Real-time self-calibration PGC-Arctan demodulation algorithm in fiber-optic interferometric sensors

Area of Science:

• Optoelectronics and Sensor Technology
• Signal Processing

Background:

• Fiber-optic interferometric sensors (FOISs) are crucial for applications like seismometers and hydrophones.
• The phase-generated carrier arctangent (PGC-Arctan) demodulation algorithm is a key technique for FOISs.
• Conventional PGC-Arctan requires a precise phase modulation depth (C), which fluctuates with environmental factors, causing distortion and failure.

Purpose of the Study:

• To introduce a novel self-calibrating PGC-Arctan (PGC-Arctan-SC) demodulation algorithm.
• To enable accurate estimation and real-time calibration of the phase modulation depth (C) in FOISs.
• To suppress nonlinear distortion and improve the performance of FOISs.

Main Methods:

• Developed the PGC-Arctan-SC algorithm for joint estimation of C using elliptical parameters.
• Employed an ellipse fitting algorithm (EFA) to suppress nonlinear distortion.
• Utilized a closed-loop proportion integration differentiation (PID) module for C calibration.

Main Results:

• Simulation results align with theoretical analysis, validating the algorithm's effectiveness.
• An all-digital PGC-Arctan-SC demodulation system was successfully implemented on an embedded SoC.
• Experimental results demonstrate accurate real-time estimation and calibration of C, achieving a signal-to-noise and distortion ratio (SINAD) of 61.57 dB.

Conclusions:

• The PGC-Arctan-SC algorithm effectively addresses the limitations of conventional PGC-Arctan demodulation.
• The proposed method ensures robust and accurate performance of FOISs under varying environmental conditions.
• This advancement offers a significant improvement for high-precision fiber-optic sensing applications.