BOREAS Level-0 C-130 Navigation Data Summary The level-0 C-130 navigation data files contain aircraft attitude and position information acquired during the digital image and photographic data collection missions. Various portions of the navigation data were collected at 1, 10, and 30 Hz. The level-0 C-130 navigation data collected for BOREAS in 1994 were improved over previous years in that the C-130 onboard navigation system was upgraded to output inertial navigation parameters every 1/30th of a second (i.e., 30 Hertz). This upgrade was encouraged by users of the aircraft scanner data with the hope of improving the relative geometric positioning of the collected images. Note that the level-0 C-130 navigation data are not contained on the BOREAS CD- ROM set. An inventory listing file is supplied on the CD-ROM to inform users of the data that were collected. See section 15 for information about how to acquire actual level-0 C-130 navigation data. Table of Contents * 1 Data Set Overview * 2 Investigator(s) * 3 Theory of Measurements * 4 Equipment * 5 Data Acquisition Methods * 6 Observations * 7 Data Description * 8 Data Organization * 9 Data Manipulations * 10 Errors * 11 Notes * 12 Application of the Data Set * 13 Future Modifications and Plans * 14 Software * 15 Data Access * 16 Output Products and Availability * 17 References * 18 Glossary of Terms * 19 List of Acronyms * 20 Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS Level-0 C-130 Navigation Data 1.2 Data Set Introduction The BOReal Ecosystem-Atmosphere Study (BOREAS) Staff Science effort covered those activities that were BOREAS community-level activities or required uniform data collection procedures across sites and time. These activities included the acquisition, processing, and archiving of aircraft navigation/attitude data to complement the digital image data. 1.3 Objective/Purpose The level-0 C-130 navigation data collected for BOREAS in 1994 were improved over previous years in that the C-130 onboard navigation system was upgraded to output inertial navigation parameters every 1/30th of a second (i.e., 30 Hz). This upgrade was encouraged by users of the aircraft scanner data with the hope of improving the relative geometric positioning of the collected images. 1.4 Summary of Parameters Level-0 C-130 navigation data in the BOREAS Information System (BORIS) contain the following parameters: • American Standard Code for Information Interchange (ASCII) summary information and documentation. • ASCII software source files. • Actual navigation data files that contain aircraft attitude and position information. 1.5 Discussion Ames Research Center (ARC) processing procedures involved extracting the Level-0 navigation data and an ASCII flight line summary file from the raw 0.15-inch cartridge tape. The Level-0 data were then transferred to BORIS along with a C header file (C130NAV) that contains two C structures matching the cartridge format and a C program that extracts data from the cartridge format and creates values in engineering units. BORIS staff processed the level-0 navigation data by: 1) Extracting pertinent header information from the ARC product and placing it in an ASCII file on disk, 2) Reading selected information from the ASCII file and loading the summary data into the BORIS online data base. 1.6 Related Data Sets Level-0 C-130 Aerial Photography Level-1b ASAS Data Level-1b MAS Data Level-0 NS001 Thematic Mapper Simulator Data Level-0 TIMS Data Level-1b TIMS Data 2. Investigator(s) 2.1 Investigator(s) Name and Title BOREAS Staff Science. 2.2 Title of Investigation BOREAS Staff Science Aircraft Data Acquisition Program 2.3 Contact Information Contact 1 ------------------- Jeffrey S. Myers Aircraft Data and Sensor Facilities NASA/Ames Research Center Moffett Field, CA (415) 604-6253 (415) 604-4987 (fax) jmyers@arc.nasa.gov Contact 2 ------------------- Jeffrey A. Newcomer NASA/GSFC Greenbelt, MD (301) 286-7858 (301) 286-0239 (fax) Jeffrey.Newcomer@.gsfc.nasa.gov 3. Theory of Measurements The NASA Earth Resources Aircraft Program at ARC operated the C-130 aircraft to acquire data for Earth science research. Several imaging sensors such as the Advanced Solid-State Array Spectroradiometer (ASAS), MODIS Airborne Simulator (MAS), NS001 Thematic Mapper Simulator (TMS), and Thermal Infrared Multispectral Scanner (TIMS) were flown on the C-130 for BOREAS. Prior to BOREAS, the C-130 navigation data were collected and recorded once per second during aircraft instrument data acquisition flights. Attempts at using these 1-Hz data to perform relative corrections of the image data proved that the corrections could be made, but that higher frequency recording of the navigation parameters was required to obtain a sufficiently accurate geometric correction. Improvements of the C-130 navigation system leading up to the BOREAS acquisition flights in 1994 resulted in a navigation parameter data set recorded at 30 Hz. These 30-Hz data are being used by BORIS staff to calculate relative geometric positions of the electromagnetic sensor measurements at the pixel level. A good relative correction of the aircraft imagery into a Cartesian coordinate system will greatly improve the association of the C-130 measurements with similar measurements taken at or near Earth's surface, from other airborne sensors, and from satellite platforms. 