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...
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Receive TEP Operations
Specification • A receive TEP shall not send DATA or CONTROL packets. It may only send ACK packets. Sliding Window The receive TEP shall maintain a sliding window, which is a range of consecutive sequence numbers that is used to determine whether each received DATA packet will be accepted or discarded. The...
Reconfigurable Processing Profile
Other • The Reconfigurable Processing (RP) profile defines a high-performance processing solution suitable for constructing nodes for mission data processing, sensor interfaces, and other applications requiring high-bandwidth processing and communications. Nodes based on the RP profile work alongside other nodes within the JAS architecture. The SMAC Profile and the Communication Profile implement...
Reconfigurable Processing Profile
Profile • The RP profile defines a high-performance processing solution suitable for constructing nodes for mission data processing, sensor interfaces, and other applications requiring high-bandwidth processing and communications. The RP profile works alongside the CH Profile and PS Profile to implement nodes within the JAS architecture. The SMAC Profile and the Communication...
Reliable Delivery
Specification • JRDDP detects lost packets, duplicate packets, out of sequence packets, and provides damaged data recovery. The protocol provides additional error detection beyond the SpaceWire physical layer by utilizing Cyclic Redundancy Checks (CRCs), packet sequence numbers, positive acknowledgement, and timeouts to detect lost or duplicated Data packets.
Remote Memory Access Protocol
Profile • RMAP is used to access memory devices across a SpaceWire data link. RMAP can be used to support many functions within a JAS-based system, such as: Configure SpaceWire routers Load and control FPGA applications Configure and control sensors Gather state of health information Initializing and retrieving the contents of memory...
Remote Memory Access Protocol
Specification • JAS should use the RMAP standard to remotely access memory devices across the SpaceWire network.
Retransmission
Specification • If an ACK packet is not received by the transmit TEP within a defined channel-specific timeout interval the DATA packet shall be retransmitted.
Routing
Profile • SpaceWire uses wormhole routing to route packets through the network. Each packet contains a header which holds the destination node address either as the route through the network or as the identity of the destination node. As soon as the header for a packet is received the switch determines the...
RP_Applications
Profile • Common instantiations of the RP profile include, but are not limited to: Sensor interface Mission data processing High-Speed Data switch Volatile Memory Storage Softcore processing
Satellite System Description
Other • The beginnings of JAS grew out of the satellite area because there was a need to more effectively approach building satellite payloads to reduce NRE and REC, reduce size, weight and power (SWaP), and respond quickly to national needs for mission applications. JAS Toolbox 1.0 is focused on satellite because...
Screened Venting
Specification • Where venting requires a screen to maintain cleanliness requirements, based on a 5µ Pall Rigidmesh screen, there shall be 1.5 in^2 or greater screen area per ft^3 of volume where the volume is the sum of multiple daisy-chained volumes. The daisy chained volumes shall be vented.
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...
Sensor Interface and Mission Data Processing
Profile • The primary role of the RP node in this application is to process mission-specific sensor data. Additionally, the node can also be designed to interface to a variety other sensor types by incorporating instantiations of the Expansion Profile. Sensor Interface and Mission Data Processing Instantiation The RP node can also...
Sequence Number Use
Specification • At the receiver TEP the sequence numbers shall be used to detect lost data packets, duplicate packets and to correctly order packets.
Serial RapidIO
Specification •
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.
Shielding
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.
Softcore Processor Instantiation
Profile • One powerful application that is frequently utilized on FPGA-based platforms is softcore processing. Softcore processors can be instantiated within the FPGA by configuring the FPGA’s logic elements to implement the microprocessor functionality. The microprocessor can easily be integrated with other logic within the FPGA to form a system-on-chip (SoC) architecture....
SOIS Applied to JAS
Profile • A simplified version of the SOIS architecture as applied to JAS is shown in the figure below. The subnetwork services are used by applications to encapsulate and describe the data that needs to be communicated regardless of the underlying physical layer. The subnetwork services are JAS-specific implementations of the respective...
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
Specification • The figure below defines the format of the SpaceWire packet. Following sections will discuss the details of SpaceWire Addressing, Protocol Identifiers, and the various protocols that have been developed using SpaceWire for JAS. SpaceWire Packet
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...
SpaceWire Interconnect
Profile • SpaceWire is a communication network designed to connect sensors, processing units, memory devices and telemetry/telecommand subsystems together within a spacecraft. It provides moderate-rate (2 to 200 Mbps), bi-directional, full-duplex, data links. Application, control, and time information is sent along a SpaceWire link in discrete packets. A SpaceWire network is comprised...
SpaceWire Logical
Profile • The SpaceWire standard defines packets and protocol identifiers. The SpaceWire Logical Layer has the flexibility to utilize standard or customized protocols. There are two classes of protocols available to JAS applications: Memory access protocols – access and control memory devices that are located on remote nodes within a network Messaging...
