The Data Status Word for Processing and Data Selection

SOI TN 96-135

R. S. Bogart & R. I. Bush

revised 29 May 1996

Introduction

In order to be able to select data for analysis meeting appropriate constraints on quality and observing conditions, it is useful to maintain a permanent flag encoding information about the data obtained in the course of processing. We propose to use a 32-bit status word associated with each MDI image or image equivalent, to be maintained in one or more permanent files to be kept online at all times. In the Data Status Word, each bit will be assigned a meaning as described below, so that data selection may be made by appropriate masking. The Data Status Word should be associated with Level 0 and Level 1 data in the header, and with more highly processed data as appropriate. In addition to the Data Status Word, there is another 32-bit word, the Data Status Status word, of which the bits are set if and only if the corresponding bits in the Data Status Word are valid. There is no Data Status Status Status Word; the bits in the Data Status Status Word are always assumed valid.

Data Status Word

The bit ordering is not significant in the Status Word, since each bit conveys unique information. For specificity, we propose the following, with the highest-order bit numbered 31 and the lowest-order bit numbered 0. In general, bits are to be set when the corresponding status departs from nominal.
bit: meaning

00: compression /decompression errors
0: no compression errors flagged or decompression errors encountered in telemetry comprising image
1: one or more compression errors flagged or decompression errors encountered in telemetry comprising image
set during level 0 processing
01: missing packets
0: no missing packets in telemetry comprising image, or N/A
1: one or more missing packets in telemetry comprising image
set during level 0 processing; applies only to high-rate data
02: missing segments
0: no missing packets in telemetry comprising image, or N/A
1: one or more missing packets in telemetry comprising image
set during level 0 processing; applies only to low-rate data
03: image completeness
0: image complete; no missing pixels
1: image incomplete; one or more nominal pixels absent
set during level 0 processing
04: image statistics
0: image statistics nominal for relevant data product
1: image statistics unusual for relevant data product
set during level 0 processing and QA checks, based on criteria TBD
05: reserved
06: Reference Time changed
0: Reference Time unchanged from original value
1: Reference Time changed from original value
set during QA checks or after
07: Sequence Identifier (SQID) changed
0: SQID unchanged from original value
1: SQID changed from original value
set during QA checks
08: reserved
09: reserved
10: Image Stabilization System (ISS) status
0: ISS on during all of relevant integration time
1: ISS off during all or part of relevant integration time
set during or after level 0 processing based on housekeeping data
11: spacecraft Position Angle
0: spacecraft position angle within 0.25 degree of solar north (TBR) during all of relevant integration time
1: spacecraft position angle more than 0.25 degree away from solar north (TBR) during all or part of relevant integration time
set TBD
12: image center
0: solar image at nominal center during all of relevant integration time
1: solar image not at nominal center during all or part of relevant integration time
set TBD
13: focus position
0: focus position nominal during all of relevant integration time
1: focus position abnormal during all or part of relevant integration time
set TBD
14: oven temperature
0: oven temperature nominal during all of relevant integration time
1: oven temperature abnormal during all or part of relevant integration time
set TBD based on housekeeping data and limits TBD
15: reserved
16: Image Processor (IP) program status
0: IP program nominal during creation of data product, or N/A
1: IP program abnormal during creation of data product
set TBD
17: binning and scaling
0: binning and scaling nominal for relevant data product, or N/A
1: binning and scaling abnormal for relevant data product
set TBD
18: onboard flat field
0: onboard flat field nominal during creation of data product, or N/A
1: onboard flat field abnormal during creation of data product
set during QA checks
19: reserved
20: reserved
21: reserved
22: reserved
23: reserved
24: original Data Product Code (DPC) valid
0: original DPC valid
1: original DPC invalid or incorrect
set during QA checks TBD
25: Data Product Code (DPC) altered
0: original DPC in use
1: DPC modified during processing or QA checks
set during QA checks TBD
26: reserved
27: reserved
28: reserved
29: reserved
30: reserved
31: reserved

Please address comments and questions to the author(s).

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