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OSCAR-11 Report





                OSCAR-11 REPORT    18 September 2000

During the period 15 August to 16 September 2000 good signals have been
received from the 145 MHz. beacon.

The battery voltage observed during daylight passes has continued to
increase. The average value observed was 13.8, with a range of
13.5 to 14.1 volts.

The internal temperatures have increased by 2.6C during the month.
They are now 3.0C and 1.6C for battery and telemetry electronics
respectively.  This rise in temperature is expected to continue until
the end of the year as the solar eclipse times become shorter.

The Z-axis magnetorquer counter reached its maximum value at the
beginning of September, preventing further attitude and spin control
corrections. During the last two weeks the spin period has varied
between 270 and 339 seconds.  Ground control operations are now
required to reset the counters.

The single WOD survey of channels 10, 20, 30, 40 (+Y, -X, +X solar
array currents, array voltage), dated January 06 has been
transmitted. Note the year of this WOD survey is incorrectly
displayed as 99. This survey clearly shows the solar eclipses, and a
spin period of 340 seconds. As this survey has been transmitted for
over six months, I have now stopped collecting further data.  The raw
data collected from about 30 passes, until mid May is now available
for download from my web site (details below).

The mode-S beacon has been heard in the San Francisco area by Ken
W7KKE.  He uses a Drake MDS converter, wide band pre-amplifier, and a
horn antenna. For the tests Ken fixed the position of the antenna to
the centre of the pass, and tracked the Doppler.  Signals were weak,
but identified by the large Doppler shift.  Thanks Ken for the
report.

The operating schedule is 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  after  each bulletin is
transmitted, 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. However the signals are very
weak, and there is a lot of Doppler. Users should also note that the
polarisation of OSCAR-11 is LHC. Even if you can't hear OSCAR-11,
your equipment may still be OK for P3-D. Any reports of reception on
2401 MHz.  would be most welcome.  Please e-mail 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, ie.
within range of Guildford, UK.  When the 435 beacon is transmitting,
the 145 beacon is normally OFF.  The data transmitted is mainly
binary.

Listeners to OSCAR-11 may be interested in visiting my web site.  The
web 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) for analysis, which is continually
being expanded, as new data is captured.  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:U2RPT53.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org


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