
                          OSCAR-11 REPORTS 2008
                          ---------------------


                     OSCAR-11 REPORT 26 January 2008


This report covers the period from 19 December 2007 to 26 January 2008.
After two months of silence from 20 November, when eclipses started, the
satellite resumed transmissions on 22 January 2008. This was three complete
20.7 day watchdog cycles after the satellite switched off. At the time of
writing signals are consistantly strong, although the polarisation is very
variable, with a cycle time of around 20 seconds, causing deep fading if
the antenna polarisation is fixed. This suggests that the satellite may be
tumbling.

If the current watchdog cycle continues uninterrupted, the 145.826 Mhz.
beacon should switch off around 01 February and on again around 11
February. However, if low battery voltage causes the watchdog timer to
reset, then the beacon should switch on 21 days later.

The real time clock in now very stable although it has lost a further 7.09
days since 20 November. On 26 January it is 81.36403 days slow.

I am indebted to Peter ZL3TC, Mark KU7Z, Gene WA4UKX, SWL Mark in CM87, Ron
G4PGY, Julian WB9YIG, John HB2HSH and Edward BX1AD for their reports. Many
thanks.

The satellite is now in continuous sunlight, and this is expected to
continue until mid March, when eclipses will start again. Unfortunately
eclipses will then become a permanent feature of the orbit, which is likely
to prevent any periods of sustained operation after March.

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, although over short periods timekeeping is accurate to 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.
More data is required to determine exactly when the date changes.

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. When
telemetry was last received it showed that one of the solar arrays had
failed, and there was a large unexplained current drain on the main 14 volt
bus. After 23 years in orbit the battery has undergone around 100,000
partial charge/discharge cycles, and observations suggest that it cannot
power the satellite during eclipses, or sometimes during periods of poor
solar attitude.

The watchdog timer now operates on a 20 day cycle. The ON/OFF times have
tended to be very consistent. The average of many observations show this to
be 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor
solar attitude may result may result in a low 14 volt line supply, which
may cause the beacon to switch OFF prematurely, and reset the watchdog
timer cycle. When this occurs, the beacon is OFF for 20.7 days.

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. If you need
to know what OSCAR-11 should sound like, there is a short audio clip for
you to hear. There is an example of the latest telemetry received from the
satellite. The website 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/



                    OSCAR-11 REPORT 17 February 2008

This report covers the period from 21 January to 17 February 2008,
overlapping the previous report by a few days, to include the two periods
of continuous operation..  The satellite was heard from 22 January to 01
February and from 11 February to 15 February.

Signals have been very variable in strength sometimes very strong,
sometimes undetectable, even at high elevations. Low signal strength was
particularly noticeable at AOS and LOS, and also towards the end of the
transmission periods.

The transmission period which started on 11 February was prematurely
terminated four days later, on 15 February. If the watchdog timer has
reset, it should switch-on again around 07 March. There should be a short
period of transmissions before permanent eclipses start in mid March. After
March it is unlikely that the satellite will support any sustained
period of operation, and will only transmit for a short time, possibly less
athn a single orbit, every 21 days.

The real time clock now serves as a crude indicator of the state of the
satellite. Between 22 and 29 January the clock was stable to within
two seconds.  During the next two days it lost 4.3 hours

Between 11 and 15 February the real time clock showed a steady loss of
time every orbit. During the four days the clock lost 4.8 hours.  When last
heard the clock was 82.76424 days slow.

I am indebted to Peter ZL3TC, Chris M0DQO, Tobias DG3LV, Edward BX1AD,
Mark KU7Z, Gene WA4UKX, SWL Mark in CM87, Ron G4PGY, Julian WB9YIG and John
HB2HSH for their reports. Many thanks.

The satellite is now in continuous sunlight, and this is expected to
continue until mid March, when eclipses will start again. Unfortunately
eclipses will then become a permanent feature of the orbit, which is likely
to prevent any periods of sustained operation after March.

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, although over short periods timekeeping is accurate to 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. When
telemetry was last received it showed that one of the solar arrays had
failed, and there was a large unexplained current drain on the main 14 volt
bus. After 23 years in orbit the battery has undergone around 100,000
partial charge/discharge cycles, and observations suggest that it cannot
power the satellite during eclipses, or sometimes during periods of poor
solar attitude.

The watchdog timer now operates on a 20 day cycle. The ON/OFF times have
tended to be very consistent. The average of many observations show this to
be 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor
solar attitude may result may result in a low 14 volt line supply, which
may cause the beacon to switch OFF prematurely, and reset the watchdog
timer cycle. When this occurs, the beacon is OFF for 20.7 days.




                    OSCAR-11 REPORT 17 March 2008

OSCAR-11 celebrated its 24th birthday on 01 March 2008.  It was designed,
built and launched, within a time scale of six months, using commercially
available components. Congratulations to Professor Sir Martin Sweeting
G3YJO, his team at the University of Surrey and associated groups of radio
amateurs, for their magnificient achievement.

This report covers the period from 17 February to 17 March 2008.  The
satellite was heard from 03 to 13 March. Previously the transmissions which
started on 11 February were terminated prematurely after only four days.
The watchdog timer cycle appears to have continued for its full 21 days,
thus restarting transmissions on 03 March.

