Phase signal solving method and device for reducing phi-OTDR phase unwrapping limitation based on auxiliary light
A -OTDR, phase unwinding technology, applied in the direction of using optical devices to transmit sensing components, measuring devices, converting sensor outputs, etc., can solve the upper limit of the pulse emission frequency, the single-frequency optical Φ-OTDR system cannot correctly realize the phase solution. Winding and other problems, to achieve the effect of the measurement range
Active Publication Date: 2020-03-27
NANJING UNIV
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Problems solved by technology
However, limited by the length of the fiber, there is an upper limit to the emission frequency of the pulse
When the pulse emission frequency increases to this upper limit, if the absolute difference is still greater than π, the single-frequency optical Φ-OTDR system will not be able to correctly achieve phase unwrapping
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[0042] The technical scheme of the present invention will be further described in detail below in conjunction with the accompanying drawings:
[0043] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as commonly understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood as having meanings consistent with the meanings in the context of the prior art, and unless defined as here, they will not be used in ideal or overly formal meanings. Explanation.
[0044] In the phase optical time domain reflectometer of the coherent detection method, the phase of the subsequent position of the fiber contains the change information of the phase at the previous position. When a disturbance event acts on the optical fiber, the phase change after the ...
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The invention provides a phase signal solving method and a device for reducing phi-OTDR phase unwrapping limitation based on auxiliary light. Main detection pulse light and auxiliary detection pulse light are alternately injected into phi-OTDR, and the period and the pulse width of the main detection pulse light are consistent. However, a certain frequency difference exists between the main detection pulse light and the auxiliary detection pulse light. Phase demodulation is respectively performed on signals obtained by coherent detection; after the statistical phase of each subsequent point ofthe reference point is subtracted from the statistical phase of the reference point; the differential phases wrapped by the main detection pulsed light and the auxiliary detection pulsed light is arranged according to a time sequence; the differential phase of the main detection pulsed light is separated out after unwrapping based on the combined pulse sequence, the phase change of the main detection pulsed light is calculated by subtracting the differential phase in the time domain, and after the correct unwrapping position is identified by means of the linear characteristic of the phase change, the accurate demodulation of the acceleration exceeding the phase unwrapping limit can be realized.
Description
Technical field [0001] The invention belongs to the technical field of optical fiber sensing, and particularly relates to a phase signal solution method and device based on auxiliary light to reduce the phase unwinding limit of the Φ-OTDR. Background technique [0002] With the rapid development of the national economy, the laying of oil and gas pipelines in our country is getting longer and longer, and the difficulty of monitoring becomes more and more difficult; the mileage of high-speed railways is changing with each passing day, and the requirements for real-time monitoring are getting higher and higher; As the number of bridges is getting longer and the total number of bridges is increasing, the requirements for meticulous testing are becoming stricter. All of the above require our monitoring methods to have the characteristics of distributed, long-distance and real-time. [0003] The Phase Optical Time Domain Reflectometer (Φ-OTDR) is a device for event detection based on th...
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Login to View More IPC IPC(8): G01D5/353
CPCG01D5/35361
Inventor 王峰钟镇张旭苹张益昕
Owner NANJING UNIV