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Backward Channel
In a data transmission circuit a backward channel is the channel that passes data in a direction opposite to that of its associated forward channel. The backward channel is usually used for transmission of request, supervisory, acknowledgement, or error-control signals. The direction of flow of these signals is opposite to that in which user information is being transferred. The backward-channel bandwidth is usually less than that of the primary channel, that is, the forward (user information) channel. For example, ADSL's upstream channel, considered a backward channel for some types of analysis, typically has a bandwidth less than one-fourth of the downstream channel. In data transmission, it is a secondary channel in which the direction of transmission is constrained to be opposite to that of the primary, ''i.e.'', the forward (user-information) channel. The direction of transmission in the backward channel is restricted by the control interchange circuit that controls the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Transmission Circuit
In telecommunication, a data transmission circuit is the transmission media and the intervening equipment used for the data transfer between data terminal equipment ( DTEs). A data transmission circuit includes any required signal conversion equipment. A data transmission circuit may transfer information in (a) one direction only, (b) either direction but one way at a time, or (c) both directions simultaneously. See duplex (telecommunications). See also * Telecommunication circuit A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved over time from generally being built on physical connections between individual hardware cables, as in an analog phone swit ... References Data transmission {{telecomm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Channel
A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for information transfer of, for example, a digital bit stream, from one or several '' senders'' to one or several '' receivers''. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second. Communicating an information signal across distance requires some form of pathway or medium. These pathways, called communication channels, use two types of media: Transmission line (e.g. twisted-pair, coaxial, and fiber-optic cable) and broadcast (e.g. microwave, satellite, radio, and infrared). In information theory, a channel refers to a theoretical ''channel model'' with certain error characteristics. In this more general view, a storage device is also a communication channel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acknowledgement (data Networks)
In data networking, telecommunications, and computer buses, an acknowledgment (ACK) is a signal that is passed between communicating processes, computers, or devices to signify acknowledgment, or receipt of message, as part of a communications protocol. The negative-acknowledgement (NAK or NACK) is a signal that is sent to reject a previously received message or to indicate some kind of error. Acknowledgments and negative acknowledgments inform a sender of the receiver's state so that it can adjust its own state accordingly. Many protocols contain checksums to verify the integrity of the payload and header. Checksums are used to detect data corruption. If a message is received with an invalid checksum (that is, the data received would have a different checksum than the message had), the receiver can know that some information was corrupted. Most often, when checksums are employed, a corrupted message received will either not be served an ACK signal, or will be served a NAK signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Error
An error (from the Latin ''error'', meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake. The etymology derives from the Latin term 'errare', meaning 'to stray'. In statistics, "error" refers to the difference between the value which has been computed and the correct value. An error could result in failure or in a deviation from the intended performance or behavior. Human behavior One reference differentiates between "error" and "mistake" as follows: In human behavior the norms or expectations for behavior or its consequences can be derived from the intention of the actor or from the expectations of other individuals or from a social grouping or from social norms. (See deviance.) Gaffes and faux pas can be labels for certain instances of this kind of error. More serious departures from social norms carry labels such as misbehavior and labels from the legal system, such as misdemeanor and crime. Departures ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Information
User information is information transferred across the functional interface between a source user and a telecommunications system for delivery to a destination user. In telecommunications systems, user information includes user overhead information Overhead information is digital information transferred across the functional interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Lin .... References * Data transmission {{Telecomm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetric Digital Subscriber Line
Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ADSL differs from the less common symmetric digital subscriber line (SDSL). In ADSL, bandwidth and bit rate are said to be asymmetric, meaning greater toward the customer premises ( downstream) than the reverse (upstream). Providers usually market ADSL as an Internet access service primarily for downloading content from the Internet, but not for serving content accessed by others. Overview ADSL works by using spectrum above the band used by voice telephone calls. With a DSL filter, often called ''splitter'', the frequency bands are isolated, permitting a single telephone line to be used for both ADSL service and telephone calls at the same time. ADSL is generally only installed for short distances from the telephone exchange (the last ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Transmission
Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication using radio spectrum, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal. Analog transmission is a method of conveying voice, data, image, signal or video information using a continuous signal which varies in amplitude, phase, or some other property in proportion to that of a variable. The messages are either represented by a sequence of pulses by means of a line code (''baseband transmission''), or by a limited set of continuously varying waveforms (''passband transmission''), using a digital modulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interchange Circuit
In telecommunication, an interchange circuit is a circuit that facilitates the exchange of data and signaling information between data terminal equipment In telecommunication, the term terminal equipment has the following meanings: * Communications equipment at either end of a communications link, used to permit the stations involved to accomplish the mission for which the link was established. * I ... ( DTE) and data circuit-terminating equipment ( DCE). An interchange circuit can carry many types of signals and provide many types of service features, such as control signals, timing signals, and common return functions. References Communication circuits Telecommunications equipment {{telecomm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Channel
In telecommunication, the term primary channel has the following meanings: # The communication channel that is designated as a prime transmission (telecommunications), transmission channel and is used as the first choice in restoring priority level, priority circuits. # In a communications network, the channel that has the highest data rate of all the channels sharing a common wiktionary:interface, interface. # The main Television channel of several operated by a broadcaster. A primary channel may support the data transfer, transfer of information in one direction only, either direction alternately, or both directions simultaneously. # On a computer motherboard, it is the first physical connector for an Integrated Drive Electronics, IDE or ATA drive. Sources * Network architecture {{telecomm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Return Channel
In communications systems, the return channel (also reverse channel or return link) is the transmission link from a user terminal to the central hub. Return links are often, but not always, slower than the corresponding forward links. Examples where this is true include asymmetric digital subscriber line, cable modems, mobile broadband and satellite internet access. The return channel need not use the same medium as the main channel. For example, some hybrid Internet access services use a one-way cable television system for the forward channel and a dial-up modem for the return channel. Even when the return and forward channels use the same medium, their differences often dictate the use of very different data modulation and coding techniques. For example, in a star radio network, only the central hub transmits on the forward link, so channel access method is a consideration only on the return link. The "forward/return" terminology is also used for spacecraft communication links ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Standard 1037C
Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. This document provides federal departments and agencies a comprehensive source of definitions of terms used in telecommunications and directly related fields by international and U.S. government telecommunications specialists. As a publication of the U.S. government, prepared by an agency of the U.S. government, it appears to be mostly available as a public domain resource, but a few items are derived from copyrighted sources: where this is the case, there is an attribution to the source. This standard was superseded in 2001 by American National Standard T1.523-2001, Telecom Glossary 2000, which is published by ATIS. The old standard is still frequently used, because the new standard is protected by copyright, as usual for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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