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Langenberg Transmission Tower
The Langenberg transmission tower (also translated as "Sender Langenberg" or "Transmission Facility Langenberg") is a broadcasting station that transmits MW, FM and TV signals. It is located in Langenberg, Velbert, Germany and has had a very turbulent history since its inauguration. The transmitter first went into service in 1927 with 60 kilowatts (kW) of power and a T-aerial hanging on two 100-metre freestanding steel-frame towers insulated against ground. Attempted manipulation In the early 1930s, communist underground groups tried to manipulate the line from the studio to the transmitter in order to broadcast their own propaganda. Their attempts failed, but they did manage to attach a red star to the top of one of the towers, which was removed on the same day. Modifications Pre-1945 In 1934 the T-aerial was replaced by an aerial hanging from a 160-metre wood framework tower and the transmission power was increased to 100 kW. However, this tower was destroyed on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Catastrophic Collapses Of Broadcast Masts And Towers
This is a list of catastrophic collapses of broadcast masts and towers. Masts and towers can collapse as a result of natural disasters, such as storms and fires; from engineering defects; and from accidents, sabotage and bendover. __TOC__ List of collapses References {{Disasters Antennas (radio) * History of structural engineering * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Towers
Several extant building fulfill the engineering definition of a tower: "a tall human structure, always taller than it is wide, for public or regular operational access by humans, but not for living in or office work, and are ''self-supporting'' or ''free-standing'', which means no guy-wires for support." This definition excludes continuously habitable buildings and skyscrapers as well as radio and TV masts. Also excluded because they are not designed for public or regular operational access are bridge towers or pylons, wind turbines, chimneys, transmission towers, sculptures and most large statues and obelisks. Towers are most often built to use their height for various purposes, and can stand alone or as part of a larger structure. Some common purposes are for telecommunications, and as a viewing platform. The Tokyo Skytree, completed in February 2012, is , making it the tallest tower, and third-tallest free-standing structure in the world. Entirely self-supported towers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Masts
The tallest structure in the world is the Burj Khalifa skyscraper at . Listed are guyed masts (such as telecommunication masts), self-supporting towers (such as the CN Tower), skyscrapers (such as the Willis Tower), oil platforms, electricity transmission towers, and bridge support towers. This list is organized by absolute height. See List of tallest buildings and structures, List of tallest freestanding structures and List of tallest buildings and List of tallest towers for additional information about these types of structures. Terminology Terminological and listing criteria follow Council on Tall Buildings and Urban Habitat definitions. Guyed masts are differentiated from towers – the latter not featuring any guy wires or other support structures; and buildings are differentiated from towers – the former having at least 50% of occupiable floor space although both are self-supporting structures. List by height This list includes structures with a minimum height of to k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Free Europe
Radio Free Europe/Radio Liberty (RFE/RL) is a United States government funded organization that broadcasts and reports news, information, and analysis to countries in Eastern Europe, Central Asia, Caucasus, and the Middle East where it says that "the free flow of information is either banned by government authorities or not fully developed". RFE/RL is a private, non-profit 501(c)(3) corporation supervised by the U.S. Agency for Global Media, an independent government agency overseeing all U.S. federal government international broadcasting services. Daisy Sindelar is the vice president and editor-in-chief of RFE. RFE/RL broadcasts in 27 languages to 23 countries. The organization has been headquartered in Prague, Czech Republic, since 1995, and has 21 local bureaus with over 500 core staff and 1,300 stringers and freelancers in countries throughout their broadcast region. In addition, it has 700 employees at its headquarters and corporate office in Washington, D.C. Radio Free Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polychlorinated Biphenyl
Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by the Stockholm Convention on Persistent Organic Pollutants in 2001. They are organic chlorine compounds with the formula C12 H10−''x'' Cl''x''; they were once widely used in the manufacture of carbonless copy paper, as heat transfer fluids, and as dielectric and coolant fluids for electrical equipment. Because of their longevity, PCBs are still widely in use, even though their manufacture has declined drastically since the 1960s, when a host of problems were identified. With the discovery of PCBs' environmental toxicity, and classification as persistent organic pollutants, their production was banned by United States federal law in 1978, and by the Stockholm Convention on Persistent Organic Pollutants in 2001. The International Agency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cage Aerial
A cage antenna (British cage aerial) is a radio antenna where a conventional design has been augmented by replacing a single long conductor with several parallel wires, connected at their ends, and held in position by ring spacers or support struts mounted on a central mast (if any). The "cage" is either mounted around a central mast (either conducting or non-conducting) or suspended from overhead wires. Purpose A cage can improve any antenna design by replacing a single wire in any section that carries large, unbalanced (radiating) current; the only issue is whether the improvement will be substantial enough to warrant the extra effort. The multiple parallel wires electrically simulate a single fat wire, roughly equivalent to a wire with a diameter half as wide as the distance separating the cage wires, giving the modified antenna higher radiation resistance, lowered conductor resistance, and a wider bandwidth without as much weight and wind resistance as the equivalent fat wire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Co-channel Interference
Co-channel interference or CCI is crosstalk from two different radio transmitters using the same channel. Co-channel interference can be caused by many factors from weather conditions to administrative and design issues. Co-channel interference may be controlled by various radio resource management schemes. Cellular mobile networks In cellular mobile communication (GSM & LTE Systems, for instance), frequency spectrum is a precious resource which is divided into non-overlapping spectrum bands which are assigned to different cells (In cellular communications, a cell refers to the hexagonal/circular area around the base station antenna). However, after certain geographical distance, these frequency bands are re-used, i.e. the same spectrum bands are reassigned to other distant cells. The co-channel interference arises in the cellular mobile networks owing to this phenomenon of frequency reuse. Thus, besides the intended signal from within the cell, signals at the same frequenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geneva Frequency Plan Of 1975
The Geneva Frequency Plan of 1975 (Aka "The Final Acts of the Regional Administrative LF/MF Broadcasting Conference (Regions 1 and 3) Geneva, 1975" or simply "GE75") is the internationally agreed frequency plan which was drawn up to implement the provisions of the Final Acts of the Regional Administrative LF/MF Broadcasting Conference (Regions 1 and 3) held in Geneva, Switzerland, in 1975. It covers radio broadcasting in the long and medium wave bands outside the Americas ( separate agreements being in place for North and South America). The plan was drawn up under the auspices of the World Administrative Radio Conference (WARC) of the International Telecommunication Union (ITU) with the assistance of the European Broadcasting Union (EBU/UER). The Geneva plan replaced the 1948 Copenhagen plan. It became necessary because of the large number of broadcasting stations in these frequency ranges leading to ever more mutual interference (Many countries had refused to ratify the Copen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilohertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its frequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
