N7RAW.TXT - Format of Nimbus 7 R tape series data
OVERALL STRUCTURE
-----------------
* Files are copies of our original R series tapes.
* Data was originally stored in 12 bit 'words' and now occupies the
12 least significant bits of a 16 bit word.
* The byte ordering within 16 bit integers follows the DEC convention
of least significant byte first.
DATA STRUCTURE
--------------
* Data is blocked together, each block (i.e. external block/record)
looking as follows:
( 3654 sync code (2 bytes indicating start of record)
( 3654 " " (" " " " " " )
( Record length in words (2 bytes)
BLOCK( Record serial number in "file" (2 bytes)
( Data records
( 2321 end of block marker (eob) (2 bytes)
( Checksum (2 bytes)
* Each internal data block/record itself contains
( 3654 sync code (2 bytes indicating start of record)
( 3654 " " (" " " " " " )
( Length of record in words (2 bytes)
BLOCK( Record serial number in "file" (2 bytes)
( Data
( 2321 end of block marker (eob) (2 bytes)
( Checksum (2 bytes)
DATA RECORD (332 16 BIT INTEGERS)
-----------
WORD FUNCTION
1 3654 (7106 Octal) SYNC CODE repeated twice in every block
2 3654 " " " " " " " " "
3 Block length (Total number of words in block, all inclusive)
4 Block #
5 Playback orbit # (15 bits) See note (1)
6 " " "
Day (9 bits) See note (1)
7 Start time of major frame (17 bits) See note (2)
8 " " " " "
Segment # of p/b orbit (5 bits) See note (3)
Sync summary bits (2 bits) See note (3)
9 Major frame number
10 Sync flags (160 bits) See note (4)
24,25 s/c latitude (24 bits) See note (5)
26,27 s/c longitude (24 bits) " " "
28 Altitude (km) (12 bits) " " "
29 SAMS digital a experiment data (2400 bits) See note (6)
229 SAMS analog hskg (392 bits) See note (7)
262 SAMS digital B (89 bits) " " "
270 Spacecraft status and events (192 bits) See note (8)
286 ACS pitch fine error
ACS foll fine error
ACS rmp A indicated rate ni
ACS rmp B indicated rate hi
329-330 [spare]
331 2321 (4421 Octal) EOB LAST FRAME FLAG (2730 (5252 Octal) for last
record; ;last record of last
"file" will contain 3371
(6453 Octal))
332 Checksum (least significant 12 bits of sum of words 1 to N-1 where
word N is the last word of the block; 1's complement
computation)
NOTES
-----
Each "tape" will contain 'm' days data with 'n' orbits per day and 'o' major
frames per orbit. The orbital data will be in ascending time order and will
have noise smoothed time.
Time and/or the Playback Orbit Segment Numbers must be used for sorting the
data.
(1) Playback orbit number
---------------------
This may be the same on several "files" of data.
WORD: 5 BITS: 0-11 most significant bit (MSB)
6 9-11 least significant bit (LSB)
Day
---
Computed from spacescraft time, runs from 1 through to 365.
BITS: 0-8
(2) Major frame time
----------------
The time will be integer seconds of day and will be ascending.
Data will be set to all binary "ones" until good time is available.
WORD: 7 BITS: 0-11 MSB
8 7-11 LSB
(3) Segment number of playback orbit
--------------------------------
Ranges from 1 to 3 with 1 being the most recent data.
BITS: 2-6
SYNC summary bits
-----------------
BIT: 0 - Sync Bit Slip Flag; set to 1 if one or more of the 80
minor frame bit slip flags is 1, otherwise set to 0.
BIT: 1 - Sync Loss Flag; set to 1 if one or more of the 80
minor frame sync loss flags is set to 1, otherwise 0.
Minor frames flagged "sync loss" will contain data from previous minor
frames. See Note (4) below.
(4) SYNC flags
----------
There are 80 bits allocated to the sync bit slip flags and 80 bits to the
sync loss flags, in pairs from minor frame 1 to 80. Sync loss flag is followed
by sync bit slip flag.
