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Aguada Transmission Station
Naval Radio Transmitter Facility Aguada is a tall guyed radio mast erected by the United States Navy. It is used as a facility of the US Navy for ashore and U.S. and NATO ships, planes, and submarines operating at sea in areas of broadcast coverage near Aguada, Puerto Rico at by using radio waves in the very low frequency range. The Aguada transmission station, originally part of "The Naval Radio Transmitter Facility Aguada", works on very low frequency (VLF) 40.75 kHz with the callsign NAU. The Naval Radio Transmitter Facility Aguada, apparently consisted of three locations with guyed towers: the primary Aguada transmission station in a 330-acre site; the Naval Radio Receiver at a 242-acre site at Campamento Santiago in Salinas, Puerto Rico; and the Naval Radio Transmitter at a 408-acre site in Isabela County. Only the tallest with a height of 367.3 metres (1205 ft) is still standing and in use., while the other two were dismantled. It is the tallest structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Masts And Towers
Radio masts and towers are typically tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: guyed and self-supporting structures. They are among the tallest human-made structures. Masts are often named after the broadcasting organizations that originally built them or currently use them. In the case of a mast radiator or radiating tower, the whole mast or tower is itself the transmitting antenna. Terminology The terms "mast" and "tower" are often used interchangeably. However, in structural engineering terms, a tower is a self-supporting or cantilevered structure, while a mast is held up by stays or guys. Broadcast engineers in the UK use the same terminology. A mast is a ground-based or rooftop structure that supports antennas at a height where they can satisfactorily send or receive radio waves. Typical masts are of steel lattice or tubular steel construction. Masts themselves play no part in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Signal
An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals, or a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of roughly 20 to 20,000 Hz, which corresponds to the lower and upper limits of human hearing. Audio signals may be synthesized directly, or may originate at a transducer such as a microphone, musical instrument pickup, phonograph cartridge, or tape head. Loudspeakers or headphones convert an electrical audio signal back into sound. Digital audio systems represent audio signals in a variety of digital formats.Hodgson, Jay (2010). ''Understanding Records'', p.1. . An audio channel or audio track is an audio signal communications channel in a storage device or mixing console, used in operations such as multi-track recording and sound reinforcement. Signal flow Signal flow is the path an audio signal will take from source to the sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Radio Systems Of The United States
A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct military uniform. It may consist of one or more military branches such as an army, navy, air force, space force, marines, or coast guard. The main task of the military is usually defined as defence of the state and its interests against external armed threats. In broad usage, the terms ''armed forces'' and ''military'' are often treated as synonymous, although in technical usage a distinction is sometimes made in which a country's armed forces may include both its military and other paramilitary forces. There are various forms of irregular military forces, not belonging to a recognized state; though they share many attributes with regular military forces, they are less often referred to as simply ''military''. A nation's military may f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications And Electronic Installations Of The United States Navy
Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquiry studying them. There are many disagreements about its precise definition. John Peters argues that the difficulty of defining communication emerges from the fact that communication is both a universal phenomenon and a specific discipline of institutional academic study. One definitional strategy involves limiting what can be included in the category of communication (for example, requiring a "conscious intent" to persuade). By this logic, one possible definition of communication is the act of developing meaning among entities or groups through the use of sufficiently mutually understood signs, symbols, and semiotic conventions. An important distinction is between verbal communication, which happens through the use of a language, and non ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of VLF-transmitters
A list of VLF-transmitters and LF-transmitters, which work or worked on frequencies below 100 kHz. List of VLF transmissions Demolished References {{Reflist Time signal radio stations Radio navigation Submarines Military radio systems Radio spectrum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaii, United States
