CN209689738U - A kind of device improving φ-OTDR frequency response - Google Patents
A kind of device improving φ-OTDR frequency response Download PDFInfo
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- CN209689738U CN209689738U CN201920471669.7U CN201920471669U CN209689738U CN 209689738 U CN209689738 U CN 209689738U CN 201920471669 U CN201920471669 U CN 201920471669U CN 209689738 U CN209689738 U CN 209689738U
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Abstract
A kind of device of this practical raising φ-OTDR frequency response for disclosing distributed fiberoptic sensor technical field, including φ-OTDR and Michelson interference emerging system, φ-OTDR system the composition includes: that laser is connected to 1 × 2 input terminal of optical splitter, optical splitter output end Out1 is sequentially connected acousto-optic modulator, erbium-doped fiber amplifier one, optical circulator port one, optical circulator port two is connected to sensing optic cable fibre core three, and optical circulator port three is sequentially connected erbium-doped fiber amplifier two, photodetector two, data acquisition module two and processing server；Alarm accuracy is higher: but the external world, when having vibration, Michelson interference system, which can detect, captures vibration event complete frequency spectrum, is matched with intrusion event template library, can be accurately identified vibration event type, improves alarm accuracy；Meanwhile φ-OTDR system can be quickly detected vibration and vibration source position, while save oscillation point bit position frequency spectrum.
Description
Technical field
Originally practical to be related to distributed fiberoptic sensor technical field, specially a kind of dress for improving φ-OTDR frequency response
It sets.
Background technique
Distributed optical fiber sensing system has a series of advantages such as small and exquisite, passive, electromagnetism interference, anticorrosive, based on auspicious
The coherent light time domain reflection technology (φ-OTDR, location type vibration optical fiber system) of benefit scattering have again it is long away from transmit, it is highly sensitive
Degree, pinpoint advantage, vibration optical fiber, especially φ-OTDR system are more and more used in petroleum, military affairs and security protection
Equal fields:
However φ-OTDR measurement is pulse Rayleigh scattering light, cannot have overlapping between the Rayleigh scattering light of adjacent pulse,
Which results in the limitation that pulse scan frequency receives sensing optic cable length (L), relationship isAnd according to Shannon's sampling theorem, when system scan frequency is ScanRatemax, system
The signal frequency that maximum can detect is ScanRatemax/2, and which results in traditional φ-OTDR systems cannot detect frequency
Rate is greater than the signal of ScanRatemax/2, and typical for φ-OTDR 50km detection range is calculated, and scan frequency is up to
2kHz, the maximum detectable frequency of system is 1KHz, the signal system of 1kHz or more can not be just accurately detected, this just leads
It has caused algorithm accurately not do accurate judgement to vibration signal, has reduced system alarm accuracy.There is presently no well
Processing mode, the mode that disclosed method has multi-wavelength to inject is (referring to " the distributing optical fiber sensing system based on multiple-pulse multi-wavelength
System and method ", publication number: 109282839A), although this method can improve system detective bandwidth, system cost is significantly improved
(at present in φ-OTDR system, narrow linewidth laser, acousto-optic modulator, φ-OTDR account for system with photodetector and always make
50% or more of valence), it is every increase all the way light injection will increase about 50% cost；If system band can be reduced by sharing laser again
Loading capability, transmission range significantly reduce；
For this purpose, it is proposed that a kind of device for improving φ-OTDR frequency response.
Utility model content
This practical purpose is to provide a kind of device for improving φ-OTDR frequency response, to solve above-mentioned background technique
The problem of middle proposition.
