OPEN LOOP SIGNAL PROCESSING CIRCUIT AND METHOD FOR A FIBER OPTIC INTERFEROMETRIC SENSOR

摘要

A signal processing circuit (10) for a fiber optic sensor (12) includes a d.c. block (14) coupled to the fiber optic sensor (12) for removing d.c. components from the fiber optic sensor output signal, and a low pass filter (16) coupled to the d.c. block (14) for reducing noise in the fiber optic sensor output signal and generate a filtered signal. A comparator (18) is coupled to the low pass filter (16) and generates a squared signal indicative of zero crossings in the filtered signal. A lock-in amplifier or synchronous demodulator (20) is coupled to the comparator (18) and generates an output signal indicative of a phase shift in the two light waves propagating in the fiber optic sensor (12).