4. Equipment 4.1 Sensor/Instrument Description The C-130 Automated Digital Data System (CADDS) provides a means for the gathering and distribution of aircraft navigational, pertinent housekeeping, and environmental data. It incorporates data from the Delco Carousel IV A-3 Inertial Navigation System (INS), the Ashtech Z12 Global Positioning System (GPS), Honeywell APN-222 Radar Altimeter, the Rosemount 102 AH2AG Total Air Temperature (TAT) Sensor , the Precision Radiation Thermometer (PRT-5), the General Eastern 1011A two-stage thermoelectric hygrometer, and a pressure transducer. 4.1.1 Collection Environment CADDS was completed and installed in 1988. Its purpose was to gather, display, and archive selected aircraft navigational and housekeeping parameters. The data system was designed to be flexible and expandable. In 1994 integration of GPS and high-frequency aircraft parameters was introduced. During a flight, one of the C-130 technicians operates the data system located just aft of the forward exit door in the cabin. After takeoff, the operator initializes the system; setting the time code; inserting the site name, principal investigator, date, project, and mission numbers in the computer; and initializing the tape drives. Prior to a data line run, the mission manager announces the time before a line start, generally 1 minute, and the data system operator presses a button to start the countdown. The technician will call out the time of the line start. A log sheet is kept that includes pertinent information. Line stops are handled in a similar fashion. During a line, the technician can enter comments as directed by the mission manager. These comments are included on the 0.25-inch tape. Because of the BOREAS requirement for high-frequency input, the data provided to the BORIS archive were simply a copy of the raw 0.25-inch cartridge. 4.1.2 Source/Platform NASA's C-130 Earth Resources Aircraft. 4.1.3 Source/Platform Mission Objectives For BOREAS, the primary C-130 mission objective esd to collect various Earth surface data in coordination with satellite overpasses for data verification and integration studies. A secondary objective was to collect data at key times when the satellites were not within range of specific sites. The C-130 was based near the BOREAS study areas, and could thus be deployed rather quickly in order to take advantage of good data collection conditions. The navigation data provide in-flight geographic location and attitude information for the onboard sensors. 4.1.4 Key Variables The key parameters used by BORIS staff and investigators are: geographic location, time, platform attitude, altitude, atmospheric pressure, dew point, and temperature in proximity to the aircraft. 4.1.5 Principles of Operation Dual two-degree-of-freedom gyros that feature self-generating gas bearings are used in the navigation system. These have very low drift characteristics and an excellent turn-on repeatability. The radar altimeter interfaces directly with the CPU chassis through an interface card located within the chassis. The interface sends a clock signal to the radar altimeter every 80 milliseconds to acquire the altitude input. No information is available for the geographic location beacons, GPS system, or barometers. The TAT system consists of an external probe with an Aerodynamic Housing. The housing corrects for inaccurate temperature readings that would result from the expansion and compression associated with high-velocity air flow. The instrument is sensitive to a temperature range of -160 to 140¤ F. It can respond at a rate of 106¤ F per second with an accuracy of 0.1% of the full scale. 