CN102564476B - Multipoint disturbance positioning method - Google Patents
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Abstract
The invention discloses a multipoint disturbance positioning method, and relates to the technical field of optical fiber distributed disturbance sensors. The method comprises the following steps of: 1, preprocessing a signal received by a detector, and extracting phase information of the signal; and 2, performing frequency domain amplitude spectrum analysis and phase spectrum analysis on the obtained phase information, extracting an amplitude value and the phase information of each frequency component, and reducing the position of the disturbance signal. The method is low in cost, and high in practicability.
Description
Technical field
The present invention relates to optical fiber distributed perturbation sensor technical field, relate in particular to a kind of multipoint disturbance positioning method.
Background technology
Fibre Optical Sensor because its high sensitivity, volume are little, lightweight, essential safety, electrical insulating property, anti-electromagnetic interference (EMI), relative cost is low, multi-functional, reliability is high, Hardware match fiber optic data communication interface, be easy to networking, particularly can realize the good characteristics such as distributed measurement, have a wide range of applications in industry, civilian and military field.Wherein, optical fiber distributed perturbation sensor is significant in fields such as circumference security protection, oil-gas pipeline monitoring, large scale structure monitoring and communication line monitorings.
Optical fiber distributed perturbation sensor can be monitored the disturbance (time varying signal) at any point place on sensor fibre, obtain the time domain waveform of disturbing signal, judge according to disturbance event character, provide warning message, provide the spatial positional information that disturbance event occurs simultaneously.
At present, according to different principle of work, optical fibre distribution type sensor can be divided into interferometer type, grating type optical fiber, optical time domain reflectometer type, the sensing technologies such as optical frequency domain reflectometer type and intensity modulation type.
Grating type optical fiber distributed sensor adopts fiber grating as sensitive element, between the interval of certain length, lay fiber grating, realize quasi-distributed sensing by multiplex technique, therefore, the spatial resolution of the distributed perturbation sensor of grating type optical fiber has uncontinuity, and is subject to the restriction at fiber grating space distribution interval.Meanwhile, fiber grating integrated based on wavelength multiplexing, fiber grating quantity that can be multiplexing on an optical fiber is subject to the restriction of range of wavelengths, and its increase of measuring length need to reduce spatial resolution as cost to increase fiber grating interval.Except spatial resolution with measure the contradiction between length, the cost of grating type optical fiber distributed sensor has also limited its application in environment on a large scale as distributed perturbation sensor.
Optical time domain reflectometer type distributed sensor can be used for detecting the variation of temperature in external environment or pressure, but its response time is longer, real-time contrast locating for external disturbance is more difficult, can not be applied to the distributed sensing to time varying signal, therefore limit its application as distributed perturbation sensor.
Optical frequency domain reflectometer type distributed sensor, based on nonlinear optical effect, Brillouin or Raman scattering, can carry out sensing by temperature and pressure to external world, but its transducing signal is relatively faint, make the detection of signal conciliate phase modulation to difficulty, simultaneously its device cost is also relatively high, limited its long apart from the application in destabilization sensing.
The Mode Coupling mechanism of intensity modulation type sensor based in single-mode fiber and multimode optical fiber, can realize the distributed sensing to disturbance, but its sensitivity and precision is lower, also to need further to solve enhanced sensitivity and puies forward high-precision problem in order to apply in practice.
To sum up, in optical fibre distribution type sensor, interferometer type distributed sensor has that the principle of realization is simple, highly sensitive, fast response time, hardware cost are low, be suitable for the good characteristics such as long-distance sensing, has become the main technical schemes of optical fiber distributed perturbation sensor.
At present, the theoretical scheme of interferometer type distributed optical fiber disturbance sensor mainly comprises: Sagnac+Mach-Ze De type, Sagnac+Michaelson, two Sagnac type, span He-Ze De type, single Sagnac type etc.
