[amsat-bb] OSCAR-11 Report

[Clive Wallis]

                   OSCAR-11 REPORT   30 November 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 .

If you place this bulletin on a terrestrial packet network,
please use the bulletin identifier $BID:U2RPT151 .CWV, to prevent
duplication.

73 Clive G3CWV   xxxxx at amsat.org (please replace xxxxx by g3cwv)