|
NOAA KLM User's GuideSection 8.3.1.3.3.1 |
Introduction Page,
NOAA KLM TOC,
AcronymsThe Data Records for LAC and HRPT data sets are archived in packed format to reduce storage requirements. Three 10-bit sensor samples are stored in a 32-bit word using the Band Interleaved by Pixel (BIP) method. The format for packed data sets is documented in Table 8.3.1.3.3.1-1. However, this format is inconvenient for data processing.
| Field Name | Start Octet | End Octet | Data Type | Word Size | Number of Words | Scale Factor | Units | Notes |
|---|---|---|---|---|---|---|---|---|
| SCAN LINE INFORMATION | ||||||||
| Scan Line Number (cumulative, starting with 1) | 1 | 2 | u | 2 | 1 | 0 | ||
| Scan Line Year (4 digit year) | 3 | 4 | u | 2 | 1 | 0 | year | |
| Scan Line Day of Year (3 digit day) | 5 | 6 | u | 2 | 1 | 0 | day | |
| Satellite Clock Drift Delta | 7 | 8 | i | 2 | 1 | 0 | milliseconds | |
| Scan Line UTC Time of Day | 9 | 12 | u | 4 | 1 | 0 | milliseconds | |
| Scan Line Bit Field bit 15: 0 = northbound data; 1 = southbound data bit 14: 1 = scan time corrected for clock drift bits 13-2: <zero fill> bits 1-0: channel 3 select (0 = 3b; 1 = 3a; 2 = transition) |
13 | 14 | u | 2 | 1 | 0 | ||
| <Zero Fill> | 15 | 24 | i | 2 | 5 | 0 | ||
| QUALITY INDICATORS | ||||||||
| Quality Indicator Bit Field If a bit is on (=1) then the statement is true. bit 31: do not use scan for product generation bit 30: time sequence error detected within this scan (see below) bit 29: data gap precedes this scan bit 28: insufficient data for calibration (see below) bit 27: earth location data not available (see below) bit 26: first good time following a clock update (nominally 0) bit 25: instrument status changed with this scan bit 24: sync lock dropped during this frame bit 23: frame sync word error greater than zero bit 22: frame sync previously dropped lock bit 21: flywheeling detected during this frame bit 20: bit slippage detected during this frame bits 19-9: <zero fill> bit 8: TIP parity error detected bits 7-6: reflected sunlight detected ch 3b (0 = no anomaly; 1 = anomaly; 3 = unsure) bits 5-4: reflected sunlight detected ch 4 (0 = no anomaly; 1 = anomaly; 3 = unsure) bits 3-2: reflected sunlight detected ch 5 (0 = no anomaly; 1 = anomaly; 3 = unsure) bit 1: resync occurred on this frame bit 0: pseudo noise occurred on this frame |
25 | 28 | u | 4 | 1 | 0 | ||
| Scan Line Quality Flags If a bit is on (=1) then the statement is true. Time Problem Code (All bits off implies the scan time is as expected.) bits 31-24: <zero fill> bit 23: time field is bad but can probably be inferred from the previous good time. bit 22: time field is bad and can't be inferred from the previous good time. bit 21: this record starts a sequence that is inconsistent with previous times (i.e., there is a time discontinuity). This may or may not be associated with a spacecraft clock update. (See bit 26, Quality Indicator Bit Field) bit 20: start of a sequence that apparently repeats scan times that have been previously accepted. bits 19-16: <zero fill> Calibration Problem Code (Note these bits complement the channel indicators; all bits set to 0 indicates normal calibration.) bit 15: scan line was not calibrated because of bad time. bit 14: scan line was calibrated using fewer than the preferred number of scan lines because of proximity to start or end of data set or to a data gap. bit 13: scan line was not calibrated because of bad or insufficient PRT data. bit 12: scan line was calibrated but with marginal PRT data. bit 11: some uncalibrated channels on this scan (see channel indicators) bits 10-8: <zero fill> Earth Location Problem Code (all bits set to 0 implies the earth location was normal) bit 7: not earth located because of bad time; earth location fields zero filled. bit 6: earth location questionable because of questionable time code. (See time problem flags above). bit 5: earth location questionable -- only marginal agreement with reasonableness check. bit 4: earth location questionable -- fails reasonableness check. bits 3-0: <zero fill> |
