Macintosh based space telemetry data acquisition system

Abstract

The general architecture and functionality of the MacTAC (Macintosh II based telemetry and command) system, including the individual telemetry modules, the various input-output interfaces, and the flexible user interface are described. This system performs telemetry data processing functions including frame synchronization, Reed-Solomon decoding, and packet reassembly at moderate data rates of up to 5 Mb/s sustained (20 Mb/s burst). The MacTAC is an easy-to-use, low-cost, transportable system designed to meet requirements specified by the Consultative Committee for Space Data Systems, while remaining flexible enough to support a wide variety of other space data processing requirements (e.g., time-division multiplexed data). In addition, the MacTAC can generate forward (uplink) data such as spacecraft commands, calculate and append a CRC, and output the data to NASCOM (NASA's ground communication network) to provide full telemetry and command capability. Semicustom VLSI gate arrays perform many of the return link (telemetry) functions of NASCOM deblocking, correlation, and frame synchronization. Reed-Solomon decoding and source packet reassembly are performed by modern microprocessor and semicustom VLSI components.<>