FOS Instrument Science Report #128

"Failure Analysis of the New FOS Peakup Algorithm"
by Joe Skapik and John Fitch

Abstract excerpted from the report:

On day 94.235 during FOS proposal 5531, a series of Exec 20 Status
Buffer messages occurred.  This error message is issued when a PIT
slew request is rejected by the DF224.  A review of what was occuring
at the time of the errors showed that the FOS was executing
a new Targe Acquisition Peakup Algorigthm which was implemented
in stored commanding and build 5.3 of the NSSC-I flight software.
Analysis of the associated science data, engineering telemetry
and commanding has shown that an error in the DF224 management of
the Take-data flag, (TDF), can result in a timing error in the
stored commanding.  A fix to the DF224 software is being developed.



For more information, please contact the above authors.