Low-Cost, High-Rate Data Processing

Abstract

The next generation telemetry system has been prototyped at GSFC. This High Rate Prototype (HRP) implementation uses a set of commercial and custom subsystem components based on state-of-the-art Very Large Scale Integration (VLSI) elements and advanced digital system technologies. It is the application of these technologies, together with standardized telemetry formats, that make it possible to build a high-performance telemetry processing systems at low cost in a short development cycle. Workstations running standard UNIX O/S, (DEC 4100 with DEC UNIX or better).

The system architecture is based on the Peripheral Component Interconnect (PCI) bus and VLSI Application-Specific Integrated Circuits (ASICs). These ASICs perform frame synchronization, bit-transition density decoding, cyclic redundancy code (CRC) error checking, Reed-Solomon error detection/correction, data unit sorting, packet extraction, annotation and other service processing at rates of up to and greater than 150 Mbps sustained. ASICs are also used for (the digital reception of Intermediate Frequency (IF) telemetry as well as the spacecraft command interface for commands and data simulations.

The HRP supports both the conventional CCSDS packet telemetry recommendations, which define telemetry Transfer Frames and source packet formats, and the CCSDS Advanced Orbiting Systems (AOS) recommendations, which define telemetry in the form of Coded Virtual Channel Data Units (CVCDU), AOS service units, and source packet formats. This paper will briefly discuss the growth of the ground satellite communication systems from the traditional architectures. It will describe the technological in-roads made by the Goddard Space Flight Center’s (GSFC) Data Systems Technology Division (DSTD) to bring the science data from the satellite directly to the user’s desktop, rapidly and at low cost. Essentially, the paper will describe the next generation “desktop” system, it’s architecture and processing capabilities, which provide autonomous high-performance telemetry acquisition at the least possible cost. The paper will also provide a glimpse into the future of data processing using FPGAs as flexible level 1 and higher level processing elements within the same system, and the use of these systems by data archiving and distribution entities. It is envisioned that many users of the National Polar Orbiting Environmental Satellites System (NPOESS) would benefit from the HRP development effort.