Merge to High bit rate digital subscriber line date September 2011 DSL technologies ITU G.991.1 is an International Telecommunication Union ITU standard for DSL that defines High bit rate Digital Subscriber Line HDSL . See also ITU T High bit rate Digital Subscriber Line HDSL External links http www.itu.int rec T REC G.991.1 en ITU T Recommendation G.991.1 High bit rate Digital Subscriber Line HDSL http www.itu.int rec recommendation.asp?type products&lang e&parent T REC G ITU T Recommendations Series G http www.itu.int ITU T index.html ITU T Category ITU T recommendations G.991.1 ... more details
DSL technologies Refimprove date July 2007 HDSL2 is the 2nd generation of HDSL with a 6dB Noise Margin, put simply it is another way to provision a T 1 line, only this technology relies on fewer wires two instead of four and therefore costs less to set up. Category Digital Subscriber Line Internet stub ... more details
Cleanup date August 2010 DSL technologies High bit rate digital subscriber line HDSL was the first DSL technology to use a higher frequency spectrum of copper, twisted pair cables. HDSL was developed in the US, as a better technology for high speed, synchronous circuits typically used to interconnect local exchange carrier systems, and also to carry high speed corporate data links and voice channels, using Digital Signal 1 T1 lines. HDSL service types include HDSL1, HDSL2 and HDSL4 and are typically transmitted over twisted pair cables or over fiber optics using the RLH Universal UHDSL fiber system. T carrier circuits operate at 1.544 Mbit s . These circuits were originally carried using a line code called alternate mark inversion AMI . Later the line code used was B8ZS . AMI did not have sufficient ... mile to 1.2 miles depending on conductor gauge and other circumstances. As in classical T carrier, HDSL ... T1 and E carrier E1 standards. A new standard was then developed by the ITU for HDSL, using the CAP ... s using two pairs of copper. HDSL gave the telcos a greater distance reach when delivering a T 1 circuit ... with AMI based repeaters that had to be used at every 35 db of attenuation about 1 mile . HDSL ... over the local serial interface. Unlike later ADSL , HDSL did not allow plain old telephone service POTS at baseband. HDSL gave way to two new technologies, called HDSL2 and symmetric digital subscriber ... and in some cases, as a generic designation for the entire HDSL family of protocols. See also ... G.991.1 High bit rate Digital Subscriber Line HDSL transceivers http www.commsdesign.com main 1999 08 9908feat2.htm HDSL Primer http www.thehistoryof.net history of dsl.html History of DSL DEFAULTSORT High Bit Rate Digital Subscriber Line Category Digital Subscriber Line bs HDSL ca High Data ... de alta velocidad binaria fr High bit rate Digital Subscriber Line it HDSL he DSL DSL pl High bit rate Digital Subscriber Line pt HDSL ru HDSL sk High Data Rate Digital Subscriber Line ... more details
Two binary, one quaternary 2B1Q is a physical layer encoder encoding used for Integrated Services Digital Network ISDN Basic Rate Interface BRI implementations. 2B1Q uses four signal levels, which are 450 mV, 150 mV, 150 mV and 450 mV, each 1Q equivalent to two bits 2b . A competing encoding technique, also used for ISDN basic rate interfaces, is 4B3T . To minimize error propagation , bit pairs dibits are assigned to voltage levels according to a Gray code , as follows class wikitable Dibit Signal level 10 450 mV 11 150 mV 01 150 mV 00 450 mV If the voltage is misread as an adjacent level, this will only cause a 1 bit error in the decoded data. 2B1Q is also used for some variants of HDSL . 2B1Q code is not DC balanced . Symbol rate is half of data rate. Bit encoding FOLDOC telecomm stub Category Line codes Category Integrated Services Digital Network ar 2 1 de 2B1Q Code it 2B1Q pl 2B1Q fi 2B1Q koodaus ... more details
Unreferenced auto yes date December 2009 Update date November 2010 Carrierless amplitude phase modulation CAP is a variant of quadrature amplitude modulation QAM . Instead of modulating the amplitude of two carrier waves, CAP generates QAM signal by combining two pulse amplitude modulation PAM signals filtered through two filters designed so that their impulse response s form a Hilbert transform Hilbert pair . CAP used for ADSL divides the available space into three bands. The range from 0 to 4 kHz is allocated for Plain old telephone service POTS transmissions. The range of 25 kHz to 160 kHz is allocated for upstream data traffic and the range of 240 kHz to 1.5 MHz is allocated for downstream data traffic. History CAP was the de facto standard for ADSL deployments up until 1996, deployed in 90 percent Citation needed date March 2011 of ADSL installs. Now it is deprecated in favour of Discrete multitone modulation Discrete MultiTone Modulation Discrete multitone modulation DMT , but it is still used for some variants of HDSL . DEFAULTSORT Carrierless Amplitude Phase Modulation Category Radio modulation modes Telecomm stub de Carrier less Amplitude Phase Modulation pl CAP telekomunikacja fi CAP tietoliikenne ... more details
