Advanced Concepts for Telemetry Data Systems

Abstract

Current telemetry data processing systems capabilities will have to be improved by as much as three orders of magnitude in order to handle the expected data rates of the Space Station era. National Aeronautics and Space Administration (NASA) processing systems can currently process telemetry data at an average input rate of about 100K bits per second while Space Station era data rates will average about 100M bits per second and could have peak rates of up to 1200 M bits per second. In order to meet the challenge of developing telemetry systems for processing high rate data at a reasonable cost, data processing and distribution systems must be data driven as opposed to being resource scheduled. If a system is to be data driven, data structures must contain a mechanism for routing of the data to its intended destination. Packet telemetry systems have been developed for the purpose of processing and routing telemetry data at higher rates than conventional time division multiplexed systems. Packet telemetry data standards are being developed by the international Consultative Committee for Space Data Standards (CCSDS) in order to facilitate development of packet telemetry systems both within NASA and international space agencies as well as for inter-agency cross support situations. These CCSDS Advanced Orbiting Systems (AOS) standards specify the overall architectural framework of future packet telemetry systems. The CCSDS AOS standard defines a CCSDS Principal Network (CPN) which covers the on-board, space link and ground systems and provides for asynchronous (e.g., Telemetry and Internetworking) and isochronous (e.g., Audio and Video) data transport services utilizing CCSDS Packets and Virtual Channels. In order to achieve efficient use of the limited resources of the space link, CCSDS Packets are multiplexed on to CCSDS Virtual Channels for transmission through the space link. This paper will mainly discuss changes to ground telemetry processing systems currently in use (such as the Packet Processor (PACOR) System), future systems under development (such as the Space Station Information System(SSIS) and the Customer Data Operations System (CDOS)), and how the CCSDS standards relate to these systems.