Level 1B "no impact" Preprocessor Update

This notice announces changes to the AIP (AMSU-A, AMSU-B, HIRS, DCS,
SEM, SBUV) and AVHRR (GAC, LAC, and HRPT) level 1B preprocessors
planned for May 15, 2002. The user should see no changes in the AVHRR
data. The following changes may be seen in the AIP level 1B data to
correct telemetry data. We believe these are also "no impact" changes.
Parallel Test data corresponding to the current operations are now
available. Users that do not have access to the CEMSCS can get level
1B test data from the anonymous ftp site under
the subdirectory pub/test1b/rel3.0. CEMSCS users will find test data
under P1S data set names for 1B*s and P1B for 1Bs. If no user issues
are brought to our attention, we plan to make the changes operational
on May 15, 2002.

Instrument Status: bytes 117 - 120 of the Data Set Quality Indicators
in the HIRS Header Record may be different than in the current
operation. The preprocessor was corrected to report the proper values
for Digital-B telemetry status. The same is true for bytes 125 - 128
of the Second Instrument Status. The affected bits are indicated

bit 15: Instrument power
bit 14: Electronics power
bit 13: Filter motor power
bit 12: Scan motor power
bit 11: Cooler heater
bit 10: Filter housing heater
bit 9: Cooler door release
bit 8: Cooler window heater
bit 7: Go to NADIR position
bit 6: Calibration sequence
bit 5: Cooler door closed
bit 4: Cooler door fully open
bit 3: Filter motor power level
bit 2: Patch temperature controller

Also under the Data Set Quality Indicators, bytes 123 - 124, the Record
Number of Status Change can be different if the above telemetry
instrument status bits are changed.

CPU values in the HIRS 1B data record - TIP Euler Angles (roll , pitch,
and yaw), attitude smode, attitude pwtip$ac, and time associated with
tip euler angles retrieved from CPU telemetry differ from the
operational data. They have been corrected so that values are pulled
from the proper scan lines in all cases.

Digital-B Telemetry: Within the HIRS data record in the bytes 4541 -
4542 of the Invalid Word Bit Flags and bytes 4543 - 4544 of the
Digital B Data may be different than in the current operation. The
preprocessor was corrected to report the proper values as listed below.

bit 15: instrument power
bit 14: electronics power
bit 13: filter motor power
bit 12: scan motor power
bit 11: cooler heater
bit 10: filter housing heater
bit 9: cooler door release
bit 8: cooler window heater
bit 7: go to nadir position
bit 6: calibration sequence
bit 5: cooler door closed
bit 4: cooler door fully open
bit 3: filter motor power level
bit 2: patch temperature controller

* Emily D. Harrod
* Product Systems Branch
* Pre-Product Processing Group
* E/SP13, Federal Building #4, room 0318
* 5200 Auth Road
* Suitland, Maryland 20746-4304
* voice 301-457-5247
* fax 301-457-5199
* email