HRPT Format

Note the bit numbering is MSB=bit 1, LSB=bit 10 in this document.

A complete description (for the KLM satellites) can be found in the NOAA documentation.

One scanline of HRPT data contains one minor frame (11090 10-bit words). The minor frame number is contained in word 7. There are three minor frames, numbered 1, 2 and 3, per major frame.

Function Number
of words
Word
Position
Description
Frame sync 6 1 0x284 = 644 (Bits 1-10=1010000100)
2 0x16F = 367 (0101101111)
3 0x35C = 860 (1101011100)
4 0x19D = 413 (0110011101)
5 0x20F = 527 (1000001111)
6 0x095 = 149 (0010010101)
ID 2 7 Bit 1: 0=internal sync, 1=AVHRR sync.
Bits 2,3: minor frame number (00 means GAC).
Bits 4-7: spacecraft address (MSB is bit 4)
Bit 8: 0=frame stable, 1=frame resync occurred
Bit 9 (KLM): 0=avhrr, 1=pseudo noise
Bit 10 (KLM): 0=3b, 1=3a
8 Spare
Time code 4 9 Frame time in msec. Bits 1-9=day count
10 Bits 4-10=msec
11-12 Bits 1-10=msec
Telemetry 10 13-17 Ramp calibration, channels 1 to 5
18-20 Target temperature, channels 3-5 (PRT 1-3)
21 Channel 3 patch temperature
22 Spare
Back scan 30 23-52 Back scan data for channels 3-5 interleaved
Space data 50 53-102 Space scan data for channels 1-5 interleaved
Sync 1 103 Sync word, bit 1: 0=sync early, 1=sync late
Bits 2-10: 9-bit binary count of 0.9984 MHz periods (MSB is bit 2)
TIP data 520 104-623 5 TIP frames of 104 words each. Bits 1-8: TIP data, bit 9=even parity check, bit 10=bit 1 (KLM: TIP data only in minor frame 1)
Spare 127 624-750 Spare
Image data 10240 751-10990 Earth view image data from one scan of AVHRR, 2048 pixels, channel interleaved
Aux sync 100 10991-11090 Aux. Sync words

TIP data

The TIP block (520 words) contains 5 TIP minor frames of 104 words each. Each two-byte word contains one 10-bit TIP word, of which bits 1 to 8 contain TIP data, the other two being parity. The bits numbered "1" to "8" are actually stored in the word as bits 9 to 2, with bits 1 and 0 used for parity. Thus there are 104 bytes of data in a TIP minor frame. See page 4-40 (table 4-14). TIP major frame count is word 3 bits 4 to 6, ie. ((words[3] & 0x70) >> 4). TIP minor frame number is TIP word 4 bit 8 and TIP word 5 bits 1 to 8, ie. (words[5] >> 2) + ((words[4] & 4) << 6). TIP analogue channel number is TIP word 3 bits 7,8 and word 4 bits 1 to 7, ie. ((words[3] & 0xC) << 5) + ((words[4] & 0x3F8) >> 3).

Analogue data is described in table 15-14 on page 15-47.

CPU-A data, see page 15-83, table 15-15, consists of 135 16-bit words, divided into 9 sub-tables of 15 words each, eg. Altitude is word 13 of table 4. The sub-tables are read out in the order 1, 2, 1, 3, 1, 4, ..., 1, 9, repeat. A full read out is thus 16 sub-tables = 16*15 = 240 words. As only 6 bytes are available in each TIP Minor Frame then each minor frame contains 3 words of CPU data. 5 minor frames will contain 15 words, ie. one sub-table can be stored in one scan line. So the complete CPU data needs 16 lines. TIP data is repeated for three lines though (or only transmitted in HRPT minor frame 1 for KLM) so the full read out needs 16*3 = 48 lines.

Note about synchronisation: words 1, 2 and 3 of each sub-table will be kept together in a minor frame (rather than 2, 3 and 4 for example). Word 1 of sub-table 1 is not necessarily in minor frame 0 though. Word 1 of sub-table 1 can be found by looking for words 14 and 15 of sub-table 9 as they will always contain 0xEB90 and 0x146F (60309 and 5231).

Attitude on pre-N14: Yaw,Roll,Pitch are table 1, words 13,14,15; scaling factor 8192. Altitude is table 4, word 4.

References: Programming and Control Handbook for Advanced TIROS-N Spacecraft Series (NOAA-E,F,G)

  1. Volume 1, 4-40 (TIP minor frame format)
  2. Volume 1, 5-56 (How to read TIP telemetry)
  3. Volume 1, 5-71 (CPU telemetry)
  4. Volume 2, 15-48 (Analogue telemetry table)
  5. Volume 2, 15-83 (CPU telemetry table)

NOAA KLM-series (NOAA-15, 16, 17)

Word 7, bit 10 indicates which channel 3A or 3B is operating (note that this is not a reliable indicator to check on pre-N15 satellites).

