Alberto Gonzalez Villafranca

SpaceFibre: A multi-Gigabit/s interconnect for spacecraft onboard data handling

SpaceFibre is a spacecraft onboard data link and network technology being developed by University of Dundee for the European Space Agency (ESA), which runs over both copper and fibre optic cables. Initially targeted at very high data rate payloads such as Synthetic Aperture Radar (SAR) and multi-spectral imaging instruments, SpaceFibre is capable of fulfilling a wider set of spacecraft onboard communications applications because of its inbuilt QoS and FDIR capabilities and its backwards compatibility with the ubiquitous SpaceWire technology. SpaceFibre operates at 2.5 Gbits/s providing 12 times the throughput of a SpaceWire link with current flight qualified technology and allowing data from multiple SpaceWire devices to be concentrated over a single SpaceFibre link. This substantially reduces cable harness mass and simplifies redundancy strategies. The innovative QoS mechanism in SpaceFibre provides concurrent bandwidth reservation, priority and scheduled QoS. This simplifies spacecraft system engineering through integrated quality of service (QoS), which reduces system engineering costs and streamlines integration and test. Novel integrated FDIR support provides galvanic isolation, transparent recovery from transient errors, error containment in virtual channels and frames, and “Babbling Idiot” protection. SpaceFibre enhances onboard network robustness through its inherent FDIR and graceful degradation techniques incorporated in the network hardware. This simplifies system FDIR software, reducing development and system validation time and cost. SpaceFibre includes low latency event signalling and time distribution with broadcast messages. This enables a single network to be used for several functions including: transporting very high data rate payload data, carrying SpaceWire traffic, deterministic delivery of command/control information, time distribution and event signalling. SpaceFibre is backwards compatible with existing SpaceWire equipment at the packet level allowing simple interconnection of SpaceWire devices into a SpaceFibre network and enabling that equipment to take advantage of the QoS and FDIR capabilities of SpaceFibre.

SpaceFibre: Adaptive high-speed data-link for future spacecraft onboard data handling

SpaceFibre is a high-speed data-link technology being developed by the University of Dundee for ESA to support spacecraft onboard data-handling applications. SpaceFibre operates at 2.5 Gbits/s, can run over fibre optic or electrical media, provides galvanic isolation, includes Quality of Service (QoS) and Fault Detection Isolation and Recovery (FDIR) support, and provides low-latency signalling. It operates over distances of 5m with copper cable and 100 m or more with fibre optic cable. SpaceFibre supports multiple virtual channels running over a single physical link. QoS capabilities built into the SpaceFibre hardware allow the bandwidth and priority of each virtual channel to be specified. Traffic flow over each virtual channel then adapts automatically taking into account virtual channels that have data ready to send and available buffer space at the far end of the link, along with link bandwidth and priority allocation. The novel QoS mechanism is simple but powerful and also allows the automatic detection of “babbling idiots” and virtual channels that are sending much less data than expected. After a brief introduction the SpaceFibre QoS and FDIR capabilities are explained. The approach taken in validating the SpaceFibre protocols and current status of the SpaceFibre development activities are then described.

SpaceWire and SpaceFibre on the Microsemi RTG4 FPGA

SpaceWire is a spacecraft on-board data-handling network which connects instruments to the mass-memory, data processors and control processors, which is already in orbit or being designed into more than 100 spacecraft. SpaceFibre is a new, multi-Gbits/s, on-board network technology, which runs over both electrical and fibre-optic cables. SpaceFibre is capable of fulfilling a wide range of spacecraft on-board communications applications because of its inbuilt quality of service (QoS) and fault detection, isolation and recovery (FDIR) capabilities. The Microsemi RTG4 is a new generation radiation tolerant FPGA. It has extensive logic, memory, DSP blocks, and IO capabilities and is inherently radiation tolerant, having triple mode redundancy built in. The RTG4 has a flash configuration memory built into the device. In addition the FPGA incorporates 16 SpaceWire clock-data recovery circuits and 24 multi-Gbits/s SerDes lanes to support high-speed serial protocols like SpaceFibre. STAR-Dundee has implemented SpaceWire and SpaceFibre IP cores using the Microsemi RTG4 Development Kit. The flight proven SpaceWire IP core was initially run at over 200 Mbits/s and the SpaceFibre IP core at 2.5 Gbits/s. With a little more work it is expected to reach 300 Mbits/s and 3.125 Mbits/s respectively. The SpaceWire IP core takes around 1% of the FPGA and the SpaceFibre IP core around 3-5% depending on the number of virtual channels supported. The use of the RTG4 with the SpaceWire and SpaceFibre IP cores provides a powerful platform for future spacecraft on-board instrument control, data-handling, and data processing. Furthermore the advanced QoS and FDIR capabilities of SpaceFibre make it suitable for a wider range of spacecraft onboard applications including integrated payload data-handling and attitude and orbit control networks and launcher applications where deterministic data delivery is required. This paper reports on the implementation and testing of the SpaceWire and SpaceFibre IP cores in the Microsemi RTG4 FPGA.

