WO2023075008A1 - Noise-reducing optical fiber sound distribution sensor - Google Patents

Noise-reducing optical fiber sound distribution sensor Download PDF

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WO2023075008A1
WO2023075008A1 PCT/KR2021/018343 KR2021018343W WO2023075008A1 WO 2023075008 A1 WO2023075008 A1 WO 2023075008A1 KR 2021018343 W KR2021018343 W KR 2021018343W WO 2023075008 A1 WO2023075008 A1 WO 2023075008A1
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optical fiber
signal
light
clock
clock signal
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PCT/KR2021/018343
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French (fr)
Korean (ko)
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김영호
김명진
김희운
김효종
신준근
정효영
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한국광기술원
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
    • G01D5/35354—Sensor working in reflection
    • G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/3537—Optical fibre sensor using a particular arrangement of the optical fibre itself
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/002—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means for representing acoustic field distribution

Definitions

  • the present invention relates to a reduced-noise optical fiber acoustic distribution sensor, and more particularly, to a reduced-noise optical fiber acoustic distribution sensor capable of synchronizing the generation of pulsed light with the sampling of a scattering signal reversely received from a sensing optical fiber.
  • OTDR Optical Time Domain Reflectometry
  • FBG Fiber Bragg Grating sensor
  • the backscattered position of the fiber optic cable can be determined by the time difference between incident and observation. In general, the position is determined using a Rayleigh scattered wave having the same frequency as the incident light. Rayleigh scattering with a large scattering coefficient is usually associated with a change in the density of an optical fiber material constituting an optical fiber cable, and there is no change in wavelength.
  • the internal clock and sampling data of the element generating the pulsed light may be different each time.
  • the timing of generating the internal clock each time a trigger signal is generated may be different each time.
  • a delay time until the internal clock is generated occurs, and this delay time can be changed every time the trigger signal is generated, so that the measurement position deviation between the sampling data sets generated in response to the pulse lights generated, which reduces the precision of data analysis.
  • measurement location deviations between sampling datasets occur, such measurement location deviations become background noise during the analysis process, and decrease sensitivity.
  • the present invention was devised to improve the above problems, and noise reduction that can improve measurement accuracy by suppressing measurement position deviation for sampling datasets for Rayleigh scattered light generated corresponding to each pulse light Its purpose is to provide a type optical fiber acoustic distribution sensor.
  • the noise reduction type optical fiber acoustic distribution sensor is synchronized with the self-generated clock and generates a first clock signal of a first period and a second clock signal of a second period set shorter than the first period.
  • a clock generator that generates; a pulse light generating unit that outputs pulse light in synchronization with the first clock signal generated from the clock generator at a first cycle; an optical circulator for transmitting the pulsed light output from the pulsed light generating unit and inputted through an input terminal to a sensing optical fiber through an output terminal, and outputting light traveling backward from the sensing optical fiber to a detection terminal; a photodetector connected to the detection end of the optical circulator and outputting an electrical signal corresponding to the received light; A processing unit for generating sampling data in synchronization with the second clock signal generated in the second cycle with respect to the signal received from the photodetector, and collecting and processing acoustic signal generation information for each position of the sensing optical fiber from the generated sampling data. ;
  • the pulse light generating unit and a light source for emitting laser light and a semiconductor optical amplifier that receives the laser light and generates and outputs pulsed light synchronized with the first clock signal.
  • a first erbium-doped optical fiber amplifier for amplifying the signal output from the semiconductor optical amplifier and transmitted through the optical fiber; It may further include a first band pass filter filtering the signal output from the first erbium-doped optical fiber amplifier so that only a signal having a set bandwidth passes.
  • the optical detector unit may include a second erbium-doped optical fiber amplifier for amplifying a signal output from the detection end of the optical circulator and transmitted through an optical fiber; a second band pass filter filtering the signals output from the second erbium-doped optical fiber amplifier so that only signals having a set bandwidth pass through; and a photodetector for receiving the light output through the second band pass filter and outputting the light as an electrical signal.
  • a second erbium-doped optical fiber amplifier for amplifying a signal output from the detection end of the optical circulator and transmitted through an optical fiber
  • a second band pass filter filtering the signals output from the second erbium-doped optical fiber amplifier so that only signals having a set bandwidth pass through
  • a photodetector for receiving the light output through the second band pass filter and outputting the light as an electrical signal.
  • the clock generator may be configured to generate the first clock signal at 10 KHz and the second clock signal at 100 MHz.
  • the pulse light generation time of the pulse light generator and the sampling time of the processing unit that generates sampling data from the Rayleigh scattering signal are synchronized using the clock signal generated by the clock generator. Measurement accuracy can be improved by suppressing measurement position deviation of the sampling data sets.
  • FIG. 1 is a view showing a noise reduction optical fiber acoustic distribution sensor according to the present invention
  • FIG. 2 is a graph for explaining the synchronization process of the pulse light generating unit and the processing unit of FIG. 1 in comparison with the conventional method;
  • 3 to 8 are graphs showing examples of signals for explanation by comparing the optical fiber acoustic distribution sensor of the present invention with the conventional method.
  • FIG. 1 is a view showing a noise reduction type optical fiber acoustic distribution sensor according to the present invention.
  • the optical fiber acoustic distribution sensor 100 includes a clock generator 110, a pulse light generator 120, an optical circulator 150, a sensing optical fiber 160, and an optical detector 170. , a processing unit 180 is provided.
  • the clock generator 110 generates a first clock signal 111 of a first cycle and a second clock signal 112 of a second cycle set shorter than the first cycle in synchronization with its own clock.
  • a self-generated clock of the clock generator 110 may be constructed to be used as the second clock signal 112 .
  • the clock generator 110 may be configured to generate the first clock signal 111 at 10 KHz and the second clock signal 112 at 100 MHz.
  • the clock generator 110 may generate the self-generated clock at 100 MHz.
  • the pulse light generating unit 120 outputs pulse light in synchronization with the first clock signal 111 generated from the clock generator 110 at a first cycle.
  • the pulse light generator 120 is constructed with a light source 121 and a semiconductor optical amplifier (SOA) 122 .
