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Intercom (Magazine)
An intercom, also called an intercommunication device, intercommunicator, or interphone, is a stand-alone voice communications system for use within a building, small collection of buildings or portably within a small coverage area, which functions independently of the public telephone network. Intercoms are generally mounted permanently in buildings and vehicles, but can also be detachable and portable. Intercoms can incorporate connections to public address loudspeaker systems, walkie talkies, telephones, and other intercom systems. Some intercom systems incorporate control of devices such as signal lights and door latches. Intercoms are used on a wide variety of properties; from houses that only require one connection between a resident and the property's entrance to multi-unit apartments that require intercom hardware to be installed in every individual apartment. Some are equipped with video and its wiring (electrical installation) can be connected to the outside with a fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Telephone Magazine (1922) (14569859438)
A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell (jingle bell). Bells are usually cast from bell metal (a type of bronze) for its resonant properties, but can also be made from other hard materials. This depends on the function. Some small bells such as ornamental bells or cowbells can be made from cast or pressed metal, glass or ceramic, but large bells such as a church, clock and tower bells are normally cast from bell metal. Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Sports
In professional sports, as opposed to amateur sports, participants receive payment for their performance. Professionalism in sport has come to the fore through a combination of developments. Mass media and increased leisure have brought larger audiences, so that sports organizations or teams can command large incomes. As a result, more sportspeople can afford to make sport their primary career, devoting the training time necessary to increase skills, physical condition, and experience to modern levels of achievement. This proficiency has also helped boost the popularity of sports.Andy Miah Sport & the Extreme Spectacle: Technological Dependence and Human Limits' (PDF) Unpublished manuscript, 1998 In most sports played professionally there are many more amateur than professional players, though amateurs and professionals do not usually compete. History Baseball Baseball originated before the American Civil War (1861–1865). First played on sandlots in particular, scoring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Party Line (telephony)
A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers. Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. A majority of Bell System subscribers in the mid-20th century in the United States and Canada were served by party lines, which had a discount over individual service. During wartime shortages, these were often the only available lines. British users similarly benefited from the party line discount. Farmers in rural Australia and South Africa used party lines, where a single line spanned miles from the nearest town to one property and on to the next. History Telephone companies offered party lines beginning in the late 1800s, although subscribers in all but the most rural areas may have had the option to upgrade to individual line service at an additional monthly charge. The service was common in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pittock Mansion Intercom
Pittock may refer to: * Pittock Block, a building in downtown Portland, Oregon, U.S. * Pittock Dam, a dam in Woodstock, Ontario, Canada * Pittock House, a house in Camas, Washington, U.S. * Pittock Mansion, a French Renaissance-style "château" in Portland, Oregon, U.S. * Markle-Pittock House, a house in southwest Portland, Oregon, U.S. People with the surname * Amelia Pittock (born 1983), professional Australian squash player * Georgiana Burton Pittock (1845–1918), pioneer and community leader in Portland, Oregon, U.S. * Gordon Pittock (1909–1983), Canadian politician * Henry Pittock (1835–1919), American pioneer, newspaper editor, publisher, and wood and paper magnate * Murray Pittock Murray G. H. Pittock MAE FRSE (born 5 January 1962) is a Scottish historian, Bradley Professor of Literature at the University of Glasgow and Pro Vice Principal at the University, where he has served in senior roles including Dean and Vice Princip ... (born 1962), Scottish historian See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Mesh Network
A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. It can also be a form of wireless ad hoc network.Chai Keong Toh Ad Hoc Mobile Wireless Networks, Prentice Hall Publishers, 2002. A mesh refers to rich interconnection among devices or nodes. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. Mobility of nodes is less frequent. If nodes constantly or frequently move, the mesh spends more time updating routes than delivering data. In a wireless mesh network, topology tends to be more static, so that routes computation can converge and delivery of data to their destinations can occur. Hence, this is a low-mobility centralized form of wireless ad hoc network. Also, because it sometimes relies on static nodes to act as gateways, it is not a truly all-wireless ad hoc network. Mesh clients are often laptops, cell phones, and other wireless devices. Mesh routers forward traffic to and from the gat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limited to 2.5 milliwatts, giving it a very short range of up to . It employs UHF radio waves in the ISM bands, from 2.402GHz to 2.48GHz. It is mainly used as an alternative to wire connections, to exchange files between nearby portable devices and connect cell phones and music players with wireless headphones. Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 35,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. The IEEE standardized Bluetooth as IEEE 802.15.1, but no longer maintains the standard. The Bluetooth SIG oversees development of the specification, manages the qualification program, and protects the trademarks. A manufacturer must meet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PMR446
