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Spacewire
SpaceWire is a spacecraft communication network based in part on the IEEE 1355 standard of communications. It is coordinated by the European Space Agency (ESA) in collaboration with international space agencies including NASA, JAXA, and RKA. Within a SpaceWire network the nodes are connected through low-cost, low- latency, full-duplex, point-to-point serial links, and packet switching wormhole routing routers. Architecture Physical layer SpaceWire's modulation and data formats generally follow the data strobe encoding - differential ended signaling (DS-DE) part of the IEEE Std 1355-1995. SpaceWire utilizes asynchronous communication and allows speeds between 2 Mbit/s and 200 Mbit/s, with initial signalling rate of 10 Mbit/s. DS-DE is well-favored because it describes modulation, bit formats, routing, flow control, and error detection in hardware, with little need for software. SpaceWire also has very low error rates, deterministic system behavior, and rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wormhole Routing
Wormhole flow control, also called wormhole switching or wormhole routing, is a system of simple flow control in computer networking based on known fixed links. It is a subset of flow control methods called ''flit-buffer flow control''. Switching is a more appropriate term than routing, as "routing" defines the route or path taken to reach the destination. The wormhole technique does not dictate the route to the destination but decides when the packet moves forward from a router. Wormhole switching is widely used in multicomputers because of its low latency and small requirements at the nodes. Wormhole routing supports very low-latency, high-speed, guaranteed delivery of packets suitable for real-time communication. Mechanism principle In the wormhole flow control, each packet is broken into small pieces called flits (flow control units or flow control digits). Commonly, the first flits, called the header flits, holds information about this packet's route (for example, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEEE 1355
IEEE Standard 1355-1995, IEC 14575, or ISO 14575 is a data communications standard for Heterogeneous Interconnect (HIC). IEC 14575 is a low-cost, low latency, scalable serial interconnection system, originally intended for communication between large numbers of inexpensive computers. IEC 14575 lacks many of the complexities of other data networks. The standard defined several different types of transmission media (including wires and optic fiber), to address different applications. Since the high-level network logic is compatible, inexpensive electronic adapters are possible. IEEE 1355 is often used in scientific laboratories. Promoters include large laboratories, such as CERN, and scientific agencies. For example, the ESA advocates a derivative standard called SpaceWire. Goals The protocol was designed for a simple, low cost switched network made of point-to-point links. This network sends variable length data packets reliably at high speed. It routes the packets using wormh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Strobe Encoding
Data strobe encoding (or D/S encoding) is an encoding scheme for transmitting data in digital circuits. It uses two signal lines (e.g. wires in a cable or traces on a printed circuit board), ''Data'' and ''Strobe''. These have the property that either Data or Strobe changes its logical value in one clock cycle, but never both. More precisely data is transmitted as-is and strobe changes its state if and only if data stays constant between two data bits. This allows for easy clock recovery with a good jitter tolerance by XORing the two signal line values. There is an equivalent way to specify the relationship between Data and Strobe. For even-numbered Data bits, Strobe is the opposite of Data. For odd-numbered Data bits, Strobe is the same as Data. From this definition it is more obvious that the XOR of Data and Strobe will yield a clock signal. Also, it specifies the simplest means of generating the Strobe signal for a given Data stream. Data strobe encoding originated in IEEE 135 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micro-D
The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smallest connectors used on computer systems. Description, nomenclature, and variants A D-sub contains two or more parallel rows of pins or sockets usually surrounded by a D-shaped metal shield, or shell, that provides mechanical support, ensures correct orientation, and may screen against electromagnetic interference. Calling that shield a shell (or D-shell) can be ambiguous, as the term shell is also short for the cable shell, or backshell. D-sub connectors have gender: parts with pin contacts are called ''male connectors'' or ''plugs'', while those with socket contacts are called ''female connectors'' or ''sockets''. The socket's shield fits tightly inside the plug's shield. Panel-mounted connectors usually have #4-40 UNC (as designated with the Unified Thread Standard) jackscrews that acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-voltage Differential Signaling
Low-voltage differential signaling (LVDS), also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial signaling standard. LVDS operates at low power and can run at very high speeds using inexpensive twisted-pair copper cables. LVDS is a physical layer specification only; many data communication standards and applications use it and add a data link layer as defined in the OSI model on top of it. LVDS was introduced in 1994, and has become popular in products such as LCD-TVs, in-car entertainment systems, industrial cameras and machine vision, notebook and tablet computers, and communications systems. The typical applications are high-speed video, graphics, video camera data transfers, and general purpose computer buses. Early on, the notebook computer and LCD display vendors commonly used the term LVDS instead of FPD-Link when referring to their protocol, and the term ''LVDS'' has mistakenly become synonymous with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Failover