4.1.6 Sensor/Instrument Measurement Geometry C-130 DATA SYSTEM DESIGN Source Parameter Precision A/C INS #1 Latitude 0.1 minute A/C INS #1 Longitude 0.1 minute A/C INS #1 True Heading 0.1 degree A/C INS #1 Drift Angle 0.1 degree A/C INS #1 Ground Speed 1.0 nautical mile per hour A/C INS #1 Wind Speed 1.0 nautical mile per hour A/C INS #1 Wind Direction 1.0 degree A/C INS #1 Distance-To-Go 0.1 nautical mile A/C INS #1 Time-To-Go 0.1 minute A/C INS #1 Cross Track Distance 0.1 nautical mile A/C INS #1 Desired Track 0.1 degree A/C INS #1 Track Angle Error 0.1 degree A/C INS #1 Pitch 0.044 degree A/C INS #1 Roll 0.044 degree APN-222 Radar Altimeter 1.0 with accuracy of (5 ft + 1/2% altitude) A/A 24-G9 True Airspeed 1.0 nautical mile per hour TCG / GPS Time 0.1 second TAT Total Air Temp 0.10 with accuracy of • 2.0 ¤C PRT-5 Surface Temp 0.17 with accuracy of 0.5 ¤C Hygrometer Dew Point 0.05 with accuracy of 0.1 ¤C Press. Transducer Pressure Altitude 10 feet GPS Z12 Time 1.0 second GPS Z12 Latitude 0.0001 minute GPS Z12 Longitude 0.0001 minute GPS Z12 Altitude 0.1 meter GPS Z12 ECEF-X Velocity 0.01 meter/sec GPS Z12 ECEF-Y Velocity 0.01 meter/sec GPS Z12 ECEF-Z Velocity 0.01 meter/sec 4.1.7 Manufacturer of Sensor/Instrument CADDS is a general-purpose system composed primarily of off-the-shelf vendor- supplied boards and subassemblies. The standard systems include the Delco Carousel IV A-3 INS (installed 1989), the Ashtech Z12 GPS system (installed 1994), the Honeywell APN-222 Radar Altimeter (1988), Rosemount 102 AH2AG TAT Sensor, the General Eastern 1011A thermoelectric hygrometer system, and pressure transducers. 4.2 Calibration See Section 4.1.6. 4.2.1 Specifications See Section 4.1.6. 4.2.1.1 Tolerance See Section 4.1.6. 4.2.2 Frequency of Calibration Systems onboard the C-130 are calibrated once per year, usually just before the beginning of the flight year. 4.2.3 Other Calibration Information None. 5. Data Acquisition Methods During a flight, one of the C-130 technicians operates the data system located just aft of the forward exit door in the cabin. After takeoff, the operator initializes the system, setting the time code; inserting the site name, principal investigator, date, project and mission numbers in the computer; and initializing the tape drives. Prior to a data line run, the mission manager announces the time before a line start, generally 1-minute, and the data system operator presses a button to start the countdown. The technician calls out the time of the line start. A log sheet is kept that includes pertinent information. Line stops are handled in a similar fashion. During a line, the technician can enter comments as directed by the mission manager. These comments are included on the PC 0.25- inch tape. The system writes a 2048 byte record to 0.25-inch cartridge tape each second. Because of the BOREAS requirement for high-frequency input, the data provided to the BORIS archive were simply a copy of the raw 0.25-inch cartridge tape. 6. Observations 6.1 Data Notes None. Pertinent in-flight comments are recorded in the digital data records. 6.2 Field Notes Flight summary reports and verbal records on videotapes are available from the C- 130 flights. 7. Data Description 7.1 Spatial Characteristics The BOREAS level-0 C-130 navigation data were collected primarily as the C-130 flew over portions of the Northern Study Area (NSA) and the Southern Study Area (SSA) during its image data acquisition missions. The SSA and the NSA are located in the southwest and northeast portions of the overall BOREAS region. Some navigation data exist in the data set that cover the BOREAS transect area between the NSA and SSA and areas outside the BOREAS region. 7.1.1 Spatial Coverage The North American Datum 1983 (NAD83) corner coordinates of the SSA are: Latitude Longitude -------- --------- Northwest 54.321 N 106.228 W Northeast 54.225 N 104.237 W Southwest 53.515 N 106.321 W Southeast 53.420 N 104.368 W The NAD83 corner coordinates of the NSA are: Latitude Longitude -------- --------- Northwest 56.249 N 98.825 W Northeast 56.083 N 97.234 W Southwest 55.542 N 99.045 W Southeast 55.379 N 97.489 W 7.1.2 Spatial Coverage Map The BOREAS level-0 C-130 navigation data were collected as the C-130 flew over portions of the NSA and SSA during its image data acquisition missions. The SSA and the NSA are located in the southwest and northeast portions of the overall BOREAS region. 7.1.3 Spatial Resolution Spatial resolution is not strictly applicable to C-130 navigational data. The sampling rate for each portion of the navigation data can be combined with aircraft position, speed, and altitude to derive a spatial component for each data sample. 7.1.4 Projection The BOREAS level-0 C-130 navigation data contain latitude and longitude coordinates in the parameter set. For BOREAS purposes of relative correction of aircraft data, the latitude and longitude values were not used. Although the latitude and longitude coordinates could be used to calculate coordinates for any map projection, BORIS staff did not assess their accuracy and therefore cannot make any statements about their validity. