Space engineering – Telemetry and telecommand packet utilization
|Publication Date:||9 October 2017|
|ICS Code (Space systems and operations):||49.140|
This Standard addresses the utilization of telecommand packets and telemetry packets for the purposes of remote monitoring and control of spacecraft subsystems and payloads. This Standard does not address missionspecific payload data packets, but the rules contained herein can be extended to suit the requirements of any mission. This Standard does not address audio and video data as they are not contained within either telecommand or telemetry packets. This Standard defines a set of services that satisfy all the fundamental operational requirements for spacecraft monitoring and control during spacecraft integration, testing and flight operations, refer to ECSS-E-ST-70-11. It also specifies the structure and contents of the telecommand packets used to transport the requests and the telemetry packets used to transport the reports. This Standard can be used by any mission, no matter what its domain of application, orbit or ground station coverage characteristics. However, it is not the intention that the PUS should be applied in its entirety to a given mission. The services defined in this Standard cover a wide spectrum of operational scenarios and, for a given mission, only a subset of these services is likely to be appropriate. Choices are made early in the design phase of a new mission resulting in the need to tailor the PUS to suit the requirements of that mission. These choices include: • the on-board system design and architecture, in terms of the number of on-board application processes, their on-board implementation (e.g. the allocation to on-board processors) and their roles (i.e. which functions or subsystems or payloads they support); • which PUS services are supported by each application process. Each mission usually documents the results of this design and selection process in a "Space-to-Ground Interface Control Document". Some missions implement a centralized architecture with a small number of application processes, whilst others have a highlydistributed architecture within which a correspondingly larger number of application processes are distributed across several on-board processors. The specification of services in this Standard is adapted to the expectation that different missions require different levels of complexity and capability from a given service. To this end, all services are optional and a given service can be implemented at one of several distinct levels, corresponding to the inclusion of one or more capability sets. The minimum capability set corresponds to the simplest possible level that also remains sensible and coherent. At least this set is included in every implementation of a given service. The standardized PUS services fulfil the following criteria: • Commonality: each standard service corresponds to a group of capabilities applicable to many missions. • Coherence: the capabilities provided by each standard service are closely related and their scope is unambiguously specified. Each standard service covers all the activities for managing interrelated state information and all activities that use that state information. • Self-containment: each standard service has minimum and well-defined interactions with other services or on-board functions. • Implementation independence: the standard services neither assume nor exclude a particular spacecraft architecture (hardware or software).