Visible channels 1, 2 and 3A have dual calibration slopes.

HRPT Minor frame 1 is the only one to contain TIP data (2 is spare and 3 is for AMSU data).


DartCom HRPT Format

DartCom format only keeps the sixth of the first six framesync words, and 23 of the last 100 aux sync words but otherwise is standard HRPT. BURL similarly drop words, keeping only the fifth and sixth of the first six framesync words, 21 of the middle 127 spare words, and none of the last 100 aux sync words.


Quorum HRPT Format

Quorum HRPT format is simply standard HRPT format (ie. unpacked into 11090 16-bit words). Four pseudo-frames are defined to hold extra information about the data. All pseudo frames start with a word 0x8000 followed by a word describing the frame contents:

The file always contains an elements frame followed by a start time frame, then HRPT frames with resync frames possibly interspersed, and finally an end time frame. Times are stored as unix 32-bit seconds since 1970, with the most significant two bytes in the third word of the frame and the least significant two in the fourth word of the frame.


Feng-Yun 1 format

Each HRPT line is twice the size of NOAA HRPT since there are ten channels instead of five, ie. 22180 words stored on disk 44360 bytes. The time code has no day and the spacecraft identifier is in the bottom four bits instead. The MVISR image data offset is 1600 instead of 750.

Frame sync 6 1 1010000100
2 0101101111
3 1101011100
4 0110011101
5 1000001111
6 0010010101
ID 2 7 Bits 1-4 = Satellite ID (FY-1C = 1100, FY-1D = 1101)
8 Spare
Time code 4 9 Bits 1-9 = binary day count
10 Bits 1-3 = 101, bits 4-10 = part of millisecond of day count
11 Part of millisecond

12

Remainder of millisecond

Telemetry (Ramp)

10

13-22

Ramp calibration of 10 channels of MVISR

Telemetry (Temp) 10 23 Temperature of first stage of radiant cooler A
24 Temperature of first stage of radiant cooler B
25 Temperature of second stage of radiant cooler A
26 Temperature of second stage of radiant cooler B
27 Temp controlling voltage of 2nd stage radiant cooler A
28 Temp controlling voltage of 2nd stage radiant cooler B
29-32 Temp of sheath of radiometer, 1 word per platinium resistance bulb
Reference Black Body 60 33-92 6 sampling words for every channel
Space 100 93-192 10 sampling words for every channel

Spare

1408

193-1600

00000 11101
00000 01100
10010 01010
...
00100 11110
11111 11000
11000 01101
11011 00101
Earth data 20480 1601-22080 2048 words for every channel from channel 1 to channel 10. Each frame contains the data obtained during one Earth scan of the MVISR sensor. Time multiplexed.
Aux. sync 100 22081-22180 11111 00010
11111 10011
01101 10101
...
01111 10000
11110 01100

SeaWiFS HRPT Format

Note that SeaWiFS data is supplied in level-0 or level-1 format. The following description refers only to the format received from the spacecraft prior to conversion to level-0. This raw format is not stored anywhere.

Function Number
of words
Word
Position
Description
Frame sync 6 1-6 As for NOAA HRPT
ID 2 7-8 Spacecraft ID, as for NOAA HRPT
Time code 4 9-12 Frame time in msec, as for NOAA HRPT
SOH TLM 620 13-632 Telemetry, NB. 8-bit format
Inst. TLM 44 633-676 Instrument telemetry
Gain & TDI 8 677-684 Gain and TDI
Image data 10304 685-10988 1285 pixels, 8 interleaved channels [encrypted]
Spare 20 10989-10990 Spare
Aux sync 100 10991-11090 Aux. Sync words

SeaWiFS Level-0 Format

Also known as NASA Frame Formatter format, this is the format used for storage of raw SeaWiFS data, as input to the level-1 conversion software. Words are stored in big-endian form. Note: the following tables used byte offsets not word offsets.

Header, 512 bytes

Function Number
of bytes
Byte
Position
Description
Magic 5 1-5 CWIF\0
Type 1 6 0 = LAC/GAC, 1=HRPT
Bits 4 317-320 Number of aux and/or sync bits used in bit error calculation
Errors 4 321-324 Number of bit errors in sync bits
AOS 4 333-336 Start time, seconds since 1970
LOS 4 337-340 End time, seconds since 1970

Record, 21504 bytes (21KB)

Function Number
of bytes
Byte
Position
Description
Quality flag 1 2 1 Number of sync bits used for error rate
Quality flag 2 1 3 Number of bit errors in sync bits
ID 4 4-7 Spacecraft ID (10-bit word in LSB of 2 bytes)
Time 8 8-15 Time tag (ditto)
SOH 775 16-790 State of health telemetry (8-bit words)
Data 20712 791-21502 44 words of TLM, 8 of Gain/TDI, 10304 of image data
Spare 2 21503-21504 Spare


Home Page Dundee Satellite Receiving Station Home Page      Send Us A Comment Send Us A Comment