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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

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

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

Communication Data Links

Specification • JAS nodes should communicate through one or more standard communications protocols. Serial communication protocols are the recommended approach but JAS does not preclude the use of parallel communication protocols. JAS also does not preclude the use of custom or legacy based communications.

Electrical Specification > Communication Data Links

Coordinate Definition

Specification • The JAS mechanical structure shall implement a coordinate system as a reference point for the design. The mounting of each component should be considered as the coordinate reference. The coordinate frame can originate on a pin-and-slot mounting. [Placeholder: Defining a coordinate frame helps to determine center of gravity, mass, envelopes...

Mechanical Specification > Mechanical Interface Design > Coordinate Definition

Design Thickness

Specification • For strength and buckling analyses, minimum material thickness shall be used. Minimum thickness is defined as the nominal thickness minus the lower tolerance and applies to metallic and nonmetallic structural elements. For modeling purposes and stiffness calculations, use nominal or expected values. For flexures the Maximum blade thickness shall be...

Mechanical Specification > Design Constraints > Structural Integrity > Design Thickness

ECSS Packet Utilization Standard

Specification • The figures below show a PUS telecommand and telemetry packet and their utilization within the CCSDS space packet specification. The PUS specification uses the user-definable fields of the CCSDS space packet in order to create a PUS packet. The specification defines a secondary header that provides additional metadata such as...

Communication Specification > JAS Packets > ECSS Packet Utilization Standard

Electrical Bonding

Specification • Each equipment design shall provide electrical continuity across mechanical interfaces in accordance with the design requirements of this specification. Electrical continuity will be achieved to the maximum practical extent by direct metal-to-metal contact across the entire interface surface. If the electrical resistance across mechanical interfaces is measured to be less...

Mechanical Specification > Environmental Exposure > Electromagnetic Compatibility > Electrical Bonding

Electrical Interconnects

Specification • JAS electrical design shall utilize commercial interconnect standards when applicable. The following sections are some examples of commercial interconnect standards that are recommended but not required.

Electrical Specification > Electrical Interconnects

Electromagnetic Compatibility

Specification • Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are important design considerations which can be mitigated by the mechanical structure. EMI limits may be in place due to application-specific requirements, but more importantly, EMI can be detrimental to electronics because of the sensitive nature of many of the modern systems and...

Mechanical Specification > Environmental Exposure > Electromagnetic Compatibility

Results 1–25 of 113