Failover is switching to a redundant or standby computer server, system, hardware component or network upon the failure or abnormal termination of the previously active application, server, system, hardware component, or network in a computer network. Failover and switchover are essentially the same operation, except that failover is automatic and usually operates without warning, while switchover requires human intervention. History The term "failover", although probably in use by engineers much earlier, can be found in a 1962 declassified NASA report. The term "switchover" can be found in the 1950s when describing '"Hot" and "Cold" Standby Systems', with the current meaning of immediate switchover to a running system (hot) and delayed switchover to a system that needs starting (cold). A conference proceedings from 1957 describes computer systems with both Emergency Switchover (i.e. failover) and Scheduled Failover (for maintenance). Failover Systems designers usually pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault-tolerant Design
Fault tolerance is the ability of a system to maintain proper operation despite failures or faults in one or more of its components. This capability is essential for high-availability, mission-critical, or even life-critical systems. Fault tolerance specifically refers to a system's capability to handle faults without any degradation or downtime. In the event of an error, end-users remain unaware of any issues. Conversely, a system that experiences errors with some interruption in service or graceful degradation of performance is termed 'resilient'. In resilience, the system adapts to the error, maintaining service but acknowledging a certain impact on performance. Typically, fault tolerance describes computer systems, ensuring the overall system remains functional despite hardware or software issues. Non-computing examples include structures that retain their integrity despite damage from fatigue, corrosion or impact. History The first known fault-tolerant computer was S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossbar Switch
In electronics and telecommunications, a crossbar switch (cross-point switch, matrix switch) is a collection of switches arranged in a Matrix (mathematics), matrix configuration. A crossbar switch has multiple input and output lines that form a crossed pattern of interconnecting lines between which a connection may be established by closing a switch located at each intersection, the elements of the matrix. Originally, a crossbar switch consisted literally of crossing metal bars that provided the input and output paths. Later implementations achieved the same switching topology in solid-state electronics. The crossbar switch is one of the principal telephone exchange architectures, together with a rotary system, rotary switch, memory switch, and a crossover switch. General properties A crossbar switch is an assembly of individual switches between a set of inputs and a set of outputs. The switches are arranged in a matrix. If the crossbar switch has M inputs and N outputs, then a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Space Agency
The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European integration. Its 2025 annual budget was €7.7 billion. The ESA Human and Robotic Exploration programme includes human spaceflight (mainly through participation in the International Space Station programme); as well as the launch and operation of missions to Mars and Moon. Further activities include science missions to Jupiter, Mercury, the Sun, Earth observation, Asteroid impact avoidance and Telecommunications missions, designing launch vehicles; and maintaining Europe's Spaceport, the Guiana Space Centre at Kourou (French Guiana). Further programmes include space safety, satellite navigation, applications and commercialisation. The main European launch vehicle Ariane 6 is operated through Arianespace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, List of the most distant astronomical objects, distant, or faint for the Hubble Space Telescope. This enables investigations across many fields of astronomy and cosmology, such as observation of the Population III star, first stars and the Galaxy formation and evolution, formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. Although the Webb's mirror diameter is 2.7 times larger than that of the Hubble Space Telescope, it produces images of comparable optical resolution, resolution because it observes in the longer-wavelength infrared spectrum. The longer the wavelength of the spectrum, the larger the information-gathering surface required (mirrors in the infrared spectrum or antenna a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burst Alert Telescope
Neil Gehrels Swift Observatory, previously called the Swift Gamma-Ray Burst Explorer, is a NASA three-telescope space observatory for studying gamma-ray bursts (GRBs) and monitoring the afterglow in X-ray, and UV/visible light at the location of a burst. It was launched on 20 November 2004, aboard a Delta II launch vehicle. Headed by principal investigator Neil Gehrels until his death in February 2017, the mission was developed in a joint partnership between Goddard Space Flight Center (GSFC) and an international consortium from the United States, United Kingdom, and Italy. The mission is operated by Pennsylvania State University as part of NASA's Medium Explorer program (MIDEX). The burst detection rate is 100 per year, with a sensitivity ~3 times fainter than the BATSE detector aboard the Compton Gamma Ray Observatory. The Swift mission was launched with a nominal on-orbit lifetime of two years. Swift is a NASA MIDEX (medium-class Explorer) mission. It was the third to be la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
