72results about How to "Realize Distributed Measurements" patented technology

The invention relates to a distributed coal mine rock burst monitoring method, belonging to a ground pressure monitoring method. The existing industrial Ethernet in a coal mine integrated automation system can be used for information transmission, a network sensor provided with an Ethernet interface is connected with a network, multiple measurements such as electromagnetic radiation, acoustic emission, micro-shock and the like which are used for reflecting signals of rock burst can be carried out, the measurement signals are transmitted into a host machine for monitoring the rock burst through the industrial Ethernet, and the host machine is used for analyzing, processing and locating a seismic source so as to realize rock burst monitoring; a main core of the network sensor is a singlechip provided with an Ethernet controller, and the measurement of three signals of electromagnetic radiation, acoustic emission and micro-shock can be realized by analog-to-digital conversion through three channels; and each sensor has the respective IP address. The method can be used for extracting features of various signals, carrying out event relativity analysis, extracting data fusion and event general features with different information, locating the seismic source and providing the analysis result of rock burst event.

The invention relates to a fiber grating distributed strain sensor and a strain monitoring method thereof, which are characterized in that an erbium-doped fiber amplifier is added into an optical fiber fading cavity to form an active fading cavity, and an optical pulse fading sequence is obtained, so the positioning accuracy of submillimeter-magnitude spatial length measurement can be realized; and a wavelength of a tunable laser is in one-to-one correspondence with positioning data of fiber grating bragg reflection space by taking a linear chirped fiber grating or a uniform fiber grating as a sensing device, and the corresponding local strain capacity is demodulated by positioning the variable quantity of a local bragg reflection wavelength to realize distributed strain sensing. In the fiber grating distributed strain sensor, the spatial resolution ratio is improved to a submillimeter magnitude by a direct time domain measurement method, and the fiber grating distributed strain sensor has a compact structure and simple algorithm, can perform on-line monitor in real time and can be used for networking, so that the fiber grating distributed strain sensor has the large application space in the field of optical fiber sensing.

The invention discloses a fiber bragg grating detection system device and method for detecting an anchoring force of an anchor rod. The fiber bragg grating detection system device consists of a fiber bragg grating sensor array, a fiber bragg grating anchor rod dynamometer, a fiber bragg grating demodulator, an optical cable and a computer, wherein the fiber bragg grating anchor rod dynamometer mainly comprises a plurality of fiber bragg grating sensors which are uniformly arranged on an annular elastic body arm and is arranged at the end part of the anchoring end of the anchor rod; meanwhile, the fiber bragg grating sensor array is distributed on a rod body of the anchor rod; the fiber bragg grating sensor array and the fiber bragg grating anchor rod dynamometer are respectively connected with the fiber bragg grating demodulator through the optical cable; and the fiber bragg grating demodulator is connected with the computer. According to the fiber bragg grating detection system device, the real-time detection on the stress of the anchor rod can be realized and the distributed measurement can be realized. The fiber bragg grating detection system device has the advantages of simple structure, convenience in mounting, high detection speed, long-distance monitoring, repeated use and easiness in protection and maintenance, and is widely applied to tunnels and slopes dug for coal mines, metallurgical mines, water conservancy, railways, roads and defense.

The invention relates to a fiber bragg grating demodulating device and method based on chromatic dispersion Mach-Zehnder interferometry. The fiber bragg grating demodulating device comprises a broadband light source, a narrow-linewidth sweep frequency laser device, a first photoswitch, an optoisolator, a semiconductor optical amplifier, a pulse digital signal source, an optical circulator, a second photoswitch, a reference grating, a sensing grating array, a Faraday rotating mirror, a first optical coupler, dispersion compesation fiber, monomode optical fiber, a second optical coupler, a photoelectric detector set, a data collecting card and an upper computer. The optical fiber dispersion effect and the traditional Mach-Zehnder interferometry are combined to construct chromatic dispersion Mach-Zehnder interferometry, optical path difference caused by the chromatic dispersion effect is used for achieving phase sensibilization, interference information of all gratings in a quasi-distributed fiber bragg grating array is recorded through high-speed time-domain optical pulses, a multi-phase demodulating technology is used for processing time domain interference signals, high-sensitivity and high-speed demodulation of the fiber bragg grating array is achieved, and the demodulating device has the advantages of being high in interference resistance and capable of achieving distributed measurement.