By Sagnac interferometer and Mach-Zehnder interferometer or Michelson interferometer combination, can realize the extraction to single-point disturbance location information, realize distributed destabilization sensing.But the shortcoming of such optical fibre distribution type sensor is: in Sagnac interferometer, in order to suppress interaction noise, need to adopt wide spectrum light source; But in Mach-Ze De or Michelson interferometer, interfere the existence of arm optical path differences due to two, can only use narrow-band light source, the contradiction that therefore light source is selected has limited the raising of its performance and practical.
For in time domain, realize Sagnac interferometer to time become the location of disturbance, also can or there is a Sagnac interferometer of two operation wavelengths simultaneously or be operated in a Sagnac interferometer of two modulating frequencies simultaneously by two Sagnac interferometers.But in this type of scheme, need to adopt two light sources, detectors and need wavelength division multiplexer and the device such as the modulator of different frequency, increase the hardware cost of system and the complicacy of structure, reduce the practicality of sensor.Wherein, the optical fiber distributed perturbation sensor based on dual wavelength sagnek interferometer can be realized simultaneously disturbances location of multiple spot, but due to the factor such as undesirable of device, the positioning precision of multipoint disturbance and range of application is limited by very large.
Span He-Ze De type optical fibre distribution type sensor light channel structure is simple, hardware cost is low, but signal dropout and polarization decay are all larger, and thereby the frequency noise of laser instrument can produce intensity noise by the poor phase noise that is converted into of interferometer brachium, simultaneously, light source requirements used has higher coherence, and cost is higher.The in the situation that of multiposition (multiple spot) disturbance simultaneously, cannot provide the accurate location of disturbance location, reduce the Practical Performance of sensor.
By contrast, single Sagnac type optical fibre distribution type sensor has embodied very large advantage.Because Sagnac interferometer is zero optical path difference, therefore there is not the inconsistent noise causing of two pickup arm length, do not have signal dropout, and polarization decay is very little.It requires low to light source coherence, and due to the reciprocity of light channel structure, can avoid the even problem of locate failure of disturbances location error that the scattering in long distance applications causes.By using high-power wideband light source, this sensor goes for long distance monitoring disturbance.Carry out corresponding pre-service, triangulo operation and spectrum analysis etc. by the disturbing signal that single Sagnac type optical fiber distributed perturbation sensor is received, can realize the location to multiple spot disturbance simultaneously.
But the localization method of existing single Sagnac type optical fiber distributed perturbation sensor cannot be realized the multiple spot function of disturbances location simultaneously.
Summary of the invention
(1) technical matters that will solve
The technical problem to be solved in the present invention is: provide a kind of cost low, and practical multipoint disturbance positioning method.
(2) technical scheme
For addressing the above problem, the invention provides a kind of multipoint disturbance positioning method, the method comprising the steps of:
S1. signal detector being received carries out pre-service, extracts the phase information of described signal;
S2. phase information step S1 being obtained is carried out frequency domain amplitude analysis of spectrum and phase spectral analysis, extracts amplitude and phase information under each frequency content, the position of reduction disturbing signal.
Preferably, the pre-service in step S1 further comprises step:
The DC terms of signal described in S1.1 filtering;
The visibility that S1.2 eliminates described signal by anti-polarization decay method and light power stabilising control method changes;
S1.3 asks for the intensity signal of step S1.2 two interference signals after treatment by asking for the method for peak-to-peak value;
S1.4 extracts phase information from described intensity signal.
Preferably, the pre-service in step S1 further comprises step:
The DC terms of signal described in S1.1 filtering;
The method that S1.2 asks for peak-to-peak value by segmentation is asked for the intensity signal of described signal;
S1.3 extracts phase information from described intensity signal.
Preferably, after step S1.1, also comprise step before S1.2:
S1.11 amplifies and filtering processing step S1.1 signal after treatment.
Preferably, in step S1.3, the method for extracting phase information is that trigonometric function phase extraction method or phase place produce carrier modulation.
