OSCAR-11 report 15 February 2006

During the period 23 January to 14 February 2006 the VHF beacon on 145.826 MHz. has been heard from 01 to 11 February.

Signals during February have tended to be stronger than in previous months, and good copy was obtained on most passes. If the current mode of operation continues, the beacon should switch ON around 22 February.

The on-board clock continues to show a very large error. On 11 February it was 22.14 days slow. However, the rate of change of error has considerably reduced since the last the last report. During the OFF period from 21 January to 01 February, no change in the clock error awas detected. During the ON period from 01 to 11 February the error increased by 362 seconds. However, all the change occurred during the first half of the ten day 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 satellite is now in continuous sunlight until around 06 May, when eclipses will start again. This should help the satellite to continue transmitting, although continuous sunlight can cause problems due to excessive temperatures. Power supply problems can be caused by poor pointing attitude, ie the sunlight illuminating the ends of the satellite, instead of the solar arrays.

The watchdog timer now appears to have resumed operation on the 20 day cycle, ie. approximately ten days ON followed by 10 days OFF. However, at any time, poor solar attitude, and battery 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/

73 Clive G3CWV
g3cwv@<no spam>amsat.org

AMSAT-UK produces a newsletter Oscar News packed full of Amateur Satellite information. For membership details contact the secretary Jim Heck G3WGM Tel: +44 (0)1258 453959 Email: g3wgm@amsat.org Website: http://www.uk.amsat.org/ Online Satellite Pass Predictions: http://www.amsat.org/amsat-new/tools/predict/

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