  • SOA semiconductor optical amplifier
  • the light source 121 emits light.
  • the light source 121 may emit laser light having a center wavelength of 1550 nm.
  • the semiconductor optical amplifier 122 generates and outputs pulsed light corresponding to the laser light received from the light source 121 in synchronization with the first clock signal 111 received through the first trigger terminal 122a.
  • a first erbium doped fiber amplifier (EDFA) 131 amplifies and outputs a signal output from the semiconductor optical amplifier 122 and transmitted through an optical fiber.
  • EDFA erbium doped fiber amplifier
  • a first band pass filter (BPF) 141 filters signals output from the first erbium-doped optical fiber amplifier 131 so that only signals having a set bandwidth pass.
  • the first band pass filter 141 may filter pulsed light output from the first erbium-doped fiber optic amplifier 131 so that only light in a band of 1550 to 1552 nm is output.
  • the optical circulator 150 receives the pulsed light generated by the pulse light generator 120 and output through the first erbium-doped fiber optic amplifier 131 through the input terminal 150a, and receives the sensing optical fiber through the output terminal 150b ( 160), the sensing optical fiber 160 reversely proceeds and outputs the light input to the output terminal 150b to the detection terminal 150c.
  • the sensing optical fiber 160 has one end connected to the output terminal 150b of the optical circulator 150 and is laid to extend in a line shape over the area to be measured.
  • the light detector 170 is connected to the detection terminal 150c of the optical circulator 150, and is scattered by the sensing optical fiber 160 and propagated in reverse to output an electrical signal corresponding to the received light.
  • the optical detector 170 includes a second erbium-doped optical fiber amplifier (EDFA) 172, a second band pass filter (BPF) 174, and a photodetector (PD) 175.
  • EDFA erbium-doped optical fiber amplifier
  • BPF band pass filter
  • PD photodetector
  • the second erbium-doped optical fiber amplifier (EDFA) 172 amplifies a signal output from the detection terminal 150c of the optical circulator 150 and transmitted through an optical fiber.
  • EDFA erbium-doped optical fiber amplifier
  • the second band pass filter (BPF) 174 filters signals output from the second erbium-doped optical fiber amplifier 172 so that only signals having a set bandwidth pass through.
  • the second band pass filter 174 is configured to pass only signals of the same band as the first band pass filter 141 so as to receive Rayleigh scattered light.
  • the second band pass filter 174 also applies filtering to output only light in the 1550 to 1552 nm band.
  • the photodetector (PD) 175 receives the light output through the second band pass filter 174 and outputs it as an electrical signal corresponding to the intensity of the light.
  • the processing unit 180 generates sampling data in synchronization with the second clock signal 112 generated in a second cycle with respect to the signal received from the photodetector 175, and generates sampling data for each position of the sensing optical fiber 160 from the generated sampling data. Acoustic signal generation information is collected and processed, and the processing result is output through the output unit 190.
  • the processing unit 180 includes a data acquisition unit 181 and a signal processing unit 182.
  • the data acquisition unit 181 starts sampling the sampling data from the signal received from the photodetector 175 through the data receiving terminal 181b in synchronization with the second clock signal 112 received through the clock terminal 181a. .
  • the data acquisition unit 181 also uses the second clock signal 112 as a sampling clock.
  • the data acquisition unit 181 matches the received sampling data corresponding to one pulse light generated by the pulse light generator 120 into one sampling data set, and the received sampling data corresponding to the next order pulse light are matched with a sampling data set of the corresponding order, and the sampling data sets corresponding to each of a plurality of pulse lights are provided to the signal processing unit 182.
  • the signal processing unit 182 identifies the acoustic signal for each position of the sensing optical fiber 160 from the sampling data sets received from the data acquisition unit 181, and outputs the processing result generated by the set processing method through the output unit 190. print out As an example, the signal processing unit 182 may be configured to output, through the output unit 190, the intensity and position of the acoustic vibration at a position where an acoustic vibration signal equal to or higher than a set acoustic vibration level is received.
  • the first clock signal 111 may be provided to the data acquisition unit 181 to be used as a trigger signal for starting sampling.
  • the data acquisition unit 181 receives the first clock signal 181 through the trigger terminal 181c. Whenever the clock signal 111 is received, it may be configured to start sampling of a new data set in synchronization with the second clock signal 112.
  • the clock generator 110 may be constructed so that driving is controlled by the signal processing unit 180.
  • the processing unit 182 when a measurement start instruction signal is received through an input unit (not shown), clock generator 110 activate
  • pulsed light generation timing and processing unit 180 sampling according to the first clock signal and the second clock signal synchronously output from the clock generator 110 of the optical fiber acoustic distribution sensor 100 of the present invention.
  • the start times are matched, and the sampling start times for each generated pulse light are matched so that the start positions of the sampling data sets are kept the same, so that the displacement of the sampling data sets is eliminated.
  • FIGS. 3, 5, and 7 4, 6 and 8 show some measurement areas of the vibroacoustic signal measured by simulation under the same conditions for the method of the present invention in FIG. 2b, vibration signal for each distance, and noise level for each distance.
  • FIG. 3 is a result of collecting 1,000 data sets with a 100 MHz data acquisition unit's own clock using a semiconductor amplifier's own clock operating at 5 kHz for a sensing optical fiber extending 19 km in length. A misalignment occurs between the trigger clock and the clock of the data acquisition unit, causing the collected data set to shake left and right.
  • FIG. 4 is a result of measuring the synchronization of the semiconductor amplifier and the data acquisition unit by simultaneously generating the first clock signal and the second clock signal synchronized through the clock generator under the same conditions, and the positional deviation between the data sets is resolved. You can check.
  • 5 and 6 overlap five OTDR data sets measured by the conventional method and the proposed method.
  • FIG. 5 it can be confirmed that a large deviation between data sets occurs due to clock deviation compared to FIG. 6 .
  • 7 and 8 are results of measuring variance for each location data of 1,000 OTDR data sets measured by the conventional method and the proposed method.
