Specification • The JAS mechanical structure shall provide EMI shielding which meets 60db shielding effectiveness from 0.1 to 1 GHz for the FPA Sensor box with covers in place.
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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...
SpaceWire Addressing
Specification • SpaceWire addresses shall follow the allowed allocation defined in the SpaceWire standard. Only logical addresses will be used for router and endpoint addresses which means they must be in the range of 0x20-0xFE. JAS applications shall use SpaceWire regional addressing in conjunction with header deletion within the SpaceWire routers. Two...
Strength Qualification
Specification • The JAS mechanical structure design shall possess sufficient strength and rigidity to withstand environmental conditions defined in this document. Load Conditions
Structural Integrity
Specification • The JAS mechanical structure design shall possess sufficient strength and rigidity to withstand environmental conditions defined in this document.
Survival Temperatures
Specification • The JAS support shall meet all performance specifications after being exposed to a minimal temperature range from -40 C to +60 C.
System Monitor and Communication Profile
Other • The System Monitoring and Communication (SMAC) Profile defines a subsystem intended for integration into JAS nodes to provide control, communication, and state-of-health (SOH) monitoring capabilities. The SMAC subsystem consists of a single, common design applied to all nodes which provides a consistent interface to the system controller regardless of the...
System Monitoring and Communication
Profile • CH Node System Monitoring and Communication An important element that must be included in each CH node is described in the SMAC Profile. The SMAC monitors and controls the state of the CH node. The SMAC also provides standard network interfaces for connectivity to other nodes.
Thermal Impact
Specification • The JAS mechanical structure shall be designed to maintain the electronics/PCBs within given displacements while the system is in operation as applied by determining thermal impacts on the mechanical structure. The operational thermal environments of a nominal orbit need to be applied to the mechanical model as necessary to ensure...
Thermal Loads
Specification • Yield and ultimate thermal loads for hardware subject to thermal tests shall be calculated by either Alternate A or Alternate B, as defined below, whichever produces the maximum load. These thermal loads are not to be used for fatigue. Alternate A: Yield thermal load (YTL) = Predicted thermal load (PTL)...
Time Distribution
Other • The JAS architecture does not specify a time distribution scheme nor limit system implementations from incorporating their own methods. Two possible time distribution schemes are presented as examples: Fully Connected A fully connected distribution provides a direct interface between each node and the host. Fully connected time distribution is more...
Time Management Service
Specification • The time access service, service type address 131 is used to access and manage time. The currently defined platform management service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 131 1 Time Set X Time Time...
Transmit TEP Operations
Specification • Transmit TEP ACKs A transmit TEP shall not send an ACK packet. Transmit TEP Sequence Number Allocation Each DATA packet transmitted shall have a sequence number allocated from the TEP's transmit window range of available sequence numbers. CONTROL Packet Sequence Number All CONTROL packets shall be transmitted with a sequence...
Transport Channel Connection
Specification • A transport channel connection shall be considered established when a transmit TEP and receive TEP are both in the OPEN state.
Unscreened Venting
Specification • All closed volumes in JAS mechanical structure shall have a minimum venting area requirement of 0.25 in^2 or greater venting area per ft^3 of volume.
Useful Metrics for Analyzing Topology Candidates
Other • Emerging high-bandwidth, low-latency network technology has made network-based architectures both feasible and potentially desirable for use in satellite payload architectures. Network architectures are capable of routing large amounts of traffic with reasonable latency, allowing considerable amounts of data between nodes to be shared. However, care must be exercised when developing...
Vacuum Impact
Specification • The JAS electronics shall consider testing in a thermal vacuum environment because inadequately heat-sunk parts will fail/burn-up. Overheating is the issue, exceeding maximum junction temperatures.
Venting
Specification • The JAS mechanical structure shall have no confined or captured volumes. Venting ports shall be provided to prevent damage, or the release of gases, due to pressure changes during testing, transportation, and launch. Threads need not be vented.
Vibration (Random)
Specification • The JAS housing support shall meet all performance specifications after being subjected to the vibration level prescribed by figure 5.5.1. This spectrum shall be applied, to the mounting brackets.
Volatile Memory Storage
Profile • The CH profile may also operate as a low- to medium-performance memory node, hosting volatile SDRAM memories that can store mission data for short periods of time. This application may be used to queue mission data, provide temporary storage of data for processing, and other similar functions. Volatile Memory Storage...
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...
X,Y, and Z Axis Random Vibration
Specification • The JAS support shall meet all performance specifications after being subjected to the random vibration environment prescribed by the figure below. Note that these are acceptance levels. This input should be used along with the program Strength Qualification Plan. Random Vibration
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