Feed back control approach for stabilization phase modulator index of PZT phase modulator in all-fiber optic gyroscope is described. Dual core fiber interferometric sensor is applied to detect phase modulating index of PZT cylinder. Fluctuation of modulator versus temperature variation can be approximately eliminated 15 dB by this method.

Data comparison and trigger skip methods are proposed to extract truly synchronized trigger from a high speed repetitive waveform to be observed on a CRT or to be written in a partially sequential digital sampling storage circuit. So far, there have been no way to automatically extract truly synchronized trigger from the input repetitive waveform in a multi-period sampling system, when an external synchronizing signal is not accompanied. Trigger extraction mechanisms from various kinds of repetitive waveform, for which, especially, a number of triggers can generate during its fundamental period are theoretically analysed. Based on the results, the principle and effectiveness of this system for various types of the waveform are described. The input waveform is taken twice in the sampling storage circuit, and successively taken two sample value streams are compared with each other. These two should agree if both are taken in the same portion of the waveform fundamental period. If they do not agree, it is judged to be due to incorrect trigger extraction, and the trigger skip number is increased. Data taking and comparison is repeated by increasing the trigger skip number untill two successively taken data streams agree with each other. Performance estimation tests of fabricated data comparison and trigger skip circuits were made using computer produces test signal, and the results showed the reliable digital data storage and simple operation.