Large Dynamic Range and High Sensitivity PGC Demodulation Technique for Tri-Component Fiber Optic Seismometer

Abstract

Three-component fiber optic seismometers are widely used in the detection of seismic signals. The arctangent approach of phase-generated carrier (PGC-Arctan) demodulation algorithm is one of the commonly used demodulation techniques in FOISs. Nonlinear factors such as phase modulation depth(C) variation and light intensity disturbance (LID) have an important impact on performance of traditional PGC demodulation algorithms. This paper introduces a new demodulation algorithm called Kalman filtering ellipse (PGC-Arctan-EKF) demodulation algorithm, which can improve the robustness of the fitting. In order to meet the requirements of high performance and low power consumption of seafloor sensing, Tri-Component fiber optic seismometer based on SoC(ARM +FPGA) is proposed in this paper. The phase self-noise of the system is better than -115 dB re rad/Hz1/2,and the large signal can reach 66 dB re rad/Hz1/2 @220Hz with the THD is -61.22 dB.

Keywords

• Tri-component fiber optic seismometer
• PGC-arctan-EKF
• ellipse fitting
• SoC