Patent ID: 7251572

Claim:
A method of measuring random timing jitter for a digital signal in a system under test, comprising the steps of: (a) processing consecutively sampled values of an instance of a bit pattern in the digital signal to produce an acquisition record; (b) measuring times of occurrence of consecutive edges in the acquisition record to form a corresponding time interval error record; (c) inspecting the acquisition record to form a transition pattern record indicative of instances in the bit pattern in the digital signal where the logical value changes; (d) forming the Fourier transform of the transition pattern record of step (c); (e) forming a work Fourier transform equal to the Fourier transform of the time interval error record of step (b); (f) forming a power density spectrum of the work Fourier transform; (g) subsequent to step (f), selecting a threshold that separates noise components within the power density spectrum of step (f) from peaks therein that are likely components of periodic timing jitter; (h) determining if a largest peak within the power density spectrum of step (f) exceeds the threshold selected in step (g); (i) only if the determination in step (h) is in the negative, then converting the work Fourier transform into a value to be understood as random timing jitter, else; (j) only if the determination in step (h) is in the affirmative, then diminishing the work Fourier transform by the convolution of the Fourier transform of the transition pattern with the Fourier transform of the sine of a frequency corresponding to the largest peak determined in step (h); and then (k) repeating steps (f), (g), (h) and (j) until step (i) has been performed.