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SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS NPOESS CrIS Raw Data (Level 0) to Sensor Data (Level 1b) Processing R. Poulin, S. Lantagne, S. Dub, Y. Dutil, S. Levesque, and F. Chateauneuf ABB Bomem, Special Projects in Radiometry, 585 Charest blvd East, Suite 300, Quebec, Qc, G1K 9H4, Canada Contact: robert.h.poulin@ca.abb.com and J. Predina ITT Industries, ITT Aerospace/Communications, 1919 West Cook Road, P.O. Box 3700, Fort Wayne, IN 46801, USA Contact: joe.predina@itt.com BOMEM Slide 2 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 2 / 18 The Cross-track Infrared Sensor (CrIS) Mission Part of NPOESS series of polar-orbiting spacecrafts (near circular orbit, 833 km altitude, 98.7 degree inclination, 101 minutes, NPP launch 2005, NPOESS launch 2007) Component of the CrIMSS (Cross-track Infrared/Microwave Sounding Suite) Produce cross-track IR spectra of the surface of the Earth IR spectral measurements to be converted to temperature, moisture and pressure profiles of the Atmosphere CrIS Space Segment At each cross-track scan, CrIS interferometer observes 30 Earth scenes, 4 calibration targets (2 Deep Space + 2 Internal Calibration Target), with interferometer sweeps in forward and reverse direction CrIS also performs a minimal amount of signal processing prior to Earth downlink at each 1.25 orbit, 35,062 FORs, 315,562 FOVs, 946,687 IGMs CrIS Ground Segment Sensor Data Record (SDR) algorithms transform CrIS interferograms into fully calibrated and geolocated spectra Environmental Data Record (EDR) algorithms transform SDRs spectra into temperature, pressure and moisture profiles Slide 3 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 3 / 18 Overall Relationship of RDRs, SDRs and EDRs Slide 4 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 4 / 18 Remove Sensor Unique Signature Same ILS at every channel center... (within same band) Same ILS for all 9 FOVs ...(within same band) Fixed SDR channel centers for all 9 FOVs..(within same band) Calibrations Performed Wavelength calibration Spectral correction of ILS distortion Radiometric (complex gain and offset) Earth mapping (FOV location & FOV shape) No Matter Which Sensor Produces the Data Uncertainty After Processing (both sensor & algorithms) LWIRMWIRSWIRRelative to: Radiometric gain0.45%0.58%0.77%287 K BB Channel center5 ppm*5 ppm*5 ppm*wavenumber ILS width [main lobe] 1.5%1.5%1.5%true FWHM Earth Mapping1.5 km1.5 km1.5 km Updated once per Orbit (101 min) Ground Processing Algorithm Enhances Data Quality Via Calibration Techniques Continuously Adapts ( = 4 minutes) * NPP Channel Center Tolerance will be 10 ppm 3.7 msec/FOV Execution Time Slide 5 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 5 / 18 Ground Calibration Software Is Partitioned into 9 Modular Groups Initialization Initialize software Initialize RDR reading pointers Data Input Low level data handling Configuration data handling Calibration data handling Ingest sensor unique cal data Monitor calibration data Compute spectrum correction matrix Science data handling Geolocation Map FOV to latitude & longitude Calculate view angles/ footprint geometry Preprocessing Perform bit trim decoding Convert interferograms to spectra Spectral Calibration Perform spectral calibration Compute laser WL from neon lamp Compute laser WL from diode parameters Radiometric Calibration Average warm target spectra Average cold target spectra Subtract sensor background radiance Calibrate sensor gain Remove phase dispersion Compute ICT radiance Isolate/reject orthogonal noise Apply spectrum correction matrix Remove ILS errors Apply user selectable apodization Map channels to fixed wavenumber grid Quality Control Identify/exclude bad data Detect/correct fringe count error Estimate NEdN (bin by bin) Flag bad FOVs Post-processing Select user required spectral bins Format data for EDRs Archive data Data Output Slide 6 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 6 / 18 Features of SDR Algorithm Science Code (1 of 8) Initialization 4Initialize software 4Initialize RDR reading pointers Data Input CCSDS packet decoding 4Low level data handling 4Configuration data handling 4Calibration data handling 4Ingest sensor unique cal data 4Monitor calibration data 4Compute spectrum correction matrix 4Science data handling Preprocessing Perform bit trim decoding 4Convert interferograms to