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OSCAR-11 Report







                OSCAR-11 REPORT    15 June 1999

During the period 15 May to 15 June 1999 consistent signals have been
received from the 145.826 MHz. beacon. The battery voltage during
daylight passes has continued to decrease slightly, the average value
observed was 13.4, with a range of 13.2 to 13.7 volts.

The internal temperatures have continued to fall, by a further 1.5
degrees C during this period. They are now 0.4C and minus 1.0C for
battery and telemetry electronics respectively.

The magnetorquer spin correction counters have now resumed their
nominal counting rates, after their unusual behaviour during the last
few months. The counting rate for the negative spin counter is now
about 6.5 counts per day, whilst the Z axis counter increments at
about 11 counts per day.

A single WOD survey dated 08-April-1999 of channels 39, 50, 52 & 63
(telemetry electronics temperature, battery charge current, battery
voltage, and BCR status), has been transmitted during this period.
This starts at 16:00 UTC.  A plot of channel 52 (battery voltage)
shows that during periods of sunlight the voltage can be seen rising
and modulated by the spacecraft spin. The shape of this modulation
suggests that one photo cell panel may be generating a smaller output
than the others. During the eclipse period the voltage steadily
decreases from 13.3 down to 12.2 volts.

Channel 63, which contains the battery charge regulator (BCR) status
shows that the switch between A & B units occurs when the satellite
enters or exits from the eclipse state.  Channel 39 (telemetry
electronics) shows a very small change in temperature, about one
degree C, of the telemetry electronics unit, as the satellite passes
through the earth's shadow.

This interesting WOD is now available for download from my web site,
details below.

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:U2RPT38.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org



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