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OSCAR-11 Reort







                OSCAR-11 REPORT    16 February 1999

Mode-S enthusiasts may be interested in an Spectrogram plot of the
this beacon, kindly sent by Mike WL7BQM.  Refer to mode-s reports
below, for details.

During the period 17 January to 16 February 1999 good signals have
been received from the 145.826 MHz. beacon. The battery voltage has
dropped slightly, averaging 13.7 volts. This is during afternoon
passes when the satellite has been illuminated for some time.  During
a couple of early morning passes, when the satellite had been in
darkness for some time battery voltages of 13.1 and 13.2 were
recorded.

The magnetorquer spin correction counters have again showed very few
spin counter increments, although the spin period remains around its
nominal value of -300 seconds. However the Z axis counter increments
normally.

The internal temperatures have fallen by about two degrees C. They
are now 5.4C and 3.8C for battery and telemetry electronics
respectively.

A single WOD survey dated 06-January-99 of solar array currents and
array voltage ie.channels 10, 20, 30, 40 (+Y, -X, +X, V), has been
transmitted.  The sound of this WOD contains a characteristic
musical tone which occurs when the constant data captured during
solar eclipses is transmitted.

Reports of the Mode-S beacon thave been received from Mike WL7BQM in
Stirling, Alaska and Al KD4VA in Sumpter South Carolina.  Mike uses a
six foot dish, Drake converter and preamplifier.  The main receiver
is a FT736 modified with a MuTec front-end.  Mike's good signals can
be seen from the AF9Y FFTDSP42 spectrogram plot, which he very
kindly sent to me.  I have now added this graph to my web site.  It's
located in the 'GRAPHS' section. It shows the Doppler effect on
frequency, and variation of signal strength.

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

Mike has observed a reduction in signal strength when the satellite
goes into eclipse, although this may be due to path obstructions,
rather than power supply reduction.

Al KD4VA uses a Meyers dish, DEM pre-amp and a Drake converter. He
receives the beacon just above the noise level.   Many thanks for
both 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.  It is considerably weaker
than DOVE, which should be used for initial testing. 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:U2RPT34.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org



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