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 Satellite Detail - UoSat OSCAR 11
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Photo of UoSat OSCAR 11

UoSat OSCAR 11
(UoSAT 2)

Spacecraft Summary

OSCAR Designation:  UoSat OSCAR 11     Oscar Number:  UO-11    
International Designator:  1984-021B     Norad Number:  14781    
Common Name:  UoSAT 2     Satellite Type:  Microsatellite    
Launch Date:  1 March, 1984     Launch Location:  Vandenberg, AFB    
Launch Vehicle:  Delta     Apogee:  637.00    
Perigee:  625.00     Inclination:  98.21    
Period:  97.34     Dimensions:  58.4cm x 35.5cm x 35.5cm    
Weight:  60.000 Kg    
Organization: University of Surrey SERG
Frequency Information
 
Mode V TLM Beacon: Semi-Operational
Downlink 145.8260 MHz AFSK 1200 BPS
 
Mode U TLM Beacon: Non-Operational
Downlink 435.0250 MHz AFSK 1200 BPS
Downlink 435.0250 MHz PSK 4800 BPS
 
Mode S TLM Beacon: Non-Operational
Downlink 2401.5000 MHz PSK 4800 BPS

Current Keplerian Elements

UO-11
1 14781U 84021B   09325.29753687  .00000125  00000-0  23832-4 0  1107
2 14781  98.0864  11.0652 0008649 184.6495 175.4693 14.79748075381062

Weekly Satellite Report

From Clive, G3CWV:
13 September 2007

Nothing heard from OSCAR-11 recently.. Eclipses finished on 20 August,
although previous observations had suggested that sustained operation
could have been supported any time after 10 August.

I would appreciate any reception reports of the satellite. Please post
to AMSAT-BB or directly to g3cwv@amsat.org .

If you are able to record as a WAV file, please do so, and make a note
of the exact time of the start of recording in UTC. Please let me know
what you have, but PLEASE DO NOT send recordings without further
discussion.

The frequency of the VHF beacon is 145.825 MHz, mode FM.

If you require further information, or need to hear what the satellite
sounds like, please visit my website -

www.users.zetnet.co.uk/clivew


----


This from Clive, G3CWV:
27 March 2006

On 01 March OSCAR-11 achieved 22 years in orbit, and in spite of numerous problems, it still continues to transmit good signals.

During the period 14 February to 26 March 2006 the VHF beacon on 145.826 MHz has been heard from 22 February to 04 March, and from 14 to 24 March.

Signals have been very consistent and excellent copy has been obtained on all passes received. If the current mode of operation continues, the beacon should switch ON around 04 April 2006.

The on-board clock continues to show a very large accumulated error. On 24 March it was 22.14308 days slow. However, the clock is now very stable. During the last month it gained 2.5 seconds, which is approximately half the monthly gain, observed when the satellite was fully operational! 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. During the last two 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, 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.

I am indebted to Bob G4VRC, Gustavo LW2DTZ, Mike DK3WN, John K7RQN and John G4PWG for their reception reports. All have reported good signals from the VHF beacon. Many thanks for those reports.

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: http://www.users.zetnet.co.uk/clivew/

Detailed Description

At 17:59 UTC on March 1, 1984, the second satellite designed and built by the University of Surrey's Spacecraft Engineering Research Group - UoSAT in the United Kingdom, UoSAT-2 (UO-11) was launched on a Delta rocket from the Western Test Range at Vandenberg Air Force Base, Lompoc, California with LANDSAT 5. It weighs 60 kg.

Among its many experiments, UoSAT-2 carried the Digital Communications Experiment, which was one of the first (if not the first) non-military use of store-and-forward techniques with Low Earth Orbiting Satellites. UoSAT-2 was the test-bed for the packet radio satellites as we know them today.

UO-11 is approaching end of life and has only been heard sporatically. There is a small chance that OSCAR-11 may have started transmitting again between 08 June to 10 June on the 2M telemetry channel. The S-Band beacon has not been heard.
Any reception reports would be appreciated. Please send any reception reports direct to Clive G3CWV (@amsat.org), or post reports to AMSAT-BB.

Reference Documents:

  • Martin Sweeting, "The UoSAT-B Experimental Amateur Spacecraft", Orbit, Vol 5, No. 1, Jan/Feb 1984, pp 12-16; Amsat Satellite Report, No. 74, Mar 19, 1984.
  • Lyle Johnson, "The OSCAR-ll Packet Experiment", Proceedings of the ARRL 3rd Computer Networking Conference, Trenton, NJ, April 15, 1984, pp. 3.64-3.67.
  • Bernie Glassmeyer, "UoSAT-OSCAR 11 Launched (Amateur Satellite Program News)", QST, May 1984, p. 87.
  • Bernie Glassmeyer, "UoSAT-OSCAR 11 Back In Service (Amateur Satellite Program News)", QST, Jul 1984, p. 77.
  • Harold E. Price and Jeff Ward, "The UO-11 DCE Message Store-and-Forward System", Proceedings of the ARRL 5th Computer Networking Conference, Orlando, FL, March 9th, 1986, pp. 5.109-5.114
  • Robert Diersing, "Processing UoSAT Whole-Orbit Telemetry Data", Proceedings of the 4th Annual AMSAT Space Symposium, Dallas, 1986, ARRL, pp 55-76.
  • Robert Diersing, "Microcomputer Processing of UoSAT-OSCAR 9 Telemetry", The ARRL Satellite Anthology, 1988, 1988, ARRL, pp 46-51.
  • Jon Bloom, "A Profile of the UoSAT-OSCAR 11 Satellite", The ARRL Satellite Anthology, ARRL, 1988, pp 52-53.
  • Martin Davidoff, The Satellite Experimenter's Handbook, 2nd edition, The American Radio Relay League, Newington, CT., 1990.
  • John A. Magliacane, " Spotlight On: UoSAT-OSCAR-11", The AMSAT Journal, Vol. 16, No. 2, Jan/Feb 1992, p. 17.
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