High-frequency vibration measurement distributed fiber sensing system based on frequency division multiplexing technology

Abstract

The invention discloses a high-frequency vibration measurement distributed fiber sensing system based on a frequency division multiplexing technology. A phase-sensitive optical time domain reflection system and a Mach-Zehnder interferometer are combined together, positioning is performed by use of a phase-sensitive optical time domain reflection technology, high-frequency vibration measurement is realized by use of the Mach-Zehnder interferometer, a vibration position corresponds to a vibration frequency by use of a spectrum mapping method, and thus the high-frequency vibration measurement distributed fiber sensing system based on the frequency division multiplexing technology is formed. The system has the following advantages: longer-distance sensing is realized; the problem that a system positioning signal-to-noise ratio is affected by frequency measurement sensitivity is solved based on a simple sequential control and modulation method; frequency blind areas of the system, exiting in a measurement frequency band are removed; positioning and frequency measurement of high-frequency multipoint vibration are realized; the apparatus provided by the invention works stably and can accurately measure the position and the frequency of vibration in multiple measurement; and accurate positioning and frequency measurement of multipoint high-frequency vibration can be realized under the condition of a low cost.

Description

technical field [0001] The invention relates to the combination of distributed optical fiber sensing technology - phase-sensitive optical time domain reflection technology and Mach-Zehnder interferometer structure to realize the measurement of high-frequency multi-point vibration. Background technique [0002] In recent years, with the rapid development of oil and gas pipelines, high-speed rail, and large buildings, distributed optical fiber sensing technology has attracted more and more attention from all walks of life. Due to its many advantages, distributed optical fiber sensing technology has become a The key technology for external information perception in long-distance and harsh environments. The phase-sensitive OTDR technology is a member of the distributed optical fiber sensing technology family. Its main function is to measure external disturbances, intrusions, etc., not only to locate them but also to measure their disturbance frequency. However, when this techno...

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Problems solved by technology

At present, there are mainly two systems that combine the two: 1. Based on the pulse modulation fusion sensor system; this system can realize the measurement of high-frequency vibration, but there is still a shortcoming: (1) The signal-to-noise ratio of the system positioning varies with (2) The system has a frequency blind zone in the measurement frequency band; (3) The system can realize the positioning and frequency measurement of high-frequency multi-point vibration, but it cannot combine the measured frequency with the vibration corresponding to the position

2. A fusion sensor system based on time multiplexing technology; (1) This system solves the problem that the positioning signal-to-noise ratio in the above system decreases with the increase of measurement frequency sensitivity, but the system structure is more complicated, and timing control and Signal demodulation is more complicated; (2) blind spots in system frequency measurement still exist; (3) multi-point high-frequency measurement still cannot achieve one-to-one correspondence

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