Patent ID: 7248981

Claim:
A jitter measuring apparatus comprising: an orthogonal signal generating unit which converts a signal to be measured into two orthogonal signals which are two signals whose phases are orthogonal to one another; an instantaneous phase calculating unit which calculates an instantaneous phase based on the two orthogonal signals converted by the orthogonal signal generating unit within a range between a lower limit phase value set in advance and an upper limit phase value set in advance; a differential value detecting unit which detects a differential value of the instantaneous phase calculated by the instantaneous phase calculating unit; a differential value correcting unit which corrects the differential value of the instantaneous phase, and which outputs a corrected differential value when the differential value of the instantaneous phase detected by the differential value detecting unit is over the range dependent on the lower limit phase value and the upper limit phase value; an offset component eliminating unit which eliminates an offset component included in the corrected differential value from the corrected differential value output by the differential value correcting unit, and which outputs a differential value from which the offset component has been eliminated; and an integration unit which determines a jitter amount of the signal to be measured by integrating the differential value which is output by the offset component eliminating unit, and from which the offset component has been eliminated.