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 = 4.6/106. 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. [T1.105.09-1996]