SPRE.TXT            SPARTAN AMATEUR RADIO EXPERIMENT

NOTE: The following is NOT an official description of SPARTAN nor SPRE.
It is only a myopic understanding from an APRtrak perspective...

    The SPARTAN Payload is a multi-flight payload build at the Goddard
Spaceflight Center in Greenbelt Maryland.  It is a scientific bus
that can carry many different experiments.  It is deployed from the
shuttle for a few day free-flight before being retrieved and brought
home.  In the past, the payload has had NO communications.  All data
is recorded on board and saved for post-flight analysis.

    The SPRE experiment was suggested by students at the University of
Maryland to add an AX.25 packet link for not only determining the
status of the on-board experiments, but also to transmit the GPS position
of the spacecraft, since GPS was already on board for attitude
determination.  The SPRE payload which consists of a typical TNC can
also be used for relaying ground station position reports in the APRS
format.

Unfortunately the SPRE GPS format is in double precision XYZ hexidecimal
format.  APRtrak was modified specifically to detect and decode this
GPS format.  APRtrak will plot the position of this spacecraft when
AX.25 SPRE position reports are received.  Secondly, the SPRE telemetry
was also not in the APRS telemetry format.  So APRtrak was further
modified to convert the SPRE telemetry into the APRtrak telemetry page.
In order to ACTIVATE this SPRE telemetry format, you must load the
backup file SPRE.BK into APRtrak.  In order not to load over any
monitored packets, the SPRE.BK file should be loaded immediately when
starting APRtrak for this mission.  APRtrak recognizes the first line
on the L-LIST to tell it to begin parsing for the SPRE telemetry format.

SUMMARY OF SPRE OPERATIONS IN APRtrak:

1) You will see the GPS position of the spacecraft whenever a position
   packet is received.
2) The alt-TELEMETRY page will show SPRE telemetry (if the SPRE.BK file
   is preloaded first)
3) You will see the position of any other APRtrak stations that have
   successfully digipeated their positions via SPRE
4) Your station will occassionally send your position.  If you enter the
   W3EAX callsign in your APRtrak UNPROTO command, then the spacecraft
   may digipeat your position.
5) You may accellerate the rate of your position reports using the X and
   P commands, but do this sparingly and with due consideration to others
6) You may automate the process into an ATTACK mode and also SHORTEN the
   length of your position reports by using the alt-SETUP-MODES-SPACE
   command.
7) If you are going to try to be seen by SPRE, make your alt-BEACON text
   as short as meaningful.  Your first name might be a good idea.  Your
   location and callsign are ALREDY BUILT-IN to the format, so do NOT
   repeat them in your alt-BEACON text.
8) APRtrak will BEEP a CONGRATULATIONS message if it sees YOUR position
   digipeated by SPRE.  If you see that, then QUIT, and give someone else
   a chance.  If you see yourself, then your half of the country also saw
   you, and there is no need to repeat it.

This file has been prepared more than 4 months in advance of flight time.
Look for AMSAT bulletins for any changes to the above procedures or any
new APRtrak versions that may be available...