SpaceWire Physical
Profile • JAS based systems will follow the SpaceWire standard for the physical characteristics. The details of the JAS-based implementation of the SpaceWire physical layer are found in the Electrical Specification.
SpaceWire Protocol Identifiers
Specification • The standard reserves protocol identifiers in the range of 1 to 239. Protocol identifiers in the range of 240-255 can be assigned by projects. The protocol identifiers ranging from 240-250 shall be reserved for JAS protocols. A list of the protocols used by JAS is shown in the table below....
SpaceWire Transport
Profile • The Transport Layer routes messages from one end-point processing element to another through switch processing elements. The following sections describe the various elements that define the SpaceWire Transport Layer.
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.
Subnetwork Services
Profile • Subnetwork services provide applications with a standardized interface to network communication resources regardless of the underlying data link. These services provide applications with a single application programming interface (API) and determine the proper network protocol and data link to use. This is accomplished through parameters provided in the API calls...
Subnetwork Services
Specification • JAS Subnetwork Services provide a set of well-defined interfaces for applications to communicate across a network. They provide a layer of abstraction between the applications and the network protocols and data links, thereby allowing applications to be more portable and reusable. The services use a combination of a standard application...
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.
Synchronization Service
Profile • The Synchronization Service provides the capability to send time and synchronization events to remote applications across the network. The Synchronization Service is based on the CCSDS SOIS Synchronization Service. The Synchronization Service works in conjunction with protocols to communicate time and time-based event messages to all nodes in the payload....
Synchronization Service
Specification • The following diagram shows how the JAS Synchronization Service fits into the overall communication stack. The Synchronization Service provides a standard interface to applications for sending and receiving time and event messages across a communication link. This service is typically used when the data link supports the ability to send...
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.
System Monitoring and Communication
Profile • PS Node System Monitoring and Communication An important element that must be included in each PS node is described in the SMAC Profile. The SMAC monitors and controls the state of the PS node. The SMAC also provides standard network interfaces for connectivity to other nodes.
System Monitoring and Communication
Profile • RP Node System Monitoring and Communication An important element that must be included in each RP node is described in the SMAC Profile. The SMAC monitors and controls the state of the RP node. The SMAC also provides standard network interfaces for connectivity to other nodes.
System Monitoring and Communication Profile
Profile • The System Monitoring and Communication (SMAC) Profile defines a subsystem intended for integration into RP, CH, and PS nodes to provide control, communication, and state-of-health (SOH) monitoring capabilities for JAS nodes. The SMAC subsystem consists of a single, common design applied to all nodes which provides a consistent interface to...
TEP Parameters
Specification • Each TEP shall be defined with the following parameters: TEP Type Definition Local SLA The SLA assigned to the TEP for each channel. Remote SLA The SLA assigned to the TEP which is connected to the local TEP. TEP Type Identifies the TEP as transmit or receive. Window Size The...
TEP States
Specification • Each TEP shall be in one of four possible operating states: TEP State Definition CLOSED The TEP does not generate any packets on the link and does not respond to any packets received. ENABLED A TEP transitions to the ENABLED state when the host has requested it to be opened...
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...
Timing Control
Profile • SMAC Timing Control The SMAC includes a time-keeping circuit that is used for synchronizing time across the entire payload. The timekeeping process has two components: receipt of the time value for the next epoch, and synchronization to a timing pulse. The receipt of time value occurs over the network. The...
Trailer
Specification • JRDDP Packet Format The JRDDP packet trailer shall be a 16-bit CCITT Cyclic Redundancy Check (CRC) computed from the Destination SLA to the last byte of the Payload field. CRC The 16-bit CCITT CRC shall be computed according to the following polynomial: CRC Polynomial for JRDDP Prior to computing each...
Transmit Priority
Specification • When more than one packet is available for transmit, all ACK packets shall be transmitted first, then CONTROL packets, then URGENT packets (if implemented), then Retransmit packets (CONTROL or DATA), then DATA packets.
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.
Urgent Messaging
Specification • Urgent messaging is a best-effort priority communications path that does NOT provide for reliable delivery, missing packet detection, or out-of-sequence packet reordering. It may optionally be implemented in this protocol to facilitate an out-of-band transport pathway that may be useful for such things as time broadcasts, exception/error control, meta messages,...
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...
Volatile Memory Storage
Profile • The RP profile may operate as a high-performance mass memory node, hosting volatile SDRAM memories that can store mission data for short periods of time. This application may be used, for example, to queue mission data or temporary data storage for processing. Volatile Memory Storage Instantiation In this application, the...
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...
Worst Case
Specification • If the link between the transmit and receive TEPs is bad, i.e. packets are corrupted or lost, and the receive TEP does not receive at least one CLOSE packet, the transmit TEP will transition to the CLOSED state after all retries have been exhausted and the receive TEP will remain...
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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