Design of a four-channel, 50 Mbps, Statistical Multiplexer and Demultiplexer

The major technical specifications and the resulting design for a 50 Mbps Statistical Multiplexer and Demultiplexer for NASA are presented. Techniques that provide the following necessary or highly desirable characteristics for a mux/demux used in a space data communications link are described in detail: (1) automatic frequency measurement and adaptive port priority assignment to allow unattended operation; (2) the ability to accommodate Doppler variation of port input rates while maintaining an uninterrupted serial output at the receive port; (3) immunity of frame detection and routing to large error bursts; and (4) internal error rate. The critical role played by the microprocessor in the subject application is pointed out.