OSCAR-11 Reort

[Clive Wallis <clivew@xxxxxxxxxxxx>]

                OSCAR-11 REPORT    18 March 1998

OSCAR-11  celebrated  its  14th  birthday  on  March  1st.   It  is a
wonderful achievement by the UOSAT  team  who  designed,  built,  and
launched  the  satellite  in  a  period of only six months.  Although
there have been various component failures during its  long  time  in
orbit,  OSCAR-11  does have the habit of bouncing back!  Great credit
to its design philosophy.

During  the last week there have been some problems with OSCAR-11 and
the 145 MHz beacon has been OFF. The beacon was  heard  on  Monday  9
March,  when  telemetry was nominal.  Nothing heard Saturday & Sunday
14/15 March on 145 or 435 Mhz.  On Tuesday 17 February it  was  heard
on the 14:44 and 16:22 passes.  On both passes the 435 MHz beacon was
switched on after AOS, during the early part of the pass, binary data
transmitted,  and  then  switched over to 145 MHz., indicating ground
control activities.  During the latter pass some binary telemetry was
received which showed the battery voltage rather low at  13.3  volts.
Nothing heard on Wednesday 05:46 pass.

The shut down may be a recurrence  of  the  watchdog  timer  problem,
which was prevalent about two years ago.

During the remainder of the reporting period ie.  February  16  to  9
March good signals have been received from the 145 MHz.  beacon.  The
battery  voltage  has  been slightly depressed, at around 13.5 volts,
otherwise telemetry is nominal.

A  single  WOD  survey  has  been transmitted, dated 06 January 1998.
This contains channels 10, 20, 30 ,40 (+Y, -X, +X array currents, and
array voltage).  The array voltage is a very good indication  of  the
solar  eclipses, changing rapidly as the satellite goes in and out of
darkness.

Reports of the mode-S beacon have been received from  VK3BNC,  N0ZHE,
and N5JDB.  All are using the Drake MMDS downconverter.

OSCAR-11  users  are  welcome  to  visit my web site. I have recently
added some audio files, including the Mode-S recording  from  KC6SZY,
which  plays  for  20 seconds.  The other audio files are examples of
each type of data transmitted by OSCAR-11, and  each  one  plays  for
about  ten  seconds. All the audio files are zipped, so that they can
be played off-line.  They should help listeners identify the  various
types  of data, and give an indication of the signal quality required
for successful decoding.  The web site also  contains  some  software
for capturing data, and decoding ASCII telemetry and WOD. There is an
archive  of  raw data (mainly WOD) for analysis, which is continually
being expanded, as new data is captured. The URL is -

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


The operating schedule is unchanged.

        ASCII status (210 seconds)
        ASCII bulletin  (60 seconds)
        BINARY SEU (30 seconds)
        ASCII TLM (90 seconds)
        ASCII WOD (120 seconds)
        ASCII bulletin (60 seconds)
        BINARY ENG (30 seconds)

There  are  also  additional  status  blocks  after  each bulletin is
transmitted, and between ASCII TLM and WOD.

The mode-S beacon is ON, transmitting  an  unmodulated  carrier,  but
telemetry indicates that it has partially failed, and delivering half
power.   This beacon is a useful test source for those testing mode-S
converters, prior to the launch of P3-D.  It is  considerably  weaker
than  DOVE,  which should be used for initial testing. Any reports of
reception  on  2401  MHz.   would  be  most  welcome.  Please  e-mail
g3cwv@amsat.org.

The 435.025 MHz. beacon is normally OFF.  However it can sometimes be
heard  when  the  satellite is being commanded by ground control, ie.
within range of Guildford, UK.  When the 435 beacon is  transmitting,
the  145  beacon  is  normally  OFF.   The data transmitted is mainly
binary.

If you place this bulletin on a terrestrial  packet  network,  please
use the bulletin identifier $BID:U2RPT23.CWV, to prevent duplication.

73 Clive G3CWV   g3cwv@amsat.org