PGC-Atan Demodulation Scheme With the Carrier Phase Delay Compensation for Fiber-Optic Interferometric Sensors

Abstract

Phase generated carrier (PGC) demodulation schemes are widely used in fiber-optic interferometric sensors. All known PGC schemes use carrier signals to obtain in-phase and quadrature components from the interference signal. The unwanted phase delay between the reference carrier signal and the modulation signal in the interference signal might exist. This effect might lead to the incorrect measurement of the phase signal in the PGC scheme. In this paper, the original PGC demodulation scheme with the carrier phase delay compensation based on the basic PGC-Atan scheme is presented. The proposed scheme provides the real-time carrier phase delay compensation over the all possible phase delay range from 0° to 360° without using phase adjustments of the carrier signal. Theoretical analysis and mathematical modeling of the proposed scheme and the basic PGC-Atan demodulation scheme were performed to compare their performance under the same conditions. The proposed scheme, the basic PGC-Atan demodulation scheme, and the PGC synchronous carrier restoration scheme were implemented in the FPGA-based electronic processing circuit of the single interferometric fiber Bragg grating sensor. Experimental results showed that the proposed scheme provides carrier phase delay compensation without using phase adjustments of the carrier signal.