CN109405956A - A kind of distributed optical fiber vibration sensing system demodulation method and device - Google Patents
A kind of distributed optical fiber vibration sensing system demodulation method and device Download PDFInfo
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- CN109405956A CN109405956A CN201811511544.9A CN201811511544A CN109405956A CN 109405956 A CN109405956 A CN 109405956A CN 201811511544 A CN201811511544 A CN 201811511544A CN 109405956 A CN109405956 A CN 109405956A
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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
Abstract
The invention discloses a kind of distributed optical fiber vibration sensing system demodulation method and devices, comprising: the identical continuous super-narrow line width laser of two-beam power obtains two-way pulsed light after acousto-optic modulation and Electro-optical Modulation respectively；The pulse width of two-way pulsed light difference setting is set to be input to sensor fibre；The backward Rayleigh scattering light of two-way pulsed optical signals can generate the difference on the frequency of setting, so that returning to Rayleigh optical signal is presented sine wave interference fringe；When disturbing signal acts on sensor fibre, the Reyleith scanttering light signal phase difference of return changes, and vibrational waveform and the position of sensor fibre perception are obtained according to phase difference.After there is interference signal, detector can be quickly obtained the information such as position and the disturbing signal intensity of disturbing signal, solve the problems, such as that Φ-OTDR Demodulation Systems algorithm is complicated and laser frequency is drifted about, ensure that the position error of system within ± 1m.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, in particular to a kind of distributed optical fiber vibration sensing system demodulation method
And device.
Background technique
Distributed optical fiber vibration sensing system may be implemented long range, distributed destabilization sensing and signal and transmit, and pass through inspection
The light intensity variation for surveying optical fiber each section back scattering interference light, realizes and invades and harasses movable detection to outside, in conjunction with optical time domain reflection
Technology can realize the accurate positionin of vibration signal.Distributed optical fiber vibration sensing system is using optical fiber itself as sensor and letter
Number transmission carrier, have many advantages, such as measurement accuracy height, fast response time, intrinsic safety, can be in inflammable, explosive, high temperature, height
Long-term stable operation in the rugged environments such as wet, high corrosion and strong-electromagnetic field interference is supervised safely in circumference security protection, petroleum pipeline
The fields such as survey, rail traffic, building structure health have a wide range of applications.
With the continuous expansion of application field, distributed optical fiber vibration sensing system can be divided into phase sensitive from principle
Optical time domain reflection technology (Ф-OTDR), polarized light time domain reflection technology (P-OTDR), coherent light time domain reflection technology (C-OTDR)
Deng.Wherein, for Ф-OTDR by high sensitivity, the advantage of measurement distance, application is more and more extensive.Ф-OTDR is usually using biography
The Rayleigh scattering light of photosensitive fibre and the local oscillator light of light source obtain interference optical field, then are shaken by the phase demodulating to interference optical field
Dynamic signal.Demodulation accuracy is easy to be influenced by the polarization state variation of light source with frequency stability.Demodulating process includes mixing, filter
The operations such as wave and difference, complexity is high, and response speed is slow.
Summary of the invention
To solve the above-mentioned problems, the invention proposes a kind of distributed optical fiber vibration sensing system demodulation method and dresses
It sets, eliminates the influence of the polarization state variation and frequency stability of light source, improve demodulation accuracy；Demodulation structure is simplified, it can be with
The amplitude-frequency information quickly vibrated reduces the demodulation response time.
To achieve the goals above, the present invention adopts the following technical scheme:
A kind of distributed optical fiber vibration sensing system demodulation method disclosed in one or more embodiments, comprising:
The identical continuous super-narrow line width laser of two-beam power obtains two-way pulsed light after acousto-optic modulation and Electro-optical Modulation respectively；Make
The pulse width of two-way pulsed light difference setting is input to sensor fibre；The backward Rayleigh scattering light of two-way pulsed optical signals can produce
The difference on the frequency of raw setting, so that returning to Rayleigh optical signal is presented sine wave interference fringe；Sensor fibre is acted in disturbing signal
When, the Reyleith scanttering light signal phase difference of return changes, and vibrational waveform and the position of sensor fibre perception are obtained according to phase difference.
