Re: [amsat-bb] AO-40 beacon frequency question.

[Geoff <vk2tfg@xxxxxxxxxxxxxx>]

nu8i wrote:

much snipped

> 
> Tnx for the reply Mike. I have no problem getting the actual Doppler value
> at any time during the orbit, what I would like to know is what the true
> beacon frequency is, and how much it varies in its space environment. This
> is more for technical curiosity reasons than operational ones, I can still
> get on and make the contacts regardless.

much snipped

   Hi Guys,
How about this for a technique? (tedious if done manually).

   (1) plot a doppler shift curve for AO40 (or whichever takes your fancy)
   (2) find the point(s) of inflexion in the curve
   (3) check the telemetry and note the transmitter temperature and the 
received frequency at the points previously noted
   (4) repeat the exercise for as many passes as you can and as many 
telemetry channels as you may think are relevant
   (5) using MS excel or something similar plot the data, graph it, add 
a "trend line" and note the trendline equation

The trend line equation should give you a pretty good idea of how much 
the beacon frequency varies in orbit. The manner in which the data 
varies from the trendline should tell you something about the variations 
being experienced in the shack.

       73 de Geoff vk2tfg (/3)

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