The invention provides a distributed fiber grating device for measuring temperature and strain of a bearing ferrule. The distributed fiber grating device comprises mechanical accessories, a measured bearing, fiber grating sensors, a fiber rotating connector and a data acquisition system, wherein a bearing base is mounted on a bearing box; a bearing end cover is fixed to the bearing base to achieve clamping fixation between a bearing outer ring and the bearing base; a bearing inner sleeve is mounted on a main shaft; an adapter shaft is fixed to the left end of the main shaft; the fiber rotating connector achieves signal transmission of the fiber grating sensors on the inner ring, omits a centering, debugging and mounting process of a fiber collimator, and is more convenient to operate; a plurality of fiber grating sensing measurement points which are circumferentially arranged along the surface of the bearing ferrule are arranged on the fiber grating sensors; the two fiber grating sensors are fixed to a measurement position of the measured bearing, and acquire the strain and the temperature of the measured bearing through the data acquisition system. The distributed fiber grating device has the advantages of strong anti-interference capability, good stability, multiple measurement points, strong adaptability and the like, and can achieve high-precision and distributed in-situ measurement on temperature and strain parameters of the bearing ferrule.

The invention relates to a distributed crack sensor based on a coaxial cable, belonging to the technical field of an engineering structure safety monitoring. The distributed crack sensor provided by the invention is characterized in that a metal conductor core on the inner layer, an insulating layer in the middle, the metal conductor layer provided with a weak link (such as sunk weak threads, dot mode weak threads and the like) and a surface anticorrosive material are sequentially arranged from inside to outside; the weak threads are machined by applying the rotation advancing traction to the coaxial cable and simultaneously utilizing a drill to carve grooves on an outer conductor layer or utilizing a puncher to continuously punch on the outer conductor layer; the depth and pitch of the weak threads select different numerical values according to the requirements of the structure on the test sensitivity and the space resolution; and when cracks are monitored, the attenuation signals which are generated because of the crack modulation of the coaxial cable are obtained through an electric time domain reflectometer to determine the occurrence position and expansion degree of the cracks. The sensor provided by the invention has the beneficial effects that the sensor is a coaxial cable distributed crack sensor provided with weak threads, the structure is simple, the durability is good, the crack monitoring scale is large, and a structural damage memory function is achieved.

The invention discloses a fiber grating monitoring system for a power transmission line, which comprises a fiber grating sensing module, a transmission module and a computation module, wherein the fiber grating sensing module is used for receiving a first optical signal transmitted from the transmission module, and transmitting a second optical signal after the reflection of the first optical signal to the computation module through the transmission module; the transmission module is used for transmitting the first optical signal and the second optical signal; and the computation module is used for acquiring the pulling force borne by the power transmission line and the inclination angle of the power transmission line according to the change of the center wavelength of the second optical signal relative to the first optical signal, and acquiring the ice cover of the power transmission line according to the pulling force and the inclination angle.

A distributed optical fiber temperature and strain detection method based on Raman scattering includes the steps of (1) establishing a distributed optical fiber temperature and strain sensing system,the distributed optical fiber temperature and strain sensing system including a Raman signal acquisition instrument, a first high precision constant temperature bath (9), a second high precision constant temperature bath (10), an optical fiber to be detected (11), a first temperature sensor (12), and a second temperature sensor (13), and the Raman signal acquisition instrument including a pulsed laser (1), a WDM (2), a first APD (3), a second APD (4), a first LNA (5), a second LNA (6), a data acquisition card (7) and a computer ( 8). The method of the invention has a reasonable design, integrates optical path, circuit and signal acquisition and processing technologies of the optical fiber Raman scattering and optical time domain reflection principle, and forms a novel temperature and strain distributed optical fiber sensing detection method based on Raman scattering.

The invention relates to a surface plasma resonance-based optical fiber multipoint micro displacement sensing method and device. The surface plasma resonance-based optical fiber multipoint micro displacement sensing device is characterized by comprising a broadband light source, a polarizer, two single-mode transmission optical fibers, a single-mode sensing optical fiber, multiple displacement probes, multiple sensitive areas and a spectrometer, wherein the sensitive areas are multiple areas obtained through corroding the sensing optical fiber; the displacement probes are single-mode optical fibers of which the end face is cut flat and golden films with different thicknesses are plated; an air chamber is an air gap between the displacement probes and the sensitive areas; an evanescent field is formed in the sensitive areas through the sensing optical fiber by light, the plasma resonance effect is generated on the surface of the golden films of the displacement probes; the absorption peak intensity of the resonant wavelength is determined by the length of the air chamber; the golden films with different thicknesses generate different resonant wavelengths, and multi-displacement measurement can be realized through the wavelength demodulation. According to the surface plasma resonance-based optical fiber multipoint micro displacement sensing method and device, disclosed by the invention, the structure is simple, the volume is small, the sensitivity is high and reuse can be realized.

