Research on demodulation parameter optimization of fiber optic acoustic sensor for broadband large signals

Abstract

The demodulation parameter optimization of fiber optic acoustic sensor for broadband large signals is studied in this paper. Firstly, the performance of fiber optic acoustic sensors in demodulating broadband large signals is introduced. The low-frequency energy of the demodulation result is significantly increased and completely submerge the effective signal. By deducing and analyzing the demodulation algorithm of fiber optic acoustic sensors, the reason why it is impossible to demodulate broadband large signals is theoretically explained. An arctangent demodulation algorithm is realized in MATLAB. White noise signals with limited frequency bands are used as simulation signal sources for demodulation testing. Through simulation analysis, the main criteria for determining the upper limit of the system's dynamic range under a certain set of demodulation parameters are provided. Finally, the arctangent demodulation algorithm is implemented in FPGA. Detection experiments on the noise signal of a certain equipment are carried out using the fiber optic microphone system developed by our institute. The experimental results prove that the dynamic range analysis of the demodulation algorithm in this paper is accurate. The fiber optic microphone system designed through parameter optimization can correctly demodulate broadband large signals.