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state geographically located within the tropics. Hawaii comprises nearly the entire Hawaiian archipelago, 137 volcanic islands spanning that are physiographically and ethnologically part of the Polynesian subregion of Oceania. The state's ocean coastline is consequently the fourth-longest in the U.S., at about . The eight main islands, from northwest to southeast, are Niihau, Kauai, Oahu, Molokai, Lānai, Kahoolawe, Maui, and Hawaii—the last of these, after which the state is named, is often called the "Big Island" or "Hawaii Island" to avoid confusion with the state or archipelago. The uninhabited Northwestern Hawaiian Islands make up most of the Papahānaumokuākea Marine National Monument, the United States' largest protected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lualualei VLF Transmitter
VLF transmitter Lualualei is a facility of the United States Navy near Lualualei, Hawaii transmitting orders to submerged submarines in the very low frequency (VLF) range. Description VLF transmitter Lualualei, which operates under the callsign NPM on 21.4 kHz and 23.4 kHz. The station's current antenna was built in 1972; it consists of two guyed masts, each 458.11 metres (1503 feet) tall, which are configured as umbrella antennas. They are fed by an overhead cable, fixed to a tall mast at one end, and at the opposite end to a smaller grounded mast near the helix building via an insulator. At the time they were built, they were the tallest towers used for military purposes in the Western hemisphere. The two masts are also the tallest towers used for long wave transmissions in the Western hemisphere. Since the collapse of Warsaw Radio Mast, they may be the world's tallest structures that are electrically insulated from the ground. See also * VLF Tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maine, United States
Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and northwest, respectively. The largest state by total area in New England, Maine is the 12th-smallest by area, the 9th-least populous, the 13th-least densely populated, and the most rural of the 50 U.S. states. It is also the northeasternmost among the contiguous United States, the northernmost state east of the Great Lakes, the only state whose name consists of a single syllable, and the only state to border exactly one other U.S. state. Approximately half the area of Maine lies on each side of the 45th parallel north in latitude. The most populous city in Maine is Portland, while its capital is Augusta. Maine has traditionally been known for its jagged, rocky Atlantic Ocean and bayshore coastlines; smoothly contoured mountains; heavily for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VLF Transmitter Cutler
The VLF Transmitter Cutler is the United States Navy's very low frequency (VLF) shore radio station at Cutler, Maine. The station provides one-way communication to submarines of the Navy's Atlantic Fleet, both on the surface and submerged. It transmits with call sign NAA, at a frequency of 24 kHz and input power of up to 1.8 megawatts, and is one of the most powerful radio transmitters in the world. Establishment at Cutler, Maine The current Cutler Naval Station was built during 1960 and became operational on January 4, 1961. It has a transmission power of 2 megawatts. As with all VLF stations, the transmitter has a very small bandwidth, and so cannot transmit audio (speech) but only coded text messages, at a relatively low data rate. The transmission consists of a continuously encrypted minimum-shift keying (MSK) signal capable of multi channel operations. The transmitter uses the frequency 24.0 kHz. During the past it used 17.8 kHz. The callsign of the stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Tallest Structures – 300 To 400 Metres
This list of supertall structures is a third part of the List of tallest structures in the world. It contains past or present structures of any type, at least tall, but lower than . Other parts are: * List of tallest structures * List of tallest structures – 400 to 500 metres See the first part for terminology and general introduction. For terminology and notes see the first part of the list. Structures (past or present) between and Notable structures (past or present) between and For practical purposes to keep the list to a reasonable length, this part of the list contains only notable structures. Structures between and under construction This is an ''incomplete'' list of structures under construction at least high and lower than . Please correct (by adding further one or by putting completed structures in the upper table, if current height is over ). See also * List of tallest structures in the world * List of cities with most skyscrapers References Exte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Supertall Structures
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication With Submarines
Communication with submarines is a field within military communications that presents technical challenges and requires specialized technology. Because radio waves do not travel well through good electrical conductors like salt water, submerged submarines are cut off from radio communication with their command authorities at ordinary radio frequencies. Submarines can surface and raise an antenna above the sea level, or float a tethered buoy carrying an antenna, then use ordinary radio transmissions, however this makes them vulnerable to detection by anti-submarine warfare forces. Early submarines during World War II mostly traveled on the surface because of their limited underwater speed and endurance, and dove mainly to evade immediate threats or for stealthy approach to their targets. During the Cold War, however, nuclear-powered submarines were developed that could stay submerged for months. In the event of a nuclear war, submerged ballistic missile submarines have to be order ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
