At 2231Z AO-7 downlink quit. In full sun, any ideas? 73 Bob W7LRD
Bob,
Some QRO CW station was hammering the transponder, forcing the mode change.
Glenn AA5PK
-----Original Message----- From: Bob- W7LRD Sent: Friday, June 13, 2014 5:39 PM To: amsat-bb@amsat.org Subject: [amsat-bb] AO-7
At 2231Z AO-7 downlink quit. In full sun, any ideas? 73 Bob W7LRD _______________________________________________ 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
Thanks Glenn- I was on ssb when it just stopped. I did not know about this forcing the mode change thing. So if too many station try to access the sat it will just switch? I had a sked with G4DOL earlier today. Did not make it but the satellite sounded good. Looking into JT65 EME. 73 Bob W7LRD
----- Original Message -----
From: "Glenn Miller - AA5PK" aa5pk@suddenlink.net To: "Bob- W7LRD" w7lrd@comcast.net, amsat-bb@amsat.org Sent: Friday, June 13, 2014 3:47:32 PM Subject: Re: [amsat-bb] AO-7
Bob,
Some QRO CW station was hammering the transponder, forcing the mode change.
Glenn AA5PK
-----Original Message----- From: Bob- W7LRD Sent: Friday, June 13, 2014 5:39 PM To: amsat-bb@amsat.org Subject: [amsat-bb] AO-7
At 2231Z AO-7 downlink quit. In full sun, any ideas? 73 Bob W7LRD _______________________________________________ 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
I have a theory, and it's just a theory based on my time managing AO-51, and looking at several of the older available publications that describe the satellite.
AO-7 is barrel shaped, with solar panels around the outside of the barrel (really an octagonal column shape). The top and bottom ends do not have solar cells or panels. (AO-51 had panels on each Z end, but only half the number of cells as the sides.) AO-7 is also magnetically stabilized, where the bottom flat end and the VHF/UHF antenna array of the satellite points towards magnetic north when in vicinity of the north magnetic pole (Northern Canada).
If you look at the position of the sun, AO-7 and north magnetic polar during most of the reported failures, the satellite is in a position where the sun is shining down on the top, and only partially illuminating the panels on the side, and at a very low (poor) angle. In this attitude, the power generated drops, and the reset occurs, especially in the presence of strong user signals.
There are other factors, including just the ageing of the solar cells leading to a reduction in power generated, precession of the orbit, and probably others.
Just food for thought.
73, Drew KO4MA
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bob- W7LRD Sent: Friday, June 13, 2014 6:40 PM To: amsat-bb@amsat.org Subject: [amsat-bb] AO-7
At 2231Z AO-7 downlink quit. In full sun, any ideas? 73 Bob W7LRD _______________________________________________ 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
Well said.
73, Bob KIØG
On Jun 13, 2014, at 4:04 PM, "Andrew Glasbrenner" glasbrenner@mindspring.com wrote:
I have a theory, and it's just a theory based on my time managing AO-51, and
participants (4)
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Andrew Glasbrenner -
Bob Cutter -
Bob- W7LRD -
Glenn Miller - AA5PK