MULTIMEGABIT OPERATION MULTIPLEXER SYSTEM

Abstract

The Multimegabit Operation Multiplexer System (MOMS) is a high data rate PCM telemetry unit capable of sampling and encoding 60 scanning radiometer and 4 vidicon channels at 250 kilosamples/second and 5 megasamples/second, respectively. This sampling capacity plus the 7-bit quantization requires a total throughput rate of 40 megasamples/second and 280 megabits/second. To produce these rates efficiently, the system was divided into a pair of identical 140-megabit blocks. A low-power 20-MHz analog multiplexer and analog-to-digital converter were developed together with a video sample-and-hold that features an aperture time error of less than 50 picoseconds. Breadboard testing of these basic building blocks confirmed the design prediction that the total system would consume 27 watts of power. Two 140-megabit output ports are suitable for quadraphase modulation.