29 | 32 | u | 4 | 1 | 0 | ||
| Calibration Quality Flags (all bits off implies a good calibration) Word 1: Channel 3b bits 15 - 8: <zero fill> bit 7: this channel is not calibrated bit 6: this channel is calibrated but questionable bit 5: all bad blackbody counts for scan line bit 4: all bad space view counts for scan line bit 3: <zero fill> bit 2: marginal blackbody view counts for this line bit 1: marginal space view counts for this line bit 0: <zero fill> Word 2: Channel 4 Word 3: Channel 5 |
33 | 38 | u | 2 | 3 | 0 | ||
| Count of Bit Errors in Frame Sync | 39 | 40 | u | 2 | 1 | 0 | ||
| <Zero Fill> | 41 | 48 | i | 4 | 2 | 0 | ||
| CALIBRATION COEFFICIENTS | ||||||||
| Visible Operational Cal Ch 1 Slope 1 | 49 | 52 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 1 Intercept 1 | 53 | 56 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 1 Slope 2 | 57 | 60 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 1 Intercept 2 | 61 | 64 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 1 Intersection | 65 | 68 | i | 4 | 1 | 0 | ||
| Visible Test Cal Ch 1 Slope 1 | 69 | 72 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 1 Intercept 1 | 73 | 76 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 1 Slope 2 | 77 | 80 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 1 Intercept 2 | 81 | 84 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 1 Intersection | 85 | 88 | i | 4 | 1 | 0 | ||
| Visible Prelaunch Cal Ch 1 Slope 1 | 89 | 92 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 1 Intercept 1 | 93 | 96 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 1 Slope 2 | 97 | 100 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 1 Intercept 2 | 101 | 104 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 1 Intersection | 105 | 108 | i | 4 | 1 | 0 | ||
| Visible Operational Cal Ch 2 Slope 1 | 109 | 112 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 2 Intercept 1 | 113 | 116 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 2 Slope 2 | 117 | 120 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 2 Intercept 2 | 121 | 124 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 2 Intersection | 125 | 128 | i | 4 | 1 | 0 | ||
| Visible Test Cal Ch 2 Slope 1 | 129 | 132 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 2 Intercept 1 | 133 | 136 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 2 Slope 2 | 137 | 140 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 2 Intercept 2 | 141 | 144 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 2 Intersection | 145 | 148 | i | 4 | 1 | 0 | ||
| Visible Prelaunch Cal Ch 2 Slope 1 | 149 | 152 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 2 Intercept 1 | 153 | 156 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 2 Slope 2 | 157 | 160 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 2 Intercept 2 | 161 | 164 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 2 Intersection | 165 | 168 | i | 4 | 1 | 0 | ||
| Visible Operational Cal Ch 3a Slope 1 | 169 | 172 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 3a Intercept 1 | 173 | 176 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 3a Slope 2 | 177 | 180 | i | 4 | 1 | 7 | ||