spectra One Time Calculation of N x N Matrix Used to Perform ILS Corrections 4 Included with CDR version of science code on 1/23/02 Requires Completion Prior to EDU2 Demonstration CrIS CCSDS Packets Processed in Single Scan Line Blocks (8 second input) Software Auto Configured Based upon Content of 1st CrIS Engineering Packet Received CDR Science Code Version Demonstrated Using ASCI Input Files No Sensor Unique Calibration Handbook Needed All Necessary Data Embedded in RDRs All Data Calibration Operations Executed in Spectral Space Slide 7 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 7 / 18 Features of SDR Algorithm Science Code (2 of 8) Spectral Calibration 4Perform spectral calibration 4Compute laser WL from neon lamp 4Compute laser WL from diode parameters Once per Orbit Metrology Wavelength Calibration Using Neon Bulb 703 nm Reference Line Wavelength Calibration Data Collected Without Disturbing Normal Scene Data Collection >2 ppm Metrology Wavelength Drift Detected & Corrected by Algorithm Over Entire Orbit Up to 128 Calibration Sweeps Averaged Achieves 5 ppm Total System Spectral Uncertainty (10 ppm for NPP) Wavelength Calibration Data Broadcast in Once/4 minute Engineering Data Packet 4 Included with CDR version of science code on 1/23/02 Slide 8 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 8 / 18 Features of SDR Algorithm Science Code (3 of 8) Radiometric Calibration 4Average warm target spectra 4Average cold target spectra 4Subtract background radiance 4Remove phase dispersion 4Calibrate sensor gain 4Reject orthogonal noise 4Compute warm target radiance 30 Averages of Warm and Cold Target References Used for Calibration Separate Calibration Average Maintained for Each Interferometer Sweep Direction and Each of 27 CrIS Detector Channels Averaging Window Spans 4 Minutes ICT Radiance Calculation Corrected for Surrounding Environment Reflections & Warm Target Emissivity Science Telemetry Deep Space Used as Cold Target Engineering Packet Data Calibration Equation 4 Included with CDR version of science code on 1/23/02 Slide 9 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 9 / 18 Features of SDR Algorithm Science Code (4 of 8) LW Band SW Band Analysis Shows Large ILS Distortion Present Due to Off-axis FOV Effect If Correction Not Performed 0.5 Bin Smear 0.5 Bin Offset LW Band MW Band Slide 10 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 10 / 18 Features of SDR Algorithm Science Code (5 of 8) Radiometric Calibration Apply spectrum correction matrix 4Remove ILS errors 1st Order Correction Removes ILS Distortion Due to Off-axis FOV Sizes and Angles 2nd Order Correction Removes Remaining ILS Distortion as Determined by Prelaunch ILS Characterization Data Engineering Data Packet 0.897 degree 1.024 degree 1.100 degree0.963 degree 321 654 987 (14.0 km)(16.0 km) (14.9 km) (13.0 km) Anti-sun S/C Velocity CrIS FOV Angles Measured via Spot Scan Test During CrIS System Integration FOV Angle Parameters Can Also be Retrieved via Software Analysis of Spectral Scene with Structure CrIS Footprint @ Nadir 4 Included with CDR version of science code on 1/23/02 Slide 11 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 11 / 18 Features of SDR Algorithm Science Code (6 of 8) Radiometric Calibration Apply spectrum correction matrix 4Apply user selectable apodization 4Map channels to fixed wavenumber grid Post-processing 4Select user required spectral bins Format data for EDRs Archive data 5 ppm Channel Centers Maintained Regardless of FOV Angular Offset & CrIS Operating Metrology Wavelength 1 1 1 Unapodized Hamming Blackman Sinc Interpolation Used to Remap Channel Centers Slide 12 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 12 / 18 Used by EDR Algorithm to Set Error Covariance Matrix (affects convergence criteria of retrieval) Integer Number of Metrology Fringe Count Errors Detected and Corrected Calibration Averages Maintain Alignment Even When Fringe Count errors Occur Features of SDR Algorithm Science Code (7 of 8) Quality Control 4Identify/exclude bad data 4Detect/correct fringe count error 4Estimate NEdN (bin by bin) 4Flag bad FOVs Quality Control Measures Wavenumber NEdN NEdN @ ICT NEdN @ scene NEdN @ DS NEdN Estimate Used by EDR Algorithm to Set Error Covariance Matrix (affects convergence criteria of retrieval) Calibration Averages Maintain Alignment Even When Fringe Count errors Occur Slide 13 