New subject: [amsat-bb] more on AO-7 eclipse

31 Jul 2007


      Drew,
         It is my understanding from recent correspondance with W3GEY/VK3GEY 
Jan King ...
(Jan 'built' AO-7) ... and earlier correspondence with N1JEZ Mike Seguin 
(AO-7 control operator) when I first posted the mail re: the timer last year 
.... that the timer is completely random when the satellite comes out of 
eclipse and since there are no imminent occurances of eclipse as far as I 
can see, I assume the mode will not change unless anything 'ontoward' occurs 
to upset the electronics.
High power *can* affect how the control systems behave ... (obviously, I'm 
not going to mention the command parameters or the power required).
If my assumption is wrong, I stand corrected. In either case, listening to 
the regular operators will confirm the mode.
The mode changes can be viewed at ... 
http://www.planetemily.com/ao7/stats2.php
The predected eclipse chart at ... 
http://www.planetemily.com/ao7/Eclipse.php
Perhaps other operators will obtain different conclusions from the above 
predictions.
Opinions are are invited.
That is, after all, precisely why we started the EU-Amsat reflector.
I CC'd this mail to the amsat-bb since the number of Stateside users has 
increased in the last 2 months and this information may be of interest to 
them too.
73 John.   [email protected]
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...
From: Andrew Glasbrenner [email protected]
Reply-To: [email protected]
To: [email protected]
CC: [email protected]
Subject: Re: [eu-amsat] AO-7 report.
Date: Tue, 31 Jul 2007 11:18:04 -0400 (GMT-04:00)
...
Every time this has happened in the past, several times over the past few 
years, the 24hr timer has >activated, switching between A and B. There is 
no reason to expect it won't again.
73, Drew KO4MA
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...
From LA2QAA.
...
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. [email protected]