Anritsu Corporation

Osamu Sugiyama

Ken Mochizuki

Tadanori Nishikobara

In order to stably measure an input interval time of a pulse signal with high precision, a time interval measuring apparatus includes a reference signal generator, a phase shifter, first and second A/D converters, an error correction unit, an instantaneous phase calculation unit, and an interval time calculation unit. The phase shifter divides a reference signal of a sine wave having a predetermined frequency from the reference signal generator into a first analog signal and a second analog signal having phases shifted to each other. The first and second A/D converters perform sampling of the first analog signal and the second analog signal from the phase shifter, respectively, at an input timing of a pulse signal to be measured, and output a first and second digital sample values. The error correction unit corrects direct current offset errors generated in, respectively, the first and second digital sample values output from the first and second A/D converters, a phase error with respect to 90&#xb0;, and an amplitude error. The instantaneous phase calculation unit calculates an instantaneous phase of the reference signal based on the corrected first and second digital sample values. The interval time calculation unit determines an input interval time of the pulse signal based on a variation of instantaneous phases.

Time interval measuring apparatus and jitter measuring apparatus using the same

An MTIE test signal generating apparatus generates a predetermined MTIE test signal. An MTIE measuring unit includes a low-pass measuring filter having a predetermined high-cut characteristic. A cycle-amplitude setting portion sets a cycle corresponding to an observation time of each of desired plural specific points for a predetermined MTIE characteristic and an amplitude corresponding to a difference in the MTIE value between adjacent specific points. Plural signal generating portions generate plural signals each having the cycle and the amplitude having repetitive waveforms and then outputting to each of the desired plural specific points. A holding time setting portion sets a holding time for holding the upper and lower limit values of the repetitive waveforms over the predetermined time so that a signal cycle having at least the shortest cycle of the plural signals is longer than a predetermined time corresponding to the predetermined high-cut characteristic of the low-pass measuring filter.

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Zama, Japan

Osamu Sugiyama