Further, make the pulse width of two-way pulsed light difference setting, concrete methods of realizing are as follows:
Two-way pulsed light enters sensor fibre after the optical fiber of different length respectively, so that two-way pulsed light is to set
Time difference is input to sensor fibre.
Further, make the pulse width of two-way pulsed light difference setting, concrete methods of realizing are as follows:
Modulation to two-way pulsed light, the modulation of modulation intervals difference setting are respectively driven using double-pulse signal generator
Pulsewidth.
A kind of distributed optical fiber vibration sensing system demodulating equipment disclosed in one or more embodiments, comprising:
Light source module, light source module are divided into two-way after connecting with coupler, wherein being sequentially connected in series acousto-optic modulator and the first optical fiber all the way
It is connect by the first optical fiber with circulator after amplifier；Another way passes through after being sequentially connected in series electrooptic modulator and the second fiber amplifier
The second optical fiber is crossed to connect with circulator；The circulator connects sensor fibre；The output of the circulator is sequentially connected in series light
Electric conversion module, high-pass filter, data acquisition module and host computer.
Further, the length of first optical fiber and the second optical fiber is different, the length of first optical fiber and the second optical fiber
Degree difference is determined by the transmission speed of modulated signal pulsewidth and light in a fiber, and the transmission time of two-way optical path is finally made to differ setting
Pulse period.
Further, the length of first optical fiber and the second optical fiber is identical, using double-pulse signal generator driving sound
Optical modulator and electrooptic modulator are modulated light pulse respectively, the modulation pulsewidth of modulation intervals difference setting.
Further, it is the coupler of 50:50 that the coupler, which selects splitting ratio,.
Further, the light source module includes: laser light source interconnected and narrow linewidth continuous laser driver.
Compared with prior art, the beneficial effects of the present invention are:
(1) using the interference optical field formed after the two-way in sensor fibre to Rayleigh scattering optical superposition, demodulation is vibrated
Signal eliminates the influence of the polarization state variation and frequency stability of light source, improves demodulation accuracy.
(2) optical path difference determining by setting, the phase difference of interference light intensity directly reflect the amplitude-frequency information of vibration signal, keep away
The processes such as mixing, filtering and difference operation are exempted from, have simplified demodulation method, reduce the response time.
(3) can according to determining optical path difference, adjust pulse width, guarantee two-way pulsed light differ a pulse width into
Enter sensor fibre, flexibility ratio is high, Yi Shixian.
(4) after there is interference signal, detector can be quickly obtained position and the disturbing signal intensity of disturbing signal
Etc. information, solve the problems, such as that Φ-OTDR Demodulation Systems algorithms is complicated and laser frequency is drifted about, ensure that the positioning of system misses
Difference is within ± 1m.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is distributed optical fiber vibration sensing system demodulating equipment structural schematic diagram in embodiment two；
Fig. 2 is distributed optical fiber vibration sensing system demodulating equipment structural schematic diagram in embodiment three；
Wherein, 1- light source module, 2- coupler, 3- signal generator, 4- driver, 5- acousto-optic modulator, 6- first mix
Doped fiber amplifier, 7- electrooptic modulator, the second erbium-doped fiber amplifier of 8-, the second optical fiber of 9-, 10- circulator, 11- sense light
Fibre, 12- photoelectric conversion module, 13- high-pass filter, 14- data acquisition module, 15- host computer, 16- dipulse signal occur
Device.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms that the present invention uses have logical with the application person of an ordinary skill in the technical field
The identical meanings understood.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
Embodiment one
A kind of distributed optical fiber vibration sensing system demodulation method is disclosed in one or more embodiments, comprising:
The identical continuous super-narrow line width laser of two-beam power obtains two-way pulsed light after acousto-optic modulation and Electro-optical Modulation respectively；Make
The pulse width of two-way pulsed light difference setting is input to sensor fibre 11；The backward Rayleigh scattering light meeting of two-way pulsed optical signals
The difference on the frequency of setting is generated, so that returning to Rayleigh optical signal is presented sine wave interference fringe；Sense light is acted in disturbing signal
When fibre 11, the Reyleith scanttering light signal phase difference of return changes, and obtains the vibrational waveform that sensor fibre 11 perceives according to phase difference
And position.
