Software for Preprocessing of Raw SAR Data

The SAR Processing System Raw Data Processor (SPS RDS) computer program is used in the Alaska SAR Facility (ASF) to scan and decode raw data that have been downlinked from the European Remote Sensing Satellite (ERS), the Japanese Earth Resources Satellite (JERS), and the RADARSAT (a Canadian Earth-observation satellite) and recorded on high-density digital tape or disk. ["SAR" means "synthetic-aperture radar."] In its scanning role, the program reads a recorded downlink bit stream, performs PRN decoding as needed, extracts auxiliary information to identify data-acquisition times, correlates this information with spacecraft state vector information to determine locations, and maps the locations to predefined fixed frames along an orbit track. These frames are stored in an archive as they become available, and are subsequently interrogated when requests for generation of image products are received. In its decoding role, this program converts a downlink bit stream that pertains to a requested frame into files that contain decoded engineering and SAR signal data that are compatible with the computers and programs used in further processing of SAR data into final image and image data products.