Digital communication technology development for space applications at Goddard Space Flight Center

At NASA's Goddard Space Flight Center (GSFC), space qualified integrated circuits for several key elements in space communication systems have been in development to increase data return in bandwidth constrained channels for future missions. Particularly in the area of digital communication, the development includes data compression, channel coding and modulation. In on-board data compression area, development focuses on a high-speed compression scheme that serves both push-broom and frame sensors. The compression ratio can be easily adjusted for different applications from lossless to visually lossless. The algorithm conforms to the Consultative Committee on Space Data Systems (CCSDS) new compression recommendation to be released 2005. The radiation-tolerant (RT) hardware will afford 20 Msamples/sec processing on sensor data. For bandwidth efficient channel coding, newly developed low density paritycheck codes (LDPCC) will double channel utilization as compared to previously used concatenated convolutional/Reed- Solomon (CC/RS) coding scheme. An RT implementation of the encoder is expected to work up to 1 Gbps serving both low-rate and high-rate missions. In modulation, a versatile multi-function base-band modulator allows missions the flexibility to choose from 2 bits/symbol/Hertz quadrature phase shift keying (QPSK)-type schemes, to 2.0, 2.25, 2.5, and 2.75 bits/symbol/Hertz 8 phase shift keying trellis-coded modulation (8-PSK TCM) schemes--all CCSDS recommendations. Along with 8PSK, 16-quadrature amplitude modulation (16-QAM), 16-ampliture phase shift keying (16-APSK), all modulations are implemented in a single RT chip with expected throughput of over 300 Mbps. This paper describes the development of these three technology areas and gives an update on their availability for space missions.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.