Chapter 2.2: Experiment Data Record (continued)

 

2.2.8 Data Specifications for HISCALE/EPAM Conversion of ARCGEN (continued)

 

LAN Logical Record References:

 

The EPAM/LAN Logical Record will be identical to the HISCALE counterpart; therefore a description of ARCGEN's references of this record is not needed.

 

Analog Housekeeping References:

 

No references in ARCGEN for processing purposes.

 

Digital Housekeeping References:

 

Byte offsets represent data presence from beginning of the LAN EDR Data Block.

 

Byte: 1180	Byte Description: Sun Pulse Timing Data - 4-F Spin. 4-F Spin is the spin count ( 0 to 79 ) at the four-format epoch. It is used to reference time sectored data to the four-format pulse and therefore to the sun. ARCGEN Specifications: Importance to Processing: Essential References: Timelan.f - line 72 Purpose of Reference: Variable assignment EPAM Status: OK
Byte: 1404	Byte Description: Sun Pulse Timing Data - 4-F Time, adds precision to this measurement. Bits Accessed: Bits 0 - 2 Bit Description: Bits 0 - 2 represent the completed sector count ( 0 to 7 ). ARCGEN Specifications: Importance to Processing: Essential References: Timelan.f - line 73 Purpose of Reference: Variable assignment EPAM Status: OK
Bytes: 1628, 2076, 2300, 2524, 2972, 3196, 3420, 284, 508, 732	Byte Description: 284, 508, 732 - Sun pulse timing changes for spin groups 8 - 10 of the previous cycle. 1628, 2076, 2300, 2524, 2972, 3196, 3420 - Sun pulse timing changes for spin groups 1 - 7 of the current cycle. Bit Description: Bit 0 represents the sign. It will be 1 if the sun pulse occurred before the 16384th pulse of the 16384 x spin clock; zero if it occurred afterward. Bits 1 - 7 represent the mantissa. An increment of the mantissa will represent 16 counts of the 16384 x spin clock. From this information one can determine the degree to which the eighth sector of a spin was truncated, during times of transient spin rate. ARCGEN Specifications: Importance to Processing: Essential References: Timelan.f - line 127 Purpose of Reference: Variable assignment, used in truncation or dilation of eighth sector time durations. EPAM Status: OK

 

Refer to reference 2 for a more detailed description of the Analog and Digital H/K.

 

Further References:

Byte offsets represent data presence from beginning of the LAN EDR Data Block.

 

Bytes: 787, 1683, 2579, 3475

Byte Description: Representative of byte 3 of LAN minor frames 29, 61, 93, 124 - sounder indicators of STO experiment. Bits Accessed: Bits 0-2 Bit Description: Sounder On: 010, 011, 111 ARCGEN Specifications: Importance to Processing: Nonessential References: Archdr.f - line 503 Purpose of Reference: To determine whether sounder is on or off. EPAM Status: Not Available For obvious reasons this data will not be available for EPAM. Therefore these bits will be set to 0 within EDRGEN. As of July 17, 1997, the ARCGEN references to these bits have not been deleted.

Bytes: 929, 930, 2721, 2722

Byte Description: Although an official description of these bytes is not available, these bytes are assumed to represent spin periods in units of 2048 xsecs. Byte: 929 930 2721 2722 Spin Period (in secs.): 00000|000 00000000 Exp. Mantissa ARCGEN Specifications: Importance to Processing: Essential References: Archdr.f - line 513 Timelan.f - line 54 Purpose of References: Archdr.f - line 513: Variable assignment, placement into main ARCGEN buffer. Timelan.f - line 54: Variable assignment, used in determination of first spin start time. EPAM Status: OK ITIME variable, array elements [8,1], [8,2] correspond to the first and last spins of the current data collection cycle (see 2.3.2). These spin periods will be calculated in EPAM EDRGEN.

 

Input File #2. Lanmerge.par

 

ASCII file consisting of three values, each of which is assigned either T (true) or F (false). Used to define logical assignments as follows:

 

1st value: no purpose

 

2nd value: allows for ARCGEN processing without magnetic field data.
T = Process without magnetic field data
F = Process with magnetic field data

 

3rd value: determine production versus analysis mode.
T = Production mode
F = Analysis mode

 

Input File #3. IDF.dat

 

Refer to reference 4 for specifics (HISCALE IDF.dat file will be used for testing).

 

Input File #4. UMAGyyddd.dat

 

Nonessential file. UMAGyyddd.dat files contain the magnetic field data. Although ARCGEN can access these files to integrate this data into the iulayyddd.pha, .rat, output files, this integration is not essential. Therefore a description of these files is currently not needed.

 

Input File #5. NAVyyddd.dat - SEDRyyddd.dat

 

NAVyyddd.dat files are created using a program (sedr2nav.f) at Fundamental Technologies which extracts the necessary coordinate information from the Supplementary Experiment Data Records (SEDR). With this being the case, the data extraction specifics below refer to the data extracted by this program, not ARCGEN. Owing to the fact that this software’s sole purpose is to create input files for ARCGEN processing, it has been assumed that data extracted by this software is essential to the overall processing--i.e., its importance can be defined as essential.

 

SEDRyyddd.dat

File Type: Sequential
Record Type: Fixed Length
Record Size: 100 (SFDU Header) + 992 (SEDR Data Block) = 1092 bytes
Byte Representations are from the beginning of the SEDR for both the SFDU Header and SEDR Data Block.

