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X.21
X.21, also referred to as X21, is an interface specification for differential communications introduced in the mid-1970s by the CCITT, now ITU-T. X.21 was the first digital signaling interface developed. The connector specification is defined by the ISO document 4903. At the time, most physical layer protocols such as RS-232-C and RS-449 use analog signaling. X.21 was first introduced as a means to provide a digital signaling interface for telecommunications. This includes specifications for DTE/ DCE physical interface elements, alignment of call control characters and error checking, elements of the call control phase for circuit switching Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel ( circuit) through the network before the nodes may communicate. The circuit guarantees the full ... services, and test loops. X.21 normally is found on a 15-pin D-sub connector and is ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Circuit-terminating Equipment
A data circuit-terminating equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a data transmission circuit. It is also called data communication(s) equipment and data carrier equipment. Usually, the DTE device is the terminal (or computer), and the DCE is a modem. In a ''data station'', the DCE performs functions such as signal conversion, coding, and line clocking and may be a part of the DTE or intermediate equipment. Interfacing equipment may be required to couple the DTE into a transmission circuit or channel and from a transmission circuit or channel into the DTE. Usage Although the terms are most commonly used with RS-232, several data communication standards define different types of interfaces between a DCE and a DTE. The DCE is a device that communicates with a DTE device in these standards. Standards that use this nomenclature include: * Federal Standard 1037C, MIL-STD-188 * RS-232 * Certain ITU-T standards in the V series (nota ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circuit Switched
Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel ( circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit. Circuit switching originated in analog telephone networks where the network created a dedicated circuit between two telephones for the duration of a telephone call. It contrasts with message switching and packet switching used in modern digital networks in which the trunklines between switching centres carry data between many different nodes in the form of data packets without dedicated circuits. Description The defining example of a circuit-switched network is the early analogue telephone network. When a call is made from one telephone to another, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Layer Protocols
Physical may refer to: *Physical examination In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ..., a regular overall check-up with a doctor * ''Physical'' (Olivia Newton-John album), 1981 ** "Physical" (Olivia Newton-John song) * ''Physical'' (Gabe Gurnsey album) * "Physical" (Alcazar song) (2004) * "Physical" (Enrique Iglesias song) (2014) * "Physical" (Dua Lipa song) (2020) *"Physical (You're So)", a 1980 song by Adam & the Ants, the B side to " Dog Eat Dog" * ''Physical'' (TV series), an American television series *'' Physical: 100'', a Korean reality show on Netflix See also {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foldoc License
The Free On-line Dictionary of Computing (FOLDOC) is an online, searchable, encyclopedic dictionary of computing subjects. History FOLDOC was founded in 1985 by Denis Howe and was hosted by Imperial College London. In May 2015, the site was updated to state that it was "no longer supported by Imperial College Department of Computing". Howe has served as the editor-in-chief since the dictionary's inception, with visitors to the website able to make suggestions for additions or corrections to articles. Open sourcing The dictionary incorporates the text of other free resources, such as the Jargon File, as well as covering many other computing-related topics. Due to its availability under the GNU Free Documentation License, a copyleft license, it has in turn been incorporated in whole or part into other free content projects, such as Wikipedia. Recognition * This site's brief 2001 review by a Ziff Davis Ziff Davis, Inc. is an American digital media and internet company. Fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T V
The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Communication Technology, such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, convenes every four years. ITU-T has a permanent secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Seizo Onoe (of Japan), whose 4-year term commenced on 1 January 2023. Seizo Onoe succeeded Chaesub Lee of South Korea, who was director from 1 January 2015 until 31 December 2022. Primary fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balanced Circuit
In electrical engineering, a balanced circuit is electronic circuitry for use with a balanced line, or the balanced line itself. Balanced lines are a common method of Signal transmission, transmitting many types of electrical Signal (electronics), signals between two points on two wires. In a balanced line, the two signal lines are of a Impedance matching, matched impedance to help ensure that Electromagnetic interference, interference, Electromagnetic induction, induced in the line, is common-mode signal, common-mode and can be removed at the receiving end by circuitry with good common-mode rejection. To maintain the balance, circuit blocks which interface to the line or are connected in the line must also be balanced. Balanced lines work because the interfering Electronic noise, noise from the surrounding environment induces equal noise voltages into both wires. By measuring the voltage difference between the two wires at the receiving end, the original signal is recovered wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unbalanced Circuit
In electrical engineering, an unbalanced circuit is one in which the transmission properties between the ports of the circuit are different for the two poles of each port. It is usually taken to mean that one pole of each port is bonded to a common potential (single-ended signalling) but more complex topologies are possible. This common point is commonly called ''ground'' or ''earth'' but it may well not actually be connected to electrical ground at all. Unbalanced circuits are to be contrasted to balanced circuits where the transmission paths are impedance balanced (the impedances are identical). Examples Passive filter The figure shows two versions of a simple low-pass filter, unbalanced version (A) and balanced version (B). Both circuits have exactly the same effect as filters, they have the same transfer function. However, on the unbalanced circuit, the bottom pole of the input port is connected directly to the bottom pole of the output port. Thus, the impedance betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RS-422
RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance, first issued in 1975, that specifies the electrical characteristics of a digital signaling circuit. It was meant to be the foundation of a suite of standards that would replace the older RS-232C standard with standards that offered much higher speed, better immunity from noise, and longer cable lengths. RS-422 systems can transmit data at rates as high as 10 Mbit/s, or may be sent on cables as long as at lower rates. It is closely related to RS-423, which uses the same signaling systems but on a different wiring arrangement. RS-422 specifies differential signaling, with every data line paired with a dedicated return line. It is the voltage difference between these two lines that defines the mark and space, rather than, as in RS-232, the difference in voltage between a data line and a local ground. As the ground voltage can differ at either end of the cable, this requ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RS-423
RS-423, also known as TIA/EIA-423, is a technical standard originated by the Electronic Industries Alliance that specifies electrical characteristics of a digital signaling circuit. Although it was originally intended as a successor to RS-232C offering greater cable lengths, it is not widely used. RS-423 systems can transmit data on cables as long as . It is closely related to RS-422, which used the same signaling systems but on a different wiring arrangement: RS-423 differed primarily in that it had a single return pin instead of one for each data pin. RS-423 specifies an unbalanced ( single-ended) interface, similar to RS-232, with a single, unidirectional sending driver, and allowing for up to 10 receivers. It is normally implemented in integrated circuit technology and can also be employed for the interchange of serial binary signals between DTE & DCE. Standard scope RS-423 is the common short form title of American National Standards Institute (ANSI) standard ''ANSI/TIA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total population of over 84 million in an area of , making it the most populous member state of the European Union. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The Capital of Germany, nation's capital and List of cities in Germany by population, most populous city is Berlin and its main financial centre is Frankfurt; the largest urban area is the Ruhr. Settlement in the territory of modern Germany began in the Lower Paleolithic, with various tribes inhabiting it from the Neolithic onward, chiefly the Celts. Various Germanic peoples, Germanic tribes have inhabited the northern parts of modern Germany since classical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
