A Digital Method of Measuring Phase Jitter

All existing phase-jitter measuring techniques are limited in their ability to discern contributions of components greater than one-quarter of the carrier frequency. The digital technique used in this instrument measures the per-cycle differences in period directly to the nearest tenth of a degree. These deviations are summed over an appropriate number of cycles and displayed as average phase jitter. By storing the largest per-cycle discontinuity, true phase hits may be recorded. In both of the above measuring modes, no filters are used; hence, all phase jitter components contribute to the reading. With the aid of a unique phase-lock loop, any audio signal (300 Hz-3 kHz) may be used as the carrier.