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    RAYLEIGH FADING MITIGATION VIA SHORT PULSE COHERENT DISTRIBUTED ACOUSTIC SENSING WITH MULTI-LOCATION BEATING-TERM COMBINATION
    4.
    发明申请
    RAYLEIGH FADING MITIGATION VIA SHORT PULSE COHERENT DISTRIBUTED ACOUSTIC SENSING WITH MULTI-LOCATION BEATING-TERM COMBINATION 审中-公开

    公开(公告)号：WO2020237032A1

    公开(公告)日：2020-11-26

    申请号：PCT/US2020/033966

    申请日：2020-05-21

    Applicant: NEC LABORATORIES AMERICA, INC. ,  NEC CORPORATION

    Inventor： IP, Ezra ,  HUANG, Yue-Kai ,  HU, Junqiang ,  MURAKAMI, Shuji

    IPC: G01H9/00

    Abstract: Aspects of the present disclosure describe Rayleigh fading mitigation via short pulse coherent distributed acoustic sensing with multi-location beating-term combination. In illustrative configurations, systems, methods, and structures according to the present disclosure employ a two stage modulation arrangement providing short interrogator pulses resulting in a greater number of sensing data points and reduced effective sectional length. The increased number of data points are used to mitigate Rayleigh fading via a spatial combining process, multi-location-beating combining (MLBC) which uses weighted complex-valued DAS beating results from neighboring locations and aligns phase signals of each of the locations, before combining them to produce a final DAS phase measurement. Since Rayleigh scattering is a random statistic, the MLBC process allows capture of different statics from neighboring locations with correlated vibration/acoustic signal. The combined DAS results minimize a total Rayleigh fade, in both dynamic fading and static fading scenarios.

    VIBRATION DETECTION USING PHASE RECOVERED FROM AN OPTICAL TRANSPONDER WITH COHERENT DETECTION
    5.
    发明申请
    VIBRATION DETECTION USING PHASE RECOVERED FROM AN OPTICAL TRANSPONDER WITH COHERENT DETECTION 审中-公开

    公开(公告)号：WO2022125705A1

    公开(公告)日：2022-06-16

    申请号：PCT/US2021/062478

    申请日：2021-12-08

    Applicant: NEC LABORATORIES AMERICA, INC. [US]/[US]

    Inventor： IP, Ezra ,  HUANG, Yue-Kai

    IPC: G01H9/00 ,  G01D5/353

    Abstract: Aspects of the present disclosure describe systems, methods. and structures for vibration detection using phase recovered from an optical transponder with coherent detection. Advantageously, our systems, methods, and structures leverage contemporary digital coherent receiver architecture in which various adaptive DSP operations performed to recover transmitted data track optical phase. The phase is extracted at low overhead cost, allowing a digital coherent transponder to perform vibration detection / monitoring as an auxiliary function to data transmission. Demonstration of vibration detection and localization based on the extraction of optical phase from payload-carrying telecommunications signal using a coherent receiver in a bidirectional WDM transmission system is shown and described.

    DISTRIBUTED ACOUSTIC SENSING IN AN OPTICAL FIBER USING DISTRIBUTED MODE COUPLING AND DELAY
    7.
    发明申请
    DISTRIBUTED ACOUSTIC SENSING IN AN OPTICAL FIBER USING DISTRIBUTED MODE COUPLING AND DELAY 审中-公开
    使用分布式耦合和延迟的光纤中的分布式声学传感

    公开(公告)号：WO2018039046A1

    公开(公告)日：2018-03-01

    申请号：PCT/US2017/047412

    申请日：2017-08-17

    Applicant: NEC LABORATORIES AMERICA, INC.

    Inventor： YAMAN, Fatih ,  MILIONE, Giovanni ,  ZHANG, Shaoliang ,  HUANG, Yue-Kai

    IPC: G01M11/00 ,  G02B6/14

    Abstract: A system and method are provided for distributed acoustic sensing in an optical fiber (300). The system includes a transmitter (2001) for simultaneously propagating a sequence of M light pulses through the optical fiber (300) using a spatial mode selected from a set of N spatial modes provided by a spatial mode selector (200) for the transmitter (2001) that is coupled to an input to the optical fiber (300), with M and N being respective integers greater than one. The system further includes a receiver (2002) for receiving the sequence of M light pulses at an output of the optical fiber (300) and detecting an environmental perturbation in the optical fiber (300) based on an evaluation of a propagation of the sequence of M light pulses through the optical fiber (300).

    Abstract translation: 提供了用于光纤（300）中的分布式声学感测的系统和方法。 该系统包括用于使用从一组N个空间模式中选择的空间模式通过光纤（300）同时传播一串M个光脉冲的发射器（2001） 由耦合到光纤（300）的输入的发射器（2001）的空间模式选择器（200）提供，其中M和N分别是大于1的整数。 该系统还包括用于在光纤（300）的输出处接收M个光脉冲序列并基于对光纤（300）的序列的传播的评估来检测光纤（300）中的环境干扰的接收器（2002） M光脉冲通过光纤（300）。

    IMPROVED DISTRIBUTED ACOUSTIC SENSING USING DYNAMIC RANGE SUPPRESSION
    9.
    发明申请
    IMPROVED DISTRIBUTED ACOUSTIC SENSING USING DYNAMIC RANGE SUPPRESSION 审中-公开

    公开(公告)号：WO2021231344A1

    公开(公告)日：2021-11-18

    申请号：PCT/US2021/031667

    申请日：2021-05-11

    Applicant: NEC LABORATORIES AMERICA, INC.

    Inventor： IP, Ezra ,  HUANG, Yue-Kai ,  JI, Philip ,  MURAKAMI, Shuji

    IPC: G01H9/00 ,  G01V1/22 ,  G01V1/40 ,  G01N29/24

    Abstract: Aspects of the present disclosure describe improved distributed acoustic sensing using dynamic range suppression of optical time domain reflectometry either by using a feedback loop comprising optical and electrical elements or using a nonlinear element in the electrical domain after coherent detection. When using a feedback loop, the amplitude of the periodic waveform of coherent OTDR can be inverted. This allows optical precompensation of the received optical signal before coherent detection with the goal of minimizing amplitude dynamic range. Alternatively, a nonlinear element in the electrical domain can reduce amplitude dynamic range before sampling by analog-to-digital converters (ADC).

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