The invention discloses a temperature measurement system based on fiber grating sensing. The temperature measurement system comprises a laser, a temperature measurement point positioning system, a synchronous trigger, a wavelength division multiplexer, a dual-channel APD (Avalanche Photo Diode) detector, an amplifying circuit, a data acquisition card, an industrial personal computer and a data display; a pulse light signal sent by the laser is coupled to sensor fiber through the wavelength division multiplexer, the sensor fiber is arranged in a temperature field to be measured by the temperature measurement point positioning system; the dual-channel APD detector is connected with the amplifying circuit; the amplifying circuit is connected with the data acquisition card; then the data acquisition card transmits data to the industrial personal computer; finally, a temperature measurement result is displayed by the data display. According to the temperature measurement system and the temperature measurement method, the cable temperature is measured through distributed fiber grating by adopting a Raman scattering principle, the system SNR (Signal to Noise Ratio) is improved and the measurement precision of the system is improved. Distributed temperature measurement along the optical fiber is realized and important reference is provided for the application of a distributed fiber temperature measurement technology in online monitoring of the cable temperature.

The invention discloses a railway foreign body line invading monitoring and relates to a protective screening monitoring system which comprises a protective screening information collection system, a protective screening information analysis system and an alarming system. When the protective screening information analysis system confirms that a protective screening is broken and / or a dangerous degree is achieved, the alarming system sends an alarming signal and / or intelligence information in one mode or a plurality of modes.

The invention provides an intelligent well drilling system and method and belongs to the field of petroleum and natural gas well-drilling. The intelligent well drilling system comprises a ground system, a downhole system and an intelligent well drilling control platform. The ground system comprises a coiled tubing vehicle set, a coiled tubing control platform, a coiled tubing roller, a lower sleeve derrick, an injection head, a rotating control head and matching blowout-prevention equipment. The coiled tubing control platform and the coiled tubing roller are arranged on the coiled tubing vehicle set, and the lower sleeve derrick is arranged on the upper portion of a wellhead. The injection head, the rotating control head and the matching blowout-prevention equipment are sequentially connected from top to bottom and then arranged at the wellhead. The downhole system comprises coiled tubing with a cable, a wet joint and a downhole intelligent pipe string. One end of the coiled tubing with the cable is wound around the coiled tubing roller, and the other end of the coiled tubing with the cable sequentially penetrates through the injection head, the rotating control head and the matching blowout-prevention equipment and then enters the wellhead to be connected with the downhole intelligent pipe string through the wet joint.

The invention relates to a distributed optical fiber downhole collecting device. The distributed optical fiber downhole collecting device comprises a downhole string, downhole optical cables and optical fiber temperature sensors; all the downhole optical cables are wound around the downhole string into a spiral shape, or a part of the downhole optical cables are wound around the downhole string into a spiral shape, and the other part of the downhole optical cables are linearly arranged on the wall at one side of the downhole string; the optical fiber temperature sensors are integrated to the downhole optical cables and arranged in the extending direction of the downhole optical cables in a distributed mode. The invention further relates to a distributed optical fiber downhole flowmeter and a downhole monitoring method. According to the distributed optical fiber downhole collecting device, as the downhole optical cables are wound around the downhole string into the spiral shape, the number of collecting points in unit space is increased, resolution is improved, and a better measurement effect is achieved; as the optical fiber temperature sensors are arranged in the extending direction of the downhole optical cables in the distributed mode, distributed measurement can be achieved without separating downhole fluid, and full-hole measurement can be achieved without moving the downhole optical cables or the sensors.