  • the proposed method can confirm a noise reduction effect of 3dB level as the dispersion data level is confirmed to be half.
  • the pulse light generation time of the pulse light generation unit and the sampling time of the processing unit that generates sampling data from the Rayleigh scattering signal are synchronized using the clock signal generated by the clock generator. Measurement accuracy can be improved by suppressing measurement position deviation of the sampling data sets.

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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  • Remote Sensing (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

The present invention relates to a noise-reducing optical fiber sound distribution sensor comprising: a clock generator for generating a first clock signal having a first period and a second clock signal having a second period configured to be shorter than the first period while being synchronized with an auto-generated clock; a pulse light generator for outputting pulse light while being synchronized with the first clock signal; an optical circulator for transmitting pulse light, which is output from the pulse light generator and is input thereto through an input end, to a sensing optical fiber through an output end, and outputting light which propagates backwards from the sensing optical fiber to a detecting end; a photo-detector connected to the detecting end of the optical circulator so as to output an electric signal corresponding to received light; and a processing unit for generating sampling data with regard to the signal received from the photo-detector while being synchronized with the second clock signal, the processing unit collecting and processing position-specific sound signal generation information regarding the sensing optical fiber from the generated sampling data. According to the noise-reducing optical fiber sound distribution sensor, the clock signal generated by the clock generator is used to synchronize the time to generate pulse light with the sampling time of the processing unit for generating sampling data from a Rayleigh scattering signal such that the measurement position deviation of sampling data sets is suppressed, thereby improving measurement precision.

Description

노이즈 저감형 광섬유 음향 분포센서Noise reduction type optical fiber acoustic distribution sensor
본 발명은 노이즈 저감형 광섬유 음향 분포센서에 관한 것으로서, 상세하게는 펄스광 발생과 센싱광섬유로부터 역으로 수신된 산란신호의 샘플링을 동기화 시킬 수 있도록 된 노이즈 저감형 광섬유 음향 분포센서에 관한 것이다.The present invention relates to a reduced-noise optical fiber acoustic distribution sensor, and more particularly, to a reduced-noise optical fiber acoustic distribution sensor capable of synchronizing the generation of pulsed light with the sampling of a scattering signal reversely received from a sensing optical fiber.
광섬유를 센서로 활용하는 기술은 분포형 방식으로서 OTDR(Optical Time Domain Reflectometry)과 포인트형 방식으로서 FBG(Fiber Bragg Grating sensor)로 구분된다. 분포형 OTDR은 측정방식에 따라 간섭형 센서(Interferometer sensor)와 강도형 센서(Intensity sensor)로 세분된다.Technologies using optical fibers as sensors are classified into OTDR (Optical Time Domain Reflectometry) as a distributed method and FBG (Fiber Bragg Grating sensor) as a point method. Distributed OTDRs are subdivided into interferometer sensors and intensity sensors according to the measurement method.
분포형 OTDR센서에 레이저 펄스를 입사시키면 다양한 방향으로 산란(Scattering)이 일어나며 역방향으로 산란하는 후방산란(Back scattering)으로 레일레이(Rayleigh), 라만(Raman), 브릴루앙(Brillouin)의 3종류의 산란이 있다. 입사시와 관측시의 시간차에 의하여 광섬유 케이블의 어느 위치에서 산란된 후방산란인가를 알 수 있는데, 일반적으로 입사광과 같은 주파수를 갖는 레일레이(Rayleigh) 산란파를 이용하여 위치를 파악한다. 큰 산란계수를 갖는 레일레이(Rayleigh) 산란은 대체로 광섬유 케이블을 구성하는 광섬유 재료의 밀도 변화와 관련되며 파장의 변화는 없다.When a laser pulse is incident on a distributed OTDR sensor, scattering occurs in various directions, and back scattering, which scatters in the reverse direction, produces three types of Rayleigh, Raman, and Brillouin. There is spawning. The backscattered position of the fiber optic cable can be determined by the time difference between incident and observation. In general, the position is determined using a Rayleigh scattered wave having the same frequency as the incident light. Rayleigh scattering with a large scattering coefficient is usually associated with a change in the density of an optical fiber material constituting an optical fiber cable, and there is no change in wavelength.
이러한 레일레이 산란광을 검출하는 광섬유 음향분포 센서는 국내 등록특허 제10-2292226호 등 다양하게 제안되어 있다.Various optical fiber acoustic distribution sensors for detecting Rayleigh scattered light have been proposed in various ways, such as Korean Patent No. 10-2292226.
그런데, 펄스광을 생성하는 요소와 레일레이 산란광을 수신하여 펄스광에 대응되는 샘플링 데이터셋을 생성하는 요소 상호간을 동기시키기 위한 트리거 신호를 발생시키더라도 펄스광을 생성하는 요소의 내부클럭과 샘플링 데이터를 생성하는 요소의 내부 클럭을 각각 운용하는 방식의 경우 트리거 신호 발생시마다의 내부 클럭 발생시기가 매번 달라질 수 있다. 이 경우 트리거 신호가 발생되었어도 내부 클럭이 발생되기 까지의 지연시간이 발생되고, 이러한 지연시간은 트리거 신호 발생시마다 매번 달라질 수 있어 펄스광들에 각각 대응되어 생성되는 샘플링 데이터셋 상호간의 측정 위치 편차가 발생되어 데이터 분석의 정밀성을 떨어뜨린다. 또한, 샘플링 데이터셋 상호간의 측정 위치 편차가 발생되면, 분석과정에서 이러한 측정위치 편차가 배경잡음이 되고, 감도를 저하시킨다.However, even if a trigger signal is generated to synchronize the elements generating the pulsed light and the element generating the sampling data set corresponding to the pulsed light by receiving the Rayleigh scattered light, the internal clock and sampling data of the element generating the pulsed light In the case of a method of operating the internal clock of each element generating the internal clock, the timing of generating the internal clock each time a trigger signal is generated may be different each time. In this case, even if the trigger signal is generated, a delay time until the internal clock is generated occurs, and this delay time can be changed every time the trigger signal is generated, so that the measurement position deviation between the sampling data sets generated in response to the pulse lights generated, which reduces the precision of data analysis. In addition, when measurement location deviations between sampling datasets occur, such measurement location deviations become background noise during the analysis process, and decrease sensitivity.
