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RE: AO40 Doppler



Hello Dave

> I use IT as my tracking program, and there are some inexplicable
> shifts in frequency that are contrary to what the program indicates.

This is an interesting observation.

I also find that, for instance, the Doppler frequency predictions from
IT+InstantTune, Nova and Wisp+WispDDE are rarely in agreement, sometimes out
to a couple of kHz.

We already know that the spacecraft itself will change from the nominal
frequency due to onboard power fluctuations such as magnetourquing and
temperature.

I recently purchased a rubidium standard oscillator accurate down to about 1
part in a 10^9 and have plugged it into my AR-5000, so I'm hoping to make
some future observations myself. I can state already that the accuracy of
the LO's on these d/cs can be rather unpredictable.

I wonder what the magnitude of the frequency anomalies are which you're
experiencing? In the past I was getting around +/- 2kHz from nominal, which
made it difficult to accurately set up an unattended station for telemetry
gathering purposes.

73 Howard G6LVB


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