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Heaviside Condition
The HEAVISIDE CONDITION, named for Oliver Heaviside (1850–1925), is the condition an electrical transmission line must meet in order for there to be no distortion of a transmitted signal. Also known as the DISTORTIONLESS CONDITION, it can be used to improve the performance of a transmission line by adding loading to the cable. CONTENTS * 1 The condition * 2 Background * 3 Derivation * 3.1 Line characteristics * 3.2 Characteristic impedance * 4 Practical use * 5 See also * 6 References * 7 Bibliography THE CONDITION Heaviside's model of a transmission line. A transmission line can be represented as a distributed element model of its primary line constants as shown in the figure
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Neper
The NEPER (symbol: Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. The unit's name is derived from the name of John Napier
John Napier
, the inventor of logarithms. As is the case for the decibel and bel, the neper is a unit of the International System of Quantities (ISQ), but not part of the International System of Units (SI), but it is accepted for use alongside the SI. CONTENTS * 1 Definition * 2 Units * 3 Applications * 4 See also * 5 Notes and references * 6 External links DEFINITIONLike the decibel , the neper is a unit in a logarithmic scale . While the bel uses the decadic (base-10) logarithm to compute ratios, the neper uses the natural logarithm , based on Euler\'s number (e ≈ 2.71828). The value of a ratio in nepers is given by L N p = ln x 1 x 2 = ln x 1 ln x 2
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Radian
The RADIAN is the standard unit of angular measure, used in many areas of mathematics . The length of an arc of a unit circle is numerically equal to the measurement in radians of the angle that it subtends; one radian is just under 57.3 degrees (expansion at  A072097 ). The unit was formerly an SI supplementary unit , but this category was abolished in 1995 and the radian is now considered an SI derived unit
SI derived unit
. Separately, the SI unit of solid angle measurement is the steradian . The radian is represented by the symbol RAD. An alternative symbol is c, the superscript letter c, for "circular measure", or the letter r, but both of those symbols are infrequently used as it can be easily mistaken for a degree symbol (°) or a radius (r). So for example, a value of 1.2 radians could be written as 1.2 rad, 1.2 r, 1.2rad, or 1.2c
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Impedance Matching
In electronics , IMPEDANCE MATCHING is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load. In the case of a complex source impedance ZS and load impedance ZL, maximum power transfer is obtained when Z S = Z L {displaystyle Z_{mathrm {S} }=Z_{mathrm {L} }^{*},} where the asterisk indicates the complex conjugate of the variable. Where ZS represents the characteristic impedance of a transmission line , minimum reflection is obtained when Z S = Z L {displaystyle Z_{mathrm {S} }=Z_{mathrm {L} },} The concept of impedance matching found first applications in electrical engineering , but is relevant in other applications in which a form of energy, not necessarily electrical, is transferred between a source and a load
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Intersymbol Interference
In telecommunication , INTERSYMBOL INTERFERENCE (ISI) is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as noise , thus making the communication less reliable. The spreading of the pulse beyond its allotted time interval causes it to interfere with neighboring pulses. ISI is usually caused by multipath propagation or the inherent non-linear frequency response of a channel causing successive symbols to "blur" together. The presence of ISI in the system introduces errors in the decision device at the receiver output. Therefore, in the design of the transmitting and receiving filters, the objective is to minimize the effects of ISI, and thereby deliver the digital data to its destination with the smallest error rate possible. Ways to alleviate intersymbol interference include adaptive equalization and error correcting codes
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Electric Telegraph
An ELECTRICAL TELEGRAPH is a telegraph that uses electrical signals , usually conveyed via dedicated telecommunication lines or radio . The electrical telegraph, or more commonly just TELEGRAPH, superseded optical semaphore telegraph systems , thus becoming the first form of electrical telecommunications . In a matter of decades after their creation in the 1830s, electrical telegraph networks permitted people and commerce to transmit messages across both continents and oceans almost instantly, with widespread social and economic impacts
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Transatlantic Telegraph Cable
A TRANSATLANTIC TELEGRAPH CABLE is an undersea cable running under the Atlantic Ocean
Atlantic Ocean
used for telegraph communications. The first was laid across the floor of the Atlantic from Telegraph
Telegraph
Field, Foilhommerum Bay, Valentia Island
Valentia Island
in western Ireland
Ireland
to Heart\'s Content in eastern Newfoundland . The first communications occurred August 16, 1858, reducing the communication time between North America and Europe
Europe
from ten days – the time it took to deliver a message by ship – to only 17 hours. Transatlantic telegraph cables have been replaced by transatlantic telecommunications cables . Landing of the Atlantic Cable of 1866, Heart's Content, Newfoundland, by Robert Charles Dudley, 1866. CONTENTS * 1 Early history * 2 Origins of the idea * 3 St
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Lord Kelvin
WILLIAM THOMSON, 1ST BARON KELVIN, OM , GCVO , PC , FRS , FRSE
FRSE
(/ˈkɛlvɪn/ ; 26 June 1824 – 17 December 1907) was a Scots-Irish mathematical physicist and engineer who was born in Belfast
Belfast
in 1824. At the University of Glasgow
Glasgow