Two summary bits will indicate that at least one minor frame sync bit slip
flag is set or one sync loss flag is set within this major frame. - See
Note (3) above.
Major frames with the summary sync loss flag set should be handled as
follows:
Take the time difference between the last major frame before the major frame
with the sync loss flag set and the first major frame after without sync loss
flag set. Determine the number of major frames which should have been
received. Then,
a) if this equals the number of major frames received, data not flagged sync
loss can be assumed to be usable,
b) if it does not equal the number of received major frames, data is missing.
Major frame times are not necessarily correct except for the following case:
(i) The first major frame with sync loss flagged data after a
major frame without the flag set - the data from minor
frame 79 back to the first minor frame in which the sync
loss flag is set is valid.
(Remaining data to be processed at the discretion of the
User.)
If all 80 individual minor frame sync loss flags are set
the frame contains data from two or more major frames.
(- This data should only processed at the discretion of
the User.)
(5) Predicted orbital ephemeris data
--------------------------------
Data will contain an implied decimal point:
Latitude and Longitude -
BIT: 23 18 15 12 9 6 3 0
S X X X X X X X X X. X X X X X X X X X X X X X X
Altitude -
BIT: 11 6 3 0
S X X X X X X X X X X X
The S (Sign) Bit will be set to "+" for Northern and "-" for Southern
Latitudes. "1" is negative, "0" is positive. The longitude and altitude will
always be positive. Longitude will be 0 to 360 degrees East.
Data will to set to all binary "ones" if initial time is not available,
until good time is available.
(6) Digital A experiment data
-------------------------
Data will be output as 10 bit 'words'.
(7) SAMS analog and digital B housekeeping
--------------------------------------
The Analog and Digital B Housekeeping data will be in separate blocks.
Within each block the data will be ordered; first by function number order and
then all samples of each function in time order.
All Analog functions will be output as 8 bit 'words'.
EXAMPLES: ANALOG FUNCTIONS NO. OF SAMPLES
---------------- --------------
12101 1 ( = 1 8-bit 'word')
12102 1 ( = 1 8-bit 'word')
. .
. .
. .
12110 16 in time order ( = 16 8-bit 'words')
DIGITAL FUNCTIONS NO. OF SAMPLES
----------------- --------------
12001 3 in time order ( = 3 bits)
12002 3 in time order ( = 3 bits)
. .
. .
. .
12018 16 in time order ( = 16 bits)
12019 16 in time order ( = 16 bits)
12020 3 in time order ( = 3 bits)
12021 3 in time order ( = 3 bits)
--------------------------------------------------------------------------------
Function Number Listing.
FUNCTION # FUNCTION NAME FORM* RATE
--------------------------------------------------------------------------------
12001 Power on/off DB 3/16
12002 Limb scan drive on/off DB 3/16
12003 Azimuth scan drive on/off DB 3/16
12004 Launch mode on/off DB 3/16
12005 PCL auto/man DB 3/16
12006 PCL memory verify/normal DB 3/16
12007 PCL memory B/memory A DB 3/16
12008 Cooler door shut/open DB 3/16
12009 Upper limb scan limit yes/no DB 3/16
12010 Lower limb scan limit yes/no DB 3/16
12011 Forward azimuth scan limit yes/no DB 3/16
12012 Backward azimuth scan limit yes/no DB 3/16
12013 BB out of fov yes/no DB 3/16
12014 BB in fov yes/no DB 3/16
12015 Serial data cmd ena/dis DB 3/16
12016 Standby mode yes/no DB 3/16
12017 PCL busy yes/no DB 3/16
12018 Azimuth forward sector yes/no DB 1/1
12019 Azimuth backward sector yes/no DB 1/1
12020 A 2/3/4 heater on/off DB 3/16
12021 B1 gain low/high DB 3/16
12101 M1 mirror temp A 1/16
12102 M2 mirror temp A 1/16
