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[jamsat-news:862] * SpaceNews 20-Jul-98 *

* SpaceNews 20-Jul-98 *

BID: $SPC0720


			  MONDAY JULY 20, 1998

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for non-commercial use.

UoSAT-OSCAR-11 experienced a potential problem at the end of June after
a long period of uneventful operation.  The telemetry status blocks showed
that the magnetorquer firing counters had stopped incrementing, and the
spin period was steadily increasing, implying that the satellite rotation
was slowing down.  Normally the Z counter increments at about ten counts
per day, and the minus spin counter about five counts per day.  These
firings maintain the spin period at around 360 seconds (one revolution
every six minutes), and keep the satellite pointing towards the earth.
The Z-axis counter got stuck at 1024 and the minus spin counter got
stuck at 486.  After six days, the spin period rose to 640 seconds.

Ground control reset the counters on 1998-Jul-01, and started a new
WOD of the magnetometer channels.  After three days, the spin period 
returned to its nominal value.  Under normal operation, the magnetorquer
control system stops working when a counter reaches 1024. This is a
feature to protect the satellite from malfunctions of the magnetorquer
control system.

During the period 1998-Jun-15 to 1998-Jul-14, reasonable signals were
received from the 145.826 MHz beacon.  Telemetry is nominal, although
the battery voltage has tended to be rather low, averaging 13.5 volts,
with 13.4 volts observed on several occasions.

The internal temperatures have remained constant and are now 1.8C
and 0.4C for battery and telemetry electronics respectively.

The WOD survey of channels 1, 2, 3, 61 (magnetometers) dated 1998-Mar-19
has been been replaced by a survey of the same channels dated 1998-Jul-01
starting at 16:24:09 UTC.  This was probably started at the same time as
the counters were reset, and shows the unusually high spin period of 640

Reports of the OSCAR-11 Mode-S beacon have been received from Ed K9EK,
Rick VE7SME, and Mike WL7BQM.  Rick's report was of particular interest
as he was using OSCAR-11 as a signal source while doing some RFI tests
at the Australian National Telescope Facility.

UoSAT-OSCAR-11's operating schedule remains unchanged:

	ASCII status (210 seconds)
	ASCII bulletin (60 seconds)
	BINARY SEU (30 seconds)
	ASCII TLM (90 seconds)
	ASCII WOD (120 seconds)
	ASCII bulletin (60 seconds)
	BINARY ENG (30 seconds)

The ASCII bulletin is currently a static message, detailing modes and
frequencies of all the amateur radio satellites.

There are additional status blocks transmitted after each bulletin and
between ASCII TLM and WOD.

The Mode-S beacon is ON transmitting an unmodulated carrier, but telemetry
indicates that it has partially failed and delivering half power.  This
beacon is a useful test source for those testing Mode-S converters prior
to the launch of P3-D.  It is considerably weaker than DOVE, which should
be used for initial testing (after it returns to the air).  Any reports
of 2401 MHz S-band beacon reception would be most welcome, and should be
directed to Clive Wallis, g3cwv@amsat.org.

The 435.025 MHz beacon is normally OFF.  However, it can sometimes be
heard when the satellite is being commanded by ground control (within
range of Guildford, UK).  When the 435 MHz beacon is transmitting, the
145 MHz VHF beacon is normally OFF.  The data transmitted is mainly binary.

Listeners to OSCAR-11 may be interested in a web site written by Clive
Wallis.  The site contains details of hardware required and some software
for capturing data, and decoding ASCII telemetry and WOD.  There is an
archive of raw data (mainly WOD) that's available for analysis, and is
continually being expanded as new data is captured.  Also included are
some audio files containing examples of each type of data transmitted
by OSCAR-11.  Each one plays for about ten seconds.  There are also
examples of Mode-S reception.  All the audio files are zipped so that
they can be played off-line.  These should help listeners identify the
various types of data transmitted by OSCAR-11, and give an indication
of the signal quality  required for successful decoding.

The URL is: http://www.users.zetnet.co.uk/clivew/

[Info via Clive Wallis, G3CWV]

Reports from Guatemala indicate that commercial land mobile stations are 
currently being licensed in the 430 to 440 MHz band against International 
Radio Regulations.  These stations may cause harmful interference to 
stations in the amateur-satellite service operating between 435 and 438 MHz.

Any amateur station experiencing interference from what appears to be
a Guatemalan land mobile station should gather as much information as 
possible about the intruder including; call sign, frequency, emission type, 
and if possible, the content of its transmission(s).  Also, note the date, 
time, and call signs of the other amateur station(s) with which you are
attempting to communicate.

Amateurs should report all of this information to your national IARU member 
society so that a formal complaint may be lodged through appropriate 
diplomatic channels.

[Info via Art Feller, W4ART via the AMSAT News Service]

Chris Jackson reported last week that the initial part of the flight
software is now running on TMSAT, and the OBC has been switched to the
downlink.  Users familiar with the digital satellites will now be able
to observe the satellite data using the standard groundstation software.

The satellite callsign is TMSAT1, and it is transmitting on 436.923 MHz. 
Presently it may be 3 kHz high in frequency due to the internal spacecraft
temperature being quite cold.

Richard W. L. Limebear, G3RWL reports that several changes have been made
to this year's AMSAT-UK Colloquium.  Some other "fine tuning" may occur,
and will be reflected on AMSAT-UK's Web page <http://www.uk.amsat.org>.

The major change is that NASA astronaut Don Thomas will not be making
the Colloquium, but Ron Parise, WA4SIR has kindly agreed to fill the
"space".  He'll be attending the International Space Station meeting
as well as the Colloquium.

There are still a few delegate vacancies should anyone suddenly decide 
they want to come to AMSAT-UK's best Colloquium yet (only 2 weeks to go).

[Info via Richard W L Limebear, G3RWL]

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 -=-=-=-=-=-=-=-=-=-=-=-=-
Internet  : kd2bd@amsat.org          |  Voice : +1.732.224.2948
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