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 13 / 18 Features of SDR Algorithm Science Code (8 of 8) Geolocation 1.5 km uncertainty @ edge of scan Map FOV to latitude & longitude @ sea level Calculate view angles to satellite Calculate footprint geometry Geolocation Algorithm Development Begins After S/C Contractor Select CrIS FOV Path Orbital Path Spacecraft Position Vector Detector Pointing Vector 7 Different Coordinate Transformations Required 1) Earth Centered Inertial (ECI) 2) Earth Centered Earth Fixed (ECEF) 3) World Geodetic System 1984 (WGS84) 4) Spacecraft Coordinate Reference 5) Instrument Coordinate System 6) Orbital Coordinate Reference 7) Topocentric-Horizon Coordinate System (THCS) Details Require SSPR Participation Slide 14 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 14 / 18 NEdN )( ~ xI ES (88%) )( ~ S Scene FCE Handling DS (6%) ICT (6%) ][ ~ nS es ][ ~ nS ds ][ ~ nS ict Process Calibration References Spectrum Correction Calibration FCE Handling Calibration FCE Handling 30 ma N 30 ma N Moving Average Moving Average mean cold reference mean hot reference ict S ~ )( ~ L )( L Health Monitoring )( L L [r.u.] ict T ds S ~ 0 1 L [r.u.] Compute Spectrum Radiometric Calibration (complex) Metrology Monitoring Algorithm Functional Flow Slide 15 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 15 / 18 Interferogram Data Packets (918 packets per 8 seconds) 306 LW, 306 MW & 306 SW packets per 8 second scan Includes earth scene, ICT cal & DS cal packets LW 2,504 byte/packet.766,224 bits/sec MW 1,698 byte/packet.519,588 bits/sec SW 512 byte/packet.156,672 bits/sec Engineering Data Packet (1 packet every 4 minutes) Engineering data and sensor characterizations 5 kbyte packet...166 bits/sec Science TLM Data Packet (1 packet every 8 seconds) Dynamically changing cal data 314 byte/packet.314 bits/sec Time of Day/Ephemeris Packet (1 packet/sec) S/C position, velocity, attitude, attitude rate, Time stamp 94 byte/packet..752 bits/sec Contained in CrIS RDR data Stream (1.44 Mbps) Only Four Types of RDR Data Packets Are Processed by SDR Science Algorithms From S/C RDR Data Stream Slide 16 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 16 / 18 Calibrated Radiance in 1305 Channels SDR Content At SDR Algorithm Output (1 of 2) Calibrated Data Real part of the spectra after Spectral Correction LW 713 bins @ 0.625cm-1 (650-1095) MW 433 bins @ 1.25cm-1 (1210-1750) SW 159 bins @ 2.5cm-1 (2155-2550) Imaginary part of the spectra before Spectral Correction (LW 713 bins, MW 433 bins, SW 159 bins) NEdN estimates (LW 713 bins, MW 433 bins, SW 159 bins) Geolocation Data Latitude/longitude @ sea level for each FOV center Major and minor elliptical footprint size for each FOV Elevation & azimuth angle from each FOV center to satellite Noise Estimates in Each Channel Mapping Data Slide 17 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 17 / 18 SDR Content At SDR Algorithm Output (2 of 2) Identifiers Spacecraft ID, CrIS sensor ID, Sensor flight software version number, SDR algorithm version number, Apodization tag FOR number, FOV number Band designator (LW,MW,SW), FOV longitude and latitude, Slant angle, Viewing angle, Size of FOV on ground Quality Control ZPD reset, Fail bit trim, Impulse noise count (0-127) Invalid data (RDR and SDR) and invalid geolocation flags FCE detected and corrected in SDR algorithm Excess NEdN, Excess Sensor Thermal drift Identifiers Help in the Archiving of Data Quality of Data Is Assessed and Tagged Slide 18 CrIS SDR Algorithms SDR Algorithms, ITSC-12, Lorne, Australia, 27 Feb. - 5 Mar. 2002 ITT INDUSTRIES - AER - ABB BOMEM - BALL - BOEING CrIS 18 / 18 Summary of Performance to Date Completed CDR on 1/23/02 Science code execution speed satisfactory 200 msec/FOV Year 2007 computer plus code optimizations can achieve the required 3.7 msec/FOV Algorithm architecture can accommodates parallel processing ILS Correction Successful Critical ILS correction algorithm demonstrated less than 0.03% correction error for all bands and all FOV positions (simulated) Preliminary validation of ILS correction algorithm was demonstrated with hardware measurements Further EDU2 validations planned SDR Algorithm Execution Time Is Very Low Risk SDR Algorithm Removal of Unique Sensor Signature Accomplished Thus Far Issue of Partly Clouded FOV and Resultant Uncorrected ILS Effects May Be a Future Limitation Next Step Is to Demonstrate Algorithm on EDU2 RDRs