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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. SpaceWire covers two (physical and data-link) of the seven layers of the OSI model for communications. 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 10Mbit/s. DS-DE is well-favored because it describes modulation, bit formats, routing, flow control, and error detection in hardware, with little need for soft ... [...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 dest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wormhole Switching
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 de ... [...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 wor ... [...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 1355 ... [...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 that provides mechanical support, ensures correct orientation, and may screen against electromagnetic interference. 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 accept screws on the cable end connector cover that are used for locking the connectors together and offering mechanical strain relief, and ca ... [...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. Systems designers usually provide failover capability in servers, systems or networks requiring near-continuous availability and a high degree of reliability. At the server level, failover automation usually uses a " heartbeat" system that connects two servers, either through using a separate cable (for example, RS-232 serial ports/cable) or a network connection. As long as a regular "pulse" or "heartbeat" continues between the main server and the second server, the second server will not bring its systems online. There may also be a third "spare parts" se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault-tolerant Design
Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the severity of the failure, as compared to a naively designed system, in which even a small failure can cause total breakdown. Fault tolerance is particularly sought after in high-availability, mission-critical, or even life-critical systems. The ability of maintaining functionality when portions of a system break down is referred to as graceful degradation. A fault-tolerant design enables a system to continue its intended operation, possibly at a reduced level, rather than failing completely, when some part of the system fails. The term is most commonly used to describe computer systems designed to continue more or less fully operational with, perhaps, a reduction in throughput or an increase in response time in the event of some partial f ... [...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 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 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 crossbar has a matrix with ''M'' × ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Space Agency
, owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (12052189474).jpg , size = , caption = , acronym = , established = , employees = 2,200 , administrator = Director General Josef Aschbacher , budget = €7.2 billion (2022) , language = English and French (working languages) , website = , logo = European Space Agency logo.svg , logo_caption = Logo , image_caption = European Space Operations Centre (ESOC) Main Control Room The European Space Agency (ESA; french: Agence spatiale européenne , it, Agenzia Spaziale Europea, es, Agencia Espacial Europea ASE; german: Europäische Weltraumorganisation) is an intergovernmental organisation of 22 member states dedicated to the exploration of space. Established in 1975 and headquartered i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive Emitter Coupled Logic
In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar transistor logic family. ECL uses an overdriven bipolar junction transistor (BJT) differential amplifier with single-ended input and limited emitter current to avoid the saturated (fully on) region of operation and its slow turn-off behavior. As the current is steered between two legs of an emitter-coupled pair, ECL is sometimes called ''current-steering logic'' (CSL), ''current-mode logic'' (CML) or ''current-switch emitter-follower'' (CSEF) logic. In ECL, the transistors are never in saturation, the input and output voltages have a small swing (0.8 V), the input impedance is high and the output impedance is low. As a result, the transistors change states quickly, gate delays are low, and the fanout capability is high. In addition, the essentially constant current draw of the differential amplifiers minimises delays and glitches due to supply-line inductance and capacitance, and the complement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swift Gamma-Ray Burst Mission
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 lau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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