XMM's Data-Handling Subsystem

A. Karlsson

Scaling the XMM data-handling system to the specific needs of the mission has resulted in a flexible and relatively uncomplicated On-Board Data-Handling (OBDH) Subsystem. The XMM spacecraft is operated in real-time and is fully compliant with the ESA packet data-handling standards. Packets are of variable length and presented to the OBDH when available. The OBDH telemetry/telecommand cycles are asynchronous to the instrument and subsystem cycles. The telemetry rates can easily be reallocated to cope with unforeseen spacecraft configurations, e.g. lost telemetry sources. The absence of requirements for automatic reconfiguration has contributed to the reduced subsystem complexity.