Preferably, the phase information of extracting is:
Wherein, A
i, B
j, C
krepresent respectively the amplitude under the different angular frequencies of multiple disturbances, ω
i, ω '
j, ω
k n' represent respectively the angular frequency of multiple disturbances,
represent respectively the initial phase under the different angular frequencies of multiple disturbances, c is the light velocity in vacuum, the refractive index that n is sensor fibre, and L is the distance of coupling mechanism apart from reference position, the length that D is fiber optic loop, z
1, z
2and z
ncorresponding multiple disturbance locations are to the distance of described reference position respectively.
Preferably, in step S2, extract after the amplitude and phase information under each frequency content, the system of equations of the incoherent equation composition of simultaneous, and solve described system of equations, obtain the position of disturbing signal.
Preferably, the optical fiber distributed perturbation sensor of the method based on single Sagnac type interferometer.
(3) beneficial effect
Method of the present invention has following beneficial effect:
1. Sagnac interferometer structure has the feature of zero optical path difference, no signal decline, and polarization decay is very little, and what adopt due to Sagnac interferometer is wide spectrum light source, can play the effect that suppresses scattering, and cost is low, in long distance applications, more preponderates.
2. by the pre-service of disturbing signal has been eliminated to the variation of the interference signal visibility that the factor such as luminous power fluctuation and signal polarization induction decline that may be subject to causes in positioning calculation process, thereby also indirectly eliminated the problem of the possible sensor localization inefficacy that visibility variation causes;
3. pass through to the pre-service of disturbing signal also filtering simultaneously phase drift signal, thereby eliminated the gradual impact of phase place;
4. use the method for triangular transformation and frequency domain spectra analysis can extract the positional information of multipoint disturbance, when realizing multipoint disturbance, locate.
Brief description of the drawings
Fig. 1 is the optical fiber distributed perturbation sensor light path principle figure of single Sagnac type interferometer;
Fig. 2 is the multipoint disturbance positioning method process flow diagram according to one embodiment of the present invention.
Embodiment
The present invention propose multipoint disturbance positioning method, by reference to the accompanying drawings and embodiment be described in detail as follows.
The object of this invention is to provide a kind of multipoint disturbance positioning method of the optical fiber distributed perturbation sensor based on single Sagnac type interferometer, by disturbing signal being carried out to, every methods such as straight, extraction cosine phase information, frequency domain spectra analysis, Simultaneous Equations, extract the positional information of different disturbing signals in multiple spot disturbance simultaneously situation.
Embodiment 1
The multipoint disturbance positioning method of the optical fiber distributed perturbation sensor of the present embodiment comprises the single Sagnac type interferometer (be not limited to this) of method based on shown in Fig. 1, and taking 2 disturbances simultaneously as example.
The light wave that laser instrument (Laser) 1 sends via coupling mechanism C light splitting after, two-beam wavelength-division is along propagating clockwise and counterclockwise, through sensor fibre and fiber optic loop, interfere at coupling mechanism C place, received by photodetector (PD) 2, through the demodulation process of signal, can determine the position of disturbance.
Wherein, coupling mechanism is for realizing the function of light splitting and coupling, and other device is as circulator, beam splitter, part reflective semitransparent film etc., and the device that also can play beam splitting and coupling is applicable equally, does not repeat at this.
As 2 disturbance f
1and f (t)
2(t) while generation, fiber lengths and propagation constant will change simultaneously, thereby cause that the phase place in interferometer changes.
Suppose two disturbing signal f
1and f (t)
2(t) the phase place variation causing is respectively:
In formula, A
i, B
jrepresent respectively the amplitude of two disturbances, ω
i, ω
j' represent respectively the angular frequency of two disturbances,
represent respectively the initial phase of two disturbances, N and M are respectively the quantity of the frequency content component of two disturbances.