Super-narrow line width laser source is divided into the identical continuous light of two beam powers, passes through acousto-optic modulator 5 (AOM) and electric light respectively
Modulator 7 (EOM) obtains two-way pulsed light, the distribution of light intensity E of two-way pulsed light1(t), E2(t) it is respectively as follows:
Wherein, A1For the modulated distribution of light intensity amplitude of acousto-optic modulator 5 (AOM), A2For electrooptic modulator 7 (EOM) modulation
Distribution of light intensity amplitude afterwards,For the modulated distribution of light intensity initial phase of acousto-optic modulator 5 (AOM),For electrooptic modulator
The modulated distribution of light intensity initial phase of 7 (EOM), f0It is the modulating frequency of AOM, fcIt is light source frequency.
Two pulsed lights differ a pulse width and are input to the sensor fibre 11 that optical path difference is L, and pulse width is denoted as Δ
t.Also, the spread speed of light in a fiber is denoted as cOptical fiber, optical path difference L=Δ t × cOptical fiber。
Two pulsed lights are rear to Rayleigh scattering distribution of light intensity E in sensor fibre 111' (t), E2' (t) be respectively as follows:
The interference optical field E (t) of backward Rayleigh scattering are as follows:
E (t)=E1'(t)+E2'(t) (3)
The interference optical field intensity I (t) of backward Rayleigh scattering are as follows:
Two DC terms for interference light intensity before above formula, the signal band of middle entry is not in the response band of photodetector
In range, so detector will not respond, last is the AC portion of interference light intensity signal.
Photodetector receives interference light intensity and exports electric current, and exchange item parts are obtained after high-pass filtering:
In formula, α=e η/h ν is light-to-current inversion than column constant, and e is electron charge, and η is quantum efficiency, and h ν is photon energy
Amount, note
When effect of vibration is in sensor fibre 11, vibration signal makes 11 length of sensor fibre and refractive index change,
Lead to phase differenceIt changes.According to phase differenceVibrational waveform and the vibration of the perception of sensor fibre 11 can be obtained
Position.
Embodiment two
A kind of distributed optical fiber vibration sensing system demodulating equipment, such as Fig. 1 are disclosed in one or more embodiments
It is shown, comprising: light source module 1 is connect with coupler 2, and the output of coupler 2 is divided into two-way, wherein being sequentially connected in series sound all the way
After optical modulator 5, the first erbium-doped fiber amplifier 6 (EDFA), it is connect by the first optical fiber with circulator 10；Another way is successively gone here and there
After connection connection electrooptic modulator 7, the second erbium-doped fiber amplifier 8 (EDFA), it is connect by the second optical fiber 9 with circulator 10；Ring
Shape device 10 connects sensor fibre 11；Meanwhile circulator 10 is sequentially connected in series photoelectric conversion module 12, high-pass filter 13, number
According to acquisition module 14 and host computer 15.
The distance of difference setting length between first optical fiber and the second optical fiber 9.
Light source module 1 includes laser light source, narrow linewidth continuous laser driver 4, and light source module 1 generates super-narrow line width laser
It is divided into two bundles the identical continuous light of optical power by coupler 2, is separately connected acousto-optic modulator 5 (AOM) and electrooptic modulator 7
(EOM)；
Signal generator 3 connects drive module, and drive module drives acousto-optic modulator 5 and electrooptic modulator 7 to continuous light
It is modulated；Modulated two-way pulsed optical signals are separately connected erbium-doped fiber amplifier and carry out power amplification, and are transferred through
The constant optical fiber link of length difference enters sensor fibre 11 using circulator 10；The backward Rayleigh scattering light of sensor fibre 11
Enter photoelectric conversion module 12 (PD) by circulator 10；Photoelectric conversion module 12 converts optical signals into electric signal, is output to
High-pass filter 13 (HPF)；High-pass filter 13 is output to data acquisition module 14 after filtering to electric signal；Data acquisition module
Analog electrical signal is converted to digital signal and gives host computer 15 by 14 (DAQ)；Host computer 15 is obtained according to obtained digital signal
The vibration information that sensor fibre 11 perceives.