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The data were collected during BOREAS' three Intensive Field Campaigns (IFCs), covering the period from 24-May-1994 through 19-Sep-1994. 7.2.2 Temporal Coverage Map IFC# Dates ----- -------------------------- FFC-T 16-Apr-1994 -- 20-Apr-1994 IFC-1 23-May-1994 -- 08-Jun-1994 IFC-2 21-Jul-1994 -- 08-Aug-1994 IFC-3 08-Sep-1994 -- 17-Sep-1994 7.2.3 Temporal Resolution Various portions of the navigation data were collected at 1, 10, and 30 Hz during the actual flights. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (c130navi.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (c130navi.def). 8. Data Organization 8.1 Data Granularity The smallest unit of level-0 C-130 navigation data is all the C-130 navigation information collected during the C-130 flights over the BOREAS areas in 1994. All of the data along with summary, documentation, and software files are contained on a single tape for distribution. All of the level-0 C-130 navigation data files are contained in one dataset. 8.2 Data Format(s) The C-130 level-0 tape contains 39 files that are mapped out as follows: FILE INTENDED NO. FILE NAME DESCRIPTION ------ ------------------ -------------------------------------------- 1 NAV.HED ASCII HEADER FILE 2 NAV.INV ASCII INVENTORY OF TAPE FILES 3 C130NAV.H INCLUDE FILE FOR TEST.C 4 C130NAV_COMPUTE.H INCLUDE FILE FOR C130NAV.COMPUTE.C 5 TEST.H INCLUDE FILE FOR TEST.C AND C130NAV_GETDAT.C 6 TEST.C ORIGINAL (ARC) VERSION OF C130_GETNAV.C 7 TEST_PRINT.C TEST.PRINT.C SOURCE CODE 8 C130NAV_EXTRACT.C C130NAV.EXTRACT.C SOURCE CODE 9 C130_GETNAV.C GSFC MODIFIED TEST.C: MAIN PROGRAM 10 MAKEFILE UNIX COMMAND FILE 11 README NASA/ARC INFORMATION 12 TEST.LISTING EXAMPLE OUTPUT 13-39 F1.DAT...F27.DAT BINARY C130 NAVIGATION DATA FILES File 1 (102-byte ASCII text records): - Description/title of each BORIS C-130 navigation data product file on tape. File 2 (102-byte ASCII text records) Contents of the navigation data tape files Listing of all dates, missions, flights, lines, and runs contained in each of the 27 binary navigation data files (files 16 to 42) on tape. Files 3 - 9 (102-byte ASCII text records) NASA/ARC supplied software for unpacking the binary navigation data files. Each file represents one C source code module or C source include file. Each file should be named as follows after being copied from tape to disk: FILE CREATED/INTENDED BYTES PER NO. FILE NAME DESCRIPTION RECORD ----- --------------- --------------------------------------- --- 3 c130nav.h Include file for test.c 102 4 c130nav_compute.h Include file for c130nav.compute.c 102 5 test.h Include file for test.c and c130nav_getdat.c 102 6 test.c Original (ARC) version of c130_getnav.c 102 7 test_print.c test.print.c source Code vvvvv 102 8 c130nav_extract.c c130nav.extract.c source Code 102 9 c130_getnav.c GSFC Modified test.c: main program 102 10 Makefile UNIX command file 80 11 README NASA/ARC information 80 12 test.listing Example output 132 File 10 (102-byte ASCII text records): Sun/UNIX MAKEFILE: This file should be renamed Makefile on a Sun workstation or an equivalent computer platform. Note that problems have been experienced attempting to use the Makefile pulled from the BORIS tape because of the padding of the fixed length records in the file. Some editing or other manipulation of the file may be necessary in order to use it successfully on a SUN system. The software enclosed on the original ARC tape delivered to GSFC was compiled and run successfully on a Sun workstation under the UNIX(r) System V Release 4.0 operating system. One attempt to compile this source failed on a Silicon Graphics IRIX (SGI) workstation under the IRIX System V.4 operating system because of the operating system could not locate system include files. No further attempt was made to port this software to the SGI, and no attempt was made to build this software under the VAX/VMS domain. File 11 (102-byte ASCII text records): The original file name was README. This file contains software notes written by NASA/ARC staff dated 27-Jun-1994. File 12: (132-byte ASCII text records): An example output file produced by the above software. This output was used at NASA/GSFC as a guide to selectively extract values such as time, roll, and pitch, needed to process MAS image data collected from the C-130 aircraft. Files 13-39 (2,048-byte binary and ASCII, combined, records): 27 files of C-130 navigation data containing multiple flight lines per file. C-130 navigation data are recorded as a 2048-byte record once per second. The data format as described by the NASA/ARC software is raw, binary, data in bytes 1-1024 and ASCII data in bytes 1025-2048. Further details of the data definitions, data type, and C structures used to manipulate the data are found