Specification • Applications require a messaging format to allow them to communicate with each other. Legacy programs may already have a messaging format that they prefer to use. There is nothing that precludes any of the JAS communication protocols or data links from supporting these formats. The JAS Packet was developed for...
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JAS Profile Introductions
Other • The JAS architecture defines a small number of Profiles that form the basis for building the components required for a sensor interface and data processing electronics system. A node inherits the attributes of one or more Profiles. A Profile describes the purpose of that node within the Architecture and defines...
JAS Rationale and Motivation
Other • JAS is a versatile, scalable, tailorable, SWAP-efficient, node-based concept for implementing embedded systems. Such systems include sensor suites, host platform interfaces, signal and data processors, data buffering and storage, command and data handling, and other supporting hardware and software. JAS Origin Sandia National Laboratories, Los Alamos National Laboratories, and others...
JAS Reliable Data Delivery Protocol
Profile • The JAS Reliable Data Delivery Protocol (JRDDP) is a reliable packet transmission protocol that can be used to send messages between applications over a SpaceWire data link. It is based on a protocol created by the National Aeronautics and Space Administration (NASA) at the Goddard Spaceflight Center in Greenbelt, Maryland,...
JAS Reliable Data Delivery Protocol
Specification • The JAS Reliable Data Delivery Protocol (JRDDP) uses the lower level SpaceWire data link layer to provide reliable packet delivery services to one or more higher level host application processes. This document specifies the functional requirements for JRDDP but does not specify the interfaces to the lower or higher level...
JAS Specific Services Definitions
Specification • The JAS specific services will be based on the PUS service concept. Most PUS services were created for communication between onboard applications and ground systems. JAS adds additional services to support more onboard payload functions. [Placeholder: Additional development is needed to define the JAS specific services to support onboard payload...
JAS Telemetry Packet
Specification • JAS Telemetry Packet All fields are shown in bits. The variable length application data field must be an integral number of bytes for the packet error control calculation. Spare bits may be used for padding purposes at the end to ensure the packets are an even number of bytes in...
JAS Toolbox Introduction
Other • The JAS standard is captured in the JAS Toolbox, and presented using a web-based content management system known as the Interactive Standards Publication Tool (ISPT). In addition to the JAS standard, the JAS Toolbox includes a set of Systems Engineering (SE) Tools, which provide system examples and modeling capabilities. The...
JAS versus PROPIN Trade Study
Other • Feature Comparison JAS has a number of positive impacts on budget, schedule, and performance. Below is a table that illustrates these advantages when comparing a JAS-based system to a PROPIN approach. Advantage Benefit Budget Schedule Performance Scalable processing systems Ability to add/remove as many nodes as are needed to support...
JEEP Packet Format
Specification • All JEEP packets shall include a fixed length header, followed by a variable length payload. The figure below shows how the JEEP packet is embedded within the standard SpaceWire packet. Note that while a SpaceWire packet may have zero or more destination addresses before the JEEP header, the JEEP requires...
Joint Architecture Standard Overview
Other • The purpose of JAS is to realize a reusable set of common hardware and software module designs that can be easily scaled, configured, adapted, interconnected and integrated with industry standards and internally supported intellectual property (IP) to provide the functionality needed to support any payload sensor suite. JAS also provides...
JRDDP Packet Format
Specification • All JRDDP packets shall include a variable length header, followed by a variable length payload, followed by a 2-byte CRC Trailer. The figure below shows how the JRDDP packet is embedded within the standard SpaceWire packet. Note that while a SpaceWire packet may have zero or more destination addresses before...
Junction Temperatures
Specification • The design shall show positive margin against thermal design so junction temperatures do not exceed maximum component values for worst case orbits at beginning (BOL) and end of life (EOL).
Life
Specification • The JAS mechanical structure shall be constructed of materials capable of performing for the necessary mission life time (for example, 3 years storage in an inert atmosphere and 10 years on orbit). This analysis will require extensive parts and materials screening and processing.
Loads
Specification • Loads shall be determined per the program Strength Qualification Plan.
Logical Connections
Specification • Upon initialization all TEPs shall be in the CLOSED state. OPEN/RESET Command When a transmit TEP transitions to the ENABLED state (as commanded by the host), it shall send an OPEN/RESET packet to its receive TEP and initiate an acknowledgement timer. CLOSE Command When a transmit TEP transitions to the...
MAGE Strength
Specification • The JAS mechanical structure shall consider tooling to hold it while installing and transporting components. Features for mounting the hardware that supports the system shall be included. A static 4 G load shall be used with positive margins per this document. Mechanical Aerospace Ground Equipment (MAGE)
Margins of Safety
Specification • Margin of Safety (MS) is defined as MS = 1/R - 1, where R is the ratio of the factored applied load (or stress) to the allowable load (or stress) and shall be greater than 0. Margin of Safety Calculation The specific failure theory used to determine the allowable load...
Mass Properties
Specification • The JAS mechanical structure shall attempt to optimize mass, center of gravity, and moments of inertia.
Material Properties and Allowables
Specification • The JAS mechanical structure design of the metallic parts shall use A Basis allowables from MIL-HDBK-5 or equivalent. The design of the composite parts shall use B Basis allowables generated using the methodology in MIL-HDBK-17 or equivalent.
Materials
Specification • The JAS mechanical structure shall be constructed of materials capable of performing at the specified orbit for a minimum of ten years after being stored in an inert gas environment and after exposure to clean air during testing, launch, and ascension. The use of the following materials is prohibited: Zinc,...
Mechanical Interface Design
Specification • The JAS mechanical structure as described in this Mechanical specification will support applications intended for a space environment and will provide stable mechanical structure for the electronics during launch and while operating in a high vacuum.
Mechanical Specification
Specification • The Mechanical Specification provides details about mechanical interface design, environmental impacts, and design constraints that should be considered for implementing mechanical structures in a JAS-based system. The figure below provides context of where the Mechanical Specification resides in the JAS standard. JAS Standard Hierarchy
Memory Access Service
Profile • The Memory Access Service is used to asynchronously read and write to memory-based devices across a network. The Memory Access Service is based on the CCSDS SOIS Memory Access Service and provides a layer of abstraction between applications and memory-based devices. It provides a common API for applications to use...
Memory Access Service
Specification • Error: unable to migrate element with tag="" The following diagram shows how the JAS Memory Access Service fits into the overall communication stack. The Memory Access Service provides a standard interface to applications that allows them to remotely access memory on a JAS node across a communication link. This is...
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