IMP-8 Experimenter(DECOM) File Format



Experimenter file is a merged of multiple logical single files. Records on
the logical single file are unblocked with a maximum length of 3528 bytes.
Each locgical file contains data recorded by one tracking station and data
of only one bit rate.

Experimenter file is created in units of one decom run which generally
covers about 4 days of data. 

Each logical file on an experimenter file contains one file ID record, a set of
data records, and one end of file mark.  The file ID record contains
thirty-six 32 bit words (144 bytes).  Each data record contains one album
of telemetry data plus orbit/attitude data corresponding to the nearest minute
preceding the start time of that album.

HEADER RECORD

DATA RECORD


All items are binary integers except average sequence time (word 15) which
is in IBM 360 floating point format.

WORD    Content       

1	Satellite I.D. (20731 for IMP-H)
2	Station I.D.
3	Analog tape No.
4	Analog file No.
5	Year, start of file (one digit)
6	Day of year, start of file (Jan 1 = 1)
7	Milliseconds of day, start of file
8	Year, end of file (one digit)
9	Day of year, end of file (Jan 1 = 1)
10	Milliseconds of day, end of file
11	Data type
12	Data rate (0 = Low, 1 = High)
13	Edit tape No.
14	Edit file No.
15      Average sequence time for file
16	Production flag (1 = Production)
17	Perigee count
18	Day of next perigee
19	Milliseconds of day, next perigee
20	Experiment ID (32 for IMP-H)
21-36   Spares



WORD	Content                               Chan.  Bits  Frame  Sequence

1       Halfword 1 : Continuity flags
        Halfword 2 : Day of year
2       Millisecond of day
3       Time quality flags :
          Byte 1 = Sequence  0 - 3
          Byte 2 = Sequence  4 - 7
          Byte 3 = Sequence  8 - 11
          Byte 4 = Sequence  12 - 15
4       Data quality flags (each quarter sequence)
          Byte 1 = Sequence 0 
          Byte 2 = Sequence 1 
          Byte 3 = Sequence 2 
          Byte 4 = Sequence 3 
5       Data quality flags : sequence 4 - 7
6       Data quality flags : sequence 8 - 11
7       Data quality flags : sequence 12 - 15
8       Pseudo-sequence counter (sequence 0)
9       S/C clock (sequence 0)
10      S/C clock (sequence 1)
11      S/C clock (sequence 2)
.            "              .
.            "              .
.            "              .
24           "              15)
25-28   APP (16,1-15) (one APP per byte)
29-32   APP (32,17-31) or APP (48,33-47) (one APP per byte)
33-40   DPP A2 (5-36) (one channel per byte)
41-48   Spare
49-51   DPP A3 (1-24) (one channel per byte)
52-54   Spare
55      OA sun time (floating point-seconds)  8,9   1-9  4  4  S.S.1
56      Earth width (floating point-seconds) 14,15  1-8  4  4  S.S.1
57      Earth time  (floating point-seconds) 12,13  1-8  4  4  S.S.1
58      Spin period (floating point-seconds) 10,11  1-8  4  4  S.S.1


