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OSCAR-11 Report







                OSCAR-11 REPORT    15 November 1999

During the period 18 October to 14 November 1999 reliable signals
have been received from the 145.826 MHz. beacon.

The Z-axis attitude correction counter has now reached its limit of
1024, which has stopped further firing of the magnetorquers. This
means that the attitude of the satellite is being controlled solely
by the action of the gravity boom gradient. The tendency of the
satellite to slow down its rotational speed has not occurred this
time, in fact the rotational speed has slightly increased. This is a
safer condition than than a decreasing speed, and is helping to keep
the satellite spinning.  The current rotational period is -242
seconds (0.248 revs/minute) compared with the usual period of around
350 seconds (0.171 revs/minute). Ground control action to reset the
counters is expected in the near future.

The battery voltage during daylight passes has remained consistently
high. The average value observed was 13.9, with a range of 13.8 to
14.0 volts. The higher value being observed many times.

The internal temperatures have risen by about one degree during
this period. They are now 7.4C and 5.6C for battery and telemetry
electronics respectively.

The single WOD survey of channels 1, 2, 3, 61 (magnetometers) dated
15 July 1999 has again been been transmitted.  This shows an
increased spin period of about 450 seconds, which was measured at the
time when the WOD was started.  This was quickly corrected by the
attitude control system, when it was operational.

Reports of the mode-S beacon have been received from Dave G3SBP and
Reg VK2RW.  Dave uses an SBS2000 down converter into an ICOM R9000
receiver, and a G3RUH design dish. Signals were S2.  Reg uses a 20
turn RHCP helix into a Swedish down converter from Parabolic. Signals
were just above the noise.   Many thanks for those reports.

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:U2RPT43.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org



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