SPACELAB HIGH DENSITY DIGITAL RECORDERS

Abstract

In 1979, NASA was faced with the problem of providing a ground facility magnetic tape recorder to store and retrieve serial Pulse Code Modulation (PCM) bit streams of up to 50 megabits per second (MBPS) which originated within Spacelab and its experiments. These recorders were required at the Kennedy Space Center (KSC), Johnson Space Center (JSC), and the Goddard Space Flight Center (GSFC). The Spacelab requirements presented a wide variety of problems which no existing “offthe- shelf” recorder could accommodate at the time. As a consequence, an extensive and complex performance specification was developed. This specification necessitated many advances in the “state-of-the-art” in the field of High Density Digital Recorders. The 9000 SL High Density Digital Recorders designed and fabricated by Thorn-EMI Technology, Inc., under contract to NASA, have successfully met or exceeded all of the Spacelab requirements as identified in the performance specification. These recorders demonstrate the latest in high density digital recording technology. This technology includes the capability of recording 50 MBPS of data with a bit error rate of better than 1 bit in 108, completely automatic bit synchronization, auto selection of the optimum replay equalization, and a data coding scheme giving up to 50% greater data packing density than traditional codes.