WORD Content Chan. Bits Frame Sequence 59 LED (DS) Halfword 1 : frame 3 4 1-2 0 Halfword 2 : frame 11 60 " " 1 . . . . . . . . 74 " " 15 75 LED (A) Halfword 1 : frame 3 reverse 9 5-8 0 Halfword 2 : frame 11 reverse 10 1-6 76 " " 1 . . . . . . . . 90 . " 15 91 LED (B) Halfword 1 : frame 3 10 7-8 0 Halfword 2 : frame 11 11 1-8 92 " " 1 . . . . . . 106 " " 15 107 MED (D) Halfword 1 : frame 3 reverse 12 1-8 0 Halfword 2 : frame 11 reverse 13 1-2 108 " " 1 . . . . . . . . 122 . " 15 123 MED (E) Halfword 1 : frame 3 13 3-8 0 Halfword 2 : frame 11 14 1-4 124 " " 1 . . . . . . 138 " " 15 139 MED (DS) Halfword 1 : frame 3 4 3-4 0 Halfword 2 : frame 11 14 5-8 140 " " 1 . . " . . " 154 " " 15 155 MED (F) Halfword 1 : frame 3 reverse 15 1-8 0 Halfword 2 : frame 11 reverse 156 " " 1 . . " . . " 170 " " 15 171 MED-R1 (LR12a3-1) 5 1-8 4 0&8 6 1-4 Halfword 1 : seq. 0 reverse Halfword 2 : seq. 8 reverse 172 MED-R2 (LR12a3-2) 6 5-8 4 0&8 7 1-8 Halfword 1 : seq. 0 reverse Halfword 2 : seq. 8 reverse 173 MED-R3 (LR12a3-5) 5 1-8 4 1&9 6 1-4 Halfword 1 : seq. 1 reverse Halfword 2 : seq. 9 reverse 174 MED-R4 (LR12a3-8) 9 5-8 4 1&9 10 1-4 Halfword 1 : seq. 1 reverse Halfword 2 : seq. 9 reverse 175 MED-R5 (LR12a3-9) 5 1-8 8 4&12 6 1-4 Halfword 1 : seq. 4 reverse Halfword 2 : seq.12 reverse 176 MED-R6 (LR12a3-13) Halfword 1 : seq. 0 reverse 5 1-8 8 0&8 6 1-4 Halfword 2 : seq. 8 reverse 177 MED-R7 (LR12a3-17) 5 1-8 4 5&13 6 1-4 Halfword 1 : seq. 5 reverse Halfword 2 : seq.13 reverse 178 MED-R8 (LR12a3-21) 5 1-8 12 0&8 6 1-4 Halfword 1 : seq. 0 reverse Halfword 2 : seq. 8 reverse 179 MED-R9 (LR12a3-26) 6 5-8 12 4&12 7 1-4 Halfword 1 : seq. 4 reverse Halfword 2 : seq.12 reverse 180 LED-R1 (LR12a3-12) 9 5-8 8 4&12 10 1-8 Halfword 1 : seq. 4 reverse Halfword 2 : seq.12 reverse 181 LED-R2 (LR12a3-16) 9 5-8 8 0&8 10 1-8 Halfword 1 : seq. 0 reverse Halfword 2 : seq. 8 reverse 182 LED-R3 (LR12a2-22) 6 5-8 12 0&8 7 1-8 Halfword 1 : seq. 0 reverse Halfword 2 : seq. 8 reverse 183 VLED-R1 (LR12a2-9) 5 1-8 10 1&5 6 1-4 Halfword 1 : seq. 1 reverse Halfword 2 : seq. 5 reverse 184 VLED-R1 (LR12a2-9) 5 1-8 10 9&13 6 1-4 Halfword 1 : seq. 9 reverse Halfword 2 : seq.13 reverse 185 VLED-R2 (LR12a2-13) 5 1-8 2 2&6 6 1-4 Halfword 1 : seq. 2 reverse Halfword 2 : seq. 6 reverse 186 VLED-R2 (LR12a2-13) 5 1-8 2 10&14 6 1-4 Halfword 1 : seq.10 reverse Halfword 2 : seq.14 reverse 187 VLED-R3 (LR12a2-17) 5 1-8 10 2&6 6 1-4 Halfword 1 : seq. 2 reverse Halfword 2 : seq. 6 reverse 188 VLED-R3 (LR12a2-17) 5 1-8 10 10&14 6 1-4 Halfword 1 : seq.10 reverse Halfword 2 : seq.14 reverse 189 VLED-R4 (LR12a2-21) 5 1-8 2 3&7 6 1-4 Halfword 1 : seq. 3 reverse Halfword 2 : seq. 7 reverse 190 VLED-R4 (LR12a2-21) 5 1-8 2 11&15 6 1-4 Halfword 1 : seq.11 reverse Halfword 2 : seq.15 reverse 191 VLED-R5 (LR12a2-25) 5 1-8 10 3&7 6 1-4 Halfword 1 : seq. 3 reverse Halfword 2 : seq. 7 