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    OCEAN CURRENT DETECTION DEVICE AND METHOD BASED ON DOUBLE-HELIX AND DOUBLE-CORE VIBRATION FIBER-OPTIC CABLE
    1.
    发明公开
    OCEAN CURRENT DETECTION DEVICE AND METHOD BASED ON DOUBLE-HELIX AND DOUBLE-CORE VIBRATION FIBER-OPTIC CABLE 审中-公开

    公开(公告)号：US20240353441A1

    公开(公告)日：2024-10-24

    申请号：US18349384

    申请日：2023-07-10

    申请人： Nanjing University

    发明人： Yixin Zhang ,  Chi Zhang ,  Xuping Zhang ,  Shuai Tong ,  Shun Wang ,  Chenyang Ding ,  Feng Wang

    IPC分类号： G01P5/26 ,  G01P13/02

    CPC分类号： G01P5/26 ,  G01P13/02

    摘要： An ocean current detection device and method based on double-helix and double-core vibration fiber-optic cable, comprises a double-core fiber-optic cable and a φ-OTDR system; the double-core fiber-optic cable comprises a first and a second optical fiber core, provided symmetrically in the double helix structure. The terminate ends of the first and the second optical fiber core are connected, and the start end of the first or the second optical fiber core is connected with the φ-OTDR system. When measuring the ocean current characteristics in the target sea area, the double-core fiber-optic cable is provided underwater to generate vortex-induced vibration. The φ-OTDR system is provided for emitting laser towards the cable, receiving returned double-core vibration signals, extracting vibration characteristics from the double-core vibration signals to determine ocean current characteristics, including ocean current flow velocity and direction, to improve the detection accuracy.

    Method for suppressing coherent and polarization-induced fading by simultaneous monitoring of loss and vibration
    3.
    发明授权
    Method for suppressing coherent and polarization-induced fading by simultaneous monitoring of loss and vibration 有权

    公开(公告)号：US12117361B2

    公开(公告)日：2024-10-15

    申请号：US17908248

    申请日：2022-03-23

    申请人： NANJING UNIVERSITY

    发明人： Yixin Zhang ,  Xiaohong Chen ,  Xuping Zhang ,  Shuai Tong ,  Lei Liang ,  Yiming Wan ,  Feng Wang

    IPC分类号： G01M11/00

    CPC分类号： G01M11/3145

    摘要： A method for suppressing coherent and polarization-induced fading by simultaneous monitoring of loss and vibration is provided. By using merely common single-mode sensing fibers, the polarization diversity-based measurement method solves the conflict between Φ-OTDR and COTDR in terms of polarization state. In addition, the method not only achieves a better coherent fading noise suppression effect but also enhances the capability of recognizing small loss events in the monitoring of loss parameters. Meanwhile, the method can suppress the influence of coherent fading on the phase demodulation of Φ-OTDR and reconstruct a vibration signal with high fidelity in the monitoring of perturbation parameters, which can effectively reduce the error rate of external perturbation warning.

    MONITORING SYSTEM AND METHOD FOR BROKEN WIRES IN PCCP BASED ON DISTRIBUTED OPTICAL FIBER SENSING
    4.
    发明公开
    MONITORING SYSTEM AND METHOD FOR BROKEN WIRES IN PCCP BASED ON DISTRIBUTED OPTICAL FIBER SENSING 审中-公开

    公开(公告)号：US20240353349A1

    公开(公告)日：2024-10-24

    申请号：US18357572

    申请日：2023-07-24

    申请人： Nanjing University

    发明人： Yixin Zhang ,  Shuai Tong ,  Xuping Zhang ,  Shaoxiong Tang ,  Ruofan Wang ,  Haoran Wang ,  Shun Wang ,  Feng Wang

    IPC分类号： G01N21/95 ,  G01N21/01

    CPC分类号： G01N21/95 ,  G01N21/01

    摘要： A monitoring system and method for broken wires in PCCP based on distributed optical fiber sensing relates to the technical field of optical fiber sensing. The monitoring system for broken wires in PCCP comprises a Sagnac interferometer, a Φ-OTDR system, a dual loopback system and a signal processing system. The Sagnac interferometer comprises a first laser, a first optical coupler, a first delay optical fiber, a Faraday rotating mirror and a first photodetector. The Φ-OTDR system comprises a second laser, a second optical coupler, an acousto-optic modulator, a circulator, a third optical coupler and a second photodetector. The dual loopback system comprises a wavelength division multiplexer and a second delay optical fiber. The invention solves the problems of low positioning accuracy, limited frequency measurement range, detection dead zone and high computing pressure in monitoring broken wires in PCCP.

    Self-heterodyne φ-OTDR system with free multi-spatial resolution
    5.
    发明授权
    Self-heterodyne φ-OTDR system with free multi-spatial resolution 有权

    公开(公告)号：US11860008B2

    公开(公告)日：2024-01-02

    申请号：US17920809

    申请日：2022-05-06

    申请人： NANJING UNIVERSITY

    发明人： Yixin Zhang ,  Jinyu Song ,  Xuping Zhang ,  Zhewen Ding ,  Shuai Tong ,  Shun Wang ,  Feng Wang

    IPC分类号： G01D5/353

    CPC分类号： G01D5/35358

    摘要： A self-heterodyne phase-sensitive optical time domain reflectometry (φ-OTDR) system with a free multi-spatial resolution includes a narrow linewidth laser source, a 1×3 fiber-optic coupler, three acousto-optic modulators (AGMs), a 3×1 fiber-optic coupler, two time-delay fibers, an erbium-doped fiber amplifier (EDFA), a circulator, a photodetector, an electrical amplifier, three filters, a data acquisition card, a pulse signal generator, and a driver module. A plurality of acousto-optic modulators using the same driver are used to couple probe light with different pulse intervals and different frequency shifts and then inject the probe light into a fiber, such that a self-heterodyne detection structure with a multi-spatial resolution is implemented, which suppressed optical background noise such as coherent fading noise, phase noise introduced by a frequency drift of a light source, and pseudo-random noise (PRN).