본 발명은 상기와 같은 문제점을 개선하기 위하여 창안된 것으로서, 펄스광들에 각각 대응되어 생성되는 레일레이 산란광에 대한 샘플링 데이터셋들에 대한 측정 위치 편차를 억제시켜 측정 정밀도를 향상시킬 수 있는 노이즈 저감형 광섬유 음향 분포센서를 제공하는데 그 목적이 있다.The present invention was devised to improve the above problems, and noise reduction that can improve measurement accuracy by suppressing measurement position deviation for sampling datasets for Rayleigh scattered light generated corresponding to each pulse light Its purpose is to provide a type optical fiber acoustic distribution sensor.
상기의 목적을 달성하기 위하여 본 발명에 따른 노이즈 저감형 광섬유 음향 분포센서는 자체 발생클럭에 동기되어 제1주기의 제1클럭신호와 상기 제1주기 보다 짧게 설정된 제2주기의 제2클럭신호를 발생하는 클럭발생기와; 상기 클럭발생기로부터 제1주기로 발생되는 상기 제1클럭신호에 동기되어 펄스광을 출력하는 펄스광 생성부와; 상기 펄스광 생성부에서 출력되어 입력단을 통해 입력되는 펄스광을 출력단을 통해 센싱광섬유로 전송하고, 상기 센싱광섬유에서 역으로 진행되는 광을 검출단으로 출력하는 광써큘레이터와; 상기 광써큘레이터의 검출단에 접속되어 수신된 광에 대응되는 전기적 신호를 출력하는 광검출부와; 상기 광검출부로부터 수신되는 신호에 대해 상기 제2주기로 발생되는 제2클럭신호에 동기되어 샘플링 데이터를 생성하고, 생성된 샘플링 데이터로부터 상기 센싱광섬유의 위치별 음향 신호의 발생정보를 수집 및 처리하는 처리부;를 구비한다.In order to achieve the above object, the noise reduction type optical fiber acoustic distribution sensor according to the present invention is synchronized with the self-generated clock and generates a first clock signal of a first period and a second clock signal of a second period set shorter than the first period. a clock generator that generates; a pulse light generating unit that outputs pulse light in synchronization with the first clock signal generated from the clock generator at a first cycle; an optical circulator for transmitting the pulsed light output from the pulsed light generating unit and inputted through an input terminal to a sensing optical fiber through an output terminal, and outputting light traveling backward from the sensing optical fiber to a detection terminal; a photodetector connected to the detection end of the optical circulator and outputting an electrical signal corresponding to the received light; A processing unit for generating sampling data in synchronization with the second clock signal generated in the second cycle with respect to the signal received from the photodetector, and collecting and processing acoustic signal generation information for each position of the sensing optical fiber from the generated sampling data. ;
본 발명의 일 측면에 따르면, 상기 펄스광 생성부는 레이저 광을 출사하는 광원과; 상기 레이저 광을 입력받아 상기 제1클럭신호에 동기되어 펄스광을 생성하여 출력하는 반도체 광증폭기;를 구비한다.According to one aspect of the present invention, the pulse light generating unit and a light source for emitting laser light; and a semiconductor optical amplifier that receives the laser light and generates and outputs pulsed light synchronized with the first clock signal.
또한, 상기 반도체 광증폭기에서 출력되어 광섬유를 통해 전송되는 신호를 증폭하는 제1 에르븀 첨가 광섬유증폭기와; 상기 제1 에르븀 첨가 광섬유 증폭기에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링하는 제1밴드패스필터;를 더 구비할 수 있다.In addition, a first erbium-doped optical fiber amplifier for amplifying the signal output from the semiconductor optical amplifier and transmitted through the optical fiber; It may further include a first band pass filter filtering the signal output from the first erbium-doped optical fiber amplifier so that only a signal having a set bandwidth passes.
또한, 상기 광검출부는 상기 광써큘레이터의 검출단에서 출력되어 광섬유를 통해 전송되는 신호를 증폭하는 제2에르븀 첨가 광섬유증폭기와; 상기 제2 에르븀 첨가 광섬유 증폭기에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링하는 제2밴드패스필터와; 상기 제2밴드패스필터를 통과하여 출력되는 광을 수신하여 전기적 신호로 출력하는 광검출기;를 구비한다.In addition, the optical detector unit may include a second erbium-doped optical fiber amplifier for amplifying a signal output from the detection end of the optical circulator and transmitted through an optical fiber; a second band pass filter filtering the signals output from the second erbium-doped optical fiber amplifier so that only signals having a set bandwidth pass through; and a photodetector for receiving the light output through the second band pass filter and outputting the light as an electrical signal.
또한, 상기 클럭발생기는 상기 제1클럭신호는 10KHz로 발생시키고, 상기 제2클럭신호는 100MHz로 발생시키도록 구축될 수 있다.In addition, the clock generator may be configured to generate the first clock signal at 10 KHz and the second clock signal at 100 MHz.
본 발명에 따른 노이즈 저감형 광섬유 음향 분포센서에 의하면, 클럭발생기에서 생성되는 클럭신호를 이용하여 펄스광 생성부의 펄스광 생성시기와 레일레이 산란신호로부터 샘플링데이터를 생성하는 처리부의 샘플링 시기가 동기됨으로써 샘플링 데이터 셋들의 측정위치 편차가 억제되어 측정정밀도를 향상시킬 수 있다.According to the noise reduction optical fiber acoustic distribution sensor according to the present invention, the pulse light generation time of the pulse light generator and the sampling time of the processing unit that generates sampling data from the Rayleigh scattering signal are synchronized using the clock signal generated by the clock generator. Measurement accuracy can be improved by suppressing measurement position deviation of the sampling data sets.
