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Leaky Feeder
A leaky feeder is a communications system used in underground mining and other tunnel environments. Manufacturers and cabling professionals use the term "radiating cable" as this implies that the cable is designed to radiate: something that coaxial cable is not generally supposed to do. Principle A ''leaky feeder'' communication system consists of a cable run along tunnels which emits and receives radio waves, functioning as an extended antenna. The cable is "leaky" in that it has gaps or slots in its outer conductor to allow the radio signal to leak into or out of the cable along its entire length. Because of this leakage of signal, line amplifiers are required to be inserted at regular intervals, typically every 350 to 500 metres, to boost the signal back up to acceptable levels. The signal is usually picked up by portable transceivers carried by personnel. Transmissions from the transceivers are picked up by the feeder and carried to other parts of the tunnel, allowing two-wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaky Feeder Cable
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Leakey may refer to: *Leakey, Texas, U.S., a city *Leakey (crater), a lunar impact crater *Leakey (surname) *7958 Leakey, an asteroid *Leakey Independent School District, a public school district based in Leakey, Texas See also *Leak (other) __NOTOC__ A leak is a way for matter to escape a container. Leak may also refer to: Information leaks * News leak, the unsanctioned release of confidential information to news media * Data leak ** Internet leak, a release of confidential informati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delhi Metro
The Delhi Metro is a mass rapid transit (MRT) system serving Delhi and its satellite cities of Ghaziabad, Faridabad, Gurgaon, Noida, Bahadurgarh and Ballabhgarh, in the National Capital Region of India. The network consists of 10 colour-coded lines serving 255 stations with a total length of . It is by far the largest and busiest metro rail system in India, and the second oldest after the Kolkata Metro. The system has a mix of underground, at-grade, and elevated stations using both broad-gauge and standard-gauge. Delhi Metro operates over 2,700 trips daily, starting at around 05:00 and ending at 23:30. Construction started in 1998, and the first elevated section ( Shahdara to Tis Hazari) on the Red Line opened on 25 December 2002. The first underground section ( Vishwa Vidyalaya – Kashmere Gate) on the Yellow Line opened on 20 December 2004. The development of the network was divided into phases. Phase I with 3 lines was completed by 2006, and Phase II in 2011 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WiFi
Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks in the world, used globally in home and small office networks to link desktop and laptop computers, tablet computers, smartphones, smart TVs, printers, and smart speakers together and to a wireless router to connect them to the Internet, and in wireless access points in public places like coffee shops, hotels, libraries and airports to provide visitors with Internet access for their mobile devices. ''Wi-Fi'' is a trademark of the non-profit Wi-Fi Alliance, which restricts the use of the term ''Wi-Fi Certified'' to products that successfully complete interoperability certification testing. the Wi-Fi Alliance consisted of more than 800 companies from around the world. over 3.05 bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transit Wireless
Transit Wireless is an American telecommunication company founded in 2005, based in New York City. It was formed as a consortium of several entities, including Dianet Communications. It specializes in building wireless communication infrastructure using distributed antenna system networks to provide Wi-Fi and cellular phone coverage in the places that are unreachable by traditional cellular phone services such as in the underground portions of the New York City Subway. In 2010, the company was injected with financial support from infrastructure company BAI Communications for its first project with the New York City Transit Authority The New York City Transit Authority (also known as NYCTA, the TA, or simply Transit, and branded as MTA New York City Transit) is a New York state public-benefit corporations, public-benefit corporation in the U.S. state of New York (state), New ..., which consisted of adding wireless access to subway stations. The architectural framework for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New York City Subway
The New York City Subway is a rapid transit system owned by the government of New York City and leased to the New York City Transit Authority, an affiliate agency of the state-run Metropolitan Transportation Authority (MTA). Opened on October 27, 1904, the New York City Subway is one of the world's oldest public transit systems, one of the most-used, and the one with the most stations, with 472 stations in operation (424 if stations connected by transfers are counted as single stations). Stations are located throughout the boroughs of Manhattan, Brooklyn, Queens, and the Bronx. The system has operated 24/7 service every day of the year throughout most of its history, barring emergencies and disasters. By annual ridership, the New York City Subway is the busiest rapid transit system in both the Western Hemisphere and the Western world, as well as the seventh-busiest rapid transit rail system in the world. In , the subway delivered rides, or about per weekday as of . On Octo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Antenna System
