A Wideband-PCM Recorder for the Space Shuttle Orbiter

Abstract

A wideband-PCM recorder has been developed for use in the avionics instrumentation subsystem of the Space Shuttle Orbiter. In direct contrast with the single function Apollo and Skylab recorders, this recorder is designed to meet a variety of present and future applications. The Shuttle recorder uses the tape transport and motor drive design from the NASA-Goddard Space Flight Center (NASA-GSFC) Standard Tape Recorder. This design was directed by the NASA-GSFC with funding provided by the Low Cost Systems Office at NASA Headquarters. Recording is accomplished on up to 14 data tracks with analog or digital data inputs. FM multiplexed analog frequencies of up to 2 MHz and digital rates of 1 Mb/s are accommodated at a tape speed of 120 inches/second. Recording time in the analog mode varies between 4 minutes for 2 MHz data to 80 minutes for 100 KHz data. The total digital data storage is 3.44 x 10⁹ bits with recording times from 1 hour for 1 Mb/s data to 19 hours for 50 Kb/s data in the serial track switching mode. A versatile command decoder and control interface are used for eight primary modes of operation. The recorder responds to over 7,000 commands which are combinations of the eight modes, four tape speeds, four delay times, four run periods and track selection. The commands are formatted as 16 bit words by onboard computers or simple, single switch panel commands initiated by the astronauts. The Shuttle recorder uses a hermetically sealed transport unit, occupies approximately 2,000 cubic inches and weighs 41 pounds. Operation through launch and re-entry vibration environments is accomplished by use of isolators which mount the transport unit to the electronics unit. Tape life is in excess of 20,000 passes without maintenance.