PMR446 (Private Mobile Radio, 446 MHz) is a licence exempt service in the UHF radio frequency band and is available for business and personal use in most countries throughout the European Union. PMR446 is typically used for small-site, same-building and line of sight outdoor activities. Equipment used ranges from consumer-grade to professional quality walkie-talkies (similar to those used for FRS/GMRS in the United States and Canada). Depending on surrounding terrain range can vary from a few hundred metres (in a city) to a few kilometres (flat countryside) to many kilometres from high ground. Historically, analogue FM is used but a digital voice mode has been available in radios conforming to digital private mobile radio (dPMR446) and digital mobile radio (DMR Tier 1) standards designed by ETSI. Originally 8 channels were available in analogue mode but this has now been increased to 16 channels. Typically PMR446 is used for both recreational and business use, addition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citizens Band Radio
Citizens band radio (also known as CB radio), used in many countries, is a land mobile radio system, a system allowing short-distance person-to-many persons bidirectional voice communication among individuals, using two way radios operating on 40 channels near 27 MHz (11 m) in the high frequency (a.k.a. shortwave) band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ( "ham" radio). In many countries, CB operation does not require a license, and (unlike amateur radio) it may be used for business or personal communications. Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to talk they press a " push to talk" button on their radio, which turns on their transmitter. Users ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorcycle Helmet
A motorcycle helmet is a type of helmet used by motorcycle riders. Motorcycle helmets contribute to motorcycle safety by protecting the rider's head in the event of an impact. They reduce the risk of head injury by 69% and the risk of death by 42%. Their use is required by law in many countries. Motorcycle helmets consist of a Polystyrene, polystyrene foam inner shell that absorbs the shock of an impact, and a protective plastic outer layer. Several variations exist, notably helmets that cover the chin area and helmets that do not. Some helmets provide additional conveniences, such as ventilation, face shields, sun visors, ear protection or intercom. Origins The origins of the crash helmet date back to the Brooklands race track in early 1914, when a medical officer, Dr. Eric Gardner, noticed he was seeing a motor cyclist with head injuries about every two weeks. He got a Mr. Moss of Bethnal Green to make canvas and shellac helmets stiff enough to stand a heavy blow and smooth e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Medical Technician
An emergency medical technician (EMT), also known as an ambulance technician, is a health professional that provides emergency medical services. EMTs are most commonly found working in ambulances. In English-speaking countries, paramedics are a separate profession that has additional educational requirements, qualifications, and scope of practice. EMTs are often employed by private ambulance services, municipal EMS agencies, governments, hospitals, and fire departments. Some EMTs are paid employees, while others (particularly those in rural areas) are volunteers. EMTs provide medical care under a set of protocols, which are typically written by a physician. Hazard controls EMTs are exposed to a variety of hazards such as lifting patients and equipment, treating those with infectious disease, handling hazardous substances, and transportation via ground or air vehicles. Employers can prevent occupational illness or injury by providing safe patient handling equipment, impleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Race Track
A race track (racetrack, racing track or racing circuit) is a facility built for racing of vehicles, athletes, or animals (e.g. horse racing or greyhound racing). A race track also may feature grandstands or concourses. Race tracks are also used in the study of animal locomotion. A ''racetrack'' is a permanent facility or building. ''Racecourse'' is an alternate term for a horse racing track, found in countries such as the United Kingdom, India, Australia, Hong Kong, and the United Arab Emirates. Race tracks built for bicycles are known as ''velodromes''. ''Circuit'' is a common alternate term for race track, given the circuit configuration of most race tracks, allowing races to occur over several laps. Some race tracks may also be known as ''speedways'', or ''raceways''. A ''race course'', as opposed to a ''racecourse'', is a nonpermanent track for sports, particularly road running, water sports, road racing, or rallying. Many sports usually held on race tracks also can occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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