A distributed antenna system, or DAS, is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure. DAS antenna elevations are generally at or below the clutter level, and node installations are compact. A distributed antenna system may be deployed indoors (an iDAS) or outdoors (an oDAS). Concept As illustrated in the figure, the idea is to split the transmitted power among several antenna elements, separated in space so as to provide coverage over the same area as a single antenna but with reduced total power and improved reliability. A single antenna radiating at high power (a) is replaced by a group of low-power antennas to cover the same area (b). The idea was described in a paper by Saleh et al. in 1987. These antennas have recently been employed by several service providers in many areas around the United States. DAS is often used in scenarios where alternate te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Services Network
The Emergency Services Network is an LTE radio communications network under development in the United Kingdom to provide unified communication for British emergency services. It is intended to replace the existing TETRA-based Airwave network in 2026, seven years after the original planned date of 2019. The ESN is intended to offer the following services: * ESN Air, to support emergency services aircraft * ESN Connect, a SIM-only offer for vehicle modems and data-only devices * ESN Direct, a push-to-talk and messaging product for smartphones As part of the construction of the ESN, almost 300 extra 4G sites will be added to extend the reach of the EE network to more remote parts of the country. The ESN will also serve the London Underground network. History In April 2014, the government announced the Emergency Services Mobile Communications Programme (ESMCP) to migrate emergency services to a 4G-based network, to be called the Emergency Services Network. One of the intentions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7 July 2005 London Bombings
The 7 July 2005 London bombings, often referred to as 7/7, were a series of four coordinated suicide attacks carried out by Islamic terrorists in London that targeted commuters travelling on the city's public transport system during the morning rush hour. Three terrorists separately detonated three homemade bombs in quick succession aboard London Underground trains across the city and, later, a fourth terrorist detonated another bomb on a double-decker bus in Tavistock Square. The train bombings occurred on the Circle line near and at Edgware Road, and on the Piccadilly line near . Apart from the bombers, 52 UK residents of 18 different nationalities were killed and more than 700 were injured in the attacks, making it the UK's deadliest terrorist incident since the 1988 bombing of Pan Am Flight 103 near Lockerbie, as well as the country's first Islamist suicide attack. The explosions were caused by improvised explosive devices made from triacetone triperoxide, pack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
King's Cross Fire
The King's Cross fire was a 1987 fire in a London Underground station with 31 fatalities, after a fire under a wooden escalator suddenly spread into the underground ticket hall in a flashover. The fire began at approximately 19:30 on 18 November 1987 at King's Cross St Pancras tube station, a major interchange on the London Underground. As well as the mainline railway stations above ground and subsurface platforms for the Metropolitan, Circle and Hammersmith & City lines, there were platforms deeper underground for the Northern, Piccadilly, and Victoria lines. The fire started under a wooden escalator serving the Piccadilly line and, at 19:45, erupted in a flashover into the underground ticket hall, killing 31 people and injuring 100. A public inquiry was conducted from February to June 1988. Investigators reproduced the fire twice, once to determine whether grease under the escalator was ignitable, and the other to determine whether a computer simulation of the fire—which wou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airwave Solutions
Airwave Solutions Ltd. is a British mobile communication company that operates the Airwave network, a mobile communications network used by Great Britain's emergency services. The Airwave network is based on the specialist Terrestrial Trunked Radio (TETRA) specification. Airwave was acquired by Motorola Solutions in February 2016 and now operates as a wholly owned subsidiary. The Airwave network is due to be replaced by the LTE-based Emergency Services Network in 2026. History Airwave was established in 2000 by BT as BT Airwave. BT Airwave along with BT Quadrant secured a Public Private Partnership (PPP) contract worth £2.5bn to supply of Professional Mobile Radio (PMR) communications to the police and other ‘blue light’ services. BT Airwave was part of the BT Wireless division which was spun off from BT Group in 2002 to ultimately become part of O2 and became Airwave O2 Limited, commonly known as O2 Airwave. In April 2007, Airwave was acquired by two Macquarie Gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Gazette International
''Railway Gazette International'' is a monthly business magazine and news website covering the railway, metro, light rail and tram industries worldwide. Available by annual subscription, the magazine is read in over 140 countries by transport professionals and decision makers, railway managers, engineers, consultants and suppliers to the rail industry. A mix of technical, commercial and geographical feature articles, plus the regular monthly news pages, cover developments in all aspects of the rail industry, including infrastructure, operations, rolling stock and signalling. History ''Railway Gazette International'' traces its history to May 1835 as ''The Railway Magazine'', when it was founded by Effingham Wilson. The ''Railway Gazette'' title dates from July 1905, created to cover railway commercial and financial affairs. In April 1914 it merged with ''The Railway Times'', which incorporated '' Herapath's Railway Journal'', and in February 1935 it absorbed the ''Railway Eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