Discrete wavelet transform fully adaptive prediction error coder: image data compression based on CCSDS 122.0 and fully adaptive prediction error coder

Abstract The Consultative Committee for Space Data Systems (CCSDS) 122.0 recommendation defines a particular image data compression algorithm for space. It is based on a discrete wavelet transform (DWT) algorithm followed by bit-plane encoder stage (BPE) based on Rice codes. The low complexity and memory efficiency of the algorithm makes it suitable for use onboard a spacecraft. On the other hand, fully adaptive prediction error coder (FAPEC) is a quick entropy coder aimed to achieve excellent compression ratios under almost any situation, including large fractions of outliers in the data and large sample sizes. A new image compression solution based on the DWT stage of the CCSDS 122.0 recommendation is presented, followed by our FAPEC entropy coder, thus removing the BPE stage. The purpose is to obtain a low-complexity algorithm for image compression able to provide similar or even better compression ratios than those obtained using the CCSDS 122.0 recommendation. A prototype of DWTFAPEC, the combination of the DWT stage with FAPEC, is presented here. Its lossless operation, as well as the results with a first lossy option with selectable quality using a wide variety of images, including the official CCSDS 122.0 image corpus as well as several astronomical and ground images, is tested. The results are satisfactory, achieving significantly better compression times. The lossless ratios are very close to those of the standard, while the lossy ratios are higher (for the same level of quality loss). Thus, DWTFAPEC can be used as an alternative to CCSDS 122.0 standard for space missions.

Prediction Error Coder: a fast lossless compression method for satellite noisy data

Abstract Lossless compression is often required for downloading data of scientific payloads in space missions. The consultative committee for space data systems (CCSDS) 121.0 recommendation on lossless data compression is a “de-facto” standard, and it has been used in several missions so far owing to the reasonable compression ratios achieved with low processing requirements. Although the Rice coder used by this standard is optimal when dealing with noiseless Laplacian-distributed data, its performance rapidly degrades when noisy data are compressed or when there is a significant fraction of outliers in the input data. An alternative to this is PEC, the Prediction Error Coder, which is the core of the FAPEC adaptive entropy coder. We describe, analyze and test PEC on real and simulated data, revealing its key role in the excellent outlier resiliency of FAPEC. PEC is a fast and noise-resilient semi-adaptive entropy coder that can achieve better performances than the CCSDS standard in the presence of noise or when the input data contains a sizable fraction of outliers, while requiring very low processing resources.

A prototype SpaceVPX lite (VITA 78.1) system using SpaceFibre for data and control planes

SpaceVPX (VITA78.0) is a new development in the area of standard backplanes for spacecraft applications, which addresses the key issue of fault tolerance. SpaceVPXLite (VITA78.1) is a derivative of SpaceVPX which is aimed at small size. SpaceFibre is the next generation of the widely used SpaceWire on-board network technology. SpaceFibre runs at multi-Gbits/s over both electrical and fibre-optic cables. SpaceFibre is capable of fulfilling a wide range of spacecraft on-board communications applications because of its inbuilt quality of service (QoS) and fault detection, isolation and recovery (FDIR) capabilities. SpaceFibre is being incorporated in the SpaceVPXLite standard as a protocol for sending information over a backplane. STAR-Dundee is developing a demonstration system of SpaceFibre in SpaceVPXLite, using the Microsemi RTG4 radiation tolerant FPGA. This demonstration system is being used as the engineering model of a UK THz radiometer instrument processing unit.

SpaceFibre network and routing switch

SpaceFibre is the next generation of the widely used SpaceWire technology for spacecraft on-board data-handling applications. SpaceFibre provides much higher performance, has integrated quality of service and fault detection, isolation and recovery capabilities. It runs over electrical or fibre optic media and is able to operate over distances of up to 5 m over electrical cables and 100 m over fibre optic cables. The SpaceFibre network layer uses the same packet format and routing concepts as SpaceWire, enhancing them with the concept of independent, parallel virtual networks, each of which operates like an independent SpaceWire network running over a single physical network. An essential component in a SpaceFibre network is the routing switch. STAR-Dundee has designed, built and tested a SpaceFibre routing switch in a commercial FPGA, using it to support the testing and validation of the network layer concepts developed for SpaceFibre. The architecture of the SUNRISE router is described and current work transferring this design to radiation tolerant technology is outlined.