[amsat-bb] Tracking EO 79

Greene, Stephan A stephan.a.greene at vencore.com
Mon Nov 14 15:07:56 UTC 2016

Yes, AO-27 used a similar technique ("TEPR") beginning not long after
launch and for similar reasons - a computationally easy (for the
satellite) way to control the transmitter (time after exiting eclipse)
to ensure a positive power budget.  Although the link to the original
page on amsat.org explaining it is broken,  a copy was posted here:
http://www.om3ktr.sk/druzice/teprstates.html    The diagram assumes the
satellite orbit is counter-clockwise and the "on" times are for
descending node (North to South) passes.  Re-order the segments for
ascending node (South the North).  The AO-27 command team later replaced
"TEPR" with "TOPR", using an algorithm based on when the satellite is
over the desired latitude band - easier for humans to understand, more
calculating on the satellite.  (Guessing this occurred in late
1996-early 1997 based on amsat-bb email archives)

The EO-79 control ops will have to adjust the timer settings in the
satellite's software periodically to keep the transponder's "on" time
roughly over the same latitude range.  Otherwise, as was experienced
with AO-27, the band of latitudes where the transponder is on will
"drift" seasonally.  It will move South approaching the Northern
hemisphere winter solstice next month, and move North until the summer

73 Steve KS1G

-----Original Message-----
From: Greg D [mailto:ko6th.greg at gmail.com]
Sent: Saturday, November 12, 2016 2:41 PM
To: Amsat BB
Subject: Re: [amsat-bb] Tracking EO 79

Didn't AO-27 do something very similar?  There was an application for it
that did the calculations.  I forget who the author was; perhaps it (the
program, not the author) could be modified for EO-79?

Greg  KO6TH

Paul Stoetzer wrote:
> It's basically calibrated for mid-northern latitudes now, so we should
> hear it on daytime NA passes.
> It wouldn't be difficult to write a script to calculate on and off
> 73,
> Paul, XE3/N8HM (currently in Progreso, Yucatán, Mexico)

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