The invention discloses a gross-volume monitoring sensing device for the corrosion states and the temperature field states of reinforcing steel bars in concrete, and a monitoring device with the gross-volume monitoring sensing device. The gross-volume monitoring sensing device comprises a broadband light source, a Y-shaped optical fiber coupler, a coupler connector, a sensing optical fiber, an LPFG (Long Period Fiber Grating) reinforcing steel bar corrosion sensing probe, an LPFG temperature sensing probe, an optical switch, a spectrograph and a computer, wherein the broadband light source enters the input end of the Y-shaped optical fiber coupler, is transmitted to the output end of the Y-shaped optical fiber coupler, is further transmitted to the LPFG reinforcing steel bar corrosion sensing probe and the LPFG temperature sensing probe respectively through the coupler connector and the sensing optical fiber, passes the optical switch, enters the spectrograph through the outgoing end of the optical switch, and is finally processed by the computer; then a curve of relationship between a transmitted spectrum and the corrosion states is output. By utilizing the device, the gross-volume monitoring on the corrosion states and the temperature field states of the reinforcing steel bars in the concrete can be realized.

The invention discloses a pressure-sensitive optical cable and a manufacture method thereof. The pressure-sensitive optical cable consists of two toothed plates made of a flexible material, and a polymer sheath tube sheathing the toothed plates, wherein the deformed teeth on the two toothed plates correspond to each other in a staggered manner; and a signal fiber is sandwiched by the deformed teeth of the two toothed plates. When a pressure is applied on the pressure-sensitive optical cable, the deformed teeth of the two toothed plates make relative movement so that the signal fiber generates bending deformation, thereby changing the bending loss of the signal fiber. Therefore, the pressure signal is converted into an optical signal, and is transmitted by the signal fiber to achieve the distal measurement. The toothed plate made of a flexible material has certain bending property, which can facilitate the manufacture, storage, transportation and use of the pressure-sensitive optical cable. Similar to the common optical cable, the pressure-sensitive optical cable has greatly reduced manufacture and use cost, and does not influence the pressure detection. The pressure-sensitive optical cable has the advantages of simple structure, reasonable design, convenience in manufacture, flexible use manner, high sensitivity and good use effect, and can achieve the distributed pressure measurement by use of measurement instruments, such as optical time-domain reflectometer.

The invention discloses a pressure-sensitive optical cable with armor layer, which takes a signal optical fiber and fiber yarns spirally wound on the signal optical fiber and which is peripherally provided with an armor layer and an outer protective layer in sequence. As pressure is applied to the pressure-sensitive optical cable, the fiber yarns spirally wound on the signal optical fiber lead the signal optical fiber to bending deformation in order to change the bending loss of the signal optical fiber. As a result, pressure signals are converted into optical signals which are then transmitted via the signal optical fiber to achieve the purpose of remote measurement. The armor layer made of fine fiber material has the characteristics of excellent bending flexibility, facilitating manufacture, storage, transportation and use of the pressure-sensitive optical cable, similarity to common optical cables, being capable of remarkably reducing manufacturing and use costs, and having no impact on pressure detection. The pressure-sensitive optical cable has simple structure, reasonable design, convenient processing and manufacturing, diversified using ways, high sensitivity and good using effect, and distributive pressure measurement can be realized by means of optical time domain reflectometer or other measurement instruments.

The invention provides a sensitive membrane and corrosion Bragg grating-based corrosion sensor and a preparation method thereof. The sensitive membrane and etching Bragg grating-based corrosion sensor comprises an optical fiber, wherein a corrosion Bragg grating is written on the optical fiber, a sensitive membrane is deposited outside the corrosion Bragg grating and is identical with monitored metal in materials with the thickness of 10nm-1 micron; the diameter of the corrosion Bragg grating is 8.6-12 microns, compared with the sensor without corrosion, the sensor with corrosion has the advantages that the central wavelength of the grating is reduced by 2-6nm, the central peak value is attenuated by 10-20dBm. The invention provides a sensor for realizing corrosion monitoring by utilizing the refractive index response mechanism of the grating, the corrosion grating responses to the refractive index of the outside environment, the wavelength of the grating is shifted by the change of the corrosion refractive index of the sensitive membrane, so that the metal corrosion process can be monitored. According to the sensor, the structure is simple, the cost is low, the sensitivity is high, non-destructive monitor can be realized, and the distributive measurement can be realized by arranging a plurality of sensors on one optical fiber.

The invention relates to a monitoring system for debris flow disasters along railway tracks. The alarm system comprises a debris flow information acquisition system, a debris flow information analysis system and an alarm system. Alarm signals and / or intelligence information are / is emitted in one or more modes under the condition that the debris flow information analysis system determines occurrence of debris flow and / or grades of debris flow disasters.

