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.
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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
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...
Entangled Networks
Other • Entangled networks are a class of networks that attempt to maximize the algebraic connectivity of the topology. These networks can be constructed with explicit complex mathematical methods or approximated by a repetitive random optimization algorithm (which is the method chosen for this analysis) (see Figure). Sample Entangled Networks The repetitive...
Envelope
Specification • The assembled JAS mechanical structure shall attempt to fit the space available without violating any system-level keep out zones.
Environmental Exposure
Specification • Unless otherwise specified, the JAS mechanical structure shall meet these specifications during or after exposure to all environmental conditions specified in the Environmental specification. All of the intended application’s performance parameters must be considered to determine if the mechanical design can withstand the impacts of all environments.
Environmental Specification
Specification • The Environmental Specification provides details about environmental design considerations that should be considered for space applications of JAS. The figure below provides context of where the Environmental Specification resides in the JAS standard. JAS Standard Hierarchy
Environmental Test Flow
Specification • Programs using JAS should practice testing per industry standards wherever possible. The following tests and operational environments shall be applied to the components or structure in the following order. Events 1 through 5 shall be used for qualification acceptance testing. Events 1-6 shall be considered for fatigue calculations. 1) 24ea,...
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.
Expansion Profile
Other • The Expansion Profile describes a board that provides new capabilities and/or additional resources that would otherwise not be available in standard node instantiations. These modules are not intended to operate standalone and will usually not have individual processing capabilities. Rather, these boards will be populated with components that allow for...
Exposure to Space Environment
Specification • This section is a system level consideration and is included for information purposes only. The view to space shall be considered for both thermal and radiation effects. Thermal-related issue: heat-dissipation Radiation-related: TID (lifetime), SEE, shielding and impact on mass
Factors of Safety
Specification • The JAS mechanical structure shall have strength margins of safety greater than zero when calculated from analytically derived structural loads. The factors of safety (FS), shown in the first table below, and test load factors, shown in the second table below, shall be applied to the limit loads. All laminated...
Fatigue
Specification • The JAS mechanical structure metallic elements shall be designed to withstand the effects of cyclic load condition caused by the design environment. The design environment includes all ground handling transportation, testing, launch and on orbit operational environments indicated in the Environmental Specification. MSFC-HDBK-505 Chapter 7 shall be implemented for fatigue...
Form Factor
Specification • While no specific form factor standard is specified in JAS it is highly recommended that programs make use of a standards-based mechanical design such as VPX defined by VITA. Although VPX is preferred, other standards may be considered for use as well. The consideration of alternate standards should carefully consider...
Fully Connected
Other • Fully connected networks are constructed by wiring every node to every other node present in the network (see Figure). For obvious reasons, these networks are the ideal topology when considering overall speed, diameter, routing complexities, reliability, and ease of construction. However, they require a massive number of links; hence, cost...
Functional Description
Profile • The PS profile defines the technologies that comprise the PS node, including both required and recommended components to define this standard node type. A block diagram of a node instantiated against the PS profile is shown below: PS Profile Block Diagram The primary components for PS node instantiations will include...
Fundamental Frequency
Specification • The first mode of the JAS mechanical structure shall be greater than 500 Hz when mounted to a rigid surface.
Gasketing
Specification • The JAS mechanical structure shall use EMI gasketing to reduce EMI emissions as appropriate for the intended application.
Generalized Star
Other • The generalized star topology is a topology that attempts to wire the network together in such a way that each node is the center of a small star (see Figure). Given a dimension d, these networks will have d! nodes and each node will have a fixed degree of d-1....
Glossary
Other • Term Definition Adaptability A system design property that refers to an architecture’s ability to be easily changed or adjusted to accommodate different system needs. Address Translation allows addresses to be translated from abstract to physical Atomic An operation during which a processor can simultaneously read a location and write it...
Gravity Release Impact
Specification • The JAS mechanical structure shall remain within given displacements as applied by determining gravity release impacts on the mechanical structure.
Grounding
Specification • Grounding provisions are required for the mechanical design to eliminate the potential for ESD charging on floating metal. Any component members with surface areas greater than 20 cm2 shall have a grounding provision. Bolted fittings are acceptable as grounding provisions if the joint meets the electrical resistance requirement for bonding....
Humidity
Specification • The JAS housing shall meet all performance specifications during exposure to relative humidity varying from 0% to 60%.
Humidity Impact
Specification • The JAS mechanical structure shall maintain the electronics/PCBs within given displacements as applied by determining humidity impacts on the mechanical structure. If composite structures are used, the humidity should remain between a saturated composite at nominal 60% RH test area and a dry composite at 0% RH humidity vacuum environment...
Hybrid Fat Trees
Other • A hybrid fat-tree is an extension to the fat-tree topology. Hybrid fat-trees perform well when minimizing average path length and network diameter. One advantage to this design is typically about half of the nodes in this design will have a fixed degree of 2. However, other nodes have large degree,...
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