The definitive description of the NOAA Level 1b format can be found in the Polar Orbiter Data Users Guide (for NOAA-AJ), or the KLM User's Guide page.

Note that this document only describes the NOAA Level 1b format as pertaining to full HRPT data for the NOAA A to J satellite series. The NOAA-K/L/M format is outlined on seperate header and data pages while the file format for selected channels of HRPT data and other data sets is not described.

This document is currently in preparation - the byte sizes and offsets need correcting and the code needs to be compared; in particular header time needs adding after 'original format ends here' part. Also the TBM part needs checking..

Notation

In a 32-bit word, bit 31 is the MSB and bit 0 is the LSB. Byte sex is big-endian.

Introduction

A NOAA Level 1b format file consists of a set of records of size 14800 bytes. The first record is the file header, subsequent records each containing one scan line of HRPT data. Before the header record is one TBM record of size 122 bytes.

TBM Header

Bytes Offset Contents
44 30 Data set name (First 42 bytes used)
1 74 Total / Selective copy (T or S)
3 75 Beginning Latitude
3 78 Ending Latitude
4 81 Beginning Longitude
4 85 Ending Longitude
2 89 Start Hour
2 91 Start Minute
3 93 Number of minutes
1 96 Appended data selection (Y or N)
20 117 Channels selected (in binary)

Header

Bytes Offset Contents
1 byte 0 Spacecraft Ident.: TIROS-N = 1, NOAAs 6 to 12 = 2,4,6,7,8,1,5.
1 1 Data type: bits 1-4 = 3 for HRPT, bits 5-8 = 1 for Embedded TIP, 2 for Stored TIP, 3 for Third CDA.
6 2 Start time: 7 bits for year, 9 bits for Julian day, 5 unused bits, 27 bits for milliseconds (GMT).
2 8 Number of scans
6 10 End time
7 16 Processing block ident: ASCII, first 5 digits = orbit number at start, last two digits = last two significant digits of orbit number at end of pass.
1 23 Ramp / Auto calibration: bits 4-8 = channels 1 to 5 respectively; bit set indicates ramp non-linearity.
2 24 Number of data gaps
6 26 DACS quality:
first two bytes = no. of input data frames containing no frame sync word errors
next two bytes = no. of DACS detected TIP parity errors
next two bytes = sum of all auxiliary sync errors detected in data for complete data set.
2 32 Calibration parameter ident.: calibration parameter input data set used to calibrate this data (2 chars, not an integer).
1 34 DACS status: bit 1 = 0 (normal data), bits 2-3 = 0 (data source = unused), bit 4 = 1 (tape forward), bit 5 = 1 (flight data), bits 6-8 = 0 (spare).
1 35 Attitude correction
1 36 Earth location tolerance
3 37 Zero filled
44 40 Data set name: (First 42 bytes used) DSS.HRPT.ND.D94001.S1642.E1701.B1234567.DU

(DSS=Dundee Satellite Systems, ND = NOAA-12, D=year+day, S=start time, E=end, B=processing block ident., DU=Dundee).

Original 1B format ends here
2 84 Year of epoch for orbit vector (xx)
2 86 Julian day of epoch (xxx)
4 88 Millisecond GMT epoch time of day (xxxxxxxx)
Keplerian elements follow.
8 92 Semi major axis: km x 103, ASCII, format = xxxxx.xxx
8 96 Eccentricity: x 103 format = .xxxx xxxx
8 100 Inclination: deg x 105, format = xxx.xxxxx
8 104 Argument of Perigee: deg, format = xxx.xxxxx
8 108 Right Ascension of Ascending Node: deg, format = xxx.xxxxx
8 112 Mean Anomaly: deg x 105, format = xxx.xxxxx
Cartesian elements follow.
8 116 X position vector: km x 104, ASCII, format = +-xxxx.xxxx (sign?)
8 120 Y:
8 124 Z:
8 128 X dot velocity vector: km/s x 106, ASCII, format = +-x.xxx xxx (7 digits?)
8 132 Y dot:
8 136 Z dot:
2 140 Yaw: degrees x 103
2 142 Roll:
2 144 Pitch:
14614 or 14612 Padding: zero filled to end of record (1479).

Data record

Bytes Offset Contents
2 bytes 0 Scan line number.
6 2 Time code: format as in header.
4 8 Quality indicators:
Byte 1: bit 1 = invalid data, bit 2 = time sequence error, bit 3 = preceding gap, bit 4 = resync on this frame, bit 5 = insufficient data for calibration, bit 6 = no earth location data, bit 7 = descending, bit 8 = pseudo noise occurred on frame.
Byte 2: bit 1 = bit sync status (drop lock during frame), bit 2 = sync error, bit 3 = frame sync lock (frame sync previously dropped lock), bit 4 = flywheeling, bit 5 = bit slippage, bits 6-8 = spare.
Byte 3: bits 1-5 = TIP parity in 1st-5th minor frame respectively, bits 6-8 = spare.
Byte 4: bits 1-6 = sync errors (number of bit errors in frame sync), bits 7-8 = spare.
40 12 Calibration coefficients: see pages 3.4, 3.14
4 bytes channel 1 slope
4 bytes channel 1 intercept
4 bytes channel 2 slope, ...
1 52 Number of meaningful zenith angles and earth location points appended to scan. Maximum = 51.
51 53 Solar zenith angles: degrees times 2. Sampled every 40 points starting at point 25. See pages 3.4 also extensions.
204 104 Earth location: latitude and longitude each 2 bytes, 128ths of a degree, East positive. Sampled every 40 points starting at point 25.
140 308 Telemetry: packed HRPT TIP data, see page 3.5
13656 448 Packed video data: see page 2.12
Original 1B format ends here.
20 14104 Additional decimal portions of solar zenith angles: packed, see page ex.7
2 14124 Clock drift delta:
52 14126 arb's extras: ch3band, gain2, inter2, xover
622 Padding: zero filled to end of record.


Author

Andrew Brooks, arb@sat.dundee.ac.uk

Revision

Document: 1.4, 31-August-1998, agp


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