Firstly, the ultra-narrow pulse width laser that light source module 1 generates is divided into two bundles by coupler 2 and respectively enters acousto-optic modulator
5 and electrooptic modulator 7, light source center wavelength 1550nm, fcFor light source frequency；Drive module drives acousto-optic modulator 5 and electric light
Modulator 7 is modulated light pulse respectively, modulating frequency f0=80MHz, modulation pulsewidth are Δ t=100ns；Two-way modulation
Optical signal afterwards passes through the first erbium-doped fiber amplifier 6 respectively, the second erbium-doped fiber amplifier 8 amplifies；Optical fibre refractivity
For nOptical fiber=1.5, the spread speed of light in a vacuum is cVacuum=3 × 108M/s, then light spread speed in a fiber are as follows:
The distance L=Δ t × c differed before first optical fiber and the second lightOptical fiber=100ns × 2 × 108M/s=20m.Pass through
Enter circulator 10 after the optical fiber of two-way length difference 20m, two-way light differs Δ tc=100ns, exactly pulse period；
Photoelectric conversion module 12 converts optical signals into electric signal, shown in phase relation such as formula (5) caused by electric current and vibration signal；
The rayleigh backscattering light that sensor fibre 11 generates inputs high-pass filter 13 by circulator 10 and is filtered, and filters out DC quantity
Leave behind of ac；
Digital signal is converted to through the data collecting card that over-sampling rate is 400MHz, and is transmitted to the progress of host computer 15
Demodulating algorithm operation is denoised, treatment process is simplified, it is fixed to improve the demodulation of distributed optical fiber vibration sensing system vibration signal waveforms
Position efficiency.
The time difference of two pulsed optical signals input is fixed；The frequency difference of two pulsed optical signals is also fixed
's；The width of two pulse signals is identical；The signal for being loaded into acousto-optic modulator 5 is input in sensor fibre 11, initial phase
Position is fixed.When effect of vibration is in sensor fibre 11, the variation of phase is directly displayed at interference of light letter in sensor fibre 11
Number waveform on, can by calculate demodulate phase value, directly obtain waveform and the position of vibration.
Embodiment three
A kind of distributed optical fiber vibration sensing system demodulating equipment disclosed in present embodiment, as shown in Fig. 2, and embodiment
Unlike device in two, in present embodiment, the first optical fiber is identical as the conveying length of the second optical fiber 9, using dipulse
Signal generator 16 drives acousto-optic modulator 5 and electrooptic modulator 7 to be modulated light pulse respectively, and modulation intervals differ one
Modulation pulsewidth enters two-way optical path, substitutes two-way optical fiber optical path difference, reduces the influence of environmental factor.
Remaining structure and the course of work are identical with embodiment two, repeat no more.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (8)
1. a kind of distributed optical fiber vibration sensing system demodulation method characterized by comprising
The identical continuous super-narrow line width laser of two-beam power obtains two-way pulse after acousto-optic modulation and Electro-optical Modulation respectively
Light；The pulse width of two-way pulsed light difference setting is set to be input to sensor fibre；The backward Rayleigh scattering of two-way pulsed optical signals
Light can generate the difference on the frequency of setting, so that returning to Rayleigh optical signal is presented sine wave interference fringe；Biography is acted in disturbing signal
When photosensitive fine, the Reyleith scanttering light signal phase difference of return changes, and the vibrational waveform of sensor fibre perception is obtained according to phase difference
And position.
2. a kind of distributed optical fiber vibration sensing system demodulation method as described in claim 1, which is characterized in that make two-way arteries and veins
Wash the pulse width of difference setting, concrete methods of realizing are as follows: two-way pulsed light enters after the optical fiber of different length respectively off
Sensor fibre, so that two-way pulsed light is input to sensor fibre with the time difference set.
3. a kind of distributed optical fiber vibration sensing system demodulation method as described in claim 1, which is characterized in that make two-way arteries and veins
Wash the pulse width of difference setting, concrete methods of realizing are as follows: respectively drive using double-pulse signal generator to two-way pulse off
The modulation of light, the modulation pulsewidth of modulation intervals difference setting.