| Visible Operational Cal Ch 3a Intercept 2 | 181 | 184 | i | 4 | 1 | 6 | ||
| Visible Operational Cal Ch 3a Intersection | 185 | 188 | i | 4 | 1 | 0 | ||
| Visible Test Cal Ch 3a Slope 1 | 189 | 192 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 3a Intercept 1 | 193 | 196 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 3a Slope 2 | 197 | 200 | i | 4 | 1 | 7 | ||
| Visible Test Cal Ch 3a Intercept 2 | 201 | 204 | i | 4 | 1 | 6 | ||
| Visible Test Cal Ch 3a Intersection | 205 | 208 | i | 4 | 1 | 0 | ||
| Visible Prelaunch Cal Ch 3a Slope 1 | 209 | 212 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 3a Intercept 1 | 213 | 216 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 3a Slope 2 | 217 | 220 | i | 4 | 1 | 7 | ||
| Visible Prelaunch Cal Ch 3a Intercept 2 | 221 | 224 | i | 4 | 1 | 6 | ||
| Visible Prelaunch Cal Ch 3a Intersection | 225 | 228 | i | 4 | 1 | 0 | ||
| IR Operational Cal Ch 3b Coefficient 1 | 229 | 232 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 3b Coefficient 2 | 233 | 236 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 3b Coefficient 3 | 237 | 240 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 3b Coefficient 1 | 241 | 244 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 3b Coefficient 2 | 245 | 248 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 3b Coefficient 3 | 249 | 252 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 4 Coefficient 1 | 253 | 256 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 4 Coefficient 2 | 257 | 260 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 4 Coefficient 3 | 261 | 264 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 4 Coefficient 1 | 265 | 268 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 4 Coefficient 2 | 269 | 272 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 4 Coefficient 3 | 273 | 276 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 5 Coefficient 1 | 277 | 280 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 5 Coefficient 2 | 281 | 284 | i | 4 | 1 | 6 | ||
| IR Operational Cal Ch 5 Coefficient 3 | 285 | 288 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 5 Coefficient 1 | 289 | 292 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 5 Coefficient 2 | 293 | 296 | i | 4 | 1 | 6 | ||
| IR Test Cal Ch 5 Coefficient 3 | 297 | 300 | i | 4 | 1 | 6 | ||
| <Zero Fill> | 301 | 312 | i | 4 | 3 | 0 | ||
| NAVIGATION | ||||||||
| Navigation Status Bit Field bits 31-17: <zero fill> bit 16: 1 = earth location corrected for TIP Euler angles bits 15 - 12: earth location indicator (0 = earth location available; 1 = user ephemeris files greater than 24 hours old; 2 = no earth location available) bits 11 - 8: spacecraft attitude control (0 = operating in YGC or NOMINAL mode; 1 = operating in another mode; 2 = attitude exceeds nominal tolerance; 3 = both 1 and 2) bits 7 - 4: attitude SMODE (0 = NOMINAL mode; 1 = rate nulling mode; 2 = YGC mode; 3 = search mode; 4 = coast mode) bits 3 - 0: attitude Passive Wheel Test In Progress (0 = NOMINAL mode/no test; 1 = yaw axis test in progress; 2 = roll axis test in progress; 3 = pitch axis test in progress) |
313 | 316 | u | 4 | 1 | 0 | ||
| Time Associated with TIP Euler Angles | 317 | 320 | u | 4 | 1 | 0 | seconds | |
| TIP Euler Angles Word 1: Roll Word 2: Pitch Word 3: Yaw |
321 | 326 | i | 2 | 3 | 3 | degrees | |
| Spacecraft Altitude above Reference Ellipsoid | 327 | 328 | u | 2 | 1 | 1 | kilometers | |
