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OSCAR-11 Report



                  OSCAR-11 REPORT

                  25 January 2005

I have now uploaded the complete 2004 telemetry and news archives to my
website. Another recent addition, is a package called ORBITS for
calculating the times of best passes for OSCAR-11 and other satellites in
sun synchronous orbit. See below for URL.

During the period 16 December 2004 to 25 January 2005 the 145.826 MHz.
beacon has been heard transmitting continuous ASCII telemetry from 24
December to 03 January and 14 January to 24 January. During this period
good signals have been received. On several occasions the signals have
been stronger than usual.

The beacon operates under control of the watchdog timer. Observations have
indicated that the cycle is approximately 10.3 days ON followed by 10.4
days OFF. Assuming that this cycle continues, the beacon should switch ON
around 04 February.

When the telemetry started on 24 December, the +Y solar array telemetry
showed eratic measurements, and now almost zero current. For some time the
+Y array had only been delivering about half the current of the other
arrays. Further investigation is required to establish whether this is a
failure of the array, or the telemetry.

At the present time the satellite is in full sunlight, and therefore
temperature changes are caused by changes in attitude, and spin rate. The
hot external surfaces will cause some nearby internal parts to warm up
faster than others. Variations of internal temperatures of up to six
degrees C have occurred. The current internal temperatures are 19C, 21C and
25C for the battery, telemetry electronics and command decoder
respectively. Solar eclipse predictions indicate that the satellite is now
in continuous sunlight, which will continue until the end of April next
year.

The battery voltage has varied between 12.2 and 13.6 volts.  The average
voltage was 13.1 volts. Voltages in the second ten day period have been
noticeably lower than those in the second period.

The period of rotation about the Z axis had been determined from the solar
array currents.  Values of between 288 and 474 seconds have been observed,
for most of the time. However, on 26/28 December the rotation was much
slower, and difficult to analyse.

Users of OSCAR-11 should note that the date in the telemetry is now
advanced by FOUR days.  The time is advanced by 20.5 minutes, and this
error is increasing by about one minute per year.

OSCAR-11 now operates in a default mode, controlled by the watch-dog timer.
The satellite transmits continuous ASCII telemetry for approximately 10.3
days on 145.826 MHz., followed by 10.4 days of silence. This regular
sequence might be interrupted by ground control, at any time.

At the present time the mode-S beacon 2401.5 MHz. and the UHF
beacon 453.025 MHz. are both OFF.

Listeners to OSCAR-11 may be interested in visiting my web site.

The web site contains details about using a soundcard for data
capture, and also details about using hardware demodulators. There is
software for capturing data, and decoding ASCII telemetry.
There is an archive of raw data for analysis, which is continually
being expanded, as new data is captured.  Originally this was for
WOD, but it is now being expanded to include ASCII telemetry. At the
present time the telemetry covers 1996 to December 2004.  I will add
other years as time permits.  In parallel there is a news archive
which provides an overview of the state of the satellite, at the
times when the telemetry was captured.

If anyone out there can provide any data, particularly for the 1984
to 1993 years, this would be most appreciated.  Please e-mail me
with details.  However please DO NOT SEND ANY FILES, before futher
discussion.

Also included are some audio files, 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, and give an indication
of the signal quality required for successful decoding.

The URL is -

      http://www.users.zetnet.co.uk/clivew/

If you place this bulletin on a terrestrial packet network, please
use the bulletin identifier $BID:U2RPT105.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org
----
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