According to Rakow, one major improvement has been to define a standard SpaceWire packet format that is consistent for decoding because the standard permits different packet formats depending upon the type of routing address scheme used. The new format supports the development of standard protocols through the assignment of protocol identifiers. As a result, several new protocols have been developed.

“One protocol performs reliable packet delivery that will be used by the GOES-R mission. Another defines memory mapping of packets, which is useful for replacing standard parallel backplanes to increase reliability and reduce mass and power while standardizing transactions between boards and subsystems no matter their location,” Rakow explained. “MMS will use this.

“I also recently led an international team of engineers to develop the hardware plug-and-play features to support software’s discovery of a network and notification when devices are added or removed. This will first be used by the Air Force Research Laboratory for PnPSat, which is a technology demonstration of a plug-and-play satellite that will be rapidly integrated from standard components. These changes have been incorporated above the (computer communication stack) layers that define SpaceWire.”

Improvements to SpaceWire itself include adding a cable redundancy mechanism that was developed for JWST and is being used for a National Reconnaissance Office (NRO) satellite. Other improvements, said Rakow, include “adding the ability to fuse many discrete signals over the SpaceWire cable to eliminate extra wires for side band signaling (one pulse per second is a common example of one of these), and adding features to provide network blockage protection into our SpaceWire router design.”

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