Phase demodulation method for phase-sensitive optical time domain reflection optical fiber sensing system

Abstract

The invention discloses a phase demodulation method for a phase-sensitive optical time domain reflection optical fiber sensing system, which comprises the following steps of generating a backward Rayleigh scattering light signal through a sensing optical fiber, converging the backward Rayleigh scattering light signal with a local oscillation light signal, and generating coherent interference to generate a beat frequency signal; acquiring a light current signal in the beat frequency signal; performing Hilbert transform on the light current signal; performing time translation transformation on the double-path orthogonal signals; performing trigonometric function transformation of product sum and difference on the obtained four paths of signals; adding and subtracting the transformed four paths of signals to obtain two paths of signals; and carrying out arc tangent transformation on the obtained two paths of signals to extract phases. According to the demodulation method, effective extraction and reconstruction of phase signals contained in system signals are achieved, then phase digital demodulation of the distributed optical fiber sensing system is achieved, noise and errors introduced by various hardware demodulation technical methods are effectively eliminated, the system is simplified, and the system cost is reduced.

Description

technical field [0001] A phase-sensitive optical time-domain reflection optical fiber sensing system signal phase digital demodulation technology and method are used to demodulate and restore the phase information of acoustic signals and vibration signals in a distributed optical fiber sensing system. It can realize the phase digital demodulation analysis of the system, and can eliminate the device noise introduced by the hardware phase demodulation method, thereby effectively improving the system signal-to-noise ratio and reducing the system demodulation cost. Background technique [0002] Based on the phase-sensitive optical time domain reflection optical fiber sensing system, it can carry out distributed multi-point real-time monitoring of tiny signals over a long distance. It has the characteristics of high sensitivity, large spatial dynamic range and high positioning accuracy. Production process detection, perimeter security, pipeline protection, marine engineering and ...

AI Technical Summary

Problems solved by technology

I / Q quadrature hardware demodulation costs are high, the system is complex, and additional hardware noise is introduced, resulting in deterioration of the system signal-to-noise ratio

Therefore, the existing demodulation methods have problems such as high cost, complex system, large noise, and large amount of calculation, which seriously affect the practicality and industrialization of the sensing system.

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