도 1은 본 발명에 따른 노이즈 저감형 광섬유 음향 분포센서를 나타내 보인 도면이고,1 is a view showing a noise reduction optical fiber acoustic distribution sensor according to the present invention,
도 2는 도 1의 펄스광 생성부와 처리부의 동기화 과정을 종래 방식과 비교하여 설명하기 위한 그래프이고,2 is a graph for explaining the synchronization process of the pulse light generating unit and the processing unit of FIG. 1 in comparison with the conventional method;
도 3 내지 도 8은 본 발명의 광섬유 음향분포센서와 종래 방식을 비교하여 설명하기 위한 신호들의 예를 나타내 보인 그래프들이다. 3 to 8 are graphs showing examples of signals for explanation by comparing the optical fiber acoustic distribution sensor of the present invention with the conventional method.
이하, 첨부된 도면을 참조하면서 본 발명의 바람직한 실시예에 따른 노이즈 저감형 광섬유 음향 분포센서를 더욱 상세하게 설명한다.Hereinafter, a noise reduction type optical fiber acoustic distribution sensor according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.
도 1은 본 발명에 따른 노이즈 저감형 광섬유 음향 분포센서를 나타내 보인 도면이다.1 is a view showing a noise reduction type optical fiber acoustic distribution sensor according to the present invention.
도 1을 참조하면, 본 발명에 따른 광섬유 음향 분포센서(100)는 클럭발생기(110), 펄스광 생성부(120), 광써큘레이터(150), 센싱광섬유(160), 광검출부(170), 처리부(180)를 구비한다.Referring to FIG. 1, the optical fiber acoustic distribution sensor 100 according to the present invention includes a clock generator 110, a pulse light generator 120, an optical circulator 150, a sensing optical fiber 160, and an optical detector 170. , a processing unit 180 is provided.
클럭발생기(110)는 자체 발생클럭에 동기되어 제1주기의 제1클럭신호(111)와 제1주기 보다 짧게 설정된 제2주기의 제2클럭신호(112)를 발생한다. 클럭발생기(110)의 자체 발생클럭은 제2클럭신호(112)로 이용되게 구축될 수 있다.The clock generator 110 generates a first clock signal 111 of a first cycle and a second clock signal 112 of a second cycle set shorter than the first cycle in synchronization with its own clock. A self-generated clock of the clock generator 110 may be constructed to be used as the second clock signal 112 .
일 예로서, 클럭발생기(110)는 제1클럭신호(111)는 10KHz로 발생시키고, 제2클럭신호(112)는 100MHz로 발생시키도록 구축될 수 있다. 반면, 자체 발생클럭을 제2클럭신호(112)로 이용되게 구축하는 경우 클럭발생기(110)는 자체 발생클럭은 100MHz로 발생시키는 것을 적용하면 된다. As an example, the clock generator 110 may be configured to generate the first clock signal 111 at 10 KHz and the second clock signal 112 at 100 MHz. On the other hand, if the self-generated clock is constructed to be used as the second clock signal 112, the clock generator 110 may generate the self-generated clock at 100 MHz.
펄스광 생성부(120)는 클럭발생기(110)로부터 제1주기로 발생되는 제1클럭신호(111)에 동기되어 펄스광을 출력한다.The pulse light generating unit 120 outputs pulse light in synchronization with the first clock signal 111 generated from the clock generator 110 at a first cycle.
펄스광 생성부(120)는 광원(121)과 반도체 광증폭기(SOA; Semiconductor Optical Amplifier)(122)로 구축되어 있다.The pulse light generator 120 is constructed with a light source 121 and a semiconductor optical amplifier (SOA) 122 .
광원(121)은 광을 출사한다. 광원(121)은 중심파장이 1550nm인 레이저광을 출사하는 것이 적용될 수 있다.The light source 121 emits light. The light source 121 may emit laser light having a center wavelength of 1550 nm.
반도체 광증폭기(122)는 제1트리거단자(122a)를 통해 수신되는 제1클럭신호(111)에 동기되어 광원(121)으로부터 입력받은 레이저광에 대응되게 펄스광을 생성하여 출력한다.The semiconductor optical amplifier 122 generates and outputs pulsed light corresponding to the laser light received from the light source 121 in synchronization with the first clock signal 111 received through the first trigger terminal 122a.
제1 에르븀 첨가 광섬유증폭기(EDFA;Erbium Doped Fiber Amplifier)(131)는 반도체 광증폭기(122)에서 출력되어 광섬유를 통해 전송되는 신호를 증폭하여 출력한다.A first erbium doped fiber amplifier (EDFA) 131 amplifies and outputs a signal output from the semiconductor optical amplifier 122 and transmitted through an optical fiber.
제1밴드패스필터(BPF;Band Pass Filter)(141)는 제1 에르븀 첨가 광섬유 증폭기(131)에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링한다. 일 예로서, 제1밴드패스필터(141)는 제1 에르븀 첨가 광섬유증폭기(131)에서 출력된 펄스광에 대해 1550 내지 1552nm 대역의 광만 출력되게 필터링하는 것이 적용될 수 있다.A first band pass filter (BPF) 141 filters signals output from the first erbium-doped optical fiber amplifier 131 so that only signals having a set bandwidth pass. As an example, the first band pass filter 141 may filter pulsed light output from the first erbium-doped fiber optic amplifier 131 so that only light in a band of 1550 to 1552 nm is output.
광써큘레이터(150)는 펄스광 생성부(120)에서 생성되어 제1 에르븀 첨가 광섬유증폭기(131)를 통해 출력된 펄스광을 입력단(150a)을 통해 입력받아 출력단(150b)을 통해 센싱광섬유(160)로 전송하고, 센싱광섬유(160)에서 역으로 진행되어 출력단(150b)으로 입력된 광을 검출단(150c)으로 출력한다.The optical circulator 150 receives the pulsed light generated by the pulse light generator 120 and output through the first erbium-doped fiber optic amplifier 131 through the input terminal 150a, and receives the sensing optical fiber through the output terminal 150b ( 160), the sensing optical fiber 160 reversely proceeds and outputs the light input to the output terminal 150b to the detection terminal 150c.
센싱광섬유(160)는 광써큘레이터(150)의 출력단(150b)에 일단이 접속되어 측정대상 영역에 라인형태로 연장되게 포설되어 있다.The sensing optical fiber 160 has one end connected to the output terminal 150b of the optical circulator 150 and is laid to extend in a line shape over the area to be measured.