To achieve the above object, originally practical to provide the following technical solutions: a kind of device improving φ-OTDR frequency response,
Including φ-OTDR and Michelson interference emerging system, the φ-OTDR system composition includes: that laser is connected to optical splitter 1
× 2 input terminals, optical splitter output end Out1 are sequentially connected acousto-optic modulator, erbium-doped fiber amplifier one, optical circulator port one,
Optical circulator port two is connected to sensing optic cable fibre core three, and optical circulator port three is sequentially connected erbium-doped fiber amplifier two, light
Electric explorer two, data acquisition module two and processing server:
The Michelson interference system composition includes: that laser is connected to optical splitter 1 × 2, optical splitter output end Out2
2 × 2 input terminal In2 of photo-coupler is connected, output end Out1, Out2 of photo-coupler are separately connected sensing optic cable fibre core one and fibre
Core two, fibre core one, two tail end of fibre core connect faraday's rotating mirror one, faraday's rotating mirror two respectively, and reflected light is through the port optical splitter In1
It is connected to photodetector one, data acquisition module one and processing service；
φ-OTDR system and Michelson's interferometer two systems work at the same time, and φ-OTDR system is used to position and assist
Vibration identification, Michelson's interferometer are mainly used to Activity recognition, and when the external world has vibration, Michelson interference system is detected
When vibrating and matching with intrusion event template library, vibration source location information is obtained from φ-OTDR system；It is vibrated when detecting
When not matching with intrusion event template library, then it will not go to consider φ-OTDR system-computed result；When φ-OTDR system is visited
When measuring multiple vibration sources, then Euclidean distance, Europe are done according to the φ-OTDR partial frequency spectrum of each position and Michelson complete frequency spectrum
The most short point of family name's distance is to invade point.
Preferably, the laser is narrow cable and wide optical fiber laser, and operation wavelength 1550nm, line width is not more than
1KHz。
Preferably, the optical splitter is 1 × 2, operation wavelength 1550nm, and splitting ratio Out2:Out1 is not more than 2:98.
Preferably, the photo-coupler is 2 × 2 photo-couplers, and operation wavelength 1550nm, both ends splitting ratio is 50:
50。
Preferably, the data acquisition module one, sample frequency are not less than 40kHz.
Preferably, its fibre core number of the sensing optic cable is no less than 4 cores, and φ-OTDR system and Michelson interference system
Sensing cable shares an optical cable.
Compared with prior art, this practical beneficial effect is:
1, the device of raising φ-OTDR frequency response, alarm accuracy are higher: when there is vibration in the external world, Michelson
Interference system, which can detect, captures vibration event complete frequency spectrum, is matched, can be accurately identified with intrusion event template library
Vibration event type out improves alarm accuracy；Meanwhile φ-OTDR system can be quickly detected vibration and vibration source position, together
The oscillation point Shi Baocun bit position frequency spectrum；When detect vibration do not matched with intrusion event template library when, then will not go to consider
φ-OTDR system-computed is as a result, reduce wrong report；When φ-OTDR system detects multiple vibration sources, then according to each position
φ-OTDR partial frequency spectrum and Michelson complete frequency spectrum do Euclidean distance, and the most short point of Euclidean distance is to invade point；
2, inexpensive: Michelson's interferometer need to only assign to the light echo of laser 1%, cause to φ-OTDR system
Influence can be ignored, the cost of two core optical cables and four optical-fiber cable difference also very little, the increased costs of a whole set of system can
To control within 10%, it is very practical.
Detailed description of the invention
Fig. 1 is this utility structure schematic diagram；
Fig. 2 is that this practical φ-OTDR partial frequency spectrum and Michelson complete frequency spectrum make Euclidean distance schematic diagram.
Specific embodiment
Below in conjunction with the attached drawing in this practical embodiment, the technical solution in this practical embodiment is carried out clear, complete
Site preparation description, it is clear that described embodiment is only this practical a part of the embodiment, instead of all the embodiments.It is based on
Embodiment during this is practical, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment belongs to the range of this practical protection.
