Macintosh based space telemetry data acquisition system

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