[amsat-bb] Re: Newbie question about AO-07

Auke de Jong sparkycivic at shaw.ca
Fri Oct 31 20:04:28 PDT 2008

AO-7 happens to be in "permenantly sun-lit" conditions.  I believe this 
current period to last fairly long, but I forget now just how much longer, 
but I think it's on the order of months.  AO-7 has a time counter that 
controls the mode A/B toggle therfore, it will change modes every 24 hours 
starting at whatever moment the last sun-rise for the spacecraft 
was(sometime in early August), and always starting in mode-B.

You can look at the logs on http://www.planetemily.com/ao7/main.php , to 
figure out what mode the satellite was most recently used.  I just read the 
log, and found that the A/B changeover time, these days, is approximately 
20:55 UTC.  It's likely that the last sunrise AO-7 experienced must have 
been about 20:55 on Aug 5.

When not in continuous sunlight, it mostly stays in mode-B, never making it 
the full 24 hours to switch, since the eclipse happens every orbit, or about 
1 hour 55 min, for some portion of those orbits.

I'm always impressed when I think about the like-a-rock reliability this old 
craft has shown!   I look forward to perhaps a future craft being launched 
that is built using the old-style analog hardware prevalent in this old 
bird.. Something retro,  maybe with the old hand-laid harnesses,  a clever 
battery-failsafe scheme, and a dose of enhanced-performance components, it 
might just last forever!


----- Original Message ----- 
From: "Mark Lunday, WD4ELG" <mlunday at nc.rr.com>
To: <amsat-bb at amsat.org>
Sent: Friday, October 31, 2008 7:04 PM
Subject: [amsat-bb] Newbie question about AO-07

> For some reason, I cannot seem to find info which indicates the mode for 
> the
> pass...mode A or B.  I usually figure it out after listening on 145 
> downlink
> and not hearing anything then going to the 29 MHz downlink.  Once, I even
> heard my downlink on 29.45 MHz at the start of the pass only to hear it
> stop.  Was not sure what happened until I started tuning around and
> discovered the bird had SWITCHED from mode A to mode B in the middle of 
> the
> pass!  So my question is...other than trial and error or listening for the
> beacons (which won't help if the bird switches during the pass), is there
> any pattern or location of information for the prediction of the mode?
> Thanks, as I am thrilled each time I can get through this oldie-but-goodie
> with 5 watts on CW.  What a blast!
> An additional question since the batteries have long ceased to function on
> AO-7, it only works during sunlight passes.  Somebody mentioned that this
> will happen less and less as we get close to winter solstice.  Is this
> because AO7 is in a northerly LEO orbit?  If it passes in the southern
> hemisphere, would it not have MORE available online time?  I see
> http://planetemily.com/ao7/Eclipse.php but it's not a predictor for 
> November
> 2008 (and I am not sure I understand it anyway).  Should I just set
> Orbitron/HRD for AO7 "in sunlight/illumination" only option?
> Mark Lunday
> wd4elg at arrl.net
> http://wd4elg.net
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