The following National Telecommunications and Information Administration definitions are taken from the International Telecommunication Union (ITU) Radio Regulations,1 as indicated by the parenthetical “RR.”
Accepted Interference:2 Interference at a higher level than that defined as permissible interference and that has been agreed upon between two or more administrations without prejudice to other administrations. (RR)
Allocation (of a frequency band): Entry in the Table of Frequency Allocations of a given frequency band for the purpose of its use by one or more (terrestrial or space) radiocommunication services or the radio astronomy service under specified conditions. This term shall also be applied to the frequency band concerned. (RR)
Carrier Power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during one radio-frequency cycle taken under the condition of no modulation. (RR)
Class of Emission: The set of characteristics of an emission, designated by standard symbols, for example, type of modulation of the main carrier, modulating signal, type of information to be transmitted, and also if appropriate, any additional signal characteristics. (RR).
1 NOTE: The definitions in this appendix are reprinted from the National Telecommunications and Information Administration’s Manual of Regulations and Procedures for Federal Radio Frequency Management (Redbook) (2003 edition), available at http://www.ntia.doc.gov/osmhome/redbook/6.pdf, accessed June 17, 2015.
2 The terms “accepted interference” and “permissible interference” are used in the coordination of frequency assignments between administrations.
Effective Radiated Power (e.r.p.) (in a given direction): The product of the power supplied to the antenna and its gain relative to a halfwave dipole in a given direction. (RR)
Equivalent Isotropically Radiated Power (e.i.r.p.): The product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain). (RR)
Gain of an Antenna: The ratio, usually expressed in decibels, of the power required at the input of a loss free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength or the same power flux-density at the same distance. When not specified otherwise, the gain refers to the direction of maximum radiation. The gain may be considered for a specified polarization. Depending on the choice of the reference antenna a distinction is made between:
- absolute or isotropic gain (Gi), when the reference antenna is an isotropic antenna isolated in space;
- gain relative to a half-wave dipole (Gd), when the reference antenna is a half-wave dipole isolated in space whose equatorial plane contains the given direction;
- gain relative to a short vertical antenna (Gv), when the reference antenna is a linear conductor, much shorter than one quarter of the wavelength, normal to the surface of a perfectly conducting plane which contains the given direction. (RR)
Harmful Interference: Interference that endangers the functioning of a radio-navigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with these Regulations. (RR)
Interference: The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation, or loss of information that could be extracted in the absence of such unwanted energy. (RR)
Mean Power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long compared with the lowest frequency encountered in the modulation taken under normal operating conditions. (RR)
Necessary Bandwidth: For a given class of emission, the width of the frequency band that is just sufficient to ensure the transmission of information at the rate and with the quality required under specified conditions. (RR) (See Annex J for formulas used to calculate necessary bandwidth.)
Occupied Bandwidth: The width of a frequency band such that, below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage β/2 of the total mean power of a given emission. Unless otherwise specified by the ITU-R for the appropriate class of emission, the value of β/2 should be taken as 0.5%. (RR)
Out-of-band Emission: Emission on a frequency or frequencies immediately outside the necessary bandwidth that results from the modulation process, but excluding spurious emission. (RR)
Peak Envelope Power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during one radio-frequency cycle at the crest of the modulation envelope taken under normal operating conditions. (RR)
Permissible Interference:3 Observed or predicted interference that complies with quantitative interference and sharing criteria contained in these Regulations or in ITU-R Recommendations or in special agreements as provided for in these Regulations. (RR)
Power: Whenever the power of a radio transmitter etc. is referred to it shall be expressed in one of the following forms, according to the class of emission, using the arbitrary symbols indicated:
- peak envelope power (PX or pX);
- mean power (PY or pY);
- carrier power (PZ or pZ).
For different classes of emission, the relationships between peak envelope power, mean power, and carrier power, under the conditions of normal operation and of no modulation, are contained in ITU-R Recommendations, which may be used as a guide. For use in formulae, the symbol p denotes power expressed in watts, and the symbol P denotes power expressed in decibels relative to a reference level. (RR)
Spurious Emission: Emission on a frequency or frequencies that are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products, and frequency conversion products, but exclude out-of-band emissions. (RR)
Unwanted Emissions: A combination of both spurious and out-of-band emissions. (RR)
3 The terms “accepted interference” and “permissible interference” are used in the coordination of frequency assignments between administrations.