광검출부(170)는 광써큘레이터(150)의 검출단(150c)에 접속되어 센싱광섬유(160)에서 산란되어 역으로 진행되어 수신된 광에 대응되는 전기적 신호를 출력한다.The light detector 170 is connected to the detection terminal 150c of the optical circulator 150, and is scattered by the sensing optical fiber 160 and propagated in reverse to output an electrical signal corresponding to the received light.
광검출부(170)는 제2에르븀 첨가 광섬유증폭기(EDFA)(172)와, 제2 밴드패스필터(BPF)(174) 및 광검출기(PD)(175)를 구비한다.The optical detector 170 includes a second erbium-doped optical fiber amplifier (EDFA) 172, a second band pass filter (BPF) 174, and a photodetector (PD) 175.
제2에르븀 첨가 광섬유증폭기(EDFA)(172)는 광써큘레이터(150)의 검출단(150c)에서 출력되어 광섬유를 통해 전송되는 신호를 증폭한다.The second erbium-doped optical fiber amplifier (EDFA) 172 amplifies a signal output from the detection terminal 150c of the optical circulator 150 and transmitted through an optical fiber.
제2 밴드패스필터(BPF)(174)는 제2 에르븀 첨가 광섬유 증폭기(172)에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링한다. 제2밴드패스필터(174)는 레일레이 산란광을 수신할 수 있도록 제1밴드패스필터(141)와 동일한 대역의 신호만 통과되게 구축된다. 일 예로서, 제1밴드패스필터(141)가 1550 내지 1552nm 대역의 광만 출력되게 필터링하는 경우 제2밴드패스필터(174)도 1550 내지 1552nm 대역의 광만 출력되게 필터링하는 것을 적용한다. The second band pass filter (BPF) 174 filters signals output from the second erbium-doped optical fiber amplifier 172 so that only signals having a set bandwidth pass through. The second band pass filter 174 is configured to pass only signals of the same band as the first band pass filter 141 so as to receive Rayleigh scattered light. As an example, when the first band pass filter 141 filters only light in the 1550 to 1552 nm band to be output, the second band pass filter 174 also applies filtering to output only light in the 1550 to 1552 nm band.
광검출기(PD)(175)는 제2밴드패스필터(174)를 통과하여 출력되는 광을 수신하여 광의 세기에 대응되는 전기적 신호로 출력한다.The photodetector (PD) 175 receives the light output through the second band pass filter 174 and outputs it as an electrical signal corresponding to the intensity of the light.
처리부(180)는 광검출기(175)로부터 수신되는 신호에 대해 제2주기로 발생되는 제2클럭신호(112)에 동기되어 샘플링 데이터를 생성하고, 생성된 샘플링 데이터로부터 센싱광섬유(160)의 위치별 음향 신호의 발생정보를 수집 및 처리하고, 처리결과를 출력부(190)를 통해 출력한다.The processing unit 180 generates sampling data in synchronization with the second clock signal 112 generated in a second cycle with respect to the signal received from the photodetector 175, and generates sampling data for each position of the sensing optical fiber 160 from the generated sampling data. Acoustic signal generation information is collected and processed, and the processing result is output through the output unit 190.
처리부(180)는 데이터 획득부(181)와 신호처리부(182)를 구비한다.The processing unit 180 includes a data acquisition unit 181 and a signal processing unit 182.
데이터 획득부(181)는 클럭단자(181a)를 통해 수신된 제2클럭신호(112)에 동기되어 광검출기(175)로부터 데이터 수신단(181b)을 통해 수신되는 신호로부터 샘플링 데이터의 샘플링을 개시한다. 데이터 획득부(181)는 제2클럭신호(112)를 샘플링 클럭으로도 이용한다.The data acquisition unit 181 starts sampling the sampling data from the signal received from the photodetector 175 through the data receiving terminal 181b in synchronization with the second clock signal 112 received through the clock terminal 181a. . The data acquisition unit 181 also uses the second clock signal 112 as a sampling clock.
데이터 획득부(181)는 펄스광생성부(120)에서 생성된 하나의 펄스광에 대응되게 수신된 샘플링 데이터들을 하나의 샘플링 데이터 셋으로 매칭시키고, 다음 차수의 펄스광에 대응되게 수신된 샘플링 데이터들을 해당 차수의 샘플링 데이터 셋으로 매칭시켜 다수의 펄스광 각각에 대응되는 샘플링 데이터셋들을 신호 처리부(182)에 제공한다. The data acquisition unit 181 matches the received sampling data corresponding to one pulse light generated by the pulse light generator 120 into one sampling data set, and the received sampling data corresponding to the next order pulse light are matched with a sampling data set of the corresponding order, and the sampling data sets corresponding to each of a plurality of pulse lights are provided to the signal processing unit 182.
신호처리부(182)는 데이터 획득부(181)로부터 수신된 샘플링 데이터셋들로부터 센싱광섬유(160)의 위치별 음향신호를 파악하고, 설정된 처리방식으로 생성한 처리결과를 출력부(190)를 통해 출력한다. 일 예로서, 신호처리부(182)는 설정된 음향 진동레벨 이상의 음향 진동신호가 수신된 위치에 대해서는 음향 진동세기 및 위치를 출력부(190)를 통해 출력하도록 구축될 수 있다. The signal processing unit 182 identifies the acoustic signal for each position of the sensing optical fiber 160 from the sampling data sets received from the data acquisition unit 181, and outputs the processing result generated by the set processing method through the output unit 190. print out As an example, the signal processing unit 182 may be configured to output, through the output unit 190, the intensity and position of the acoustic vibration at a position where an acoustic vibration signal equal to or higher than a set acoustic vibration level is received.