12103 Limb LVDT temp A 1/16
12104 Azimuth LVDT temp A 1/16
12105 A 2/3/4 detector temp (warm) A 1/16
12106 BB motor temp A 1/16
12107 Limb motor temp A 1/16
12108 Azimuth motor current A 1/16
12109 Sensor foot temp A 1/16
12110 Mirror position register A 1/1
12111 Sensor elect temp A A 1/16
12112 Sensor elect temp B A 1/16
12113 Bay module A temp A 1/16
12114 Bay module B temp A 1/16
12115 A 2/3/4 lens temp (cold) A 1/16
12117 B1 Detector radiator temp A 1/16
12118 F/T Thermister bias voltage A 1/16
12119 Power supply volts A 1/16
12120 A 1/2 sieve heater current A 1/16
12121 A 3 sieve heater current A 1/16
12122 A 4 sieve heater current A 1/16
12123 B 1/2 sieve heater current A 1/16
12124 C1 sieve heater current A 1/16
12125 C2 sieve heater current A 1/16
12126 C3 sieve heater current A 1/16
12127 Mirror azimuth position A 1/16
12128 Synch error A 1/16
12129 Parity error A 1/16
12130 Overvoltage trip A 1/16
12131 Limb scan drive auto/man A 1/16
12132 Manual BB out A 1/16
12133 Cooler door release 1 on/off A 1/16
12134 Cooler sun shield temp A 1/16
Digital data DA 5/1
Digital data DA 5/1
Digital data DA 5/1
--------------------------------------------------------------------------------
* Form of function: A = Analog
DA = Digital A
DB = Digital B
The Analog and Digital B information will be arranged on the "tape" with the
format that follows.
ANALOG SAMPLES:
MSB LSB
BIT: 11 10 9 8 7 6 5 4 3 2 1 0
_______________________________________________________________________
| First analog function/sample | MSB of sample #2 |
|_______________________________________________|_______________________|
| LSB of sample #2 | 3rd function/sample |
|_______________________|_______________________________________________|
| 4th function/sample | etc. |
|_______________________________________________|_______________________|
DIGITAL SAMPLES:
DB1 no. of samples - 51
DB2 - 32
DB3 - 6
spare - 7
(8) SPACECRAFT STATUS AND EVENTS
----------------------------
Spacecraft status and events are listed in the table below.
Where Digital B functions are used for status, all (3) samples will be used.
Where an event flag is used, 3 bits will be used to indicate state.
--------------------------------------------------------------------------------
NO. FUNCTION/EVENT # DESCRIPTION BIT/STATE (1/0)
--------------------------------------------------------------------------------
1 EV-27 Satellite day/night day(=1)/night(=0)
2 FN-6601 TLM pwr on/off on/off
3 FN-16001 DSAS pwr on/off on/off
4 FN-22008 IR zip/dip to tr1 zip/dip
5 FN-22009 IR zip/dip to tr2 zip/dip
6 FN-22010 IR zip/dip to tr3 zip/dip
7 FN-18006 TR1 power on/off on/off
8 FN-18036 TR2 power on/off on/off
9 FN-18056 TR3 power on/off on/off
10 (SPECIAL EVENT) Xponder A/B power 0=both off, 1=A on,
2=B on, 3=both on
11 FN-19002 Xponder ranging A on/off
12 FN-19006 Xponder ranging B on/off
13 FN-7160 WB Xmtr A pwr on/off
14 FN-7260 WB Xmtr B pwr on/off
15 FN-7165 WB Xmtr A/B selected A/B
16 FN-8001 CZCS channel 1 pwr on/off
17 FN-8002 CZCS channel 2 pwr on/off
18 FN-8003 CZCS channel 3 pwr on/off
19 FN-8004 CZCS channel 4 pwr on/off
20 FN-8005 CZCS channel 5 pwr on/off
21 FN-8006 CZCS channel 6 pwr on/off
22 FN-8007 CZCS elect. pwr on/off
23 FN-8008 CZCS scan drive on/off
24 (SPECIAL EVENT) CZCS cal lamp status 0=both off, 1=1 on,
2=2 on, 3=unknown
25 SPECIAL EVENT CZCS recording CZCS data yes=1/no=0
26 SPECIAL EVENT Real time data collection yes=1/no=0
27 EV-72 THIR status O=off, 1=rad on,
2=all on, >= 3=fail
28 FN-11001 LIMS elect on/off
29 FN-11004 LIMS adapt screen on/off
30 FN-11005 LIMS ACQ scan on/off
31 FN-11006 LIMS calib space yes/on
32 FN-11007 LIMS source calib yes/on
33 FN-12001 SAMS power on/off
34 FN-12002 SAMS limb scan drive on/off
