OSCAR 11 Celebrates 21 Years

OSCAR-11 achieved 21 years in orbit on 01 March 2005.
It's still working and sending reliable telemetry on it's VHF beacon. Congratulations to Professor Sir Martin Sweeting G3YJO and his team for this fine achievement.

During the period 15 February to 09 March 2005 reliable signals have been received from the 145.826 MHz. beacon, transmitting continuous ASCII telemetry from 25 February to 06 March. At times signals have been weaker than usual, and subject to local interference (QRN), which has been stronger than usual.

The beacon operates under control of the watchdog timer. Observations have indicated that the cycle is approximately 10.3 days ON followed by 10.4 days OFF. Assuming that this cycle continues, the beacon should switch ON around 17 March.

The internal temperatures have decreased by about five degrees C. They are now 14C, 13C and 20C for the battery, telemetry electronics and command decoder respectively. At the present time the satellite is in full sunlight, and therefore temperature changes are caused by changes in attitude, and spin rate. The hot external surfaces will cause some nearby internal parts to warm up faster than others.
A Solar eclipse predictions indicate that the continuous sunlight will continue until the end of April, when eclipses will start.

The battery voltage has varied between 11.7 and 13.7 volts. The average voltage was 12.4 volts, unchanged since the last report. Low battery voltage have occurred when the internal temperatures were depressed. The period of rotation about the Z axis had been determined from the solar array currents. Values of between 431 and 590 seconds have been observed.

Users of OSCAR-11 should note that the date in the telemetry is now advanced by FOUR days. The time is advanced by 20.6 minutes, and this error is increasing by about one minute per year.

OSCAR-11 now operates in a default mode, controlled by the watch-dog timer. The satellite transmits continuous ASCII telemetry for approximately 10.3 days on 145.826 MHz., followed by 10.4 days of silence. This regular sequence might be interrupted by ground control, at any time. At the present time the mode-S beacon 2401.5 MHz. and the UHF beacon 453.025 MHz. are both OFF.

Listeners to OSCAR-11 may be interested in visiting my web site. The web site contains details about using a soundcard for data capture, and also details about using hardware demodulators. There is software for capturing data, and decoding ASCII telemetry. 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 covers 1996 to December 2004. 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.

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/

[ANS thanks Clive, G3CWV for the above information]