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White Alice
The White Alice Communications System (WACS, "White Alice" colloquially) was a United States Air Force telecommunication network with 80 radio stations constructed in Alaska during the Cold War. It used tropospheric scatter for over-the-horizon links and microwave relay for shorter line-of-sight links. Sites were characterized by large parabolic, tropospheric scatter antennas as well as smaller microwave dishes for point-to-point links. The system connected remote Air Force sites in Alaska, such as Aircraft Control and Warning (AC&W), Distant Early Warning Line (DEW Line) and Ballistic Missile Early Warning System (BMEWS), to command and control facilities and in some cases it was used for civilian phone calls. The network was originally operated by the USAF, but was turned over to RCA for operations after 1969. The opening of satellite communication links in the 1970s made the system obsolete, and in 1979 it was replaced by an RCA satellite link that connected all of the statio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Alice Site, Tropospheric Antennas HAER AK-21-A-2
White is the lightness, lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully diffuse reflection, reflect and scattering, scatter all the visible spectrum, visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide. In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek and Roman temples were faced with white marble, and beginning in the 18th century, with the advent of neoclassical archite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Historic American Engineering Record
Heritage Documentation Programs (HDP) is a division of the U.S. National Park Service (NPS) responsible for administering the Historic American Buildings Survey (HABS), Historic American Engineering Record (HAER), and Historic American Landscapes Survey (HALS). These programs were established to document historic places in the United States. Records consist of measured drawings, archival photographs, and written reports, and are archived in the Prints and Photographs Division of the Library of Congress. Historic American Buildings Survey In 1933, NPS established the Historic American Buildings Survey following a proposal by Charles E. Peterson, a young landscape architect in the agency. It was founded as a constructive make-work program for architects, draftsmen and photographers left jobless by the Great Depression. It was supported through the Historic Sites Act of 1935. Guided by field instructions from Washington, D.C., the first HABS recorders were tasked with docume ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabola
In mathematics, a parabola is a plane curve which is mirror-symmetrical and is approximately U-shaped. It fits several superficially different mathematical descriptions, which can all be proved to define exactly the same curves. One description of a parabola involves a point (the focus) and a line (the directrix). The focus does not lie on the directrix. The parabola is the locus of points in that plane that are equidistant from both the directrix and the focus. Another description of a parabola is as a conic section, created from the intersection of a right circular conical surface and a plane parallel to another plane that is tangential to the conical surface. The line perpendicular to the directrix and passing through the focus (that is, the line that splits the parabola through the middle) is called the "axis of symmetry". The point where the parabola intersects its axis of symmetry is called the "vertex" and is the point where the parabola is most sharply curved. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Channel
A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for information transfer of, for example, a digital bit stream, from one or several '' senders'' to one or several '' receivers''. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second. Communicating an information signal across distance requires some form of pathway or medium. These pathways, called communication channels, use two types of media: Transmission line (e.g. twisted-pair, coaxial, and fiber-optic cable) and broadcast (e.g. microwave, satellite, radio, and infrared). In information theory, a channel refers to a theoretical ''channel model'' with certain error characteristics. In this more general view, a storage device is also a communication channel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexing
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - a physical transmission medium. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910. The multiplexed signal is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end. A device that performs the multiplexing is called a multiplexer (MUX), and a dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diversity Scheme
In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more Channel (communications), communication channels with different characteristics. Diversity is mainly used in radio communication and is a common technique for combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver. Alternatively, a redundant forward error correction code may be added and different parts of the message transmitted over different channels. Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels. Diversity techniques The following classes of diversity schemes can be identified: * Time diversity: Multiple versions of the same signal are transmitted at dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Diversity
