The Jurassicprok Interferometric Calibration Software (also called “Calibration Processor” or simply “CP”) estimates the calibration parameters of an airborne synthetic- aperture-radar (SAR) system, the raw measurement data of which are processed by the Jurassicprok software described in the preceding article. Calibration parameters estimated by CP include time delays, baseline offsets, phase screens, and radiometric offsets. CP examines raw radar-pulse data, single-look complex image data, and digital elevation map data. For each type of data, CP compares the actual values with values expected on the basis of ground-truth data. CP then converts the differences between the actual and expected values into updates for the calibration parameters in an interferometric calibration file (ICF) and a radiometric calibration file (RCF) for the particular SAR system. The updated ICF and RCF are used as inputs to both Jurassicprok and to the companion Motion Measurement Processor software (described in the following article) for use in generating calibrated digital elevation maps.
This program was written by Elaine Chapin, Scott Hensley, and Paul Siqueira of Caltech for NASA’s Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393- 3425. Refer to NPO-40015.
This Brief includes a Technical Support Package (TSP).
Calibration Software for Use With Jurassicprok
(reference NPO40015) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) concerning the calibration software for the GeoSAR system, specifically the JurassicProk processor. GeoSAR is an advanced airborne interferometric Synthetic Aperture Radar (InSAR) system designed for terrain mapping, capable of collecting data at two frequencies: X-Band and P-Band. The system operates by simultaneously mapping swaths on both sides of the aircraft, utilizing two across-track interferometric baselines for P-Band and a single baseline for X-Band.
Accurate calibration of the GeoSAR system is crucial for producing digital elevation models (DEMs) with sub-meter level planimetric and vertical accuracies. The calibration process involves determining yaw and pitch biases, which measure the antennas' orientation relative to the aircraft. It also includes calculating common range delays, differential time, and interferometric phase delays. The mechanical positions of the antennas are monitored using a Laser Baseline Metrology System (LBMS), and baseline calibration focuses on measuring the offset between the mechanical center and the electrical phase center of the antennas.
To enhance the accuracy of the interferometric data, a phase screen is applied to compensate for multipath and leakage effects. The calibration parameters are estimated using the GeoSAR calibration processor, which compares raw pulse data and DEMs produced by the JurassicProk processor with ground truth data. This processor is modular, allowing for quality checks and reuse of code for validation and quality assurance tasks. It is designed to combine data from multiple data takes to improve parameter estimation and offers flexibility in removing bad data.
The document also provides contact information for further assistance through the NASA Commercial Technology Program and highlights the availability of additional resources from the NASA Scientific and Technical Information (STI) Program Office. Overall, the Technical Support Package serves as a comprehensive guide for understanding the calibration processes and software associated with the GeoSAR system, emphasizing its significance in aerospace technology and terrain mapping applications.
