Nominal power is a measurement of a mediumwave radio station's output used in the United States. Measurement is the process of estimating the magnitude of some attribute of an object such as its length or weight relative to some standard ( unit of measurement) such as Medium Wave (MW is a part of the Medium frequency (MF radio band used mainly for AM broadcasting. This article is about radio broadcasting for other uses see Radio (disambiguation. The United States of America —commonly referred to as the 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. For the band see Broadcast (band Broadcasting is the distribution of audio and/or Video signals which transmit In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for In Radio transmission, transmitter power output ( TPO) is the actual amount of power (in Watts of Radio frequency (RF energy
- 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. An omnidirectional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal Alternating current (AC In Telecommunications, a carrier wave, or carrier is a Waveform (usually Sinusoidal) that is modulated (modified with an input signal Frequency is a measure of the number of occurrences of a repeating event per unit Time.
- 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). A directional antenna or beam antenna is an antenna which radiates greater power in one or more directions allowing for increased performance on transmit and receive Towers are tall human-made Structures that are always taller than they are wide usually by a significant Margin.
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. In Physics and Engineering, a phase vector ("phasor" is a representation of a Sine wave whose amplitude ( A) phase ( θ)
Nominal power is ultimately a historical artifact of the regulatory regime employed by the FCC prior to the 1980s. This article is for the legal term For regulation of genes see Regulation of gene expression. The 1980s was the decade spanning from January 1 1980 to December 31 1989. 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. In physics interference is the addition ( superposition) of two or more Waves that result in a new wave pattern The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. 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.
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. In popular usage "marketing" is the promotion of products especially Advertising and Branding However in professional usage the term has a wider meaning of In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός
See also: effective radiated power, the regulatory analogue for VHF and UHF broadcasting
In radio Telecommunications, effective radiated power or equivalent radiated power (ERP is a standardized theoretical measurement of radio frequency (RF Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz.