Although I have severely limited satellite visibility I have been copying telemetry from ARISSat1 for some weeks. I live in a valley surrounded by chalk hills and cliffs over 100 metres higher than me so my visible horizon is +12 degrees to +18 degrees at best. Also my 3+3 element short crossed yagi and rotator are in the attic! This worked beautifully when the satellite batteries held up and now when ARISSat is powered up. However I notice it can take 10 minutes or more from the time the satellite enters sunlight until the system bursts into life. At present this means loss of telemetry at this location when ARISSat is over the Atlantic, and even on overhead passes if it has been in sunlight for less than 10 minutes. Question is why it takes ARISSat so long after entering sunlight before it starts transmitting? Surely if the batteries have failed high resistance the voltage should be up within seconds of entering sunlight. Dick G4BBH
Hi Dick,
I think the delay is the result of the timer circuit that was mandatory for its release during the spacewalk from the ISS. The delay timer had to be there, and there is no way to defeat it, so it just has to run its course every time it exits eclipse.
As you have probably noticed, the orbit is changing (precessing?) so for a week or two conditions are favorable in your QTH, then it changes so that the bird spends much of the overhead time either in eclipse, or just after eclipse and the bird isn't transmitting. The good news is that it will "come around again" so that conditions are favorable at a given QTH.
As an admitted telemetry nut myself, it's painful to know the bird is at high elevation over my QTH, yet no telemetry is being sent or received...but it'll come back around :)
The truly painful days will be when it's re-entering...doubt we'll get press like UARS!
73,
Mark N8MH
At 10:35 AM 9/24/2011 +0100, Richard Ferryman wrote:
Although I have severely limited satellite visibility I have been copying telemetry from ARISSat1 for some weeks. I live in a valley surrounded by chalk hills and cliffs over 100 metres higher than me so my visible horizon is +12 degrees to +18 degrees at best. Also my 3+3 element short crossed yagi and rotator are in the attic! This worked beautifully when the satellite batteries held up and now when ARISSat is powered up. However I notice it can take 10 minutes or more from the time the satellite enters sunlight until the system bursts into life. At present this means loss of telemetry at this location when ARISSat is over the Atlantic, and even on overhead passes if it has been in sunlight for less than 10 minutes. Question is why it takes ARISSat so long after entering sunlight before it starts transmitting? Surely if the batteries have failed high resistance the voltage should be up within seconds of entering sunlight. Dick G4BBH _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (2)
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Mark L. Hammond -
Richard Ferryman