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OSCAR-11 Report




                OSCAR-11 REPORT    23 September 2002

Chris G7UPN, UoSAT Ground Controller, has recently outlined the current
problems he is experiencing with this satellite.  He says

"Due to the cold temperature, we are currently unable to command the
spacecraft to rectify the problem.  The reason the Tx cycles is a
watchdog timer that cycles the power on and off every few days to
ensure that we don't have the same problem which occurred on UoSAT-1
(where the transmitter gets left on and the receivers are therefore
blocked).

At the moment there's not a lot we can do to rectify the problem.
We will continue to look at it periodically, however for now it will
have to remain in its current state."

Thanks Chris for the information.

During the period 17 August to 22 September the 145.826 beacon has
been heard transmitting continuous ASCII telemetry from 18 August to
23 August and from 06 September to 10 September.  Once again I am
indebted to Jeff KB1M who has provided some excellent telemetry while I
have been away on holiday.  Many thanks Jeff.

The internal temperatures have increased by two degree C. They are
now +3.4C and 2.0C for battery and telemetry electronics
respectively. This temperature rise is expected to continue during
the next few months, due to the reduction in solar eclipse time, and
should assist ground control in commanding the satellite.

The battery voltage observed during daylight passes has varied
between 13,1 and 14.1 volts

The mode-S beacon on 2401.5 MHz. has been heard by many stations
including ZL1AOX, OE1VKW, OE6AG, PE1ITR, WA6WFW, ZL2MV. OZ1MY, W7KKE,
IW1AM and K5OE.  These reports indicate that the recent problems on
OSCAR-11 have not effected the operation of this beacon. Many thanks
for those reports.

Viktor OE1VKW has been monitoring the S-band beacon and has added two
sound files to his web site.  These are in CW and FM modes, recorded
while the VHF beacon was off.  Analysis of the FM mode recording with a
'waterfall' display reveals a continuous modulation of 2400 Hz.  This
confirms VE7BPB's previous observations.

The URL for Victor's web site is -

http://cacofonix.nt.tuwien.ac.at/~oe1vkw/uo11/uo11.html


To Summarise. The normal operating schedule for OSCAR-11 is currently
suspended. The VHF beacon transmits continuous ASCII telemetry for a
few days, followed by an OFF period of about 14 days.

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. 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 for analysis, which is continually being
expanded, as new data is captured.  Originally this was for WOD, but
it is now being expanded to include ASCII telemetry. At the present
time the telemetry is just for 2002, and 2001.  I will add other
years as time permits.  In parallel there is a news archive which
provides an overview of the state of the satellite, at the times when
the telemetry was captured.

Telemetry from 1993 to 2000 should be relatively easy to archive, as
I already have the data on disk. Data prior to 1993 will take a lot
longer to archive, as I have to convert it from tape to disk.  A
tedious process!  The early data is often of poor quality, and there
are many long gaps where no recordings were made.

If anyone out there can provide any data, particularly for the 1984
to 1993 years, this would be most appreciated.  Please e-mail me
with details.  However please DO NOT SEND ANY FILES, before futher
discussion.

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:U2RPT77.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org

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