The invention relates to a monitoring method for LPFG (Long Period Fiber Grating) transverse load direction characteristic based on resonance amplitude modulation and an asphalt pavement pressure sensor, belonging to the field of optical sensing testing. The method comprises the following steps of: (1) demarcating a linear area of long cycle fiber Bragg grating resonance peak amplitude and transverse load relation curve; (2) during the transverse load monitoring, selecting the linear sections of all external loading varying ranges falling in the liner area, selecting the angle corresponding to the linear section of the highest sensitivity in the linear section according with the condition as a thrust surface; (3) using the characteristics of the long cycle fiber Bragg grating resonance peak amplitude and the transverse load relation to process pressure monitoring. The method is high in sensitivity and is not easy to be disturbed.

The invention provides a hybrid optical fiber sensing system based on a phase generated carrier technology, which comprises a narrow linewidth laser, a modulator, a pulse generator, an isolator, an erbium-doped optical fiber amplifier, a circulator, an optical fiber grating, a pump source, a wavelength division multiplexer, an optical fiber DFB laser array, a Michelson interferometer, a dense wavelength-division multiplexing module, an avalanche diode detector, a photodetector array, a carrier wave circuit, a data acquisition card, a signal processing module and a display. Through adopting thephase generated carrier technology, distributed acoustic sensing and optical fiber DFB laser array mixed vibration or acoustic signal measurement are realized, the characteristic of high sensitivityof the optical fiber DFB laser array and the characteristic of mass channels of the distributed acoustic sensing technology are fused, and high-sensitivity weak signal distributed measurement is realized.

The invention discloses a sensing method of a single-ended Brillouin distributed-type sensing system of a Brillouin adjustable frequency shifter structure. The method includes 1), generating continuous detection light; 2) generating pulse pump light; 3), generating stimulated Brillouin effect; 4), generating backscattering signal light; 5) collecting and processing data. The sensing method has theadvantages that by the single-end structure, measurement distances in BOTDA (Brilouin optical time domain analysis) can be effective measurement distances; the sensing system has longer effective measurement distances than gain-type BOTDA systems. The invention further discloses the single-ended Brillouin distributed-type sensing system of the Brillouin adjustable frequency shifter structure.

The invention relates to a distribution type long period fiber grating nucleic acid sensor system and a method for detecting the polymorphism of a single nucleotide which belong to the testing field of a biosensor. The system consists of a Broad Band light source (1), a tree type fiber coupler (2),a sensing fiber (4), a computer (7), a spectrograph and a terminal reflection type long period fiber grating nucleic acid sensor probe (5) or a distribution type long period fiber grating nucleic acid sensor probe. In the method, the SNP of the DNA in a sample to be detected is detected through measuring the change of a resonance peak caused by the change of a dielectric constant in the test liquid of the sample to be detected. The distribution type long period fiber grating nucleic acid sensor system and a method for detecting the polymorphism of a single nucleotide have the characteristics of high sensitivity, the realization of distributed measurement and real-time high pass detection.

The invention provides a large-mining-height stope coal wall rib spalling depth measurement method, which is suitable for coal wall rib spalling depth monitoring and prevention under a large-mining-height condition. The method is characterized by selecting one rib spalling measurement point every a certain distance on a large-mining-height working face; mounting a glass fiber reinforced plastic anchor rod uniformly provided with fiber grating sensors on a coal wall; carrying out real-time transmission data analysis through a computer to obtain stress and its variation of each section of the anchor rod; and according to the phenomenon that the anchor rod section corresponding to the rib spalling section decreases in stress, obtaining depth range of the rib spalling. The method monitors therib spalling depth on the basis of preventing coal wall rib spalling, and provides favorable conditions for safe and efficient mining of the large-mining-height working face.

The invention relates to a tunnel construction safety pre-warning method based on a detection optical fiber monitoring technology. Safety accidents easily occur in a space without linings in the tunneling process, and occurrence of the disasters is difficult to predict by a conventional means. The method includes the steps that a detection optical fiber is laid on the wall of a construction tunnel, broadband optical signals sent out by a broadband light source are transmitted to the detection optical fiber through an isolator and a 3dB coupler, a set of reflected lights with different wavelengths are generated through wavelength choice of the detection optical fiber, the reflected lights pass the 3dB coupler again and are received by a wavelength demodulator, wavelength changes, namely, stress changes are monitored after the wavelengths are identified, and disaster pre-warning information is obtained and sent to a dedicated or public network to be released to engineers. According to the method, high-precision and non-interference measurement can be achieved, service life is long, signal transmission distance is long, and the method is suitable for safety monitoring of long and large tunnels, measurement results are not influenced by factors of external disturbance, transmission loss, equipment aging and the like, and information capacity is large.