한편, 제1클럭신호(111)는 데이터 획득부(181)에 샘플링 스타트용 트리거 신호로서 이용되게 제공될 수 있고, 이 경우 데이터 획득부(181)는 트리거단자(181c)를 통해 수신된 제1클럭신호(111)가 수신될 때 마다 제2클럭신호(112)에 동기되어 새로운 데이터 셋에 대한 샘플링을 시작하도록 구축될 수 있다.Meanwhile, the first clock signal 111 may be provided to the data acquisition unit 181 to be used as a trigger signal for starting sampling. In this case, the data acquisition unit 181 receives the first clock signal 181 through the trigger terminal 181c. Whenever the clock signal 111 is received, it may be configured to start sampling of a new data set in synchronization with the second clock signal 112.
또한, 클럭발생기(110)는 신호처리부(180)에 의해 구동이 제어되게 구축될 수 있고, 이 경우 처리부(182)는 입력부(미도시)를 통해 측정시작 지시신호가 수신되면 클럭발생기(110)를 가동시킨다.In addition, the clock generator 110 may be constructed so that driving is controlled by the signal processing unit 180. In this case, the processing unit 182, when a measurement start instruction signal is received through an input unit (not shown), clock generator 110 activate
한편, 도 2a의 종래방식에서와 같이 반도체 광증폭기에서 발생되는 자체 클럭을 데이터 획득부의 트리거신호로서 이용하는 경우 데이터 획득부의 자체 클럭과 트리거신호가 일치하지 않는 경우가 발생하고, 이러한 불일치에 의한 지연차이는 트리거신호 발생시마다 달라져 샘플링 데이터셋 상호간의 샘플링 시작 위치가 달라지는 문제점을 야기시킨다.On the other hand, when the self-clock generated by the semiconductor optical amplifier is used as the trigger signal of the data acquisition unit, as in the conventional method of FIG. is changed every time a trigger signal is generated, causing a problem that sampling start positions between sampling datasets are different.
이에 반해 도 2b에서와 같이 본 발명의 광섬유 음향 분포센서(100)의 클럭발생기(110)에서 동기되어 출력되는 제1클럭신호와 제2클럭신호에 따라 펄스광 생성시기와 처리부(180)의 샘플링 시작시기가 일치되고, 매번 발생되는 펄스광에 대한 샘플링 시작시기가 일치되어 샘플링 데이터셋 상호간의 시작위치가 동일하게 유지됨으로써 샘플링 데이터 셋들의 위치 어긋남이 해소된다.On the other hand, as shown in FIG. 2B, pulsed light generation timing and processing unit 180 sampling according to the first clock signal and the second clock signal synchronously output from the clock generator 110 of the optical fiber acoustic distribution sensor 100 of the present invention. The start times are matched, and the sampling start times for each generated pulse light are matched so that the start positions of the sampling data sets are kept the same, so that the displacement of the sampling data sets is eliminated.
이러한 차이를 확인하기 위해 동일한 조건에 대해 도 2a의 종래 방식에 대해 측정된 진동음향신호의 일부 측정영역, 거리별 진동신호 및 거리별 잡음크기에 대해 측정한 결과가 도 3, 도 5 및 도 7에 도시되어 있고, 도 2b의 본 발명의 방식에 대해 동일 조건으로 시률레이션하여 측정된 진동음향신호의 일부 측정영역, 거리별 진동신호 및 거리별 잡음크기가 도 4, 도 6 및 도 8에 도시되어 있다.In order to confirm this difference, the measurement results for some measurement areas of the vibroacoustic signal measured for the conventional method of FIG. 2a, the vibration signal for each distance, and the noise level for each distance under the same conditions are shown in FIGS. 3, 5, and 7 4, 6 and 8 show some measurement areas of the vibroacoustic signal measured by simulation under the same conditions for the method of the present invention in FIG. 2b, vibration signal for each distance, and noise level for each distance. has been
도 3은 19 km의 길이로 연장된 센싱 광섬유에 대하여 5kHz로 동작하는 반도체 증폭기 자체클럭을 이용하여 1천개의 데이터셋을 100MHz의 데이터획득부 자체클럭으로 수집한 결과이다. 트리거 클럭과 데이터 획득부의 클럭 사이 위치 어긋남이 발생하여 수집한 데이터 셋이 좌우로 흔들리는 현상이 발한다. 이에 반해, 도 4는 같은 조건에서 클럭 발생기를 통해 동기화된 제1클럭신호와 제2클럭신호를 동시에 생성하여 반도체 증폭기와 데이터획득부를 동기화하여 측정한 결과로서, 데이터 셋 간의 위치 어긋남이 해소된 것을 확인할 수 있다. FIG. 3 is a result of collecting 1,000 data sets with a 100 MHz data acquisition unit's own clock using a semiconductor amplifier's own clock operating at 5 kHz for a sensing optical fiber extending 19 km in length. A misalignment occurs between the trigger clock and the clock of the data acquisition unit, causing the collected data set to shake left and right. On the other hand, FIG. 4 is a result of measuring the synchronization of the semiconductor amplifier and the data acquisition unit by simultaneously generating the first clock signal and the second clock signal synchronized through the clock generator under the same conditions, and the positional deviation between the data sets is resolved. You can check.
도 5와 도 6은 종래방식과 제안방식으로 측정한 OTDR 데이터 셋 5개를 중첩한 것이다. 도 5는 도 6에 비하여 클락 어긋남에 의해 데이터 셋 간의 편차가 크게 발생한 것을 확인할 수 있다. 도 7과 도 8은 종래방식과 제안방식으로 측정한 OTDR 데이터 셋 1,000개의 각 위치 데이터 별 분산을 측정한 결과이다. 종래방식 대비 제안방식은 분산 데이터 레벨이 절반수준으로 확인됨에 따라 3dB 수준의 노이즈 감소 효과를 확인할 수 있다.5 and 6 overlap five OTDR data sets measured by the conventional method and the proposed method. In FIG. 5 , it can be confirmed that a large deviation between data sets occurs due to clock deviation compared to FIG. 6 . 7 and 8 are results of measuring variance for each location data of 1,000 OTDR data sets measured by the conventional method and the proposed method. Compared to the conventional method, the proposed method can confirm a noise reduction effect of 3dB level as the dispersion data level is confirmed to be half.
