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    Method providing increased signal-to-noise (SNR) for coherent distributed acoustic sensing
    5.
    发明授权
    Method providing increased signal-to-noise (SNR) for coherent distributed acoustic sensing 有权

    公开(公告)号：US11698289B2

    公开(公告)日：2023-07-11

    申请号：US17555924

    申请日：2021-12-20

    Applicant: NEC Laboratories America, Inc.

    Inventor： Junqiang Nochur Hu ,  Ting Wang ,  Shuji Murakami

    IPC: G01H9/00

    CPC classification number: G01H9/004

    Abstract: A method providing an increased signal-to-noise (SNR) characteristic for coherent distributed acoustic sensing (DAS) systems, the method employing fiber coils (microphones) made from sections of an optical sensing fiber that collect acoustic signals and uses multiple differential pairs of the microphones for signal averaging to improve the SNR. An analysis determines complex products (beating products) for a pair of locations that are part of a fiber microphone along the length of the optical sensing fiber that are used to determine a phase change in-between locations along the length of the optical sensing fiber.

    Rayleigh fading mitigation via short pulse coherent distributed acoustic sensing with multi-location beating-term combination
    6.
    发明授权
    Rayleigh fading mitigation via short pulse coherent distributed acoustic sensing with multi-location beating-term combination 有权

    公开(公告)号：US11566937B2

    公开(公告)日：2023-01-31

    申请号：US16879505

    申请日：2020-05-20

    Applicant: NEC Laboratories America, Inc.

    Inventor： Ezra Ip ,  Yue-Kai Huang ,  Junqiang Hu ,  Shuji Murakami

    IPC: G01H9/00 ,  G01B9/02015 ,  G01B9/02 ,  G01D5/353 ,  G01V1/18

    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.

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