The data handling system of the Helios probes

The Helios data handling system, which meets the specific, complex requirements for large data handling systems without using a computer and still achieves flexibility, is described. The five telemetry formats consist of minor frames of 144 words (8 bit/word) and frames of 72 minor frames; data are identified by the minor frame number, spacecraft time, and data handling mode identifications. Measurement of shock data, interruptions of the data link, mode change, coding of telemetry data and commands, spin-synchronization, and timing are described. The system can handle the data of ten experiments, processes 320 housekeeping channels, performs a shock data measurement program, and provides a storage capacity of 0.5 Mbit. Diagrams are given for data sharing, a sample format, the shock data storage sequence, the Helios trajectory, data distribution in the system, and the angular relationship of the pulse sequence.