35 FN-12003 SAMS azimuth scan drive on/off
36 FN-13001 SBUV/TOMS master power on/off
37 FN-13002 SBUV pwr enable enb/dis
38 FN-13005 SBUV step scan set/reset
39 FN-13006 SBUV continuous scan set/reset
40 FN-13007 SBUV cage cam set/reset
41 FN-13008 SBUV/TOMS wavelength cal set/reset
42 FN-13009 TOMS pwr enable enb/dis
43 FN-13020 SBUV/TOMS elect cal on/off
44 SPECIAL EVENT SBUV/TOMS frame counter
(First in Time)
45 SPECIAL EVENT SBUV/TOMS frame counter
(Second in Time)
46 FN-14001 ERB elect on/off
47 FN-14002 ERB scan on/off
48 FN-14011 ERB stepper driver off/no
49 FN-14016 ERB chopper operating yes/no
50 FN-15001 SMMR data system on/off
51 FN-15002 SMMR channel 1 pwr on/off
52 FN-15003 SMMR channel 2 pwr on/off
53 FN-15004 SMMR channel 3 pwr on/off
54 FN-15005 SMMR channel 4 pwr on/off
55 FN-15006 SMMR channel 5 pwr on/off
56 FN-15007 SMMR scan power on/off on/off
57 FN-17001 SAM II power on/off
58 FN-17015 SAM II standby on/off
59 FN-17014 SAM II scan mode on/off
60 FN-17013 SAM II slew code on/off
61 FN-17012 SAM II gimbal code on/off
62 - Spare -
63 - " -
64 - " -
--------------------------------------------------------------------------------
ACS Functions.
-------------
--------------------------------------------------------------------------------
FUNCTION # FUNCTION NAME FORM* RATE
--------------------------------------------------------------------------------
1112 Pitch fine error A 1/1
1122 Roll fine error A 1/1
1169 Rmp A indicated rate (hi res) A 1/1
1179 Rmp B Indicated rate (hi res) A 1/1
--------------------------------------------------------------------------------
* FORM OF FUNCTION: A = ANALOG
DA = DIGITAL A
DB = DIGITAL B
The ACS functions included in the output block will be arranged by function
number order, and all samples of that function in time order. (See SAMS Analog
Housekeeping paragraph for greater detail of the data arrangement.)
Pitch bias (if used) will be indicated on pitch fine error telemetry.
Most of the information in this document has been selected from the raw data
format given in NIMBUS G Document #NG-32. See this document for other details
if required.
********************************************************************************
The following notes were made when the original magnetic tapes were copied to
optical disk.
1) Playback orbit numbers -
Although they should be consecutive (give or take a couple of numbers),
this is not always the case. The very improbable-looking numbers are being
attributed to human error because they were actually manually inputted, and
no checksum errors occurred during our copying (impling that the data is
correct).
2) Day numbers -
On the whole these are sensible. There are some unexplainable "day 0"s
however which only last a few major frames at a time, at the most.
3) Times -
(i) negative times
The correct manipulation of long and short integers initially caused
a problem in calculations when crossing the 32767 integer*2 boundary
and hence the appearance of negative time values in logfiles. The
data copied from magnetic tape was not affected in any way.
This is the case for all R Series tapes from R00000 to R00050,
inclusive.
(ii) zero time values
It is being assumed that major frames did sometimes have start time
values of zero seconds. (- There are no errors flagged to indicate
corrupt data.)
The log files for R00051 and R00052 show zero times all the way
through. This is due to incorrect buffer input and hence incorrect
calculations. All data written to the virtual tape files is however
correct.
4) Several parity errors occured on tape R00148 and as a result of this
we were unable to obtain any data after day 23.
5) Several parity errors occur towards the end of tape R00171.