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

A pulse modulation and digital filtering technology, applied in the direction of using wave/particle radiation, measuring ultrasonic/sonic/infrasonic waves, instruments, etc., can solve the problems of lack of anti-noise ability, difficult to demodulate phase information of external vibration signals, etc., to achieve anti-noise The effect of strong ability, simple method and high demodulation efficiency

Active Publication Date: 2019-12-03
NANJING UNIV OF SCI & TECH
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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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  • Optical fiber sensing demodulation method based on digital filtering and binary pulse modulation
  • Optical fiber sensing demodulation method based on digital filtering and binary pulse modulation
  • Optical fiber sensing demodulation method based on digital filtering and binary pulse modulation

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Embodiment Construction

[0023] combine figure 1 , a kind of optical fiber sensing demodulation method based on digital filtering and binary pulse modulation of the present invention, comprises the following steps:

[0024] Step 1. Modulate and interfere the laser light source to obtain the laser interference light intensity I with phase modulation s . Among them, Michelson interferometer is used for interference, and the phase demodulation principle of Michelson interferometer is as follows: figure 2 As shown, after the coherent light emitted by the laser passes through the isolator and the phase modulator, it is divided into two paths by the 2×2 coupler and enters the reference arm and the interference arm of the interferometer respectively. The other end of the device is output, and the output interference light intensity signal is received by the photodetector. The polarization fading can be overcome by using the Faraday rotator, and the structure is simple and the price is low. Specifically:...

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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 ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01H9/00
CPCG01H9/004
Inventor 崔珂彭文俊任仲杰朱日宏薄煜明钱婕妤
Owner NANJING UNIV OF SCI & TECH
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