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[jamsat-news:1073] * SpaceNews 26-Apr-99 *

* SpaceNews 26-Apr-99 *

BID: $SPC0426


		 	 MONDAY APRIL 26, 1999

UoSAT-12 was successfully launched just before 0500 UTC last Wednesday
morning from Baikonur.  By Thursday, SSTL satellite operators at the
Surrey Space Centre ground station in Guildford, Surrey, UK reported
that their UoSAT-12 minisatellite had successfully passed the Initial
Signal Acquisition phase.  During this phase, the satellite's downlink
was activated, on-board systems enabled and telemetry data received from
all essential bus subsystems. 

Telemetry data received at Guildford and collected by co-operating AMSAT
ground stations around the world indicates that all systems are operating as
expected; received signals from the satellite are strong and the telecommand
uplink is reliable.  Thanks to DB2OS and VK5AGR for forwarding telemetry
during this important phase of the mission.

Operators have also uploaded flight software to the satellite's primary
on-board computer.  This multi-tasking software will collect telemetry
throughout the satellite's orbit and support the Attitude Acquisition
Phase of the mission. 

During Attitude Acquisition, on-board software will gradually bring the
satellite to an Earth-pointing state.  Simultaneously, operators will
perform further satellite tests.  Payload tests will start when the
satellite is Earth-pointing.

All indications from Surrey are that the ISC Kosmotras Dnepr launch was
highly successful, delivering the satellite safely and accurately to orbit.

The OBC is now running with the callsign UO120-11.  The BBS is closed for
general use at this stage although the downlink is on permanently on so
stations can receive the downlink on 437.400 MHz FSK.

Keplerian elements for UoSAT-12 have object number 25694.  This is called
SNAP-1 by NORAD but is actually UoSAT-12.  Actually, SNAP-1 is a nano-sat
that was to be launched with UoSAT-12 but was not launched.  The object
being tracked by NORAD is actually the shroud from the launcher.

The following keps are correct for UoSAT-12:

1 25694U 99022B   99111.87871775  .00019922  00000-0  30916-2 0    40
2 25694  64.5610 316.4522 0001414  11.6425 348.4724 14.73155686    88

[Info via Chris Jackson, G7UPN/ZL2TPO]

AMSAT-OSCAR-10 has come out of hibernation, and many reports have indicated
that the satellite is performing quite well.  Several groundstations are
making digital contacts through AO-10's analog transponder using PSK31
modulation.  PSK31 uses a baud rate of 31.25 and a bandwidth of 31 Hz
and an alphabet similar to morse code with short codes used for common
letters.  PSK31 achieves a text speed of about 50 wpm, and uses software
developed by G3PLX running on a PC with a soundcard.

Peter Klein, KD7MW reports that by using the narrowest possible filters
in his transmitter and receiver, the performance of PSK31 even without
error-correction is certainly better than most modes, and has the added
advantage for live QSOs that the performance degrades very gracefully
as the signal drops.

*Very* careful on-the-fly tuning was required to use PSK31 via AO-10
due to slight downlink frequency variations caused by the satellite
itself.  The downlink signal was observed to vary back and forth 25 Hz
or more during an approximately 2-minute transmission.  Peter found
that if he used the PSK31 communications software and watched the
phase circle carefully and hit the appropriate arrow key 3-5 times
(Hz) when the phase indicator began to shift, he could keep the signal
properly tuned.  This variation was independent of the doppler shift.  

So the bad news is that while the transponder is stable enough for CW or
SSB, it's not quite stable enough for the tuning requirements of PSK31.
Groundstations must "ride the receive tone frequency", and if you stop to
read what you're copying, you'll miss something.  A couple of determined
operators will be able to pull off a QSO on BPSK, but they will have to
work for it.

Anyone wishing to attempt a PSK31 contact with Peter via AO-10 are asked
to contact him via email: kd7mw@amsat.org

[Info via Peter Klein, KD7MW]

Comments and input for SpaceNews should be directed to the editor
(John, KD2BD) via any of the paths listed below:
WWW       : http://www.njin.net/~magliaco/
INTERNET  : kd2bd@amsat.org, magliaco@email.njin.net

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-=-=-=-=-=-=-=-=-=-=-=-=- John A. Magliacane, KD2BD -=-=-=-=-=-=-=-=-=-=-=-=-
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