Pulse coding-combined distributed optical fiber vibration sensing method and device

Abstract

The invention discloses a pulse coding-combined distributed optical fiber vibration sensing method and device. For a random-order coding matrix, the main diagonal elements are all "0", and the rest elements are all "1", and each row of the matrix is sequentially injected into the distributed optical fiber vibration sensing device, wherein the device comprises a narrow-line-width laser, a driving module, an FPGA coding modulator containing an SOA (semiconductor optical amplifier), an optical fiber circulator, a sensing optical fiber, an APD detector module, an A / D module and an industrial personal computer. A pulse coding principle and an optical fiber rayleigh scattering phase change demodulation vibration principle are combined, so that the dynamic range of the sensing system is enlargedunder the condition that the spatial resolution is not changed, and the measuring length and the measuring precision are increased. The device can be suitable for monitoring of leakage of water, oil,gas pipelines within a relatively large range and monitoring of large-scale civil engineering security and protection.

Description

technical field [0001] The invention relates to a distributed optical fiber vibration sensing device, in particular to a distributed optical fiber vibration sensing method and device using pulse coding, belonging to the technical field of optical fiber sensing. Background technique [0002] (Phase Optical Time Domain Reflectometer) is a distributed optical fiber vibration sensing system made by Rayleigh backscattering. When the external vibration acts on the optical fiber, it will cause the deformation of the core in the optical fiber, change the refractive index and length of the core, and cause the optical phase in the optical fiber to change. A narrow linewidth optical pulse is injected into the optical fiber as a detection signal. When the optical pulse propagates along the optical fiber, the Rayleigh scattered light is continuously transmitted backward due to the interaction between the photon and the core lattice. When there is vibration in the outside world, the ph...

AI Technical Summary

Problems solved by technology

It can be seen that it is impossible to obtain a large dynamic range and a high spatial resolution at the same time, and the two cannot have both

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