Frequency Sharing occurs when a frequency band is allocated to more than one radiocommunication service. This condition implies a potential threat of harmful interference.
Concerning Frequency Sharing the ITU-R Radio Regulations use the following definitions:
Interference: The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, or loss of information which could be extracted in the absence of such unwanted energy.
Permissible Interference: Observed or predicted interference which complies with quantitative interference and sharing criteria contained in the ITU-R Radio Regulations or in CCIR Recommendations or in special agreements as provided for in the ITU-R Radio Regulations. The term "permissible interference" is used in the coordination of frequency assignments between administrations.
Acceptable Interference: Interference at a higher level than that defined as permissible interference and which has been agreed upon between two or more administrations without prejudice to other administrations. The term "permissible interference" is used in the coordination of frequency assignments between administrations.
Harmful Interference: Interference which endangers the functioning of a Radionavigation Service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with the ITU-R Radio Regulations.
Protection Ratio (R.F.): The minimum value of the wanted-to-unwanted signal ratio, usually expressed in decibels, at the receiver input, determined under specified conditions such that a specified reception quality of the unwanted signal is achieved at the receiver input.
Coordination Area: The area associated with an earth station outside of which a terrestrial station sharing the same frequency band neither causes nor is subject to interfering emissions greater than a permissible level.
Coordination Contour: The line enclosing the coordination area.
Coordination Distance: Distance on a given azimuth from an earth station beyond which a terrestrial station sharing the same frequency band neither causes nor is subject to interfering emissions greater than a permissible level.
Equivalent Satellite Link Noise Temperature: the noise temperature referred to the input of the receiving antenna of the earth station corresponding to the radio frequency noise power which produces the total observed noise at the output of the satellite links using other satellites and from terrestrial systems.
Effective Boresight Area (of a steerable satellite beam): An area on the surface of the Earth within which the boresight of a steerable satellite beam is intended to be pointed.
There may be more than one unconnected effective boresight area to which a single steerable satellite beam is intended to be pointed.
Effective Antenna Gain Contour (of a steerable satellite beam): An envelope
of antenna gain contours resulting from moving the boresight of a steerable
satellite beam along the limites of the
Last modified: January 4, 1998