In the physical sciences and in telecommunication, the term frequency shift has the following meanings:

A Doppler shift

Any change in frequency

Any change in the frequency of a radio transmitter or oscillator. (Note: In the radio regime, frequency shift is also called rf shift.)

In facsimile, a frequency modulation system where one frequency represents picture black and another frequency represents picture white. Frequencies between these two limits may represent shades of gray

This article contains material from the Federal Standard 1037C (in support of MIL-STD-188), which, as a work of the United States Government, is in the public domain.