UO-11 Report – December 5, 2010

AMSAT News Service Bulletin 332.02
December 5th, 2010

UO-11 Report – December 5, 2010

This report covers the period from 29 October to 30 November 2010. During this time the satellite has been heard from 30 October to 09 November and 19 to 29 November . At the time of writing it is is expected to switch-on 10 December.

Excellent signals have been reported from stations located around the world, and good copy obtained from decoded telemetry frames.

The satellite is now transmitting during eclipses, although signals are weaker at those times. This indicates that there is still some capacity remaining in the battery.

The on-board clock is now very stable.  It gained eight seconds during November. This is comparable with its accuracy when the satellite was fully operational, when it gained approximately one minute per year. However, there is still an accumulated loss of 309 days, which has occurred during eclipses of the last few years.

Operation during eclipses and stability of the on-board clock suggest that some part of the system may have recently failed ‘open circuit’ thus reducing the overall power drain of the system, and allowing more power to be available during eclipses. When analogue telemetry was last transmitted, an unexplained current drain was observed. This fault may have cleared.

The Beacon frequencies are –

  • VHF 145.826 MHz.  AFSK FM  ASCII Telemetry
  • UHF 435.025 MHz.  OFF
  • S-band 2401.5 MHz. OFF

Reception reports have been received from  Gene WA4UKX, Horatio CX8AF, David G8OQW and Michael M0MPM/PA3BHE . Many thanks for those and to everyone who posted reports on the satellite status website.

At the present time, while OSCAR-11 is operating in a predictable way, I no longer need direct reports by e-mail. However, could you continue to enter reports on the general satellite status website. This is a very convenient and easy to use facility, which shows the current status of all the amateur satellites, and is of use to everyone. Reports around the expected times of switch-on and switch-off are of special interest. The URL is http://oscar.dcarr.org/index.php

OSCAR-11 transmits on 145.826 MHz., set receiver to NBFM. The satellite has a characteristic sound, rather like  raspy slow morse code, sending “di di dah dah dah dah dah dah dah” sent over a period of five seconds. If you are receiving a very weak signal, switch the receiver to CW or SSB. You should hear several sidebands around the carrier frequency and should be able to hear the characteristic ‘morse code like’ sound on at least one sideband.

Please note that you need a clean noise-free signal to decode the signals, and your receiver must be set to NBFM mode, for a decoder to work.

If you need to know what OSCAR-11 sounds like, there is an audio clip on my website www.g3cwv.co.uk/ which may be useful for identification and as a test signal for decoding.

The current status of the satellite, is that all the analogue telemetry channels, 0 to 59 are zero, ie they have failed. The status channels 60 to 67 are still working. The real time clock is showing a large accumulated error, but is now incrementing accurately to within a few seconds per month. The day of the month has a bit stuck at ‘one’ so the day of the month may show an error of +40 days for some dates. The time display has switched into 12 hour mode. Unfortunately, there is no AM/PM indicator, since the time display format was designed for 24 hour mode.

The spacecraft computer and active attitude control system have switched OFF, ie. the satellite’ attitude is controlled only by the passive gravity boom gradient, and the satellite is free to spin at any speed.

The watchdog timer operates on a 20 day cycle. The ON/OFF times have tended to be very consistent. The average of many observations have shown this to be 20.7 days, ie. 10.35 days ON followed by 10.35 days OFF.

Listeners to OSCAR-11 may be interested in visiting my website. If you need to know what OSCAR-11 should sound like, there is a short audio clip for you to hear. The last telemetry received from the satellite is available for download. The website contains an archive of news & telemetry data which is updated from time to time. 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.g3cwv.co.uk .

73 Clive G3CWV