On-board processing architectures and technology

An overview of research and development work in the area of onboard processing satellites is presented, with an emphasis on the role that Comsat is playing in this area. The bulk demultiplexer/demodulator (group demodulator) approach used in connection with LR-TDMA and FDMA carriers is discussed; the work on 120-Mb/s TDMA modems is summarized; the baseband processor is described; and an overview of the status of the technology for onboard processing satellites is presented. A critical factor for onboard processing satellites to become a reality is the advance of the underlying technology. For the near future, high-speed low-power digital signal processing will be mainly based on Si technologies (CMOS, CMOS/SOS), with GaAs being used mostly for high-speed memories and multiplexers, and at the analog-to-digital interface. It is concluded that in the future, as a result of continuing research and development in GaAs, a generation of high-speed digital signal processing devices with enhanced radiation resistance will emerge.