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Longley–Rice Model
The Longley–Rice model (LR) is a radio propagation model: a method for predicting the attenuation of radio signals for a telecommunication link in the frequency range of 40 MHz to 100 GHz.John S. Seybold ''Introduction to RF propagation'' John Wiley and Sons, 2005 , page 143 Longley-Rice is also known as the irregular terrain model (ITM). It was created by scientists Anita Longley and Phil Rice of the then Central Radio Propagation Laboratory in Boulder, Colorado for the needs of frequency planning in television broadcasting in the United States in the 1960s and was extensively used for preparing the tables of channel allocations for VHF/ UHF broadcasting there. LR has two parts: a model for predictions over an area and a model for point-to-point link predictions. Publications A description of the method was published by the U.S. government under the title ''"Prediction of tropospheric radio transmission loss over irregular terrain. A computer method-1968"'', A. G. Longley an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation Model
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems. Several different types of propagation are used in practical radio transmission systems. ''Line-of-sight propagation'' means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used for medium-distance radio transmission, such as cell phones, cordless phones, walkie-tal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunication
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Range
A frequency band is an interval in the frequency domain, delimited by a lower frequency and an upper frequency. The term may refer to a radio band or an interval of some other spectrum. The frequency range of a system is the range over which it is considered to provide satisfactory performance, such as a useful level of signal with acceptable distortion characteristics. A listing of the upper and lower limits of frequency limits for a system is not useful without a criterion for what the range represents. Many systems are characterized by the range of frequencies to which they respond. Musical instruments produce different ranges of notes within the hearing range. The electromagnetic spectrum can be divided into many different ranges such as visible light, infrared or ultraviolet radiation, radio waves, X-rays and so on, and each of these ranges can in turn be divided into smaller ranges. A radio communications signal must occupy a range of frequencies carrying most of its ener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Broadcasting
A television network or television broadcaster is a telecommunications network for distribution of television program content, where a central operation provides programming to many television stations or pay television providers. Until the mid-1980s, television programming in most countries of the world was dominated by a small number of terrestrial networks. Many early television networks (such as NBC, the ABC, or the BBC) evolved from earlier radio networks. Overview In countries where most networks broadcast identical, centrally originated content to all of their stations and where most individual television transmitters therefore operate only as large " repeater stations", the terms "television network", "television channel" (a numeric identifier or radio frequency) and "television station" have become mostly interchangeable in everyday language, with professionals in television-related occupations continuing to make a differentiation between them. Within the industry, a ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point-to-point Link
In telecommunications, a point-to-point connection refers to a communications connection between two communication endpoints or nodes. An example is a telephone call, in which one telephone is connected with one other, and what is said by one caller can only be heard by the other. This is contrasted with a ''point-to-multipoint'' or ''broadcast'' connection, in which many nodes can receive information transmitted by one node. Other examples of point-to-point communications links are leased lines and microwave radio relay. The term is also used in computer networking and computer architecture to refer to a wire or other connection that links only two computers or circuits, as opposed to other network topologies such as buses or crossbar switches which can connect many communications devices. ''Point-to-point'' is sometimes abbreviated as ''P2P''. This usage of ''P2P'' is distinct from ''P2P'' meaning ''peer-to-peer'' in the context of file sharing networks or other data-shar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPLAT!
SPLAT! (short for an RF Signal Propagation, Loss, And Terrain analysis tool) is a GNU GPL-licensed terrestrial radio propagation model application initially written for Linux but has since been ported for Windows and OS X. SPLAT! can use the Longley-Rice path loss and coverage prediction using the Irregular Terrain Model to predict the behaviour and reliability of radio links, and to predict path loss. History Development started in 1997 by John A. Magliacane, KD2BD. The latest version 1.4.2 was published in 2014. In 2020 several authors started the development of a completely reworked version which was not published yet. The authors introduce multithreading, georeferenced outputs (GeoTIFF) and metrication Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional units of measurement to the metric system. This process began in F ... as defaults. Referen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