in the C include file C130NAV.h (Tape file 3) listed above. A description of the fields contained on each data record follows: Binary C-130 Navigation Data Record Format: Description Units Byte #'s ----------- ------ --------- Record counter 1 - 2 Time code (BCD, dddhhmmsst) 3 - 7 ddd = Julian Day hh = hour of the day (0..23) mm = minutes (0..59) ss = seconds (0..59) t = tenths of seconds (0..9) MSB Event flag 8 Bits 12345678: 1: 0 --> INS1 1 --> INS2 2: 0 --> VCR off 1 --> VCR on 3: reserved 4: 0 --> AR1700 off 1 --> AR1700 on 5: reserved 6: 0 --> Keyboard 1 --> Thumbwheel 7&8: 00 --> line never occurred 01 --> line start 10 --> line stop 11 --> line abort Status flag --> bits 12345678 9 Record counter 1 - 2 Distance to go meters 10 - 15 Time to go seconds 16 - 21 Cross track distance meters 22 - 27 Desired track - 28 - 33 Track Angle Error - 34 - 39 Drift angle degrees 40 - 45 Align St - 46 - 51 Latitude degrees 52 - 57 Longitude degrees 58 - 63 Ground speed m/sec 64 - 69 Track angle degrees 70 - 75 True heading degrees 76 - 81 Wind speed m/sec 82 - 87 Wind angle (direction) degrees 88 - 93 Vertical profile distance meters 94 - 99 Vertical speed m/sec 100 - 105 A/D parameters, sampled 10 times per record 8 parameters each as follows: 106 - 265 PRT-5 data °C PRT-5 range °C TAT °C Hygrometer (dew point) °C Software use only - Pressure altitude meters Reserved - Reserved - S/D parameters sampled 30 times per record 5 parameters each as follows: 266 - 565 Pitch1 degrees Roll1 degrees Pitch2 degrees Roll2 degrees tHead degrees Thumbwheel month number (ASCII) 566 - 567 Thumbwheel day (of month) (ASCII) 568 - 569 Thumbwheel year (e.g., 94) (ASCII) 570 - 571 Thumbwheel site number (ASCII) 572 - 575 Thumbwheel Julian day (ASCII) 576 - 578 Thumbwheel mission number (ASCII) 579 - 581 Thumbwheel glight number (ASCII) 582 - 584 Thumbwheel A... G... L... (ASCII) 585 - 587 Thumbwheel project number (ASCII) 588 - 592 Thumbwheel line number (ASCII) 593 - 595 Thumbwheel run number (ASCII) 596 - 597 Keyboard line number (ASCII) 598 - 600 Keyboard run number (ASCII) 601 - 602 Keyboard site number (ASCII) 603 - 605 Keyboard mission number (ASCII) 606 - 608 Keyboard project number (ASCII) 609 - 613 Keyboard flight number (ASCII) 614 - 616 Comment (ASCII) 617 - 696 Record counter for RS232 (BCD) 697 - 700 NS001 scan line counter (BCD) 701 - 704 Frame counter (Unspecified) 705 - 709 Filler (Unspecified) 710 Time code (Unspecified) 711 - 717 Time code event (Unspecified) 718 - 724 Time code period (Unspecified) 725 - 726 N/S velocity (Unspecified) 727 - 732 E/W velocity (Unspecified) 733 - 738 filler - 739 - 1024 Record counter (Unspecified) 1025 - 1029 VCR status (Unspecified) 1030 - 1036 AR1700 status (Unspecified) 1037 - 1043 Line status (Unspecified) 1044 - 1050 Time (DDDHHMMSSt) (ASCII) 1051 - 1060 Filler set to lower-case "x" 1061 - 1070 Distance to go meters 1071 - 1081 Filler set to lower-case "x" 1082 - 1085 Time to go seconds 1086 - 1094 Filler set to lower-case "x" 1095 - 1098 Cross-track distance degrees 1099 - 1108 Filler set to lower-case "x" 1109 - 1111 Desired track - 1112 - 1120 Filler set to lower-case "x" 1121 - 1124 Track angle error - 1125 - 1134 Filler set to lower-case "x" 1135 - 1138 Drift angle degrees 1139 - 1147 Filler set to lower-case "x" 1148 - 1151 Reserved for align - 1152 - 1160 Filler set to lower-case "x" 1161 - 1164 Latitude degrees 1165 - 1175 Filler set to lower-case "x" 1176 - 1179 Longitude degrees 1180 - 1191 Filler set to lower-case "x" 1192 - 1195 Ground speed m/sec 1196 - 1203 Filler set to lower-case "x" 1204 - 1207 Reserved for track angle degrees 1208 - 1216 Filler set to lower-case "x" 1217 - 1220 True heading degrees 1221 - 1229 Filler set to lower-case "x" 1230 - 1233 Wind speed m/sec 1234 - 1241 Filler set to lower-case "x" 1242 - 1245 Wind angle direction degrees 1246 - 1253 Filler set to lower-case "x" 1257 Reserved for vert pro distance meters 1258 - 1266 Filler set to lower-case "x" 1267 - 1270 Vertical speed m/sec 1271 - 1280 Filler set to lower-case "x" 1281 - 1284 PRT-5 °C 1285 - 1290 Dew point °C 1291 - 1296 TAT °C 1297 - 1302 RESERVED - 1303 - 1346 Pitch degrees 1347 - 1350 Roll degrees 1351 - 1354 True heading degrees 1355 - 1358 Filler (set to lower case "x") - 1359 - 1362 Radar Altitude meters 1363 - 1367 Filler (set to lower case "x") - 1368 - 1420 Month number (ASCII) 1421 - 1422 Day (of the month) (ASCII) 1423 - 1424 Year (last 2 digits) (ASCII) 1425 - 1426 Thumbwheel site number (ASCII) 1427 - 1430 Thumbwheel Julian day (ASCII) 1431 - 1433 Thumbwheel mission number (ASCII) 1434 - 1436 Thumbwheel flight number (ASCII) 1437 - 1439 Thumbwheel A... G... L... (ASCII) 1440 - 1442 Thumbwheel project number (ASCII) 1443 - 1447 