How to Design High-Speed Digital Signals for an Onboard Network in Spacecraft

29 Nov 2021

The quantity of data to be transmitted between devices onboard spacecraft can reach up to several tens of Gb/s, and that volume is constantly increasing. Data transmission is much more than transmitting 0s and 1s. The type of information, the speed, and the signal integrity are key issues which also must be considered. The high-speed links have to be adapted to the environment. When designing the links for spacecraft, engineers have to take into account parameters for outgassing, resistance to radiation, and weight-saving.

More and more data

The increasing number of devices on spacecraft, as well as the quantity of data to be transmitted, make the use of more adapted networks necessary. In some cases, the bus network topology to the MIL-STD-1553-B with a data rate close to 1 Mb/s needs to be replaced by point-to-point links with faster data transmission including high-speed data links up to several tens of Gb/s. These networks may be made with several physical links to allow redundancy or to share the bandwidth.

As an example, SpaceWire according to ECSS-E-ST-50-12 (ESA standard) is a data-handling network for use onboard spacecraft. It connects instruments, mass-memory, processors, downlink telemetry, and other onboard sub-systems. SpaceWire provides high-speed (up to 400 Mb/s), bi-directional, full-duplex data-links, which connect SpaceWire enabled devices. Data-handling networks can be built to suit particular applications using point-to-point data-links and routing.

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