
ambient temperature goes up and down. I'm using the LO design published in
1989 QST with a PTC thermistor on the crystal. The UEK-300 probably isn't
any more stable.

73,

John
KD6OZH

----- Original Message -----
From: "Gunther Meisse" <gjmouse@neo.rr.com>
To: <amsat-bb@AMSAT.Org>
Sent: Tuesday, 11 September 2001 01:40 UTC
Subject: [amsat-bb] Doppler lesson


> Set me straight!
>
> I always thought that the frequency increased as the object approached and
> fell as the object went away.
>
> Well, I picked up the bird (AO-40) tonight at about MA 6 or so. The beacon
> freq was falling fast as the bird started to streak away, as I would
expect.
> Then at about MA 15-20 I suddenly noticed that the freq was going UP and
> continues at this time (MA-26). Nova continues to say that the range
> continues to increase (About 28,500km), thus I would think that the freq
> should continue to fall until apogee, at which time the range would start
to
> fall and the freq would start to again rise.
>
> Is there something I don't understand, or am I seeing a massive drift in
my
> UEK-3000 DC? I leave my Downconverter on all the time and it has been rock
> stable. I think I have noticed this before but it just hit me tonight.
>
> 73 from your old DAAAAAAA -BBer
> Gunther Meisse
> W8GSM
> AMSAT LM# 594
>
> I have a feeling I am going to be embarrassed by the answer.
>
> ----
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