reverse 192 VLED-R5 (LR12a2-25) 5 1-8 10 11&15 6 1-4 Halfword 1 : seq.11 reverse Halfword 2 : seq.15 reverse 193 Halfword 1:MED-S(IN) sector 1 reverse 0 1-8 2 0 1 1-2 Halfword 2:MED-S(IN) sector 2 reverse 1 3-8 2 0 2 1-4 194 Halfword 1:MED-S(IN) sector 3 reverse 2 5-8 2 0 3 1-6 Halfword 2:MED-S(IN) sector 4 reverse 3 7-8 2 0 4 1-8 195 Halfword 1:MED-S(IN) sector 5 reverse 11 1-8 2 0 12 1-2 Halfword 2:MED-S(IN) sector 6 reverse 12 3-8 2 0 13 1-4 196 Halfword 1:MED-S(IN) sector 7 reverse 13 5-8 2 0 14 1-6 Halfword 2:MED-S(IN) sector 8 reverse 14 7-8 2 0 15 1-8 197 Halfword 1:VLED-S(IN) sector 1 reverse 0 1-8 10 0 1 1-2 Halfword 2:VLED-S(IN) sector 2 reverse 1 3-8 10 0 2 1-4 198 Halfword 1:VLED-S(IN) sector 3 reverse 2 5-8 10 0 3 1-6 Halfword 2:VLED-S(IN) sector 4 reverse 3 7-8 10 0 4 1-8 199 Halfword 1:VLED-S(IN) sector 5 reverse 11 1-8 10 0 12 1-2 Halfword 2:VLED-S(IN) sector 6 reverse 12 3-8 10 0 13 1-4 200 Halfword 1:VLED-S(IN) sector 7 reverse 13 5-8 10 0 14 1-6 Halfword 2:VLED-S(IN) sector 8 reverse 14 7-8 10 0 15 1-8 201-400 Same as above for page 1 401-600 Same as above for page 2 601-800 Same as above for page 3 801-879 Orbit/attitude data corresponding to nearest minute preceding the album start time 880-882 Zeros
DPP Locations WORD BYTE PAGE DPP# SNAPSHOT 33 1 0 A2, 5-8 0 2 0 A2, 5-8 1 3 0 A2, 5-8 2 4 0 A2, 5-8 3 34 1 0 A2, 9-12 0 2 0 A2, 9-12 1 3 0 A2, 9-12 2 4 0 A2, 9-12 3 35 1 0 A2, 13-16 0 2 0 A2, 13-16 1 3 0 A2, 13-16 2 4 0 A2, 13-16 3 36 1-4 0 A2, 17-20 0-3 37 1-4 0 A2, 21-24 0-3 38 1-4 0 A2, 25-28 0-3 39 1-4 0 A2, 29-32 0-3 40 1 0 A2, 33-36 0 2 0 A2, 33-36 1 3 0 A2, 33-36 2 4 0 A2, 33-36 3 49 1 0 A3, 1-4 0 2 0 A3, 1-4 2 3 0 A3, 5-8 0 4 0 A3, 5-8 2 50 1 0 A3, 9-12 1 2 0 A3, 9-12 3 3 0 A3, 13-16 0 4 0 A3, 13-16 2 51 1 0 A3, 17-20 1 2 0 A3, 17-20 3 3 0 A3, 21-24 0 4 0 A3, 21-24 2 233-240 Same as words 33-40 for page 1 249-251 Same as words 49-51 for page 1 433-440 Same as words 33-40 for page 2 449-451 Same as words 49-51 for page 2 633-640 Same as words 33-40 for page 3 649-651 Same as words 49-51 for page 3
ORBIT/ATTITUDE DATA (All numbers are IBM floating point) WORD Content 801 Day of year, time of orbit data in the record 802 Milliseconds of day 803 Longitude (deg.) satellite position in geocentric coordinates 804 Latitude (deg.) 805 Longitude (deg.) satellite position in magnetic coordinates 806 Latitude (deg.) 807 R (earth radii) a geomagnetic coordinate of the satellite position, C.U.L. 808 r, radial distance of the satellite from the center of the earth (km.) 809 GSEx Satellite position in Geocentric Solar ecliptic coordinates(km.) 810 GSEy 811 GSEz 812 GSMx Satellite position in Geocentric Solar magnetospheric Coordinates (km.) 813 GSMy 814 GSMz 815 GSEx Moon position in Geocentric Solar ecliptic coordinates(km.) 816 GSEy 817 GSEz 818 GSMx Moon position in Geocentric Solar magnetospheric