A DATABASE-DRIVEN SOFTWARE SYSTEM FOR SATELLITE TELEMETRY DECOMMUTATION

Abstract

Satellite Telemetry can be characterized as having relatively low bandwidths, complex wavetrains, and very large numbers of measurands. Ground systems which monitor on-orbit vehicles must process, analyze, display, and archive the telemetry data received during contacts with the satellites. Data from perhaps thousands of individual measurands must be extracted from very complex wavetrains and processed during a live contact. Most commercially available telemetry systems are not well suited to handling satellite wavetrains because they were built for range telemetry and flight test applications which typically deal with limited numbers of measurands. This paper describes the design of a software system which was built specifically to process satellite telemetry. The database-driven system performs full decommutation of very complex wavetrains entirely in software. The system provides for defining the satellite vehicle's telemetry in multiple databases which define the wavetrain formats, the measurands themselves, how they are to be processed, and associated data conversion and calibration information. The database accommodates the complexities typically found in satellite telemetry such as multiple wavetrain formats, embedded streams, measurand dependencies, segmented measurands, and supercommutated, subcommutated, and sub-subcommutated data. A Code Generator builds a set of control structures from the wavetrain and measurand definitions in the database. It then generates highly optimized in-line software libraries for processing the satellite vehicle's telemetry. These libraries are linked to a Server process for run-time execution. During execution, raw telemetry frames are passed to the Server which uses the libraries to decommutate, limit check, convert, and calibrate the measurand data. A Client process attaches to the Server process to allow user applications to access both raw and processed telemetry for display, logging, and additional processing.