| Angular Relationships (relative azimuth range ± 180.00 degrees) Word 1: Solar Zenith Angle, Point 25 Word 2: Satellite Zenith Angle, Point 25 Word 3: Relative Azimuth Angle, Point 25 Word 4: Solar Zenith Angle, Point 65 ... (set of 3 angles every 40 points) ... Word 153: Relative Azimuth Angle, Point 2025 |
329 | 634 | i | 2 | 153 | 2 | degrees | |
| <Zero Fill> | 635 | 640 | i | 2 | 3 | 0 | ||
| Earth Location (North latitude and East longitude are positive) Word 1: Latitude, Point 25 Word 2: Longitude, Point 25 Word 3: Latitude, Point 65 ... (lat/lon word pair every 40 points) ... Word 102: Longitude, Point 2025 |
641 | 1048 | i | 4 | 102 | 4 | degrees | |
| <Zero Fill> | 1049 | 1056 | i | 4 | 2 | 0 | ||
| HRPT MINOR FRAME TELEMETRY | ||||||||
| Frame Sync The first sixty bits (six 10-bit values: 644, 367, 860, 413, 527, 149) from a 63 bit pseudonoise generator starting in the all 1's state. The generator polynomial is: x6 + x5 + x2 + 1 |
1057 | 1068 | u | 2 | 6 | 0 | ||
| ID Word 1 bits 15-10: <zero fill> bit 9: 0 = internal sync; 1 = AVHRR sync bits 8-7: 0 = not an HRPT frame but a GAC frame; 1 = minor frame 1; 2 = minor frame 2; 3 = minor frame 3 bits 6-3: spacecraft address bit 2: 0 = frame stable; 1 = frame resync occurred bit 1: 0 = pseudonoise AVHRR input; 1 = normal AVHRR input bit 0: 0 = AVHRR Ch 3b; 1 = AVHRR Ch 3a Word 2 bits 15-10: <zero fill> bits 9-0: <undefined> |
1069 | 1072 | u | 2 | 2 | 0 | ||
| Time Code Word 1 bits 15-10: <zero fill> bits 9-1: binary day count bit 0 = 0 Word 2 bits 15-10: <zero fill> bit 9 = 1 bit 8 = 0 bit 7 = 1 bits 6-0: most significant part of binary millisecond of day count Word 3 bits 15-10: <zero fill> bits 9-0: part of binary millisecond of day count Word 4 bits 15-10: <zero fill> bits 9-0: least significant part of binary millisecond of day count |
1073 | 1080 | u | 2 | 4 | 0 | ||
| Telemetry Word 1: Ramp Calibration AVHRR Channel 1 Word 2: Ramp Calibration AVHRR Channel 2 Word 3: Ramp Calibration AVHRR Channel 3 Word 4: Ramp Calibration AVHRR Channel 4 Word 5: Ramp Calibration AVHRR Channel 5 Words 6-9: AVHRR Internal Target Temperature Data Three readings from one of the four platinum resistance thermometers (PRT). A different PRT is sampled for each scan; every fifth scan will contain a reference value of 0 in place of each reading. Word 6: PRT Reading 1 Word 7: PRT Reading 2 Word 8: PRT Reading 3 Word 9: Patch Temperature Word 10: <undefined> |
1081 | 1100 | u | 2 | 10 | 0 | ||
| Back Scan Ten words of calibration target view data from each AVHRR channel 3, 4, 5. Word 1: Channel 3, Word 1 ... Word 3: Channel 5, Word 1 Word 4: Channel 3, Word 2 ... Word 30: Channel 5, Word 10 |
1101 | 1160 | u | 2 | 30 | 0 | ||
| Space Data Ten words of space view data from each AVHRR channel 1, 2, 3, 4, 5 Word 1: Channel 1, Word 1 ... Word 5: Channel 5, Word 1 Word 6: Channel 1, Word 2 ... Word 50: Channel 5, Word 10 |
1161 | 1260 | u | 2 | 50 | 0 | ||
| Sync Delta bits 15-10: <zero fill> bit 9: 0 = AVHRR sync early; 1 = AVHRR sync late bits 8-0: 9-bit binary count of 0.9984 MHz periods |
1261 | 1262 | u | 2 | 1 | 0 | ||
| <Zero Fill> | 1263 | 1264 | i | 2 | 1 | 0 | ||
| AVHRR SENSOR DATA | ||||||||
| Sensor Data, Band Interleaved by Pixel (BIP) Word 1 bits 31-30: <zero fill> bits 29-20: Channel 1, Point 1 bits 19-10: Channel 2, Point 1 bits 9-0: Channel 3, Point 1 Word 2 bits 31-30: <zero fill> bits 29-20: Channel 4, Point 1 bits 19-10: Channel 5, Point 1 bits 9-0: Channel 1, Point 2 ... Word 3414 bits 31-30: <zero fill> bits 29-20: Channel 5, Point 2048 |
1265 | 14920 | u | 4 | 3414 | 0 | ||
| <Zero Fill> | 14921 | 14928 | i | 4 | 2 | 0 | ||
| DIGITAL B TELEMETRY | ||||||||
