A Spacecraft Microelectronic PCM Multiplexer-Encoder

The design and development of a 98-channel microelectronic pulse code modulation (PCM) multiplexer-encoder is described. The PCM was developed under contract to NASAMSC, Houston, and has been qualified to Apollo spacecraft environments. The unit accepts 98 channels of analog information (0 to 5 volts) and converts these data into an 8-bit code. A serial, binary coded output at selected bit rates ranging from 800 bits per second through 51.2 kc is provided. Primary emphasis is on the packaging techniques used. The advanced circuit design methods employed and the unique integrated circuit devices developed especially for the program are also discussed.