Page 20 May June 2014 TCA

AMATEUR RADIO SATELLITES

Like its predecessor, UoSAT-2
transmits telemetry data on
the VHF beacon at 1200
baud, using asynchronous
Keith Baker, VA3KSF/KB1SF AFSK, although all its
PO Box 33
Corunna, ON N0N 1G0 analog telemetry channels
E: va3ksf@rac.ca have long since failed.
A BRIEF HISTORY
UO-11
UO-11 was launched on
In previous columns, I’ve March 1,1984 from
been sharing information Vandenberg Air Force Base
about the growing feet of (AFB) in California with the
Amateur Radio satellites aim of providing telemetry
now in orbit and how you and other digital services
can receive their signals or, for Amateur
if properly licensed, actually Radio and
work through them. educational
In this installment, I’ll discuss users.
yet another “oldie but During its many Professor Sir Martin Sweeting , G3YJO, the then Director
goodie” in our Amateur years of of the University of Surrey’s Space Centre in England
(left) oversees the fnal assembly of UoSAT-2 which later
satellite feet as well as operation it became UO-11 on orbit. (Courtesy: AMSAT-UK/SSTL)
take a brief look back at has survived UoSAT-2 (UO-11) is shown on the left mounted
some Amateur satellites both long on a “shake table” minus its solar panels. Satellites
that are no longer with us. periods of are regularly subjected to such “shake and bake”
I’ll then discuss AMSAT’s eclipse and tests to insure they are able to withstand the harsh
latest project called FOX-1. continuous full environment of space. (Courtesy: AMSAT-UK/SSTL)
UO-11 (also known as sunlight. At that time, the satellite was not expected to be
UoSAT-OSCAR 11, UoSAT-2 In 2002, its heard from again for any continuous period until
or UoSAT-B) was the second batteries 2019, when there would be some eclipse-free
in a series of Amateur began failing periods. Miraculously, the satellite started
satellites built at the transmitting once again in November 2008.
University of Surrey in and, much like
England. It remains active, AO-7, it began These transmissions continued until March,
though unstable with operating principally with power generated from followed by yet more long periods of silence.
irregular periods of its solar panels – panels which were bought at a Then, after another 21-month gap in
transmission. The satellite premium compared to those of UoSAT-1, the observations, UO-11 resumed sending telemetry
was still heard transmitting design having been space tested by its in December 2009 and it has apparently
telemetry throughout 2013, predecessor. The satellite’s so-called “watchdog continued its watchdog timer-controlled
more than 29 years after timer” (a device to reset the satellite’s main transmission regime ever since although now on
launch! It transmits a computer if all contact with the ground is lost) a 10-days-on, 10-days-off schedule.
beacon on 2m, with started suspending activity for up to three weeks
inactive beacons on 70 cm at a time following numerous power anomalies. Sadly, the satellite’s orbital condition has not
otherwise improved apart from a small recovery
and 2.4 GHz. Then, in 2005, all the satellite’s analog telemetry of its battery power, allowing some broadcasts
The satellite carried a channels failed. Long solar eclipses also caused to continue into partial eclipse.
so-called “Digitalker” UO-11’s watchdog timer to completely reset the
(speech synthesizer) satellite from time to time, switching it off for As of late, the satellite has been heard reliably
during its 10-day on/off transmission cycle.
magnetometers, a CCD approximately 15 days.
camera, a Geiger-Müller In 2008, solar eclipses became a permanent Excellent signals have been reported from
stations located around the world, and some
tube and a microphone to feature of every orbit, sometimes causing the
detect satellite vibrations satellite to switch off after only one orbit. useable decoded telemetry frames have also
been obtained.
caused by micrometeoroid
impacts.
UO-11 FREQUENCY AND MODE DATA
Portions of this article Beacons (MHz) Mode Status
previously appeared as
“Spotlight on UOSAT-2 145.826 AFSK FM ASCII Telemetry Semi-Operational
(UO-11)” in the May 2012
edition of Monitoring Times 435.025 Non-Operational
Magazine). Thank you MT!
2401.50 Non-Operational
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