In order to handle the enormous volume of data generated by the PRISM and the AVNIR-2, the ALOS has data compression (DC) capability.
Each telescope of the PRISM generates 320 Mbps raw data, so 960 Mbps data is transferred to DC. The data is compressed to 240 Mbps using a JPEG-like technique consisting of the discrete cosine transform (DCT) and Huffman encoding. The AVNIR-2 generates 160 Mbps of raw data that is compressed using Differential Pulse Code Modulation (DPCM), a loss less data compression technique based on that of the AVNIR.
Compressed data of the PRISM and the AVNIR-2, and uncompressed PALSAR data are then transferred to the Mission Data Coding (MDC) system where an error correction code (Reed-Solomon (255,223) interleave depth 5) is added. The Bit Error Rate requirement of ALOS mission data is 1 x 10^-16 . The Mission Data Recorder (MDR) is a mass data storage device. It will hold 720 Gbits enough for 50-minute data recording at 240 Mbps.
Real-time or recorded data will then be transferred to the Data Relay Technology Satellite (DRTS), which is a Japanese geostationary data relay satellite, via the DRC subsystem.