fractional frequency offset
A measure of the deviation of the frequency of a signal from a reference, expressed as a ratio. The ratio is dimensionless but typically expressed as parts per million, ppm. For example,
4. 6 ppm =
4. 6/10
6. Fractional frequency offset = [(f-fr) / fr] where: f = the actual frequency output of the signal in question, and fr = the reference frequency. Synonym [in ITU-T Recommendation G.810] fractional frequency deviation. [T1.10
5. 09-1996]