| Invalid Word Bit Flags (if bit = 1, associated telemetry bit was not updated during most recent minor frame cycle - possibly due to lost frame) bit 15: motor/telemetry bit 14: electronics/telemetry bit 13: channel 1 status bit 12: channel 2 status bit 11: channel 3a status bit 10: channel 3b status bit 9: channel 4 status bit 8: channel 5 status bit 7: channel 3a/3b select status bit 6: voltage calibrate status bit 5: cooler heat bit 4: scan motor bit 3: telemetry lock bit 2: earth shield bit 1: patch control bit 0: <zero fill> |
14929 | 14930 | u | 2 | 1 | 0 | ||
| AVHRR Digital B Data bit 15: motor/telemetry (0 = off; 1 = on) bit 14: electronics/telemetry (0 = off; 1 = on) bit 13: channel 1 status (0 = disable; 1 = enable) bit 12: channel 2 status (0 = disable; 1 = enable) bit 11: channel 3a status (0 = disable; 1 = enable) bit 10: channel 3b status (0 = disable; 1 = enable) bit 9: channel 4 status (0 = disable; 1 = enable) bit 8: channel 5 status (0 = disable; 1 = enable) bit 7: channel 3a/3b select status (0 = 3b; 1 = 3a) bit 6: voltage calibrate status (0 = off; 1 = on) bit 5: cooler heat (0 = off; 1 = on) bit 4: scan motor (0 = low; 1 = high) bit 3: telemetry lock (0 = off; 1 = lock) bit 2: earth shield (0 = disable; 1 = deploy) bit 1: patch control (0 = off; 1 = on) bit 0: <zero fill> |
14931 | 14932 | u | 2 | 1 | 0 | ||
| <Zero Fill> | 14933 | 14944 | i | 4 | 3 | 0 | ||
| ANALOG HOUSEKEEPING DATA (TIP) | ||||||||
| Invalid Word Bit Flags (if bit = 1, associated telemetry word was not updated during most recent minor frame cycle - possibly due to lost frame) bits 31 - 23: <zero fill> bit 22: reference voltage (word 22) bits 21-2: words 21 through 2 (in order) bit 1: patch temperature (word 1) bit 0: <zero fill> |
14945 | 14948 | u | 4 | 1 | 0 | ||
| Word 1: Patch Temperature Word 2: Patch Temperature Extended Word 3: Patch Power Word 4: Radiator Temperature Word 5: Black Body Temperature 1 Word 6: Black Body Temperature 2 Word 7: Black Body Temperature 3 Word 8: Black Body Temperature 4 Word 9: Electronics Current Word 10: Motor Current Word 11: Earth Shield Position Word 12: Electronics Temperature Word 13: Cooler Housing Temperature Word 14: Baseplate Temperature Word 15: Motor Housing Temperature Word 16: A/D Converter Temperature Word 17: Detector #4 Bias Voltage Word 18: Detector #5 Bias Voltage Word 19: Channel 3b Blackbody View Word 20: Channel 4 Blackbody View Word 21: Channel 5 Blackbody View Word 22: Reference Voltage |
14949 | 14970 | u | 1 | 22 | 0 | ||
| <Zero Fill> | 14971 | 14976 | i | 2 | 3 | 0 | ||
| CLOUDS FROM AVHRR (CLAVR) | ||||||||
| <Reserved> CLAVR Status Bit Field bits 31 - 1: <undefined> bit 0: CLAVR status (0 = disable, CCM codes zero-filled; 1 = enable) |
14977 | 14980 | u | 4 | 1 | 0 | 1 | |
| <Reserved> | 14981 | 14984 | u | 4 | 1 | 0 | ||
| <Reserved> CCM (Clear/Cloudy/Mixed) Codes (0 = unknown; 1 = clear; 2 = cloudy; 3 = partly cloudy) Word 1 bits 15-14: CCM Point 1 ... bits 1-0: CCM Point 8 ... (set of 8 CCM Codes per word) ... Word 256 bits 15-14: CCM Point 2041 ... bits 1-0: CCM Point 2048 |
14985 | 15496 | u | 2 | 256 | 0 | ||
| FILLER | ||||||||
| <Zero Fill> | 15497 | 15872 | i | 4 | 94 | 0 | 1 | |
