Q) Which of the following may be a cause of radio frequency interference?
A. Fundamental overload
C. Spurious emissions
D. All of these choices are correct
Fundamental overload - fundamental overload of a reciever is interference caused by very strong signals from a nearby source.
Harmonics - Powerful station transmitters may produce a small amount of output at twice their operating frequency (the "second harmonic"), and this can be a source of interference for stations operating at the same frequency as the second harmonic.
Spurious emissions - An emission, on frequencies outside the necessary bandwidth of a transmission, the level of which may be reduced without affecting the information being transmitted.
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 Radio Regulations.