Antenna diversity, also known as space diversity or spatial diversity, is any one of several wireless diversity schemes that uses two or more antennas to improve the quality and reliability of a wireless link. Often, especially in urban and indoor environments, there is no clear Line-of-sight propagation, line-of-sight (LOS) between transmitter and receiver. Instead the signal is reflected along multiple paths before finally being received. Each of these bounces can introduce phase shifts, time delays, attenuations, and distortions that can destructively interfere with one another at the aperture of the receiving antenna. Antenna diversity is especially effective at mitigating these Multipath propagation, multipath situations. This is because multiple antennas offer a receiver several observations of the same signal. Each antenna will experience a different interference environment. Thus, if one antenna is experiencing a Fading, deep fade, it is likely that another has a suffici ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boswell Bay White Alice Communications System Site - Tropospheric Antennas
Boswell may refer to: Places Canada * Boswell, British Columbia, a rural community * Boswell, British Columbia (Central Coast), a former cannery town * Mount Boswell, Alberta England * Boswell, a hamlet in Elkington, Lincolnshire United States * Boswell, Indiana, a town * Boswell, Oklahoma, a town * Boswell, Pennsylvania, a borough * Boswell Bay, Alaska, a place in Alaska People * Boswell (surname) *James Boswell (1740–1795), Scottish lawyer, diarist, author, and biographer of Samuel Johnson * Clan Boswell, a Lowland Scottish clan * Boisil or Boswell (died 661), Christian saint and abbot * Boswell Williams (1926–2014), Saint Lucian politician *Chris Boswell, placekicker for the Pittsburgh Steelers Education * The Boswells School, a secondary school in Chelmsford, Essex, England * Boswell High School, Fort Worth, Texas, United States * Boswell School, Izard County, Arkansas, United States, a school building on the National Register of Historic Places Other use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerial Tramway
An aerial tramway, sky tram, cable car, ropeway, aerial tram, telepherique, or seilbahn is a type of aerial lift which uses one or two stationary ropes for support while a third moving rope provides propulsion. With this form of lift, the grip of an aerial tramway cabin is fixed onto the propulsion rope and cannot be decoupled from it during operations. In comparison to gondola lifts, aerial tramways generally provide lower line capacities and higher wait times. Terminology Because of the proliferation of such systems in the Alpine regions of Europe, the French and German names, ''téléphérique'' and ''Seilbahn'', respectively, are often also used in an English language context. ''Cable car'' is the usual term in British English, as in British English the word ''tramway'' generally refers to a railed street tramway while in American English, ''cable car'' may additionally refer to a cable-pulled street tramway with detachable vehicles; e.g., San Francisco's cable cars. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Generator
A diesel generator (DG) (also known as a diesel Genset) is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy. This is a specific case of engine generator. A diesel compression-ignition engine is usually designed to run on diesel fuel, but some types are adapted for other liquid fuels or natural gas. Diesel generating sets are used in places without connection to a power grid, or as an emergency power supply if the grid fails, as well as for more complex applications such as peak-lopping, grid support, and export to the power grid. Diesel generator size is crucial to minimize low load or power shortages. Sizing is complicated by the characteristics of modern electronics, specifically non-linear loads. In size ranges around 50 MW and above, an open cycle gas turbine is more efficient at full load than an array of diesel engines, and far more compact, with comparable capital costs; but for regular part-loading, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Army Corps Of Engineers
, colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = LTG Scott A. Spellmon , commander1_label = Chief of Engineers and Commanding General of the U.S. Army Corps of Engineers , commander2 = MGbr>Richard J. Heitkamp, commander2_label = Deputy Chief of Engineers and Deputy Commanding General , commander3 = MGKimberly M. Colloton, commander3_label = Deputy Commanding General for Military and International Operations , commander4 = MGbr>William H. Graham, commander4_label = Deputy Commanding General for Civil and Emergency Operations , commander5 = COLbr>James J. Handura, commander5_label = Chief of Staff for the U.S. Army Corps of Engi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boswell Bay White Alice Communications System Site
Boswell may refer to: Places Canada * Boswell, British Columbia, a rural community * Boswell, British Columbia (Central Coast), a former cannery town * Mount Boswell, Alberta England * Boswell, a hamlet in Elkington, Lincolnshire United States * Boswell, Indiana, a town * Boswell, Oklahoma, a town * Boswell, Pennsylvania, a borough * Boswell Bay, Alaska, a place in Alaska People * Boswell (surname) *James Boswell (1740–1795), Scottish lawyer, diarist, author, and biographer of Samuel Johnson * Clan Boswell, a Lowland Scottish clan * Boisil or Boswell (died 661), Christian saint and abbot * Boswell Williams (1926–2014), Saint Lucian politician *Chris Boswell, placekicker for the Pittsburgh Steelers Education * The Boswells School, a secondary school in Chelmsford, Essex, England * Boswell High School, Fort Worth, Texas, United States * Boswell School, Izard County, Arkansas, United States, a school building on the National Register of Historic Places Other use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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