Optical fiber sensing demodulation method based on digital filtering and binary pulse modulation

Abstract

The invention discloses an optical fiber sensing demodulation method based on digital filtering and binary pulse modulation. The method comprises the following steps: firstly, modulating and interfering a laser light source to obtain laser interference light intensity I<s> with phase modulation; secondly, calibrating the laser interference light intensity I<s> with a three-step phase-shift methodaccording to the difference between corresponding position times to obtain three-step phase-shift light intensity signals I<1>', I<2>' and I<3>'; thirdly, performing spectral analysis and low-pass filtering on I<1>', I<2>' and I<3>' to obtain new three-step phase-shift intensity signals I<1>, I<2> and I<3>; fourthly, processing I<1>, I<2> and I<3> with an anti-tangent method to obtain phase information theta'' of the laser interference light intensity; and finally performing bandpass filtering on theta'' to obtain an external vibration signal to finish demodulation. The method disclosed by theinvention has the advantages of low complexity, high efficiency, high noise immunity, capability of correctly demodulating the external vibration signal, and very good application prospect.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, in particular to an optical fiber sensing demodulation method based on digital filtering and binary pulse modulation. Background technique [0002] Optical fiber sensors with optical fiber as the transmission carrier have the advantages of anti-electromagnetic interference, high sensitivity, and easy detection of harsh environments. Therefore, low-frequency and high-sensitivity optical fiber acceleration sensors are widely used in earthquake monitoring, oil exploration, and vibration monitoring of buildings. There are many noises in the actual sensor system, such as light source jitter noise, light source frequency noise, etc. Therefore, the resistance to noise is one of the important reference factors for signal detection technology. At present, fiber optic sensors based on various principles have been reported at home and abroad, among which the interferometric fiber optic sensor ...

AI Technical Summary

Problems solved by technology

However, the traditional binary pulse phase modulation and demodulation method has a lack of anti-noise ability, and it is difficult to demodulate the correct phase information and external vibration signals when the signal contains noise information.

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