Frequency deviation

Frequency deviation($f_{\Delta }$) is used inFM radioto describe the difference between the minimum or maximum extent of a frequency modulated signal, and the nominal center orcarrier frequency.The term is sometimes mistakenly used as synonymous withfrequency drift,which is an unintended offset of an oscillator from its nominal frequency.

The frequency deviation of a radio is of particular importance in relation tobandwidth,because less deviation means that more channels can fit into the same amount offrequency spectrum.TheFM broadcastingrange between 87.5 and 108 MHz uses a typical channel spacing of 100 or 200 kHz, with a maximum frequency deviation of +/-75 kHz, in some cases leaving a buffer above the highest and below the lowest frequency to reduce interaction with other channels.

The most common FM transmitting applications use peak deviations of +/-75 kHz (100 or 200 kHz spacing), +/-5 kHz (15–25 kHz spacing), +/-2.5 kHz (3.75-12.5 kHz spacing), and +/-2 kHz (8.33 kHz spacing, 7.5 kHz spacing, 6.25 kHz spacing or 5 kHz spacing).

See also

• Frequency modulation
• Carson bandwidth rule

References

• This article incorporatespublic domain materialfromFederal Standard 1037C.General Services Administration.Archived fromthe originalon 2022-01-22.(in support ofMIL-STD-188).