Originally practical referring to FIG. 1-2, that a kind of technical solution is provided: a kind of device improving φ-OTDR frequency response, including
φ-OTDR and Michelson interference emerging system, the φ-OTDR system composition includes: that laser is connected to optical splitter 1 × 2
Input terminal, optical splitter output end Out1 are sequentially connected acousto-optic modulator, erbium-doped fiber amplifier 1, optical circulator port one, light
Circulator port two is connected to sensing optic cable fibre core three, and optical circulator port three is sequentially connected erbium-doped fiber amplifier 22, photoelectricity
Detector 23, data acquisition module 24 and processing server:
The Michelson interference system composition includes: that laser is connected to optical splitter 1 × 2, optical splitter output end Out2
2 × 2 input terminal In2 of photo-coupler is connected, output end Out1, Out2 of photo-coupler are separately connected sensing optic cable fibre core one and fibre
Core two, fibre core one, two tail end of fibre core connect faraday's rotating mirror 1, faraday's rotating mirror 28 respectively, and reflected light is through the end optical splitter In1
Mouth is connected to photodetector 1, data acquisition module 1 and processing service；
φ-OTDR system and Michelson's interferometer two systems work at the same time, and φ-OTDR system is used to position and assist
Vibration identification, Michelson's interferometer are mainly used to Activity recognition, and when the external world has vibration, Michelson interference system is detected
When vibrating and matching with intrusion event template library, vibration source location information is obtained from φ-OTDR system；It is vibrated when detecting
When not matching with intrusion event template library, then it will not go to consider φ-OTDR system-computed result；When φ-OTDR system is visited
When measuring multiple vibration sources, then Euclidean distance, Europe are done according to the φ-OTDR partial frequency spectrum of each position and Michelson complete frequency spectrum
The most short point of family name's distance is to invade point.
Wherein, laser is narrow cable and wide optical fiber laser, and operation wavelength 1550nm, line width is no more than 1KHz；
Optical splitter is 1 × 2, operation wavelength 1550nm, and splitting ratio Out2:Out1 is not more than 2:98；
Photo-coupler is 2 × 2 photo-couplers, and operation wavelength 1550nm, both ends splitting ratio is 50:50；
Data acquisition module 1, sample frequency are not less than 40kHz；
Its fibre core number of sensing optic cable is no less than 4 cores, and φ-OTDR system and Michelson interference system sensing cable share one
Root optical cable.
Embodiment: it is assumed that cable length 50km, φ-OTDR system works in a pulsed fashion, scan frequency 2kHz, every transmitting
512 pulses handle a data；Michelson interference system works in continuous mode, and sample rate 50KHz is (in order to match two
The frequency resolution of person, is conveniently calculated Euclidean distance), every 100ms (5k sampling) data of processing, two systems
It is light echo through photodetector to data acquisition module, analysis data is finally handled by processing server:
Specific steps:
S1: the every acquisition 100ms of Michelson interference system does Fast Fourier Transform (FFT) (FFT) to 5k data, obtains frequency spectrum
F1, frequency resolution 4Hz, 0~20kHz of frequency range；
512 data are FFT by the every acquisition 250ms of S2: φ-OTDR system, obtain the frequency spectrum f2 (x) of each position, x generation
Mass color cable position (m), frequency resolution 4Hz, 0~1kHz of frequency range；
S3: when system detects vibration (judging by zero passage and peak value), frequency spectrum f1 is brought into algorithm, with intrusion event mould
Plate matches, and judges whether event is effective intrusion event:
A: if intrusion event and φ-OTDR system only detect a point vibration and set, which is intrusion event point,
Alarm intrusion event；
B: if intrusion event and φ-OTDR system detect multiple points vibrations, then need to calculate each bit position
The Euclidean distance of frequency spectrum and Michelson interference complete frequency spectrum, as Fig. 2 φ-OTDR partial frequency spectrum and Michelson complete frequency spectrum are done
Shown in Euclidean distance schematic diagram, the frequency range of φ-OTDR partial frequency spectrum and the covering of Michelson complete frequency spectrum is different, to count
Just need to intercept the part (the right figure) of the two frequency spectrum intersection if calculating frequency spectrum Euclidean distance, frequency point corresponds, calculation formula
It is as follows:
Wherein, f1It (i) is frequency spectrum f1I-th bit frequency modulus value, f2(x, i) is frequency spectrum f2(x) i-th bit frequency modulus value, dx
It is the Euclidean distance at the x of position between Michelson complete frequency spectrum, obtains min (d by sorting to comparex), x is to invade
Point, intrusion event of alarming
C: if event is not intrusion event, being considered as interference signal, ignores the event；
S4: enter subsequent cycle and repeat step 1-3, by above step, system can be adopted signal without frequency loss
Collection processing, can significantly improve system alarm accuracy.
