NASA/JPL airborne three-frequency polarimetric/interferometric SAR system

The NASA/JPL airborne SAR system (popularly known as "AIRSAR") has been flown aboard the NASA Ames Research Center DC-8 since 1987. AIRSAR is a three frequency (P-, L-, and C-bands) polarimetric radar with the interferometric capability. Modes of operation are possible with the AIRSAR system, it has three basic operational modes (polarimetric, across track interferometry, and along track interferometry). The AIRSAR hardware consists of RFE (RF Electronics), digital electronics, antenna, control computer, on-board processor, and power distribution subsystems. A single DCG (Digital Chirp Generator) generates the chirp waveform and it is up-converted to L-band. Subsequent up- and down- conversions produce C- and P- band chirp signals, respectively. The return echo is amplified by LNA (Low Noise Amplifier) and digitized by 8-bit ADC (Analog-to-Digital Converter). The digital data from six channels are multiplexed and stored on tape using the high density digital recorder. During the AIRSAR mission, a real time correlator produces low resolution imagery to assess the general health of the radar and to verify that the correct area has been imaged. Data processing to produce high quality image products happens in the weeks and months following a flight campaign after proper calibration parameters are generated. The current integrated processor can process both polarimetric and interferometric data. The authors present detailed mission description, hardware configuration, and data processing.