도 3 내지 도 8의 비교 그래프를 통해 확인할 수 있는 바와 같이 본 발명의 동기방식이 잡음크기를 줄일 수 있음을 확인할 수 있다.As can be confirmed through the comparison graphs of FIGS. 3 to 8, it can be confirmed that the synchronization method of the present invention can reduce the noise level.
이상에서 설명된 노이즈 저감형 광섬유 음향 분포센서에 의하면, 클럭발생기에서 생성되는 클럭신호를 이용하여 펄스광 생성부의 펄스광 생성시기와 레일레이 산란신호로부터 샘플링데이터를 생성하는 처리부의 샘플링 시기가 동기됨으로써 샘플링 데이터 셋들의 측정위치 편차가 억제되어 측정정밀도를 향상시킬 수 있다. According to the noise reduction optical fiber acoustic distribution sensor described above, the pulse light generation time of the pulse light generation unit and the sampling time of the processing unit that generates sampling data from the Rayleigh scattering signal are synchronized using the clock signal generated by the clock generator. Measurement accuracy can be improved by suppressing measurement position deviation of the sampling data sets.

Claims (5)

  1. 자체 발생클럭에 동기되어 제1주기의 제1클럭신호와 상기 제1주기 보다 짧게 설정된 제2주기의 제2클럭신호를 발생하는 클럭발생기와;a clock generator for generating a first clock signal of a first period and a second clock signal of a second period set to be shorter than the first period in synchronization with the self-generated clock;
    상기 클럭발생기로부터 제1주기로 발생되는 상기 제1클럭신호에 동기되어 펄스광을 출력하는 펄스광 생성부와;a pulse light generating unit that outputs pulse light in synchronization with the first clock signal generated from the clock generator at a first cycle;
    상기 펄스광 생성부에서 출력되어 입력단을 통해 입력되는 펄스광을 출력단을 통해 센싱광섬유로 전송하고, 상기 센싱광섬유에서 역으로 진행되는 광을 검출단으로 출력하는 광써큘레이터와;an optical circulator for transmitting the pulsed light output from the pulsed light generating unit and inputted through an input terminal to a sensing optical fiber through an output terminal, and outputting light traveling backward from the sensing optical fiber to a detection terminal;
    상기 광써큘레이터의 검출단에 접속되어 수신된 광에 대응되는 전기적 신호를 출력하는 광검출부와;a photodetector connected to the detection end of the optical circulator and outputting an electrical signal corresponding to the received light;
    상기 광검출부로부터 수신되는 신호에 대해 상기 제2주기로 발생되는 제2클럭신호에 동기되어 샘플링 데이터를 생성하고, 생성된 샘플링 데이터로부터 상기 센싱광섬유의 위치별 음향 신호의 발생정보를 수집 및 처리하는 처리부;를 구비하는 것을 특징으로 하는 노이즈 저감형 광섬유 음향 분포센서.A processing unit for generating sampling data in synchronization with the second clock signal generated in the second cycle with respect to the signal received from the photodetector, and collecting and processing acoustic signal generation information for each position of the sensing optical fiber from the generated sampling data. A noise reduction optical fiber acoustic distribution sensor comprising:
  2. 제1항에 있어서, 상기 펄스광 생성부는The method of claim 1, wherein the pulsed light generating unit
    레이저 광을 출사하는 광원과;a light source for emitting laser light;
    상기 레이저 광을 입력받아 상기 제1클럭신호에 동기되어 펄스광을 생성하여 출력하는 반도체 광증폭기;를 구비하는 것을 특징으로 하는 노이즈 저감형 광섬유 음향 분포센서.and a semiconductor optical amplifier that receives the laser light and generates and outputs pulsed light synchronized with the first clock signal.
  3. 제2항에 있어서, 상기 반도체 광증폭기에서 출력되어 광섬유를 통해 전송되는 신호를 증폭하는 제1 에르븀 첨가 광섬유증폭기와;The optical fiber amplifier according to claim 2, comprising: a first erbium-doped optical fiber amplifier for amplifying the signal output from the semiconductor optical amplifier and transmitted through the optical fiber;
    상기 제1 에르븀 첨가 광섬유 증폭기에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링하는 제1밴드패스필터;를 더 구비하는 것을 특징으로 하는 노이즈 저감형 광섬유 음향 분포센서. The noise reduction optical fiber acoustic distribution sensor, characterized in that it further comprises a first band pass filter filtering the signal output from the first erbium-doped optical fiber amplifier so that only signals having a set bandwidth pass through.
  4. 제3항에 있어서, 상기 광검출부는The method of claim 3, wherein the photodetector
    상기 광써큘레이터의 검출단에서 출력되어 광섬유를 통해 전송되는 신호를 증폭하는 제2에르븀 첨가 광섬유증폭기와;a second erbium-doped optical fiber amplifier for amplifying a signal output from the detection terminal of the optical circulator and transmitted through an optical fiber;
    상기 제2 에르븀 첨가 광섬유 증폭기에서 출력되는 신호에 대해 설정된 밴드폭의 신호만 통과되게 필터링하는 제2밴드패스필터와;a second band pass filter filtering the signals output from the second erbium-doped optical fiber amplifier so that only signals having a set bandwidth pass through;
    상기 제2밴드패스필터를 통과하여 출력되는 광을 수신하여 전기적 신호로 출력하는 광검출기;를 구비하는 것을 특징으로 하는 노이즈 저감형 광섬유 음향 분포센서. and a photodetector for receiving the light output through the second band pass filter and outputting the light as an electrical signal.
  5. 제1항에 있어서, 상기 클럭발생기는 상기 제1클럭신호는 10KHz로 발생시키고, 상기 제2클럭신호는 100MHz로 발생시키는 것을 특징으로 하는 노이즈 저감형 광섬유 음향 분포센서. [Claim 2] The noise reduction optical fiber acoustic distribution sensor according to claim 1, wherein the clock generator generates the first clock signal at 10 KHz and the second clock signal at 100 MHz.
PCT/KR2021/018343 2021-10-29 2021-12-06 Noise-reducing optical fiber sound distribution sensor WO2023075008A1 (en)

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