MultiCom is the products name of a broad range of broadband router and firewalls, including VPN IPSec gateway with strong encryption and security, developed and manufactured by Lightning MultiCom in Switzerland , Europe . MultiCom products development originated at EPFL in Lausanne , in the Laboratory of Computer Communication in 1992 by a group of computer enthousiasts, which earlier developed the Smaky Swiss computer system. Later that year a startup, Lightning MultiCom was founded to commercialize these products, allowing multiple ways of network communication. The very first product developed, the Classic MultiCom, has been used by http www.switch.ch SWITCH , the Swiss academic Network for early remote links over ISDN . Later, the Pocket MultiCom 1998 http www.heise.de ct 98 21 088 review by C t has been considered as a high performance ISDN router computing router despite its small size. In 1999, the engineers took the decision to embedd the open source Linux operating system into MultiCom products for broadband Internet access for ADSL , CATV and HDSL SDSL lines. Carriers such as France Telecom and Swisscom , and Swiss banks picked the http www.lightning.ch products.html MultiCom Products for linking companies and schools to the Internet . Industrial http www.lightning.ch solutions.html Solutions have been developed around the MultiCom products. Even the European Space Agency has used these products for the European Geostationary Navigation Overlay Service EGNOS GPS extension project for its ground network. Category Computer hardware ... more details
transport systems, but if a copper Metallic span is used, the T1 is typically carried over an HDSL encoded copper line. Four wire HDSL does not require as many repeaters as conventional T1 spans. Newer two wire HDSLHDSL 2 equipment transports a full 1.544 Mbit s T1 over a single copper wire pair ... cable is used. HDSL 2 does not employ repeaters as does conventional four wire HDSL, or newer HDSL 4 systems. One advantage of HDSL is its ability to operate with a limited number of bridge taps, with no tap being closer than convert 500 ft m from any HDSL transceiver. Both two or four wire HDSL equipment ... more details
Refimprove date December 2008 DSL technologies Symmetric digital subscriber line SDSL can have two meanings In the wider sense it is a collection of Internet access technologies based on Digital subscriber line DSL that offer symmetric Bandwidth computing bandwidth Upstream networking upstream and downstream computer science downstream . It is considered the opposite of asymmetric digital subscriber line ADSL technologies where the upstream bandwidth is lower than the downstream bandwidth. In the narrow sense SDSL is a particular DSL variant that supports data only on a single line and does not support analog calls. SDSL technology SDSL is a rate adaptive digital subscriber line DSL variant with T carrier T1 E carrier E1 like data rates T1 1.544 Data rate units Megabit per second Mbit s , E1 2.048 Mbit s . It runs over one pair of copper wires, with a maximum range of convert 10000 ft m . It cannot co exist with a conventional voice service on the same pair as it takes over the entire bandwidth. ref cite web url http www.cisco.com en US docs internetworking technology handbook DSL Dig Subscr Ln.html wp1020696 title Internetworking Technology Handbook publisher Cisco Systems, Inc. accessdate 2008 12 03 ref Standardization efforts S DSL is a Proprietary protocol proprietary technology that was never standardized. As such it usually only interoperates with devices from the same vendor. It is the predecessor of single pair high speed digital subscriber line G.SHDSL which was standardized in February 2001 by International Telecommunication Union ITU T with recommendation G.991.2. ref cite web url http www.itu.int rec T REC G.991.2 en title G.991.2 Single pair high speed digital subscriber line SHDSL transceivers publisher ITU T accessdate 2008 12 04 ref SDSL is often confused with G.SHDSL and High bit rate Digital Subscriber Line HDSL ref cite web url http www.blackbox.co.uk technical techoverviews dsl.asp?id 2&tx Technology 20Overviews title Technology Overviews DSL pub ... more details
Multiple issues context July 2009 wikify July 2009 refimprove March 2011 A circuit ID is a company specific identifier assigned to a data or voice network between two locations. This circuit, for example a tie line , is then leased to a customer by that ID. A subscriber having an issue with a circuit contacts the telecommunications provider to provide this circuit ID for action on the designated circuit. Telecom Circuit ID formats The Local Exchange Carrier LEC circuit ID s are based on Telcordia Technologies Common Language Coding. At one time, the abbreviations were meaningful for example, HC for hi capacity but the complexity of the business no longer allows for it. XX YYYY 000000 111 CC SEG prefix service code service code modifier serial suffix company identifier segment name Prefix, set by administration areas for each company. They may or may not be based on Local access and transport area LATA Service