Thumbwheel line number (ASCII) 1448 - 1450 Thumbwheel run number (ASCII) 1451 - 1452 Keyboard line number (ASCII) 1453 - 1455 Keyboard run number (ASCII) 1456 - 1457 Keyboard site number (ASCII) 1458 - 1460 Keyboard mission number (ASCII) 1461 - 1463 Keyboard project number (ASCII) 1464 - 1468 Keyboard flight number (ASCII) 1469 - 1471 Filler set to lower-case "x" 1472 Comment (ASCII) 1473 - 1552 Record counter for RS232 1553 - 1560 Site name (ASCII) 1561 - 1581 Filler set to lower-case "x" 1582 NS001 scan line count (BCD ) 1583 - 1588 Filler set to lower-case "x" 1589 - 1598 GPS data (ASCII) 1599 - 1730 Filler set to lower-case "x" 1731 - 1768 Event time code (Unspecified) 1769 - 1786 Photo frame count #1 (Unspecified) 1787 - 1797 Filler set to lower-case "x" 1798 Photo frame count #2 (ASCII) 1799 - 1809 Filler set to lower case "x" 1810 - 2048 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms None. 9.2 Data Processing Sequence 9.2.1 Processing Steps ARC received the raw 0.25-inch cartridge tape from the C-130 technicians. The data files were read and loaded to disk. Distribution to the BORIS archive consisted of the raw data files along with C structures to read and process the data. BORIS staff further processed the level-0 C-130 navigation data by: 1) Extracting pertinent header information from the level-0 product and writing it to a disk file. 2) Reading the information in the disk file and loading the on line data base with needed information. 9.2.2 Processing Changes ARC applied no special or additional processing to the C-130 navigation data from BOREAS. 9.3 Calculations 9.3.1 Special Corrections/Adjustments ARC made no special adjustments or offsets to the data. 9.3.2 Calculated Variables ARC made no special adjustments or offsets to the data. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error Not all high-frequency samples (30 for synchro-digital (S/D) and 10 for analog- digital (A/D)) change between consecutive records. One explanation is the navigation system sampled the same value (at exactly a 1-second interval) for consecutive records. This can happen in relatively stable, level flight. Another explanation is that the navigation system failed to record all high- frequency samples (30 for S/D or 10 for A/D). Tests show the second explanation to be true most of the time, and samples were skipped at random during the 1- second interval. The field for the average true heading to a tenth of a degree contains four digits. The first digit prints as a sign (+/-), thus overwriting the hundreds digit of average true heading. No algorithm has been found to convert time reported by GPS to universal time. 10.2 Quality Assessment 10.2.1 Data Validation by Source Data distribution to NASA/ARC occurs at the conclusion of the deployment. Data tapes are presented in total for documentation and archive. Data evaluation consists primarily of identifying component failure (i.e. radar altitude, GPS values, pressure measurements.). 10.2.2 Confidence Level/Accuracy Judgment The quality of the data is judged to be good. 10.2.3 Measurement Error for Parameters See sections 4.1.6 and 8.2. 10.2.4 Additional Quality Assessments Quality Assessment performed by BORIS staff: BORIS staff built and ran the software provided by NASA/ARC on a Sun workstation. This software listed values for all parameters on selected 1-per- second C-130 navigation file records. A subset of this information was redirected to ASCII files and printed. A copy of the ARC software was modified to produce ASCII listings of selected 1, 10- and 30-Hz data, including pressure and radar altitude, pitch, roll, drift and time stamps for entire flight lines. These listings were transferred to a Macintosh and plotted with the Microsoft Excel program. Certain problems found in the data as revealed by these plots are described in Section 11.1. 10.2.5 Data Verification by Data Center 11. Notes 11.1 Limitations of the Data See Section 11.2 11.2 Known Problems with the Data To date, the following discrepancies/problems have been noted in the data : • BORIS staff found that the second and third data files (tape files 17 and 18), f1.dat and f2.dat, are duplicates. • BORIS staff created time series plots and found significant noise in the 10- and 30 Hz data. It was discovered that the 30-Hz data intermittently provided fewer than 30 samples per record, although it was not clear from where the values were missing or if the sampling rate was different for each 1-second interval. • Several spurious/outlier values were present, particularly in the first three recorded 30-Hz values per record. These seemed to be left over from the last fully sampled (30-Hz) record in the data set. o The C-130 navigation data records have