[amsat-bb] Re: Satellite Orbit Prediction in Python

Mark VandeWettering kf6kyi at gmail.com
Mon Sep 28 10:11:23 PDT 2009

Joseph Armbruster wrote:
> Awesome stuff!!  I'll have to check out this library tonight.  I 
> started hacking at something similar but started digging into the 
> internals of SGP4/SDP4, then got distracted and never finished.  If 
> you have a rotator, it'd be a cool quick project to slap pyserial on 
> there and control your rotator.  It'd be pretty awesome to have a Kep 
> to Rotator Control in about 10 lines of code :-)
> Joe
That reminds me, I should give thanks to Howard, G6LVB.  I've never met 
Howard, but his G6LVB tracker project first put me onto G3RUH's Plan 13 
work.  Howards PIC based tracker implements Plan 13 to do automatic 
antenna guiding, and seems very cool.

I have actually experimented with using my library to predict and 
compensate for Doppler shift using my FT-817.    I used pyserial to send 
out frequency change commands as documented in the FT-817 manual.   It 
worked reasonably well.  For example, following is a simple visual 
display of a pass of the three small satellites COMPASS-1, CUTE-1.7 APD 
and SEEDS that I did back on Jun 13, 2008. 

WARNING: this JPG is 1.7Mb, and 1600x8000 or so in size.   Don't blame 
me if your computer melts trying to display it.


You can see COMPASS-1 at the beginning, with its sharply whistling 
tones.   Then CUTE will step in, and finally SEEDS.   You can clearly 
see the steps in frequency every second or so.

If you'd rather have the audio, you can get it here: 


73 Mark K6HX

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