Coordinates (km.) 819 GSMy 820 GSMz 821 GEIx Satellite position, in Geocentric equatorial inertial(km.) 822 GEIy 823 GEIz 824 GEIx Sun position in Geocentric equatorial inertial(A.U.) 825 GEIy 826 GEIz 827 Longitude, Sub-solar point in geomagnetic coordinates(deg.) 828 Latitude 829 Distance from the satellite to the moon (km.) 830 Distance parallel to the x-axis from the satellite to the moon(km.) 831 1st row, 1st column, geocentric solar energetic to geocentric solar magnetospheric transformation matrix. 832 1st row, 2nd column 833 1st row, 3rd column 834 2nd row, 1st column 835 2nd row, 2nd column 836 2nd row, 3rd column 837 3rd row, 1st column 838 3rd row, 2nd column 839 3rd row, 3rd column 840 1st row, 2nd column, geocentric equatorial inertial-to-geocentric solar ecliptic transformation matrix. 841 1st row, 2nd column 842 1st row, 3rd column 843 2nd row, 1st column 844 2nd row, 2nd column 845 2nd row, 3rd column 846 3rd row, 1st column 847 3rd row, 2nd column 848 3rd row, 3rd column 849 Right ascension, Satellite position in celestial inertial(deg.) 850 Declination 851 Right ascension, Velocity vector in inertial(deg.) 852 Declination 853 Magnitude of the velocity (km./sec.) 854 L, McIlwain parameter (earth radii) 855 B, Magnetic field strength (Gamma) 856 B/B0, Ratio of the magnetic field strength at the satellite-to-the-field strength at the invarient equator 857 Satellite-earth-sun angle, Lsep(deg.) 858 Satellite-earth-moon angle(deg.) 859 Right ascension, magnetic vector in celertial inertial(deg.) 860 Declination 861 Longitude, Sub-solar point in geocentric equatorial inertial(deg.) 862 Latitude 863 GSEx, theoretical geomagnetic field in geocentric solar ecliptic coordinatesIin gamma) 864 GSEy 865 GSEz 866 Type of data item indicator: 1 = regular satellite data item 2 = ascending node crossing data item 3 = North point data item 4 = descending node data item 5 = south point data item 6 = sunlight entrance data item 7 = sunlight exit data item 867 Date of data (YR MO DAY) 868 Longitude, Geodetic satellite position (deg.) 869 Latitude 870 Height above spheroid (Km.) 871 Ascending node crossing number (pass number) 872 Year of data (YR) 873-875 Zero fill for spares 876 Delta time between time of Ephemeris item and next previous sun pulse which stopped OA - ST counter(seconds) 877 Spin period (seconds) 878 Right ascension, Spin vector in celestial inertial(deg.) 879 Declination
NOTES: Longitude is positive east of Greenwich and negative west of Greenwish (-180- to + 180-) North latitude is positive and south latitude is negative (--90' to +90') Date of data (word number 867) equals day + 100 (months + year (100)) Example: February 10, 1967 at 2 hours U.T. is recorded as 670210 in word 867, 41 in day count (word 301), 7200000 in milliseconds of day (word 802), and 67 in year of data (word 872).