been assumed to be 1-second apart and uncorrected, steadily increasing time stamps for each record do exist in the file. Plots of ARC "Corrected" times, however, show redundant or unequally spaced time stamps from record to record. Plots of "Corrected" times, for example, showed that record n started at 30.9 seconds, record n+1 at 31.8 seconds, and record n+2 at 32.9 seconds. This may be an issue for those attempting to interpolate times for 10- and 30-HZ data. o During actual data acquisition, the comment field buffer was not cleared from flight line to flight line; as a result, data collection field notes appear in subsequent flight lines until a new comment or field note was entered. Therefore, some field notes refer to flight-line-run combinations other than the flight line represented by the record containing the comment. o It was discovered that Site 433, Line 1 shown on the ARC hardcopy color map in the C-130 Mission Summary Report for Mission 94-006-07 is actually composed of three flight lines (Lines 3, 4 and 5). The navigation data also reflect this set of three lines to be Site 433, Line 1. O For its use in relative correction of aircraft images, BORIS staff interpolated and smoothed the data to achieve a consistent temporal resolution of the needed variables, but only after selectively deleting known outlying values. Discussions with ARC staff indicated that hardware and software upgrades were being made to prevent or reduce these problems in future C-130 flights. Users of this data set, however, should quality check the C-130 navigation parameter values further before use. 11.3 Usage Guidance All of the files on the BORIS C-130 navigation data tape should be copied to disk. The ASCII header file should be read, and output files should be named according to this document. The software files were compiled and linked without incident on a Sun workstation by BORIS staff using the UNIX make command. An attempt to build the software under the SGI and VAX/VMS operating systems was unsuccessful; the C language compilers were unable to locate certain system ".h" include files. No further attempt was made to port the Sun software and Makefile to either SGI/IRIX or VAX/VMS platforms. It is likely that the ".dat" files will have to be byte-swapped in order for ARC software to read these data on SGI and VAX/VMS platforms. Several flight lines are contained in each of the ".dat" files. The inventory file, which is the second file on the tape, shows which flight mission data are contained in each ".dat" file. Within this listing, certain line, flight, date, and other information are missing, blank, filled, or filled with a lower-case 'x'. Because of the automated fashion in which the inventory listing was compiled at GSFC. Blank or dummy flight, line, and run numbers exist because this is what was contained on the ARC data tape for these designators. 11.4 Other Relevant Information Not applicable. 12. Application of the Data Set To date, BORIS staff, in conjunction with MAS data processing personnel have used the C-130 navigation data to calculate relative coordinates for flight lines of MAS data pixels scanned from the C-130 aircraft over the BOREAS SSA and NSA. The C-130 navigation data provided aircraft position and attitude at 1, 10, and 30 Hz. These parameters were used to derive relative Cartesian X and Y grid coordinates for each MODIS flight line image pixel using software that models the MAS sensor scanning system. The theory and working algorithms that were implemented to achieve this are described in detail in the BORIS documentation provided for the BORIS MAS Level 1-B data set. This algorithm could provide the basis for deriving relative position coordinates for other sensors that were in operation during this or other C-130 flights. 13. Future Modifications and Plans No modification is planned for the C-130 navigation data currently logged in the BORIS data base. The BOREAS experience, however, has led to hardware modifications at NASA/ARC in an effort to improve the completeness and integrity of acquired C-130 navigation data. 14. Software 14.1 Software Description The NASA/ARC navigation data unpacking software is written in C and compiles and runs under the SunOS Version 5.0+ operating system. The BORIS software is written in C and is operational under the VAX/VMS Version 5.0+, OpenVMS Versions 5.5-2 and SGI System V.4+ operating systems at GSFC. The primary dependencies in the VMS software are the tape I/O library and Oracle data base utility routines on the VAX computers. NASA/ARC provided the BORIS archive with the raw 2,048-byte data. To facilitate accessing and understanding, NASA/ARC also provided a supplemental software distribution containing a C structure that gives a name to each parameter (c130nav.h) and then provides code that transfers the 2,048-byte record into the structure (c130nav_extract.c). The user can access these parameters by name from the C130VALUES structure. BORIS staff developed software and command procedures for: 1) writing the ASCII summary information, ARC data extraction software, and binary navigation files to tape. 2) Creating an ASCII inventory of the binary data file contents and logging this information as well as the software and summary information on tape into the BORIS Oracle data base tables. 