NASA NTRS1972
The design and operation of a quad redundant data terminal and a multiplexer/demultiplexer (MDU) is described. The most unique feature is the design of the quad redundant data terminal. This is one of the few designs where the unit is fail/op, fail/op, fail/safe. Laboratory tests confirm that the unit will operate satisfactorily with the failure of three out of four channels. Although the design utilizes state-of-the-art technology, the waveform error checks, the voting techniques, and the parity bit checks are believed to be used in unique configurations. Correct word selection routines are also novel. The MDU design, while not redundant, utilizes, the latest state-of-the-art advantages of light coupler and interested amplifiers. Much of the technology employed was an evolution of prior NASA contracts related to the Addressable Time Division Data System. A good example of the earlier technology development was the development of a low level analog multiplexer, a high level analog multiplexer, and a digital multiplexer. A list of all drawings is included for reference and all schematic, block and timing diagrams are incorporated.