Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/ops/swat/safing/94297/fos_103194.status Дата изменения: Mon Apr 26 17:33:55 1999 Дата индексирования: Sun Mar 2 03:08:16 2014 Кодировка: Поисковые слова: ngc 6520

From DOXSEY@avion.stsci.edu Mon Oct 31 01:42:04 1994
Subject: FOS blue-side microprocessor is OK
To: blacker@stsci.edu
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Last week the FOS went into safemode while operating
on the blue side. The safemode entry was caused by the NSSC-I
safemode processor noticing that the FOS microprocessor telemetry
data was incorrect. Analysis of the telemetry showed that the
microprocessor had hung-up in some manner. The most likely cause
was an unusual noise pulse when the high voltage relay was closed.
The FOS blue side microprocessor has experienced noise pulses on
the reset line when this relay closes. An operational workaround
was developed some time ago to handle this situation. This hang-up
of the microprocessor may have been due to a slightly different
response to the relay closure.

This morning the blue side of the FOS was activated, with
the exception that all high voltage commanding had been removed
from the sequence. The microprocessor came up properly, went
through the proper initialization process, and then successfully
carried out all the steps of the observation. At this point, it
appears that the microprocessor is ok. The FOS observing program
will continue as planned, with the next blue side observation
taking place next Saturday, including setting of the high voltage.
This observation will indicate whether the HV relay closure is
now generating a different interference in the microprocessor, or
whether the recent safing was a one-time upset to the microprocessor.