Hi Zach,
Thanks for your report. See why we like updates to http://oscar.dcarr.org/ ? ;) It's so nice to look and see a report that the satellite has been ON since hearing a report that it was OFF.
The power is fluctuating between only 2 points during power management--from full power around 1.47 Watts (!) to OFF. The satellite makes these adjustments on the basis of battery voltage (is it high enough?) and solar panel voltage (basically, is there sun or not?). These two conditions--battery voltage and solar panel voltage--are both taken into account by the satellite's power management software. So, if battery voltage drops--even though the solar panels "see" sunlight--the power will go off.
As command stations we make manual adjustments in the transmitter power to 1) not drain the batteries before eclipse happens (which happens if it's turned up too high), and 2) keep the transmitter power high enough that the satellite internal temps don't get too warm (which happens when the power is too low). Watching the satellite's telemetry/conditions is pretty much a daily event, especially during periods like we are in right now because the length of eclipse is increasing every day!
Keep in my mind that for satellites, being in eclipse or the sun isn't like being in a room and turning the light OFF (dark) and ON (light). It's a more complex...it's probably a bit more like turning the light OFF and ON via a dimmer switch--various shades of gray going from dark to sun and back to dark. Then, add in the reality that the satellite is a cube that is spinning (albeit very slowly right now) and wobbling, and the complexity goes way up.
So---don't be surprised if the transmitter goes OFF a few minutes before eclipse; and it might stay OFF until a few minutes after re-entering the sun. The batteries have to come back up in voltage for the transmitter to come back on. And keep in mind that for the next several weeks, the lengh of eclipse is increasing, so AO-51 will be OFF more each day.
I hope that explanation helps you and others better understand what is going on with AO-51! It's an amazingly complex bird with lots of features and functions. Fortunately, other than having aging batteries it seems to be in excellent condition.
73!
Mark N8MH
At 07:54 AM 1/2/2011 -0500, Zachary Beougher wrote:
I was on the 1153z AO51 pass this morning, and it shut off on me at about 1157z, came back on briefly, went back off, and then it went behind the trees before I ever heard it come back on. I didn't note any projected eclipses on that particular pass. I figured the on/off was just the power fluctuations (is that what it is called????), but I was wondering if anyone else in the Midwest/West was listening to that pass? I was trying out a D7 I got from a friend yesterday, and I couldn't tell if after AO51 shut off, came back on, then went back off if the reason I could not hear anything else was do to my poor receiving behind the trees, or did AO51 stay off for that long period of time (it would have been off all the way to LOS here, which was at 1205z)? Could someone else that was listening to the 1153z AO51 pass tell me if after AO51 went off, on, off at approx. 1157z if it came back on afterward? A recording would always be appreciated if possible.
73!
Zack KD8KSN
-----Original Message----- From: Andrew Glasbrenner Sent: Saturday, January 01, 2011 11:49 PM To: Clint Bradford Cc: amsat-bb Subject: [amsat-bb] Re: AO-51 Status
Correct. The shutdowns should only be happening during morning passes (when the eclipses), or if we have the data transmitter on for too long like this afternoon. However, when the repeater is on, it should be very strong, at about 1.5 watts on the downlink.
Users can leave the 67Hz tone on and forget about it. If not needed, it won't hurt to be there. No need to think about it after enabling it on your uplink.
73, Drew KO4MA
-----Original Message-----
From: Clint Bradford [email protected] Sent: Jan 1, 2011 10:19 PM To: AMSAT BB [email protected] Subject: [amsat-bb] AO-51 Status
Confirming this "possibly OFF during eclipse periods" is NOT a situation where we can use a 67.0 tone to turn it ON for two minutes. This is a "harder-coded" off period - is that correct?
Clint, K6LCS _______________________________________________ Sent via [email protected]. 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
Sent via [email protected]. 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
Sent via [email protected]. 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
Mark L. Hammond [N8MH]