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Symmetric Digital Subscriber Line
A symmetric digital subscriber line (SDSL) is a digital subscriber line (DSL) that transmits digital data over the copper wires of the telephone network, where the bandwidth in the downstream direction, from the network to the subscriber, is identical to the bandwidth in the upstream direction, from the subscriber to the network. This symmetric bandwidth can be considered to be the opposite of the asymmetric bandwidth offered by asymmetric digital subscriber line (ADSL) technologies, where the upstream bandwidth is lower than the downstream bandwidth. SDSL is generally marketed at business customers, while ADSL is marketed at private as well as business customers. More specifically, SDSL can be understood as: * ''In the wider sense'', an umbrella term for all DSL variant which offer symmetric bandwidth, including IDSL, which offers 144 kbit/s, HDSL, HDSL2, G.SHDSL, which offers up to 22.784 Mbit/s over four pairs of copper wires, as well as the SDSL variant below ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Subscriber Line
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access. In ADSL, the data throughput in the upstream (networking), upstream direction (the direction to the service provider) is lower, hence the designation of ''asymmetric'' service. In symmetric digital subscriber line (SDSL) services, the downstream and upstream data rates are equal. DSL service can be delivered simultaneously with plain old telephone service, wired telephone service on the same telephone line since DSL uses higher frequency bands for data transmission. On the customer premises, a DSL filter is installed on each telephone to prevent undesirable interaction between DSL and telephone service. The bit rate of consumer ADSL services typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proprietary Protocol
In telecommunications, a proprietary protocol is a communications protocol owned by a single organization or individual. Intellectual property rights and enforcement Ownership by a single organization gives the owner the ability to place restrictions on the use of the protocol and to change the protocol unilaterally. Specifications for proprietary protocols may or may not be published, and implementations are not freely distributed. Proprietors may enforce restrictions through control of the intellectual property rights, for example through enforcement of patent rights, and by keeping the protocol specification a trade secret. Some proprietary protocols strictly limit the right to create an implementation; others are widely implemented by entities that do not control the intellectual property but subject to restrictions the owner of the intellectual property may seek to impose. Examples The Skype protocol is a proprietary protocol. The Venturi Transport Protocol (VTP) is a pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Interface Bit Rates
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, but lists are frequently written down on paper, or maintained electronically. Lists are "most frequently a tool", and "one does not ''read'' but only ''uses'' a list: one looks up the relevant information in it, but usually does not need to deal with it as a whole". Lucie Doležalová,The Potential and Limitations of Studying Lists, in Lucie Doležalová, ed., ''The Charm of a List: From the Sumerians to Computerised Data Processing'' (2009). Purpose It has been observed that, with a few exceptions, "the scholarship on lists remains fragmented". David Wallechinsky, a co-author of '' The Book of Lists'', described the attraction of lists as being "because we live in an era of overstimulation, especially in terms of information, and lists help ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISDN
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking systems with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance. Prior to ISDN, the telephone system consisted of digital links like T1/ E1 on the long-distance lines between telephone company offices and analog signals on copper telephone wires to the customers, the " last mile". At the time, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leased Line
A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by businesses to connect geographically distant offices. Unlike traditional telephone lines in the public switched telephone network (PSTN) leased lines are generally not switched circuits, and therefore do not have an associated telephone number. Each side of the line is permanently connected, always active and dedicated to the other. Leased lines can be used for telephone, Internet, or other data communication services. Some are ringdown services, and some connect to a private branch exchange (PBX) or router (computing), network router. The primary factors affecting the recurring lease fees are the distance between end stations and the Bandwidth (computing), bandwidth of the circuit. Since the connection does not carry third-party communic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Relay
Frame Relay (FR) is a standardized wide area network (WAN) technology that specifies the Physical layer, physical and data link layers of digital telecommunications channels using a packet switching methodology. Frame Relay was originally developed as a simplified version of the X.25 system designed to be carried over the emerging Integrated Services Digital Network (ISDN) networks. X.25 had been designed to operate over normal telephone lines that were subject to noise that would result in lost data, and the protocol featured extensive error correction to address this. ISDN offered dramatically lower error rates, in effect zero, and the extensive error correction overhead was no longer needed. The new protocol suite was essentially a cut-down X.25 with no error correction, leading to lower overhead, better channel efficiency, and often significantly overall higher performance than X.25. Like X.25, Frame Relay is normally used in a circuit switched layout, where connections betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Legacy System
