James Duffey queried...
"When AO-7 is powered all the time doesn't the on board housekeeping unit control the mode and switch between mode A and Mode B?"
"The following information is from AMSAT NEWSLETTER dated Sept 1974
The two repeaters are operated alternately by means of a timer arrangement, but repeater selection and output power control can also be accomplished by ground command."
And . "from Jan King, W3GEY, who provided the following information in an email ...
It appears that the 24 hour clock that would cycle the transponders between modes A and B is working but, it gets reset every time the satellite goes into eclipse"
Which by my understanding, will produce a change of mode from A to B (or B to A if you prefer) every 24 hours with no eclipse event. I believe there have been cases where excessive power drain (usage) has resulted in a mode change mid-timer, but I haven't been able to document that.
Roger WA1KAT
----- Original Message ----- From: "James Duffey" JamesDuffey@comcast.net To: la2qaa@amsat.org Cc: amsat-bb@amsat.org; Eu-amsat@yahoogroups.com Sent: Sunday, August 05, 2007 11:32 AM Subject: [amsat-bb] Re: AO-7 report.
John - When AO-7 is powered all the time doesn't the on board housekeeping unit control the mode and switch between mode A and Mode B?
Having a full time Mode B LEO linear transponder is great, in my opinion, having a Mode A LEO one will be even better. - Duffey On Jul 31, 2007, at 5:32 AM, John Hackett wrote:
A study of the AO-7 eclipse charts for the last 3 years shows a progression toward non-elipse orbits in late 2007 - 2008.
In effect, this means that AO-7 in all probability will not change mode unless anything untoward happens.
It also means that we appear to have a permanent mode-B LEO linear transponder for the forseeable future ... providing operators follow the recommended operating proceedure.
Please *do* decrease your power as the satellite approaches TCA to avaoid FM'ing.
This not only helps the satellite, it helps the other operators in the passband.
Don't be fooled by propagation anomolies. The mode-B transponder is working well and will continue to do so providing the alligators go and play somewhere else. Under normal circumstances you do NOT !! need a lot of power. Please use only the necessary to maintain adequate communications. If you can't copy people adequately, you should improve your receiving capabilities rather than increasing your uplink power ... remember, aluminium is cheap and it's a lot more user friendly to everyone concerned .... with perhaps the exception of your neighbours.
For all intents and purposes, AO-7 is a QRP satellite. Please treat it as such.
73 John. la2qaa@amsat.org
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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