While there has been shown and described that this practical embodiment for the ordinary skill in the art can be with
A variety of variations, modification, replacement can be carried out in the case where not departing from this practical principle and spirit to these embodiments by understanding
And modification, this practical range are defined by the appended claims and the equivalents thereof.
Claims (6)
1. a kind of device for improving φ-OTDR frequency response, including φ-OTDR and Michelson interference emerging system, feature
Be: φ-OTDR system composition includes: that laser is connected to 1 × 2 input terminal of optical splitter, optical splitter output end Out1 according to
Secondary connection acousto-optic modulator, erbium-doped fiber amplifier one (1), optical circulator port one, optical circulator port two is connected to sensing
Optical cable fibre core three, optical circulator port three are sequentially connected erbium-doped fiber amplifier two (2), photodetector two (3), data acquisition
Module two (4) and processing server:
The Michelson interference system composition includes: that laser is connected to optical splitter 1 × 2, the Out2 connection of optical splitter output end
Photo-coupler 2 × 2 input terminal In2, output end Out1, Out2 of photo-coupler are separately connected sensing optic cable fibre core one and fibre core
Two, fibre core one, two tail end of fibre core connect faraday's rotating mirror one (7), faraday's rotating mirror two (8) respectively, and reflected light is through optical splitter In1
Port is connected to photodetector one (6), data acquisition module one (5) and processing server.
2. a kind of device for improving φ-OTDR frequency response according to claim 1, it is characterised in that: the laser
For narrow cable and wide optical fiber laser, operation wavelength 1550nm, line width is not more than 1KHz.
3. a kind of device for improving φ-OTDR frequency response according to claim 1, it is characterised in that: the optical splitter
It is 1 × 2, operation wavelength 1550nm, splitting ratio Out2:Out1 are not more than 2:98.
4. a kind of device for improving φ-OTDR frequency response according to claim 1, it is characterised in that: the optical coupling
Device is 2 × 2 photo-couplers, and operation wavelength 1550nm, both ends splitting ratio is 50:50.
5. a kind of device for improving φ-OTDR frequency response according to claim 1, it is characterised in that: the data are adopted
Collect module one (5), sample frequency is not less than 40kHz.
6. a kind of device for improving φ-OTDR frequency response according to claim 1, it is characterised in that: the sense light
Its fibre core number of cable is no less than 4 cores, and φ-OTDR system and Michelson interference system sensing cable share an optical cable.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113776643A (en) * | 2021-09-24 | 2021-12-10 | 中国电子科技集团公司第三十四研究所 | Fiber fence intrusion signal simulation equipment based on Michelson interferometer |
| CN115901043A (en) * | 2022-11-17 | 2023-04-04 | 重庆大学 | Power cable external force monitoring system and method based on distributed optical fiber sensing |
-
2019
- 2019-04-09 CN CN201920471669.7U patent/CN209689738U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113776643A (en) * | 2021-09-24 | 2021-12-10 | 中国电子科技集团公司第三十四研究所 | Fiber fence intrusion signal simulation equipment based on Michelson interferometer |
| CN113776643B (en) * | 2021-09-24 | 2023-08-01 | 中国电子科技集团公司第三十四研究所 | Optical fiber fence intrusion signal simulation equipment based on Michelson interferometer |
| CN115901043A (en) * | 2022-11-17 | 2023-04-04 | 重庆大学 | Power cable external force monitoring system and method based on distributed optical fiber sensing |
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