The invention discloses a Brillouin optical fiber sensing system and sensing method with an adjustable frequency shifting structure. The Brillouin optical fiber sensing system is composed of a narrow-linewidth laser device, a first optical coupler, an optical amplifier, a scrambler, a second optical circulator, an erbium-doped fiber amplifier, a signal processing unit, a signal modulating unit, and an adjustable frequency shifting unit. In addition, the method includes: step one, generating continuous light; second two, generating pump light; step three, carrying out a stimulated Brillouin effect; step four, generating backscattered signal light; and step five, carrying out data collection and processing. The system having advantages of low cost and high system stability is capable of realizing distributed measurement of the temperature and strain. The sensing method is operated conveniently; the frequency shift adjustment is carried out conveniently; and the frequency shift is controlled easily. Meanwhile, the frequency modulation module employs the polarization maintaining device, so that the influence on light by the light polarization state is reduced and the obtained optical signal becomes stable.

The invention discloses an annular whisker optical fiber stress monitoring device which comprises a plurality of annular structures composed of an optical cable, wherein a part of the annular structures is contained in a matrix; and at least one end of the optical cable is connected with a test unit. When a stress is applied to the annular whisker optical cable, the bending curvature of the optical cable is reduced so that the bending curvature of the optical fiber in the optical cable is also reduced to change the bend loss of the optical fiber. A stress signal is transformed into an optical signal and then transmitted to the test unit through the optical fiber, thus achieving the purpose of remote monitoring; and if the optical cable is changed into a pressure-sensitive optical cable, the monitoring sensitivity and the monitoring accuracy of the optical fiber stress monitoring device can be further improved. The annular whisker optical fiber stress monitoring device of the invention has the advantages of simple structure, rational design, convenient processing and manufacturing, flexible usage mode, high sensitivity and good use effect; and testing instruments such as an optical time domain reflectometer and the like can achieve distributed stress monitoring.

The invention discloses a polarized light time domain reflectometer based on dual polarization state time division multiplexing. The polarized light time domain reflectometer comprises a light source,a phase modulator, a pulse modulator, a circulator, a sensing optical fiber, a full polarization state detection device, a photoelectric detector, a signal acquisition card and a processor, wherein an output port of the phase modulator is connected with an input port of the pulse modulator through an optical fiber, and the phase modulator is used for enabling the polarization state of light output by the phase modulator to be perpendicular to each other on the Bonding ball; and the full polarization state detection device is connected with the photoelectric detector through an optical fiber,and the full polarization state detection device is used for realizing detection of three polarization states which are perpendicular to one another. According to the polarized light time domain reflectometer, dual-polarization-state time division multiplexing full-polarization-state detection is used, so that the phenomenon of traditional POTDR signal fading is completely eliminated under the condition that depolarization is not considered, and the effect of improving system positioning and event recognition stability is achieved.

The invention discloses a monitoring system for automatic sensing of a pipeline leakage point of a central air conditioner. The monitoring system for automatic sensing of the pipeline leakage point ofthe central air conditioner comprises a sensing light source, an optical fiber circulator, a sensitive optical fiber and a data processing module, wherein the sensing light source is used for emitting pulse laser; the first port of the optical fiber circulator is used for receiving the pulsed laser, the second port of the optical fiber circulator is used for connecting a sensitive optical fiber laid on the wall of a central air conditioning pipeline, and the third port of the optical fiber circulator is used for connecting a photoelectric conversion module; the sensitive optical fiber is usedfor returning backward scattered light containing phase fluctuation in the transmission process of the pulse laser when a leakage point exists on the pipeline to the optical fiber circulator, outputting the backward scattered light to the photoelectric conversion module through the third port of the optical fiber circulator, and then arriving at a data processing module; and the data processing module is used for analyzing and processing electrical signals, determining the length from the leakage point position to the input end of the sensitive optical fiber based on the time when the sensinglight source emits the pulse laser and the time when the electrical signal with micro-vibration information is received, and determining the leakage point position on the pipeline in combination withthe corresponding relation between the length of the optical fiber and the pipeline position of the central air conditioner to improve the maintenance efficiency.