| NOTES: 1) 13Nov1998: Redefine reserved CLAVR section to include CLAVR Status Bit Field (Fagan, 24Sep1998); adjust trailing zero-fill. Clouds from AVHRR (CLAVR) is a complex set of tests to detect daytime and nighttime cloud cover using multi-channel AVHRR sensor data and a surface type database. The first application of CLAVR at NOAA was to support the AVHRR Pathfinder Atmosphere (PATMOS) Project, which reprocessed AVHRR data to correct for calibration drift and produce a consistent record of atmospheric parameters for climate change studies. More information about the NOAA/NASA Pathfinder Program and PATMOS is available at http://orbit-net.nesdis.noaa.gov/crad/sat/atm/aerosol/tarfox /index/patmos.html . Pathfinder products are available through the Satellite Active Archive at http://www.saa.noaa.gov/. At this time CLAVR is not part of the operational processing system for NOAA Level 1b GAC, LAC, and HRPT data sets. Therefore, bit 0 of the NOAA Level 1b CLAVR Status Bit Field is set to zero, and the Clear/Cloudy/Mixed (CCM) Codes are zero-filled. Please note that the NOAA Level 1b format allocates space for only a minimal subset of CLAVR parameters needed to generate products that require cloud masks. NESDIS intends to implement CLAVR operationally as part of the Modernized AVHRR Processing System (MAPS), but not earlier than June 2002. The actual implementation date is subject to change dependent upon available resources and mission priorities. More information about current CLAVR research and development at NOAA is available online at http://orbit-n et.nesdis.noaa.gov/crad/sat/atm/cloud/clavrx/. | ||||||||
NESDIS archive systems support the selection of any combination of one to five channels, and sensor data word sizes of 8 or 16 bits (this is known as the unpacked format). The unpacking process stores each (10-bit) sensor data value in a separate eight or sixteen bit word. When 8-bit words are selected, the sensor data is reduced from ten to eight bits by removing the least significant two bits. When 16-bit words are selected, the sensor data is stored in the least significant ten bits and the six most significant bits are zero-filled. If a customer does not require all five channels from the AVHRR instrument, the unpacked format can also be reduced to any subset of active channels. At this time, however, the archive extraction programs do not differentiate between channels 3A and 3B. Channel selected data sets are not available in packed format. In all cases, the sensor data is stored in BIP order.
Tables 8.3.1.3.3.1-2 and 8.3.1.3.3.1-3 (containing the 8 and 16-bit unpacked structure, respectively) summarize how the selection of channel and sensor data word size affects the data set structure and record length documented in Table 8.3.1.3.3.1-1. The alignment of data words on eight octet (i.e., 64 bit) boundaries is maintained by adding binary zero-fill after the sensor data section.
| Number of Channels | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Pre-Data | 1 - 1264 | 1 - 1264 | 1 - 1264 | 1 - 1264 | 1 - 1264 |
| Sensor Data | 1265 - 3312 | 1265 - 5360 | 1265 - 7408 | 1265 - 9456 | 1265 - 11504 |
| Alignment Zero-Fill | 3313-3320 | 5361-5368 | 7409-7416 | 9457-9464 | 11505-11512 |
| Post-Data | 3321-3880 | 5369-5928 | 7417-7976 | 9465-10024 | 11513-12072 |
| Trailing Zero-Fill | 3881-4096 | 5929-6144 | 7977-8192 | 10025-10240 | 12073-12288 |
| Record Length | 4096 | 6144 | 8192 | 10240 | 12288 |
| Number of Channels | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Pre-Data | 1 - 1264 | 1 - 1264 | 1 - 1264 | 1 - 1264 | 1 - 1264 |
| Sensor Data | 1265 - 5360 | 1265 - 9456 | 1265 - 13552 | 1265 - 17648 | 1265 - 21744 |
| Alignment Zero-Fill | 5361-5368 | 9457-9464 | 13553-13560 | 17649-17656 | 21745-21752 |
| Post-Data | 5369-5928 | 9465-10024 | 13561-14120 | 17657-18216 | 21753-22312 |
| Trailing Zero-Fill | 5929-6144 | 10025-10240 | 14121-14336 | 18217-18432 | 22313-22528 |
| Record Length | 6144 | 10240 | 14336 | 18432 | 22528 |
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