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    DISTRIBUTED ACOUSTIC SENSING USING DYNAMIC RANGE SUPPRESSION
    1.
    发明申请
    DISTRIBUTED ACOUSTIC SENSING USING DYNAMIC RANGE SUPPRESSION 有权

    公开(公告)号：US20210356776A1

    公开(公告)日：2021-11-18

    申请号：US17316621

    申请日：2021-05-10

    Applicant: NEC Laboratories America, Inc.

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

    IPC: G02F1/125 ,  G01H9/00

    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 pre-compensation 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).

    AUTOMATIC CALIBRATION FOR BACKSCATTERING-BASED DISTRIBUTED TEMPERATURE SENSOR
    2.
    发明公开
    AUTOMATIC CALIBRATION FOR BACKSCATTERING-BASED DISTRIBUTED TEMPERATURE SENSOR 审中-公开

    公开(公告)号：US20240302225A1

    公开(公告)日：2024-09-12

    申请号：US18598386

    申请日：2024-03-07

    Applicant: NEC Laboratories America, Inc.

    Inventor： Philip JI ,  Ting WANG ,  Yaowen LI ,  Junqiang HU ,  Shuji MURAKAMI ,  Jian FANG

    IPC: G01K15/00 ,  G01K11/32

    CPC classification number: G01K15/005 ,  G01K11/32

    Abstract: Disclosed are vehicle-infrastructure interaction systems and methods employing a distributed fiber optic sensing (DFOS) system operating with pre-deployed fiber-optic telecommunication cables buried alongside/proximate to highways/roadways which provide 24/7 continuous information stream of vehicle traffic at multiple sites; only require a single optical sensor cable that senses/monitors multiple locations of interest and multiple lanes of traffic; the single optical sensor cable measures multiple related information (multi-parameters) about a vehicle, including driving speed, wheelbase, number of axles, tire pressure, and others, that can be used to derive secondary information such as weight-in-motion; and overall information about a fleet of vehicles, such as traffic congestion or traffic-cargo volume. Different from merely traffic counts, our approach can provide the count grouped by vehicle-types and cargo weights. Precise measurements are facilitated by high temporal sampling rates of the distributed acoustic sensing and a dedicated peak finding algorithm for extracting the timing information reliably.

    RAYLEIGH FADING MITIGATION VIA SHORT PULSE COHERENT DISTRIBUTED ACOUSTIC SENSING WITH MULTI-LOCATION BEATING-TERM COMBINATION
    3.
    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：US20200370950A1

    公开(公告)日：2020-11-26

    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 ,  G01B9/02

    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.

    Method Providing Increased Signal-To-Noise (SNR) for Coherent Distributed Acoustic Sensing
    4.
    发明申请
    Method Providing Increased Signal-To-Noise (SNR) for Coherent Distributed Acoustic Sensing 有权

    公开(公告)号：US20220196461A1

    公开(公告)日：2022-06-23

    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

    Abstract: An advance in the art is made according to aspects of the present disclosure directed to a DAS method that utilizes a differential phase to detect phase change(s) between two locations of a DAS sensing fiber to ascertain vibrational/acoustic activities/environment at intermediary fiber location(s) between the two locations. Additionally, systems, methods, and structures according to aspects of the present disclosure may employ a fiber coil comprising a segment of fiber wrapped in acoustic sensitive material (“acoustic signal collector”). The material responds to an environmental acoustic signal, which results in strain(s) applied to the fiber. Furthermore, rather than using a measured phase difference between the two ends of the fiber coil, systems, methods, and structures according to aspects of the present disclosure utilize all samples collected from one end of the fiber coil to the other end of the fiber coil (the left side of the coil to the right side of the coil)—which may be extended further. Every two samples covering a partial or an entire section of the fiber coil are used as a pair (a “differential pair”) to determine a phase difference and the results from all the pairs are averaged to form one output exhibiting a reduced noise level and more stable signal as compared to prior art methods.

    FIBER-OPTIC ACOUSTIC ANTENNA ARRAY AS AN ACOUSTIC COMMUNICATION SYSTEM
    7.
    发明申请
    FIBER-OPTIC ACOUSTIC ANTENNA ARRAY AS AN ACOUSTIC COMMUNICATION SYSTEM 有权

    公开(公告)号：US20240405890A1

    公开(公告)日：2024-12-05

    申请号：US18731283

    申请日：2024-06-01

    Applicant: NEC Laboratories America, Inc.

    Inventor： Wataru KOHNO ,  Jian FANG ,  Shuji MURAKAMI ,  Ting WANG

    IPC: H04B11/00 ,  G01H9/00 ,  H04B13/02

    Abstract: Disclosed are systems, methods, and structures employing a distributed fiber optic sensing (DFOS)/distributed acoustic sensing (DAS) system operating as an underwater wireless acoustic antenna in which an optical fiber sensor cable serves as a distributed acoustic antenna that receives multiple data from transmitters using an optical interrogator. Sensing channels, in the form of acoustic-antenna-array systems are located near transmitters taking advantage of the fact that these channels are automatically synchronized. The sensing channels may also be manually selected from software controlling the interrogator, and acoustic repeaters may be introduced as one data transmission mechanism. Acoustic tata transmission using an orthogonal frequency division multiplexed (OFDM) signal is demonstrated as a cure for data transmission using a DAS, such as multipath fading impacting bit error rate (BER) and limitations in acoustic transmission bandwidth.

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