Spectrum Management - From the Early Years to the 1990s

by Laval Desbiens

Page 07 of 26

Definition of Interference


Below are a few definitions adapted from the Dictionary of Technical Terms for Aerospace Use (http://roland.lerc.nasa.gov/~dglover/dictionary//menu.html) and the McGraw-Hill Dictionary of Scientific and Technical Terms, 1978.



Extraneous signals, noises, etc. [e.g., a radio program] that hinder proper reception of the desired signal in electronic equipment.


The level of disruption of the usable or desired signal will vary according to the signal reception conditions and the intensity of the interfering signal.


A transmitter used in [voluntary] jamming of radio or radar transmissions.


Voluntary jamming has been used in some countries to prevent citizens from listening to broadcasts from other countries. It is also used in electronic warfare.


The interference is not always voluntary, i.e., the person causing the jamming may not know that his or her transmissions are interfering with another user's reception.


The jamming signal can originate from a transmitter but it can also come from another receiver, an electrical installation or metallic components that are not necessarily part of an electrical installation.


Any system or technique used to counteract the jamming of communications or of radar operation.


Including repairing defective installations, improving an antenna system, or adding a filter to the transmitter or receiver.


Co-channel interference

The phenomenon which results when waves of the same or nearly the same frequency are superposed.


One frequency being shared by many users in the same area is a type of interference that must be accepted for lack of available frequencies.

The noise produced on either side of the carrier frequency of a transmitter can be a source of interference.



Electrical disturbances in a communication channel as a result of coupling with other communication channels.


The usual industry term is "intermodulation". More than two transmitters can be involved.


Simply put, interference is any phenomenon that prevents or degrades the reception of a desired signal in some form.


Spectrum Management - From the Early Years to the 1990s

by Laval Desbiens