14.2 Software Access All of the described software is available upon request. BORIS staff would appreciate knowing of any problems discovered with the software, but cannot promise to fix them. 15. Data Access 15.1 Contact for Data Center/Data Access Information These BOREAS data are available from the Earth Observing System Data and Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 15.2 Procedures for Obtaining Data BOREAS data may be obtained through the ORNL DAAC World Wide Web site at http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax. 15.3 Output Products and Availability Requested data can be provided electronically on the ORNL DAAC's anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes, or diskettes. The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are also available. 16. Output Products and Availability 16.1 Tape Products The BOREAS level-0 C-130 navigation data can be made available on 8-mm, Digital Archive Tape (DAT), or 9-track tapes at 6250 or 1600 Bytes per inch (BPI). 16.2 Film Products Color aerial photographs and video records were made during data collection. The video record includes aircraft crew cabin intercom conversations and an audible tone that was initiated each time the sensors were triggered. The BOREAS data base contains an inventory of available BOREAS aircraft flight documentation, such as flight logs, videotapes, and photographs. 16.3 Other Products None. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation NASA. 1990. C-130 Earth Resources Aircraft Experimentor's Handbook. National Aeronautics and Space Administration. ARC Research Center. Moffett Field, California. Airborne Instrumentation Research Project - Flight Summary Reports for Flight No. 94-004-09 to 94-009-09 4/16 - 9/17, 1994. NASA ARC Research Center. Airborne Missions and Applications Division. Moffett Field, California. 94035. 17.2 Journal Articles and Study Reports Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Sellers, P. J., F. G. Hall, R. D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K. J. Ranson, P. M. Crill, D. P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P. G. Jarvis, S. T. Gower, D. Halliwell, D. Williams, B. Goodison, D. E. Wickland, and F. E. Guertin. 1997. BOREAS in 1997: Experiment Overview, Scientific Results and Future Directions. Journal of Geophysical Research 102 (D24): 28, 731-28,770. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms A/O - Analog-digital ARC - Ames Research Center ASAS - Advanced Solid-State Array Spectroradiometer ASCII - American Standard Coding for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BPI - Bytes Per Inch CADDS - C-130 Automated Digital Data System CCT - Computer Compatible Tape CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center DAT - Digital Archive Tape EOS - Earth Observing System EOSDIS - EOS Data and Information System GPS - Global Positioning System GSFC - Goddard Space Flight Center INS - Inertial Navigation System MAS - MODS Airborne Simulator MODIS - Moderate-Resolution Imaging Spectrometer NAD 83 - North American Datum 1983 NASA - National Aeronautics and Space Administration ORNL - Oak Ridge National Laboratory PRT-5 - Precision Radiation Thermometer SCSI - Small Computer Serial Interface S/D - synchro-digital SGI - Silicon Graphics IRIX TAS - True Air Speed TAT - Total Air Temperature TIMS - Thermal Infrared Multispectral Scanner TMS - Thematic Mapper Simulator URL - Uniform Resource Locator 20. Document Information 20.1 Document Revision Date(s) Written: 20-Jul-1995 Last Updated: 26-Feb-1998 20.2 Document Review Date(s) BORIS Review: 03-Jan-1997 Science Review: 09-Jan-1797 20.3 Document ID 20.4 Citation The BOREAS Level-0 C-130 navigation data were collected and processed from the original aircraft tapes by personnel of the Medium Altitude Aircraft Branch at NASA/ARC. BORIS staff reviewed repackaged, and documented the data received from ARC into the current product. The contributions of ARC and BORIS staff to enhancing and checking this data set are greatly appreciated. 20.5 Document Curator 20.6 Document URL Keywords C-130 Navigation INS C130_NAV_L0.doc 04/17/98