Group delay is an important parameter describing network transfer delay and distortion characteristics.Traditional definition and measurement formula of group delay is based on derivative

which has some inherent faults: the inconsistency of resolution and accuracy

incapacity to describe the global phase character of signal bandwidth and difficulty to describe phase distortion quantificationally.To resolve these problems

a new group delay definition and measurement formula has been put forward based on Taylor series expansion

which has been used in the GPS timing receiver RF cable group delay measurement.The experiment shows that the accuracy of the new group delay measurement is better than 0.01ns and consistent with the GPS signal delay.The maxim difference between the signal delay measured by GPS timing receiver and the zero order group delay measured by the new group delay measurement method is less than 0.3ns.