Yunling Lou

The NASA/JPL Three-frequency Polarimetric Airsar System

The NASA/Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL AIRSAR) system has now completed four flight campaigns. The authors describe the current state of this system and provide insight into how flight seasons are planned for this instrument. The data processors and data products are described. A table containing relevant system parameters is provided.

The NASA/JPL Multifrequency, Multipolarisation Airborne SAR System

The Jet Propulsion Laboratory has designed, built and tested a new suite of polarimetric synthetic aperture radars, operating at L-, C- and P-Band. The three radars have been designed to replace and upgrade the system that was destroyed in an accident in 1985. A series of ground and flight tests have been conducted out of Ames Research Center, Mountain View, California during JanuaryFebruary of 1988 and the radar has flown over the Goldstone Calibration site in a sequence of experiments designed to calibrate the system. The radar has also taken part in a series of science campaigns in Alaska, California, Arizona and the East Coast of the USA. This paper will describe this new imaging radar system for the benefit of the user community.

Review of the NASA/JPL airborne synthetic aperture radar system

AIRSAR has served as a test-bed for both imaging radar techniques and radar technologies for over a decade. In fact, the polarimetric, cross-track interferometric, and along-track interferometric radar techniques were all developed using AIRSAR. We present the up-to-date system configuration, the expected performance and data accuracy in the standard radar modes.

Progress report on the NASA/JPL airborne synthetic aperture radar system

AIRSAR has served as a test-bed for both imaging radar techniques and radar technologies for over a decade. In fact, the polarimetric, cross-track interferometric, and along-track interferometric radar techniques were all developed using AIRSAR. In this paper, we present the up-to-date system configuration and expected performance in the standard radar modes. In addition, we describe the various experimental modes available to researchers. Finally, we discuss on-going improvements with AIRSAR and future direction of the program.

Relative Phase Calibration Of The NASAD/C-8 Three Frequency Polarimetric SAR System

Relative phase calibration of radar polarimetry data may be achieved by utilizing the phase information of the receiver calibration tone and knowledge of the antenna path differences among channels measured upon installation of the radar polarimeter. This calibration method does not require any assumptions on the scattering behavior of the scene. This method of phase calibration may be verified by examining the polarization signatures of calibration instruments such as the trihedral corner reflectors.

Onboard Radar Processor Development for Rapid Response to Natural Hazards

The unique capabilities of imaging radar to penetrate cloud cover and collect data in darkness over large areas at high resolution makes it a key information provider for the management and mitigation of natural and human-induced hazards. Researchers have demonstrated the use of UAVSAR data to determine flood extent, forest fire extent, lava flow, and landslide. Data latency of at most 2-3 h is required for the radar data to be of use to the disaster responders. We have developed a UAVSAR on-board processor for real time and autonomous operations that has high fidelity and accuracy to enable timely generation of polarimetric and interferometric data products for rapid response applications. This on-board processor design provides a space-qualification path for technology infusion into future space missions in a high-radiation environment with modest power and weight allocations. The processor employs a hybrid architecture where computations are divided between field-programmable gate arrays, which are better suited to rapid, repetitious computations, and a microprocessor with a floating-point coprocessor that is better suited to the less frequent and irregular computations. Prior to implementing phase preserving processor algorithms in FPGA code, we developed a bit-true processor model in MATLAB that is modularized and parameterized for ease of testing and the ability to tradeoff processor design with performance. The on-board processor has been demonstrated on UAVSAR flights.

JPL Airsar Processing Activities and Developments

In 1988, the JPL AIRSAR instrument was flown and operated for the first time. This three frequency, quad-pol SAR has since produced a wealth of data (> 45 terabits) over the past 4 years. The formidable task of processing this data has been carried out on a hybrid computer system at JPL known as the “730 Processor.” The 730 Processor was developed in 1987 and 1988 using available computers and now suffers from several limitations related to its age. In the past two years, we have made significant advances in the area of processing the JPL AIRSAR data. Compared to the original 730 processor, these advances include: increased swath width, increased number of looks, increased processor throughput and decreased processor turn-around time (including photo product). These advances are made possible by new processing algorithms, software and hardware. In addition to these processor improvements, a more mature understanding of the AIRSAR system in general has made it possible for the processor to routinely produce calibrated data based on internal calibration tests. Starting with the processing of 1991 acquired data, this new processor has become operational for the routine processing of AlRsARdata

Prospects for operational use of airborne polarimetric SAR for disaster response and management

Rapid response to natural disasters resulting from events such as earthquakes, volcanoes, floods, and tsunamis or anthropogenically induced events such as oil spills often requires response time measured in hours to days. The type of information required spans information on the magnitude and location of damage needed by immediate response teams to longer time scale information to monitor recovery efforts. Airborne radar can play an important role in response to disasters given its day/night and all weather imaging capability coupled with its unique set of measurement observables such as millimeter level surface deformation from radar interferometry and polarimetric scattering data. The properties a radar sensor must possess to have a useful role, e.g., frequency, resolution, swath width, etc., depends on the intended application. In this paper we discuss the potential for radar like the NASA/JPL UAVSAR system to respond to disaster management and provide examples from existing UAVSAR data collection to illustrate its potential.

The interferometric data calibration for the AIRSAR PacRim II mission

This paper focuses on the cross- track interferometric data calibration results and height accuracy analysis. We also present the key elements of the calibration technique for cross-track interferometric SAR data processed with the AIRSAR Integrated Processor.

Improved absolute radiometric calibration of a UHF airborne radar

The AirMOSS airborne SAR operates at UHF and produces fully polarimetric imagery [1]. The AirMOSS radar data are used to produce Root Zone Soil Moisture (RZSM) depth profiles. The absolute radiometric accuracy of the imagery, ideally of better than 0.5 dB, is key to retrieving RZSM, especially in wet soils where the backscatter as a function of soil moisture function tends to flatten out [2]. In this paper we assess the absolute radiometric uncertainty in previously delivered data, describe a method to utilize Built In Test (BIT) data to improve the radiometric calibration, and evaluate the improvement from applying the method.