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Encyclopedia > Nominal power

Nominal power is a measurement of a mediumwave radio station's output used in the United States. AM broadcasters are licensed by the Federal Communications Commission to operate at a specific nominal power, which may be (and usually is) different from the transmitter power output. Measurement is the determination of the size or magnitude of something. ... Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ... A radio station is a site configured for broadcasting sound. ... The United States of America — also referred to as the United States, the U.S.A., the U.S., America, the States, or (archaically) Columbia—is a federal republic of 50 states located primarily in central North America (with the exception of two states: Alaska and Hawaii). ... Broadcast could refer to: Broadcast, an electronica musical group broadcasting, the distribution of audio and video signals Broadcast address, an IP address allowing information to be sent to all machines on a given subnet. ... The Federal Communications Commission (FCC) is an independent United States government agency, created, directed, and empowered by Congressional statute. ... Wikipedia does not yet have an article with this exact name. ... Mechanical power In physics, power (symbol: P) is the amount of work W done per unit of time t. ... Transmitter power output (TPO) is the actual amount of power (in watts) of RF energy that a transmitter produces at its output. ...

  • For non-directional stations, nominal power is normally equal to the RF power presented to the antenna, as determined from the base current and the antenna's nominal impedance at the carrier frequency.
  • For directional stations, nominal power is normally equal to the RF power at the common point (the point at which the transmitter output branches off into separate phasing networks for each tower).

In both cases, nominal power excludes losses in transmission lines between the tower or phasor and the transmitter; however, it includes losses in a resistor network used to decrease the efficiency of the antenna system. An omnidirectional antenna is an antenna system which radiates maximum power uniformly in all directions. ... Rf or RF may stand for: Radio frequency, a term in broadcasting Right field(er), a defensive position in baseball Rutherfordium (Rf), symbol for the chemical element RF, rheumatoid factor RF, a Mazda piston engine The Russian Federation This is a disambiguation page — a navigational aid which lists other pages... In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ... In electrical engineering, impedance is a measure for the manner and degree a component resists the flow of electrical current if a given voltage is applied. ... A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... A directional antenna is an antenna which transmits or receives maximum power in a particular direction. ... A tower is a high structure, usually man-made. ... Loss has several meanings including: Loss in electronics is the ratio of the system output to system input In electronics, loss is the ratio of system output to system input. ... In physics a Phasor describes the phase of a particle in a simple harmonic motion or a wave motion. ...


Nominal power is ultimately a historical artifact of the regulatory regime employed by the FCC prior to the 1980s. In the old system, rather than allowing licensees to choose any power level which would meet the efficiency and interference standards for their class, stations were restricted to a small set of power levels: 50, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, and 50000 watts. A station whose maximum coverage would otherwise be available at 4500 watts (given a specific directional pattern and antenna system efficiency) had a choice of either living with 2500 watts, or reducing the antenna efficiency to a level which would allow for 5 kW. Newly-constructed stations could fairly easily design an antenna system to meet the requirements, but stations on or moving to a shared tower with higher efficiency had a problem. The resistor network exception was created to allow stations to reduce their antenna efficiency without having to modify the existing tower. In the context of government and public services regulation (as a process) is the control of something by rules, as opposed to its prohibition. ... Events and trends The 1980s marked an abrupt shift towards more conservative lifestyles after the momentous cultural revolutions which took place in the 1960s and 1970s and the definition of the AIDS virus in 1981. ... Efficiency is the capability of acting or producing effectively with a minimum of waste, expense, or unnecessary effort. ... In communications, interference is anything which alters, modifies, or disrupts a message; as it travels along a channel, between a source and a receiver. ... The watt (symbol: W) is the SI derived unit for power. ...


Rules changes in the 1980s did away with the fixed set of power choices, allowing stations to choose an appropriate power level for their antenna system ("dial-a-power"), so there should no longer be any need for the concept of nominal power. However, stations still take advantage of the resistor exception in some cases, simply because they perceive the marketing advantage of higher power (or at least "round" power) to be worth the cost of the wasted energy. Traditionally, Marketing has been a term applied to the craft of linking the producers (or potential producers) of a product or service with customers, both existing and potential. ... Energy is a fundamental quantity that every physical system possesses; it allows us to predict how much work the system could be made to do, or how much heat it can exchange. ...


See also: effective radiated power, the regulatory analogue for VHF and UHF broadcasting In radio telecommunications, effective radiated power or ERP is determined by subtracting system losses from system gains. ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... This article is about the radio frequency. ...


  Results from FactBites:
 
epanorama.net/Amplifier power (1968 words)
Power measurement of an amp requires that the amp is properly terminated by Ohmic resistances of nominal value both at input and output.
The nominal power for speakers is defined quite differently: The continous power is measured by pink noise rather than a sinousoidal signal and it is applied for 24 hours.
If a manufacturer chooses to quote a power rating at 4 ohms in their advertising, the amp must be capable of delivering this much power after a 'warmup' period of operation at 1/3 power (which level actually dissipates _more_ heat in the output stage than full-power operation).
Definition of Nominal power (461 words)
For non-directional stations, nominal power is normally equal to the RF power presented to the antenna, as determined from the base current and the antenna's nominal impedance at the carrier frequency.
For directional stations, nominal power is normally equal to the RF power at the common point (the point at which the transmitter output branches off into separate phasing networks for each tower).
Nominal power is ultimately a historical artifact of the regulatory regime employed by the FCC prior to the 1980s.
  More results at FactBites »

 
 

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