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Acknowledgement and Retransmit

Specification • The receiver shall send a positive acknowledgment (ACK) packet for each DATA packet received without error.

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Overall Functional Description > Acknowledgement and Retransmit

Allocation of Service Types and Subtypes

Specification • The PUS provides a standard set of services that are targeted for communication between spacecraft and ground systems. Many of them may not be applicable to on-board communication between applications. However, nothing precludes their use in a JAS-based system. The PUS can be extended to add additional functionality to existing...

Communication Specification > JAS Packets > Packet Service Definitions > Allocation of Service Types and Subtypes

Backplane Connectors

Specification • JAS electrical design should utilize commercial connector standards when applicable. The VPX plug-in module to backplane connector is a Tyco Electronics MultiGig RT2 connector system which was chosen for its rugged mechanical performance and high-speed electrical performance, rated to 6.4 Gb/s and demonstrated to support data rates greater than 10...

Electrical Specification > Electrical Interconnects > VPX > Backplane Connectors

Backplane Topology

Specification • The backplane is a key element in achieving high-speed connections between the plug-in modules or nodes in the case of a JAS system. VPX compliant backplanes support a minimum signaling rate of at least 3.125 Gbps on any differential point-to-point connection. There are a small number of required signals on...

Electrical Specification > Electrical Interconnects > VPX > Backplane Topology

Buckling and Crippling

Specification • Evaluation of buckling strength shall consider the combined action of primary and secondary stresses and their effects on general instability, local or panel instability, crippling, and creep.

Mechanical Specification > Design Constraints > Structural Integrity > Buckling and Crippling

Buffer Fragmentation and Reassembly

Specification • In cases where a higher-level transmit application (or higher layer in a communications stack) must transmit a buffer of data that exceeds the JRDDP MTU size, the buffer must be fragmented into a series of JRDDP packets and then reassembled at the receive TEP before returning the buffer to the...

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Overall Functional Description > Buffer Fragmentation and Reassembly

Buffer Segmentation and Reassembly

Specification • In cases where a higher-level transmit application, or higher layer in a communications stack, must transmit a buffer of data that exceeds the JEEP MTU size, the buffer must be segmented into a series of JEEP packets and then reassembled at the receive TEP before returning the buffer to the...

Communication Specification > SpaceWire > Protocols > JAS Efficient Exchange Protocol > Buffer Segmentation and Reassembly

CCSDS Telecommand and Telemetry Format Packet Standard

Specification • CCSDS Space Packet The CCSDS packet format consists of a packet primary header and packet data field. The header provides routing information for the packet and metadata that describes the packet. The data field is intended to be a user-defined field that can be customized for applications. Details of how...

Communication Specification > JAS Packets > CCSDS Telecommand and Telemetry Format Packet Standard

Channel Closing Process

Specification • The following sections present the interactions (in the form of UML Sequence Diagrams) between transmit and receive endpoints while closing a channel. Various error conditions are presented in order to show nominal, delayed, and worst case scenarios. The hexagonal icons represent the TEP states while the dashed green lines represent...

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Channel Operations > Channel Closing Process

Channel Independence

Specification • Each transport channel shall operate independently from other transport channels.

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Overall Functional Description > Channel Independence

Channel Operations

Specification •

Communication Specification > SpaceWire > Protocols > JAS Reliable Data Delivery Protocol > Channel Operations

Coating Surface Resistivity

Specification • The thickness of all chemical film treatments need to be controlled to provide low surface resistivity. Surface resistivity shall be less than 1 x 109 ohm/ square.

Mechanical Specification > Environmental Exposure > Electromagnetic Compatibility > Coating Surface Resistivity

Coating Volume Resistivity

Specification • All paints and coatings shall have a volume resistivity less than 1 x 109 ohm-cm.

Mechanical Specification > Environmental Exposure > Electromagnetic Compatibility > Coating Volume Resistivity