code, the type of service this circuit is providing Service code modifier, modifies the service code, often used for different billing options. Serial number, 6 digit numeric identifier Suffix, if a service has multiple legs or drops this will further identify the location. Company identifier, identifies the controlling LEC. Segment, the drop NAME for a multi point circuit. Example 73 HCGS 123456 000 NE is a T1 Circuit by New England Telephone 44 AQDU 987654 000 G4 is a HDSL Circuit by G4 Telecom Service Codes Qwest Serial number format AA BBBB CCCCCCC DDD EE F ref name qwest cite web url http www.qwest.com wholesale systems WebHelp reference circuit id formats guide.htm title Guide to Circuit ID Formats publisher Qwest accessdate 2011 03 08 ref A Prefix 1 2 alphanumeric characters. Optional. B Service Code Modifier 2 4 Characters. Required. C Serial Number 1 4 digits. Required D Suffix 3 character suffix to the serial number. May be required. Rarely used E CO Company Code 2 4 alphabetic characters NW, MS, PN Required. F Segment 1 3 alphanumeric characters. Opt ... more details
Infobox scientist Researchers category region Europe era 21st century Researchers color B0C4DE Image and caption image Pedro crespo.jpg caption Professor Pedro Crespo CEIT, 2010 Information name Pedro Crespo Bofill death date death place fields Electrical Engineering, Electronics & Communications school tradition main interests Telecommunications known for Professor of Engineering at Tecnun and Head of Electronics & Communications Research at CEIT influences influenced residence Donostia San Sebasti n , Spain citizenship Spanish nationality workplaces alma mater University of Southern California doctoral advisor academic advisors doctoral students notable students awards Bell Communications Research Award of Excellence Pedro Crespo full name Pedro M. Crespo Bofill is the current Professor of Electrical Engineering at the Tecnun School of Engineering of the University of Navarre in Spain, as well as the Head of the Electronics & Communications Department at CEIT Research Institute. ref http www.ceit.es index.php?option com personal&view detalle&trbId 125&catId 118&prsId 0&Itemid 25&lang en ref Armed with two Master of Science degrees in Applied Mathematics and Electrical Engineering, Professor Crespo began his lecturing career as a teaching assistant at the University of Southern California , where he subsequently obtained a PhD in Electrical Engineering in 1984. He spent eight years at the laboratories of Bell Communications Research now Telcordia Technologies in New Jersey USA , gaining international recognition as a member of the group that originally researched, developed and obtained patents connected with the first HDSL and ADSL modems. ref http www.unav.es english news 51.html ref Dr Crespo is a senior member of the Institute of Electrical and Electronics Engineers IEEE and a recipient of the Bell Communications Research Award for his contributions to the development of ISDN . ref http www.tecnun.es ieeeitsp ref Prior to his appointment in CEIT , he was the te ... more details
DSL technologies Image VDSL Modem.jpg thumb This VDSL modem used in Taiwan provides 4 Ethernet ports and an internal filter for voice data separation. Very high bit rate digital subscriber line VDSL or VHDSL ref cite web url http www.kpn.com artikel.htm?contentid 2895 publisher KPN title KPN starts VDSL trials ref is a digital subscriber line DSL technology providing faster data transmission over a single flat untwisted or twisted pair of copper wires up to 52 Mbit s Downstream networking downstream and 16 Mbit s Upstream networking upstream , ref cite web url http computer.howstuffworks.com vdsl2.htm publisher HowStuffWorks title VDSL Speed ref and on coaxial cable up to 85 Mbit s down and upstream ref cite web url http www.etherwan.com Product ViewProduct.asp?View 64 publisher EtherWAN title Industrial VDSL Ethernet Extender Over Coaxial Cable, ED3331 ref using the frequency band from 25 kHz to 12 MHz. ref cite web url http www.itu.int rec T REC G.993.1 200406 I en publisher ITU title G.993.1 06 04 ref These rates mean that VDSL is capable of supporting applications such as high definition television , as well as telephone services voice over IP and general Internet access , over a single connection. VDSL is deployed over existing wiring used for Plain old telephone service analog telephone service and lower speed DSL connections. This standard was approved by ITU in November 2001. Second generation systems very high speed digital subscriber line 2 VDSL2 ITU T G.993.2 approved in February 2006 use frequencies of up to 30 MHz to provide data rates exceeding 100 Mbit s simultaneously in both the upstream and downstream directions. The maximum available bit rate is achieved at a range of about 300 meters performance degrades as the loop attenuation increases. Development The concept of VDSL was first published in 1991 through a joint Bellcore Stanford research study. The study searched for potential successors to the then prevalent ... more details
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