Optical fiber measuring apparatus, gyrometer, central navigation system and inertial stabilization system

PURPOSE: To measure fluctuation of parameter causing an irreversible disturbance by an arrangement in which a digital processor sorts digitized samples into two types to produce digital mean values and then compares them. CONSTITUTION: When measuring parameters are stable, an electronic control means introduces constant amplitude modulation of phase shift between light waves propagating in the opposite directions through a closed optical path through a phase modulator 7. Consequently, a detector 5 generates a modulation signal which is digitized through a converter 11 and subjected to digital processing 12. The processor 12 delivers a zero signal to an accumulator 15 and sustain a constant value in a register. When the measuring parameters fluctuate, the periodic phase shift between light waves on the optical path is superposed on a predetermined phase shift. Consequently, the detector 5 generates a signal which is digitized through the converter 11 and subjected to digital processing thus producing a signal having non-zero level. That signal is fed to the accumulator 15 and varies a register 14 thus reducing phase shift being introduced by the modulator 7. COPYRIGHT: (C)1990,JPO