brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell


UO-11 also wakes up from its nap…

Another old time satellite might be waking up from its sleep as it comes out of a period of eclipses. Joanne Maenpaa mentioned that UO-11's telemetry beacon had been heard on 145.825, so I decided to try to give it a listen on its pass to the east. Despite the fact that it was fairly low, I heard the 1200 baud AFSK telemetry quite clearly. I don't have the ability to decode it (couldn't find any Mac programs that would), but I recorded a couple of minutes of it using Audacity on my mac anyway. Because someone might be able to decode it from this data, here's the compressed .wav file:

UO-11 Telemetry, 2008-01-23 around 04:27 UTC

Here's a screen dump of Audacity, showing the 1200 and 2400 Hz carriers that make up the AFSK signal.

Spectrum of UO-11 Telemetry

Addendum: Douglas Quagliana, KA2UPW did what I hoped someone would: ran my recording successfully through his own UO-11 decoder. From the email he sent me:

Hi Mark,
 Thanks for posting the recording!

 I downloaded your recording and ran it through
my DSP soundcard UO-11 demodulator. Most of the
data in your recording looks like this, although
other sections are quite noisy.

UOSAT-2           0711024074656

All of the columns of zeros are telemetry channels that have
failed. This agrees with what Clive has previously reported.

Earlier Clive reported:
>The current status of the satellite, is that all the analogue
>telemetry channels, 0 to 59 are zero, ie they have failed.
>The status channels 60 to 67 are still working. The real
>time clock is showing a large accumulated error [...]

Last month the clock was about 74 days slow, but it is now
about 81 days off.

In the past UO-11 also used to send stored ASCII bulletins
as well, but I think that capability of the satellite ended
when the spacecraft computer turned off. Anyone know
for sure?

Thanks alot Douglas for the decode.

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AO-16 lives, in a very strange way…

This just came across the amsat-bb mailing list:

Since AO-16 was recovered approximately 6 months ago, the command team has 
attempted to reload the satellite software almost a dozen times without 
success. Subsequently a series of memory tests were performed which points 
towards a hardware failure which prevents restarting the spacecraft software 
successfully. This team included Bruce Rahn WB9ANQ and Jim White WD0E 
advising Mark Hammond N8MH as the primary groundstation. Mark put in many 
early hours during the multiple reloads and test sessions, with Bruce, Jim, 
and others advising. Thank you to all involved for your hard work.

After the conclusion that the spacecraft computer system was damaged and as 
discussions about decommissioning were taking place, Jim recalled a series 
of low level commands included in the spacecraft design by Tom Clark, K3IO 
during construction. One of these commands allows an uplink receiver to be 
directly tied to a downlink transmitter. The twist is that the uplink is 
regular FM but the downlink via the BPSK transmitter is DSB (Double 
Sideband). Mark placed the satellite in this mode early this week and some 
testing was undertaken. The satellite hears VERY well, and the reduced 
bandwidth by using either USB or LSB on the groundstation receiver allows 
for a very robust downlink. Tuning the downlink is just like on a linear 
transponder, meaning it is tight and with fast Doppler. Uplink tuning is not 
required, just as with the FM mode V/U satellites. QSOs were made between 
N8MH, WD4ASW, KO4MA, K5QXJ, and WA6FWF. My personal observations include 
being able to access and hear the satellite within one degree of the 
horizon, much lower than any other current bird for my QTH. This should be 
an easy satellite with omni antennas and a 70cm preamp.

With that explanation, I'm happy to open the satellite to general use on 
voice for a test period. Please submit reports either to the -bb or to . The uplink is 145.920 FM, and the downlink is 437.026 SSB 
± Doppler shift. Please restrict your uplink power to a reasonable level, 
and do not transmit without being able to hear the downlink. All the general 
single-channel guidelines apply. Enjoy this bird's new life!

73, Drew KO4MA
AMSAT-NA VP Operations 

Whacky! I don't have any UHF SSB equipment, so it really doesn't help me much, but I can imagine that using a cheap 2m handheld for the uplink, and either a TH-F6A or more capable transciever for the downlink would be possible. Neat! I'll have to give this a try sometime.

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