Permissible Interference:3 Observed or predicted interference which 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); and

  • 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 which 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: Consist of spurious emissions and out-of-band emissions. (RR)


The terms “accepted interference” and “permissible interference” are used in the coordination of frequency assignments between administrations.

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