Signals have been very variable in strength sometimes very strong,
sometimes undetectable, even at high elevations. Low signal strength was
particularly noticeable at AOS and LOS, and also towards the end of the
transmission period, which on this occasion, lasted the full ten days.

The next transmissions should start on 24 March. However, permanent
eclipses start a few days beforehand, which will probably cause the
transmission period to be terminated prematurely, and may even prevent it
being heard at all. After March it is unlikely that the satellite will
support any sustained period of operation, and will only transmit for a
short time, possibly less than a single orbit, every 21 days.

The real time clock now serves as a crude indicator of the state of the
satellite. Between 04 and 13 March showed an average loss of over two hours
per day. time every orbit. When last heard the clock was 83.0958 days slow.

I am indebted to Peter ZL3TC, Mark KU7Z, John KB2HSH, Antonio EA1CXG,
Edward BX1AD and Andrew VK5LAC  for their reports. Many thanks.

The satellite is now in continuous sunlight, and this is expected to
continue until mid March, when eclipses will start again. Unfortunately
eclipses will then become a permanent feature of the orbit, which is likely
to prevent any periods of sustained operation after March.



                    FINAL MONTHLY OSCAR-11 REPORT

                            21 April 2008

RECEPTION REPORTS REQUESTED!

In the years ahead, it is possible that you may hear OSCAR-11, by accident,
when tuning round the frequency. If you are able to record the satellite on
audio tape or as a WAV file (not MP3), please do so, as it is unlikely
that it will be heard on the next pass!

Please send reception reports to xxxxx@amsat.org (replace xxxxx by
g3cwv) or post to amsat-bb.  If you have a file, please let me know what
you have, before sending it!

If you need to hear what the satellite sounds like, please visit my website
www.users.zetnet.co.uk/clivew/  The satellite transmits on 145.826 MHz. set
receiver to NBFM.

                   ----------------------------

This is the 144th monthly report for OSCAR-11. Unless there is an
unexpected change of status (such as occured with OSCAR-7), I'm expecting
this to be my last report.

This report covers the period from 17 March to 21 April 2008.  During
this period the satellite has not been heard and no reports of reception
have been received.

Transmissions were expected to resume on 24 March, after the beacon
switched-off on 14 March.  However, permanent eclipses started a few days
beforehand, which probably caused the transmission period to be terminated
prematurely. It is now unlikely that the satellite will support any
sustained period of operation, and will only transmit for a short time,
possibly less than a single orbit, every 21 days.

I am indebted to  all those who sent reception reports during the last 12
years.  Initially there was much interest in hearing the mode-S beacon,
which was very weak. Recently, interest has changed to hearing when the
two metre beacon switched on/off. Special thanks must go to Jeff KB2M who
recorded telemetry during my holidays, and Peter ZL3TC, who has monitored
the beacon daily, during recent months. Many thanks to everyone.

The Beacon frequencies are -

VHF 145.826 MHz.  AFSK FM  ASCII Telemetry

UHF 435.025 MHz.  OFF

S-band 2401.5 MHz. OFF

The satellite is now subject to eclipses during every orbit.  Long term
predictions indicate that eclipses will occur until 2019, when there will
be some eclipse free periods until 2023.  However these very long term
predictions should be regarded with caution, as large tracking errors can
accumulate over long periods of time.

When telemetry was last received it showed that one of the solar arrays had
failed, and there was a large unexplained current drain on the main 14 volt
bus. After 24 years in orbit the battery has undergone over 100,000 partial
charge/discharge cycles, and observations suggest that it cannot power the
satellite during eclipses lasting more than about ten minutes, or
sometimes even during periods of poor solar attitude.

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, although over short periods timekeeping is accurate to a few
seconds per month. When last heard the clock was 83.0958 days slow.  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 now operates on a 20 day cycle. The ON/OFF times have
tended to be very consistent. The average of many observations show this to
be 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor
solar attitude may result may result in a low 14 volt line supply, which
may cause the beacon to switch OFF prematurely, and reset the watchdog
timer cycle. When this occurs, the beacon is OFF for 20.7 days.

OSCAR-11 was the second satellite from the University of Surrey,
www.ee.surrey.ac.uk/SSC.  It was designed, built and launched, within a
time scale of six months, by a team headed by Martin Sweeting G3YJO.
Amateur radio groups working at various locations in the world, also
contributed to the project. It used commercially available 'off the shelf'
components (COTS). Following the success of these satellites, in 1985
Surrey Satellite Technology Ltd. www.sstl.co.uk was formed, as a commercial
venture. This grew into a major company which has produced over 27 small
satellite projects for a global market.

The University of Surrey has recently agreed to sell it's major
shareholding to EADS-Astrium. This agreement is now awaiting regulatory
approval. The joint company will have the experience of manufacturing
large and small satellites, for geo-synchronous and low earth orbits.

In regognition of his work, Martin G3YJO, was appointed Professor at the
University of Surrey.  He received an OBE in the 1995 Queens birthday
honours list, and in 2002 a knighthood in the New Year's honours list.

Listeners to OSCAR-11 may be interested in visiting my website, which is
being updated to reflect the current status of the satellite. 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 has now been updated. 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/

                                                    Clive Wallis   G3CWV


                                                    Compiled 22 April 2008

