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
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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...
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.
Custom Communications
Specification • Custom communications specifications by definition are not described by any single specification. The electrical parameters will be determined by the components involved in the design. For example, if the communications utilize gigabit (GTX) transceivers in an FPGA then the electrical requirements will be prescribed by the GTX specifications.
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
Specification • The Electrical Specification provides details about power distribution, electrical interconnects, and communication data links that are used within a JAS-based system. The figure below provides context of where the Electrical Specification resides in the JAS standard. JAS Standard Hierarchy
Ethernet
Specification • Ethernet comprises a family of networking technologies with numerous media types and standards; 100Base-T (IEEE 802.3-2008:section 8) and 1000Base-T (IEEE 802.3-2008:section 40) the most popular in use today.
Mezzanine Connector
Specification • A very useful option for plug-in modules is the ANSI/VITA 57 standard FPGA Mezzanine Card or FMC. This standard specifies an industry standard form factor utilizing a low profile, high-speed, high-pin count connector. The FMC connector can support very high bandwidths. The FMC approach solves the problem of how to...
PCI Express
Specification • PCI Express, or PCIe, is another multi-lane high speed serial interconnect technology. Each lane is a full-duplex data stream comprised of two differential signaling pairs, one for transmitting and one for receiving.
Power Distribution Architecture
Specification • JAS will accept at least one primary input power source supplied to the system. The primary input power will connect directly to the Power Supply or PS node in a JAS arrangement. The PS node converts the primary input voltage to a lower voltage which is then sent to all...
Primary Power Conversion
Specification • JAS will provide the capability to convert primary power to secondary power.
Primary Power Conversion Efficiency
Specification • The converter should be optimized for efficiency to reduce power consumption and avoid unnecessary heat generation through power dissipation. The exact design of the primary converter will depend upon the required efficiency and the exact nature of the input power.
Primary Power Conversion Galvanic Isolation
Specification • The primary power converter should provide galvanic isolation between the primary power and the secondary power.
Primary Power Conversion Noise Reduction
Specification • The converter should reduce or eliminate noise and/or fluctuations in the primary input power.
Primary Power Redundancy
Specification • JAS will implement the application requirements for primary power supply redundancy.
Rear Transition Module
Specification • The rear transition module (RTM) of the VPX standard is a plug-in module at the back of the circuit card chassis that is in line with the front plug-in module or node. The backplane connectors on the RTM are the same as those used on the plug-in nodes. Also, as...
Secondary POL Conversion
Specification • JAS nodes should include POL conversion as needed. POL conversion has become very popular as the voltage requirements of electronic components have continued to drop. It is quite common for many digital electronic devices to use voltages of 1.8 VDC and below. Routing high current, low voltages around a printed...
Serial RapidIO
Specification • Serial RapidIO (or just RapidIO) is a high-performance packet-switched, interconnect technology utilizing either 8b/10b or 64b/67b encoding on data links, or lanes, with speeds up to 6.25 Gbps. Multiple lanes may be used in increase data throughput.
Space VPX
Specification • While no specific node-to-node interconnection method is specified in JAS it is highly recommended that the nodes make use of a standards-based chassis and backplane. SpaceVPX is similar to VPX but intended for space applications. [Placeholder: There may be sub-specs we can reference here, similar to the subspecs for VITA...
Space Wire
Specification • SpaceWire is a full-duplex, point-to-point, serial data communications protocol in which the data is encoded on two differential signal pairs in each direction. This is the preferred JAS communication protocol for data rate below 200 Mbps. The electrical specifications for SpaceWire communications are described in the European Cooperation for Space...
VPX
Specification • While no specific node-to-node interconnection method is specified in JAS it is highly recommended that the nodes make use of a standards-based chassis and backplane such as VPX defined by VITA. The VPX standard provides high-speed switched serial interconnects between plug-in modules or nodes while providing for parallel bus interconnects...