The format of each page of data under the relaxed ground rules is shown
in the attached table. Data should be blocked 1 album (4 pages) per
physical record, so that the first page of each record is page 0 of the
album. It should be noted that the format is given in terms of 360 relative
word locations. Since IBM 360 words are 32 bits in length, the bit patterns
of each data line will not occupy an even number of tape characters. For
example, the first data item of each record (day of year for page 0) will
occupy the first 5 characters plus the first 2 bits of the 6th. The second
data item (milliseconds of day for page 0) will occupy the last 4 bits of
the 6th character, the 7th through 10th characters, and the first 04 bits of
the 11th.

Floating point numbers

All floating point numbers on the tape should be in IBM 360 format as follows:

Each 32-bit number consists of a sign bit, a 7-bit characteristic, and
a 24-bit fraction:


-
     S Characteristic                 Fraction

 bit 0 1            7 8                      31

The fraction (bits 8-31) is expressed inm hexadecimal digists. The radix
point of the fraction is assumed to be immediately to the left of the
high-order fraction digit.

The characteristic fraction indicates the power of 16 by which to multply
the fraction. It is treated as an excess 64 number with a range from -64
tp 63, corresponding to binary values of 0 - 127.
to 63, corresponding to binary values of 0 - 127.

Both positive and negative numbers have true fractions. A sign bit of 0
or 1 indicates that the number is positive or negative, respectively.

Reverse

Those data items labeled "reverse" should have their bit orders reversed
and right-justified in their respective halfwords. For example, each LED(A)
halfword (360 words 91-106) should contain bits 6-1 of channel 10 followed
by bits 8-5 of channel 9 right-justified.



Explanatory Notes Fill Data Padding is done on a sequence basis, that is, a telemetry sequence will contain either all fill or none. Data in padded sequences will appear as zero. No album will be written with all four pages padded, however as little as one sequence of data could appear in a record. A spacecraft (S/C) clock readout is provided every sequence. If a sequence is fill, its corresponding S/C clock will be zero. The pseudo-sequence count and the time (in day of year and milliseconds of day) are provided every pa.:,e and correspond to sequence 0 of that page. If sequence 0 is padded (and'the entire page is not missing), the the pseudo-sequence count and time given are the extrapolated values that would be expected at the start of sequence 0. This may result in the extrapolated pseudo-sequence overlapping a previous value. If an entire page is missing, all data including time, pseudosequence count, S/C clocks, and data quality flags are zero. Continuity Flags 20 = 0 indicates no fill data in paae 21 = 0 indicates no time discontinuity following- Quality Flags Time and Data Quality Flaas are 2-bit integers as follows: Value Time Quality Data Quality 0 Analog, time unverified Excellent (PE < 10 to the power -6) 1 Analog time verified by Good (PE < 10 -4) S/C clock 2 Analog time in error - Fill S/C clock used 3 Time put with fill data Undetermined computed Time Quality Flags occur once per sequence (2 bits per sequence) The flags for 4 sequences are packed in one byte. Data Quality Flags are provided every 1/4 sequence. The flags for one sequence are packed in a byte as follows: 0 1 2 3 4 5 6 7 Frames Frames Frames Frames 0-3 4-7 8-11 12-15 Spacecraft Clock The Spacecraft Clock appears as an integer, of which the least significant bit (20) counts at the sequence rate. The main frame count and the data rate bits have been dropped. All complementation, bit reversal and rearrangement has been done. The result is a 22-bit counter that is incremented every sequence (approximately 1.27841 seconds) and recycles in approximately 62 days. Bits 2121 = Telemetry sequence 2'32 2 = Telemetry snapshot 2124 - Telemetry page 221 ... 21 - Telemetry album In the case or low bit rate (400 BPS), redundant bits (a5a6) have been removed so that the clock counts normally. This results in a 20-bit counter that is incremented every sequence (approximately 5.11364 seconds) and recycles in approximately 62 days. The clock value has been time corrected where n&cessary and possible. APP's (Analog Performance Parameters) Each APP appears as a one byte integer representing count values from. 0 to 255. APP's 16, 1-15 appear every pa-e APP's 32, 17-31 appear only on even pages (page 0 and page 2 as determined by the S/C clock). APP's 48, 33-47 appear only on odd pages (1 and 3). DPP's(Digital Performance Parameters) ------------------------------------- All DPP's are provided for each page. DPP's A2 occur once per snapshot for a total of 4 each per page. DPP's A3 occur once per 2 snapshots for a total of 2 each per page. Each group of 8 significant bits represents 4 DPP's as follows: DD3@@ IkD3@@ Thus for DPP A2, 5-8: D4 = DPP A2-8, D3 = DPP A2-7, = DPP A2-6, @ = DPP A2-5.