he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics , and did much to unify the emerging discipline of physics in its modern form. He worked closely with mathematics professor Hugh Blackburn in his work. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. For his work on the transatlantic telegraph project he was knighted in 1866 by Queen Victoria , becoming Sir William Thomson
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Electrical Element
ELECTRICAL ELEMENTS are conceptual abstractions representing idealized electrical components , such as resistors , capacitors , and inductors , used in the analysis of electrical networks . All electrical networks can be analyzed as multiple electrical elements interconnected by wires. Where the elements roughly correspond to real components the representation can be in the form of a schematic diagram or circuit diagram . This is called a lumped element circuit model . In other cases infinitesimal elements are used to model the network in a distributed element model . These ideal electrical elements represent real, physical electrical or electronic components but they do not exist physically and they are assumed to have ideal properties, while actual electrical components have less than ideal properties, a degree of uncertainty in their values and some degree of nonlinearity
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Rational Function
In mathematics , a RATIONAL FUNCTION is any function which can be defined by a RATIONAL FRACTION, i.e. an algebraic fraction such that both the numerator and the denominator are polynomials . The coefficients of the polynomials need not be rational numbers , they may be taken in any field K. In this case, one speaks of a rational function and a rational fraction over K. The values of the variables may be taken in any field L containing K. Then the domain of the function is the set of the values of the variables for which the denominator is not zero and the codomain is L. The set of rational functions over a field K is a field, the field of fractions of the ring of the polynomial functions over K
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International Standard Book Number
The INTERNATIONAL STANDARD BOOK NUMBER (ISBN) is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an e-book , a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. The method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit STANDARD BOOK NUMBERING (SBN) created in 1966. The 10-digit ISBN format was developed by the International Organization for Standardization (ISO) and was published in 1970 as international standard ISO 2108 (the SBN code can be converted to a ten digit ISBN by prefixing it with a zero)
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Special
SPECIAL or SPECIALS may refer to: CONTENTS * 1 Music * 2 Film and television * 3 Other uses * 4 See also MUSIC * Special (album) , a 1992 album by Vesta Williams * "Special" (Garbage song) , 1998 * "Special" (Mew song) , 2005 * "Special" (Stephen Lynch song) , 2000 * The Specials
The Specials
, a British band * "Special", a song by Violent Femmes on The Blind Leading the Naked * "Special", a song on
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Maxwell's Equations
MAXWELL\'S EQUATIONS are a set of partial differential equations that, together with the Lorentz force
Lorentz force
law, form the foundation of classical electromagnetism , classical optics , and electric circuits . They underpin all electric, optical and radio technologies, including power generation, electric motors, wireless communication, cameras, televisions, computers etc. Maxwell's equations
Maxwell's equations
describe how electric and magnetic fields are generated by charges , currents , and changes of each other. One important consequence of the equations is that they demonstrate how fluctuating electric and magnetic fields propagate at the speed of light. Known as electromagnetic radiation , these waves may occur at various wavelengths to produce a spectrum from radio waves to γ-rays
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Repeater
In telecommunications , a REPEATER is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or baud rate . There are several different types of repeaters; a TELEPHONE REPEATER is an amplifier in a telephone line , an optical repeater is an optoelectronic circuit that amplifies the light beam in an optical fiber cable ; and a radio repeater is a radio receiver and transmitter that retransmits a radio signal. A broadcast relay station is a repeater used in broadcast radio and television
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Permeability (electromagnetism)
In electromagnetism , PERMEABILITY is the measure of the ability of a material to support the formation of a magnetic field within itself. Hence, it is the degree of magnetization that a material obtains in response to an applied magnetic field. Magnetic permeability
Magnetic permeability
is typically represented by the (italicized) Greek letter µ . The term was coined in September 1885 by Oliver Heaviside
Oliver Heaviside
. The opposite of magnetic permeability is magnetic reluctance. In SI units, permeability is measured in henries per meter (H/m or H·m−1), or equivalently in newtons per ampere squared (N·A−2). The permeability constant (µ0), also known as the magnetic constant or the permeability of free space, is a measure of the amount of resistance encountered when forming a magnetic field in a classical vacuum
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Cut-off Frequency
In physics and electrical engineering , a CUTOFF FREQUENCY, CORNER FREQUENCY, or BREAK FREQUENCY is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced (attenuated or reflected) rather than passing through. Typically in electronic systems such as filters and communication channels , cutoff frequency applies to an edge in a lowpass , highpass , bandpass , or band-stop characteristic – a frequency characterizing a boundary between a passband and a stopband. It is sometimes taken to be the point in the filter response where a transition band and passband meet, for example, as defined by a half-power point (a frequency for which the output of the circuit is −3 dB of the nominal passband value)
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