4. a kind of distributed optical fiber vibration sensing system demodulating equipment characterized by comprising light source module, light source module with
It is divided into two-way after coupler connection, wherein being sequentially connected in series after acousto-optic modulator and the first fiber amplifier all the way by the first optical fiber
It is connect with circulator；Another way connects after being sequentially connected in series electrooptic modulator and the second fiber amplifier by the second optical fiber and circulator
It connects；The circulator connects sensor fibre；The output of the circulator is sequentially connected in series photoelectric conversion module, high-pass filtering
Device, data acquisition module and host computer.
5. a kind of distributed optical fiber vibration sensing system demodulating equipment as claimed in claim 4, which is characterized in that described first
The length of optical fiber and the second optical fiber is different, and the length difference of first optical fiber and the second optical fiber is by modulated signal pulsewidth and light in light
Transmission speed in fibre determines, the transmission time of two-way optical path is finally made to differ the pulse period of setting.
6. a kind of distributed optical fiber vibration sensing system demodulating equipment as claimed in claim 4, which is characterized in that described first
The length of optical fiber and the second optical fiber is identical, drives acousto-optic modulator and electrooptic modulator to light arteries and veins using double-pulse signal generator
Punching is modulated respectively, the modulation pulsewidth of modulation intervals difference setting.
7. a kind of distributed optical fiber vibration sensing system demodulating equipment as claimed in claim 4, which is characterized in that the coupling
It is the coupler of 50:50 that device, which selects splitting ratio,.
8. a kind of distributed optical fiber vibration sensing system demodulating equipment as claimed in claim 4, which is characterized in that the light source
Module includes: laser light source interconnected and narrow linewidth continuous laser driver.
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| CN109959403A (en) * | 2019-03-29 | 2019-07-02 | 武汉理工大学 | A kind of many reference amounts large capacity sensor-based system |
| CN110058198A (en) * | 2019-03-25 | 2019-07-26 | 杭州电子科技大学 | A kind of Underwater Navigation method based on distributed fiberoptic sensor |
| CN111147133A (en) * | 2019-12-24 | 2020-05-12 | 武汉理工光科股份有限公司 | Real-time monitoring system and method for traffic flow based on phi-OTDR |
| CN111157102A (en) * | 2020-01-02 | 2020-05-15 | 河海大学常州校区 | Positioning method for eliminating frequency interference in distributed optical fiber sensing system |
| CN112504429A (en) * | 2020-11-24 | 2021-03-16 | 姚峰 | High-precision demodulation algorithm for strong interference DVS |
| CN112504629A (en) * | 2020-11-24 | 2021-03-16 | 北京大学 | Light scattering parameter measuring system and measuring method thereof |
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| CN110058198A (en) * | 2019-03-25 | 2019-07-26 | 杭州电子科技大学 | A kind of Underwater Navigation method based on distributed fiberoptic sensor |
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| CN112504629B (en) * | 2020-11-24 | 2021-08-24 | 北京大学 | Light scattering parameter measuring system and measuring method thereof |
| CN112747815B (en) * | 2021-01-06 | 2024-02-02 | 苏州光格科技股份有限公司 | Coherent fading noise suppression method in distributed optical fiber acoustic wave sensing system |
| CN112747815A (en) * | 2021-01-06 | 2021-05-04 | 苏州光格科技股份有限公司 | Coherent fading noise suppression method in distributed optical fiber acoustic wave sensing system |
| CN113008356A (en) * | 2021-02-26 | 2021-06-22 | 中煤科工集团重庆研究院有限公司 | Distributed optical fiber detection optical pulse modulation and demodulation method |
| CN113111491A (en) * | 2021-03-16 | 2021-07-13 | 电子科技大学 | Simulation method suitable for complex detection waveform optical fiber Rayleigh scattering sensing system |
| CN113111491B (en) * | 2021-03-16 | 2022-12-30 | 电子科技大学 | Simulation method suitable for complex detection waveform optical fiber Rayleigh scattering sensing system |
| CN114495388A (en) * | 2021-11-18 | 2022-05-13 | 河南顺博建筑智能化工程有限公司 | Perimeter security system |
| CN114543973A (en) * | 2022-02-28 | 2022-05-27 | 华中科技大学 | Distributed ultrahigh frequency vibration signal measuring method and optical fiber sensor |
| CN114543973B (en) * | 2022-02-28 | 2023-07-25 | 华中科技大学 | Distributed ultrahigh frequency vibration signal measurement method and optical fiber sensor |
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