[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

OSCAR-11 Report




                OSCAR-11 REPORT    18 May 2002

During the period 08 April to 17 May 2002 consistent signals have
been received from the 145.826 MHz. beacon. However, some
interference has been experienced on the channel.  CW from RS-21 and
packet from various unidentified sources has spoilt some passes. Once
again I am indebted to Jeff KB2M, who provided telemetry data while I
was away on holiday. Many thanks Jeff.

The internal temperatures have decreased by two degrees C. They are
now 2.0C and -0.2C for battery and telemetry electronics
respectively. The battery voltage observed during daylight passes has
decreased by 0.2 volts. The average value observed was 13.4 with a
range of 13.0 to 13.8 volts.

The rate at which the SEU counter increments, has continued to
increase, from 932 to 1150 counts per day. Decoding the SEU binary
telemetry shows six memory locations 39C0, 21C0 3EC0, 37B1, 180 and
F96 failing for most of the time. Some other locations also fail less
frequently. The permanent memory failures tend to mask out the
display of the less frequent failures, owing to the limited storage
for this data in the satellite. A program for decoding the SEU
packets (U2PKT.ZIP) may be downloaded from my website. URL details
below.

The WOD survey of channels 10, 20, 30, 40 ( +Y, -X, +X array
currents, & array voltage ) dated 06 January 2002 has been
transmitted.  This data may now be downloaded from my web site,
details below. Users should note that the date of this WOD survey in
the status messages is incorrectly listed as 2001. There is also an
error in the time of this survey due to satellite clock drift.  A
more accurate start time is 05-January-2002 23:49:30 UTC.

The spin period has increased from 295 to 697 seconds. Most of this
increase has occurred steadily during the last three weeks. The
increasing spin period means that the satellite rotates slower, and
this could result in uneven heating of the four sides exposed to the
sun . The attitude is controlled solely by the gravity boom gradient,
as the Z-axis magnetorquer counter has reached saturation (1024).
Ground control action is awaited to reset the magnetorquer pulse
counters.

The mode-S beacon on 2401.5 MHz. has been heard by Nick GM4OGI. His
report was of special interest, as his dish is fixed. He has received
S2 signals between elevations of 2 and 33 degrees, with the dish
pointing at 170 degree azimuth, mainly via ground scatter. Many
thanks for that 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 (number 115) is currently a static message,
detailing modes and frequencies of some 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, nominally transmitting an unmodulated
carrier on 2401.5 MHz. There is however a VERY low level of AFSK
modulation which has been detected on strong signals. Telemetry
indicates that the beacon has partially failed, and is delivering
half power.  This beacon is a useful test source for those testing
mode-S converters, as an alternative to OSCAR-40. 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 OSCAR-40 when
commissioning is complete. Any reports of reception on 2401.5 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:U2RPT72.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home