Legacy or Legacies may refer to: Arts and entertainment Comics * " Batman: Legacy", a 1996 Batman storyline * '' DC Universe: Legacies'', a comic book series from DC Comics * ''Legacy'', a 1999 quarterly series from Antarctic Press * ''Legacy'', a 2003–2005 series released by Dabel Brothers Productions * Legacy, an alternate name for the DC supervillain Wizard * Legacy (Marvel Comics), an alias used by Genis-Vell, better known as Captain Marvel * Marvel Legacy, a comic book line introduced in 2017 * '' Star Wars: Legacy'', a 2006 series from Dark Horse * '' X-Men: Legacy'', a 1991 series from Marvel Comics * Legacy Virus, a fictional virus from the Marvel Universe Film * ''Legacy'', a 1975 American film starring Joan Hotchkis * '' Legacy: A Mormon Journey'', a 1990 film produced by The Church of Jesus Christ of Latter-day Saints * ''Legacy'' (1998 film), an American film starring David Hasselhoff * ''Legacy'' (2000 film), an American documentary film * ''Legacy'' (2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east. Europe shares the landmass of Eurasia with Asia, and of Afro-Eurasia with both Africa and Asia. Europe is commonly considered to be Boundaries between the continents#Asia and Europe, separated from Asia by the Drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea, and the waterway of the Bosporus, Bosporus Strait. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and Europe ... is formed by the Ural Mountains, Ural River, Caspian Sea, Caucasus Mountains, and the Black Sea with its outlets, the Bosporus and Dardanelles." Europe covers approx. , or 2% of Earth#Surface, Earth's surface (6.8% of Earth's land area), making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Bit Rate Digital Subscriber Line
High-bit-rate digital subscriber line (HDSL) is a telecommunications protocol standardized in 1994. It was the first digital subscriber line (DSL) technology to use a higher frequency spectrum over copper, twisted pair cables. HDSL was developed to transport DS1 services at 1.544 Mbit/s and 2.048 Mbit/s over telephone local loops without a need for repeaters. Successor technology to HDSL includes HDSL2 and HDSL4, proprietary SDSL, and G.SHDSL. Standardization HDSL was developed for T1 service at 1.544 Mbit/s by the American National Standards Institute (ANSI) Committee T1E1.4 and published in February 1994 as ANSI Technical Report TR-28. This American variant uses two wire pairs with at a rate of 784 kbit/s each, using the 2B1Q line code, which is also used in the American variant of the ISDN U interface. First products were developed in 1993. A European version of the standard for E1 service at 2.048 Mbit/s was published in February 1995 by the Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Telecommunication Union
The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information and communications technology, information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union, the first formal and permanent international organization. The organization significantly predates the UN, making it the oldest UN agency. Doreen Bogdan-Martin is the Secretary-General of ITU, the first woman to serve as its head. The ITU was initially aimed at helping connect Telegraphy, telegraphic networks between countries, with its mandate consistently broadening with the advent of new communications technologies; it adopted its current name in 1932 to reflect its expanded responsibilities over radio and the telephone. On 15 November 1947, the ITU entered into an agreement with the newly cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-pair High-speed Digital Subscriber Line
Single-pair high-speed digital subscriber line (SHDSL) is a form of symmetric digital subscriber line (SDSL), a data communications technology for equal transmit and receive (i.e. symmetric) data rate over copper telephone lines, faster than a conventional voiceband modem can provide. As opposed to other DSL technologies, SHDSL employs trellis-coded pulse-amplitude modulation (TC-PAM). As a baseband transmission scheme, TC-PAM operates at frequencies that include those used by the analog voice plain old telephone service (POTS). As such, a frequency splitter, or DSL filter, cannot be used to allow a telephone line to be shared by both an SHDSL service and a POTS service at the same time. Support of symmetric data rates made SHDSL a popular choice by businesses for private branch exchange (PBX), virtual private network (VPN), web hosting and other data services. SHDSL features symmetrical data rates in both the upstream and downstream directions, from 192 kbit/s to 2,312&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mbit/s
In telecommunications, data transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multiples of bits per second (bit/s) and bytes per second (B/s). For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second (Mbit/s). Standards for unit symbols and prefixes Unit symbol The International System of Quantities, ISQ symbols for the bit and byte are ''bit'' and ''B'', respectively. In the context of data-rate units, one byte consists of 8 bits, and is synonymous with the unit Octet (computing), octet. The abbreviation bps is often used to mean bit/s, so that when a ''1 Mbps'' connection is advertised, it usually means that the maximum achievable bandwidth is 1 Mbit/s (one million bits per second), which is 0.125 MB/s (megabyte per second), or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
