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OSCAR-11 Report



                  OSCAR-11 REPORT

                   07 May 2006

RECEPTION REPORTS REQUESTED! I am expecting the VHF beacon on 145.826 MHz.
to switch ON around 15/16 May.  Due to solar eclipses (see below) the
beacon may only transmit for a short time, perhaps only a few orbits. Any
reception reports would be appreciated.  Please e-mail g3cwv@amsat.org, or
post to AMSAT-BB.  If you are unfamiliar with the sound of OSCAR-11, there
is an audio clip on my website www.users.zetnet.co.uk/clivew/

During the period 16 April to 06 May 2006 the VHF beacon on 145.826
MHz. has been heard from 25 April to 05 May. Signal strengths have been
very variable during this ten day period, sometimes too weak to detect,
even with the receiver set to CW mode, at other times signals were of good
decoding quality. Frequent changes in polarisation were also observed on
some passes.

OSCAR-11's VHF beacon switched OFF on 05 May, as expected. This was just
one day before the solar eclipses were due to start. These eclipses will
continue until 04 August 2006, reaching a maximum duration of 22% around
19 June. If the satellite behaves in the same way as it did last year, the
beacon may only be heard for very short times, during the eclipse season.

The on-board clock continues to show a very large accumulated error. On 05
May it was 22.76456 days slow.  The clock lost two hours during the last
OFF period, and nine hours during the last transmission period. The
observations of clock errors suggest that the clock may slow or stop when
the battery voltage is low.

All the analogue telemetry channels, 0 to 59 are zero, ie they have failed.
The status channels 60 to 67 are still working.

The watchdog timer now appears to have resumed operation on the 20 day
cycle. During the last three months the ON/OFF times have been very
consistent, and many observations show this to be 20.7 days, ie. 10.3 days
ON followed by 10.4 days OFF. However, during the present solar eclipse
season, power supply problems, may result in a low 14 volt line supply,
which may cause the beacon to switch OFF prematurely, and reset the
watchdog timer cycle.

The Beacon frequencies are -

VHF 145.826 MHz.  AFSK FM  ASCII Telemetry

UHF 435.025 MHz.  OFF

S-band 2401.5 MHz. OFF

Listeners to OSCAR-11 may be interested in visiting my website which
contains an archive of news & telemetry data. It also contains details
about using a soundcard or hardware demodulators for data capture.  There
is software for capturing data, and decoding ASCII telemetry.  The URL is
www.users.zetnet.co.uk/clivew/

If you place this bulletin on a terrestrial packet network, please
use the bulletin identifier $BID:U2RPT121.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org
----
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