MIDISS: A Unique Multi-Processor Telemetry Ground Station

Abstract

An optimum architecture for real-time telemetry data acquisition and display has been developed. It provides a high degree of flexibility and throughput while using a minimum of hardware: as applied to the MIDISS system, this approach enables users to specify data processing for each sensor on several satellites independently of downlink formats. Each user can specify and modify CRT displays without interrupting the data processing performance. Processing may include algebraic manipulation, logical branching, logic products, time averaging, etc. This flexibility is provided by SPACETALK, a FORTRAN-like language that enables the user to deal with each sensor by name. Users can also format and transmit uplink commands. Hardware minimization is evidenced by MIDISS's compactness. It consists of a 16-bit minicomputer and a SPACEPIPE (microcomputer-based, front-end processor) that decommutates multiple downlinks, provides rate-buffering, and performs data compression and alarm-checking. The minicomputer is thus free to perform extensive data processing for those downlink channels that are changing at significant rates,