 

Byte	1         100	101            1092
	SFDU HEADER	SEDR DATA BLOCK

 

SFDU Header References:

 

Bytes: 11-16	Byte Description: Representative of the Spacecraft Event Time (SCET) - Time of validity of the SEDR record, elapsed seconds since Jan 1, 1950 (UTC). Bit Description: Word 3 Word 4 Bits: 16-23 24-31 0-7 8-15 Coarse Time: 00000000 00000000 00000000 00000000 Word 4 Bits: 26-23 24-31 Fine Time: 00000000 00000000 EPAM Status: TBD Acquisition of this information should not be a problem. The ACE Science Center at Caltech will be providing the necessary ASC functions to create this time from EPAM Level 1 data. Still, until these functions are actually created, EPAM Status will remain TBD.
Bytes: 101-108	Byte Description: Bytes 101-104 refer to Right Ascension of S/C Spin Axis, S/C Centered, Earth Mean Equator and Equinox of 1950.0. Bytes 105-108 refer to Right Declination of S/C Spin Axis, S/C Centered, Earth Mean Equator and Equinox of 1950.0. EPAM Status: TBD Acquisition of this information should not be a problem. The ACE Science Center at Caltech will be providing the necessary ASC functions to create the above information from EPAM Level 1 data. Still, until these functions are actually created the EPAM Status will remain TBD.
Bytes: 145-156	Byte Description: Cartesian Position X, Y, and Z Components of S/C, Sun Centered, Earth Mean Ecliptic and Equinox of 1950.0. Bytes 145-148: X Component Bytes 149-152: Y Component Bytes 153-156: Z Component Bit Description: Refer to end of SEDR Data Extraction Specifics subsection. EPAM Status: TBD Acquisition of this information should not be a problem. The ACE Science Center at Caltech will be providing the necessary ASC functions to create the above information from EPAM Level 1 data. Still, until these functions are actually created, EPAM Status will remain TBD.
Bytes: 289-300	Byte Description: Cartesian Position X, Y, and Z Components of Earth, Sun Centered, Earth Mean Ecliptic and Equinox of 1950.0. Bytes 289-292: X Component Bytes 293-296: Y Component Bytes 297-300: Z Component Bit Description: Refer to end of SEDR Data Extraction Specifics subsection. EPAM Status: TBD Acquisition of this information should not be a problem. The ACE Science Center at Caltech will be providing the necessary ASC functions to create the above information from EPAM Level 1 data. Still, until these functions are actually created, EPAM Status will remain TBD.
Bytes: 313-324	Byte Description: Cartesian Position X, Y, and Z Components of Jupiter, Sun Centered, Earth Mean Ecliptic and Equinox of 1950.0. Bytes 313-316: X Component Bytes 317-320: Y Component Bytes 321-324: Z Component Bit Description: Refer to end of SEDR Data Extraction Specifics subsection. EPAM Status: TBD Acquisition of this information should not be a problem. The ACE Science Center at Caltech will be providing the necessary ASC functions to create the above information from EPAM Level 1 data. Still, until these functions are actually created, EPAM Status will remain TBD.

  

Refer to Tables 2.6 - 2.11 for definitions of all 1092 bytes of the SEDR SFDU Record.

 

Bit Description for Bytes 101-108, 145-156, 289-300, 313-324:

 

The current SEDR’s received for the HISCALE mission use a floating-point format. The floating-point-words appear as follows:

 

Bit Positions 0          1	7	8                       31
Sign	Characteristic	Fraction

 

Sign will indicate the sign of the quantity represented by the floating- point word. If sign = 0, the quantity will be evaluated as positive; if sign =1, the quantity will be evaluated as negative.

 

Characteristic allows the calculation of the value of the characteristic (or exponent) (base 16) of the floating-point word. The characteristic will be evaluated as (CHAR16 - 4016).

 

Fraction consists of the most significant digits of the mantissa of the floating-point quantity, which will be a hexadecimal fraction, the value of which will always lie between 0 and (0.FFFFFFFFFFFFFFFFFFFFFFFFF16).

 

For a more detailed description of evaluation of these floating-point words, including example algorithms, refer to reference 3; pg. 12-13.

 

References:

 

Ulysses/HISCALE:

1. International Solar Polar Mission SIS - Experimental Data Record-1983, T. H. Choo & revision of this document by R. D. Shaffer and N. E. White-Aug. 1990.
2. LAN Experiment Data System Performance and Interface Specifications, D. R. Guynn Jr.-March 1981
3. Software Interface Specification: Supplementary Experiment Data Records to Ulysses Principal Investigators-July 13, 1984; revised January 27, 1992.
4. Ulysses HISCALE Handbook (this document), Rajat Sahi and Thomas P. Armstrong, April 1996; revised 1999-2000, T. P. Armstrong and T. Hunt-Ward.

 

ACE/EPAM

1. Specific Instrument Interface Specification - May 1995.
2. ACE Spacecraft Telemetry Frame Format Descriptions, R. F. Conde, March 19, 1996.
3. ACE Spacecraft Command & Data Handling Component Specification, prepared by J. F. Bogdanski, R. F. Conde, and S. P. Williams.

 

 

Next: Section 2.2.8 (Table 2.15) Continued

 

Return to Chapter 2 Table of Contents