Disturbance location is along being expressed as to the travel-time of detector counterclockwise and clockwise:
In formula, L is the distance (do not comprise an arm of fiber optic loop) of coupling mechanism C apart from reference position (as shown in dotted line in accompanying drawing in present embodiment 1, the mid point of corresponding sensor fibre while not comprising fiber optic loop D), the length that D is fiber optic loop, z
1, z
2corresponding two disturbance locations are to the distance of reference position, τ respectively
1, τ
2be respectively disturbance that A orders along counterclockwise and clockwise direction arrive travel-time of PD2, τ
3, τ
4be respectively disturbance that B orders along counterclockwise and clockwise direction arrive travel-time of PD2, c is the light velocity in vacuum, the refractive index that n is sensor fibre.
The signal receiving at detector place is:
In formula, K
1the visibility of interferometer, I
0depend on the luminous power that laser instrument 1 is exported.
As shown in Figure 2, comprise step according to the multipoint disturbance positioning method of one embodiment of the present invention:
S1. signal detector being received carries out pre-service, comprises step:
S1.1 filtering DC terms, removes DC terms and low-frequency disturbance item in signal, can realize by directly add electric capacity on circuit every straight mode, also can realize by modes such as active and passive high-pass filterings, and its effect is identical.Also can amplify and the processing such as filtering the signal after straight, to suppress Noise and Interference, amplify and the method for filtering is the mature technology of this area, not repeat at this.
The computing method that S1.2 asks for peak-to-peak value by segmentation are asked for K
1i
0, eliminate because of the decline variation of the interference signal visibility causing of luminous power fluctuation and signal polarization induction, can obtain:
This step is carried out segmentation to ask for the object of peak-to-peak value is the product information of light intensity in order to obtain interference signal and visibility and play and eliminate the interference signal visibility variation causing due to factors such as luminous power fluctuation and the declines of signal polarization inducement signal the signal after straight.And the method for being eliminated that interference signal visibility changes and being obtained light intensity and visibility information by asking for peak-to-peak value or alternate manner by anti-polarization decay technology and light power stabilising control technology is suitable for too.
S1.3 applies respectively trigonometric function phase extraction algorithms to formula (8), (object that extracts the phase information in trigonometric function by trigonometric function phase extraction algorithms is to provide basic preparation for signal framing below to extract phase information, and by other phase unwrapping, recover, remove parcel, solution twines algorithm or similar phase information extraction algorithm extracts the phase information in trigonometric function, comprise that phase place produces carrier wave (Phase Generated Carrier, PGC) method of modulation (comprising PGC internal modulation and PGC external modulation) etc. is suitable for too), can obtain:
By formula (1)-Shi (6) substitution formula (9), can obtain:
Formula (10) is used and poor eliminate indigestion formula, can be obtained:
(11)
The quantity of supposing the composition that frequency is identical is P, and formula (8) can be reduced to:
Wherein, the composition that frequency is identical can be expressed as:
Wherein:
(14)
(15)
S2. formula (12) is carried out respectively to frequency domain amplitude analysis of spectrum and phase spectral analysis, the positional information of reduction undesired signal.
In the present embodiment, taking t as variable, formula (12) is carried out respectively to frequency domain amplitude analysis of spectrum and phase spectral analysis, extract amplitude and phase information under each frequency content, and the system of equations of the incoherent equation composition of simultaneous.Obviously, in formula (12), each at least can obtain two equations, can draw six equations, in these six equations, comprise A
i,
b
j,
z
1and z
2six unknown numbers.To these six equations simultaneousness system of equations, easily prove that the Jacobian matrix of this system of equations is not degenerated, obvious solving equation group can extract the position z of two disturbances
1and z
2.
The method that also can analyze by other frequency domain amplitudes and phase spectrum, as long as its final purpose is the method that can extract amplitude and phase information under each frequency content, all applicable.
In the process of Simultaneous Equations, need to carry out simple classification and discuss, repeat no more herein.
The location algorithm of 2 disturbances is generalized to and 3 above disturbances at 3, can realizes detection and the location of the optical fiber distributed perturbation sensor multiple spot disturbance simultaneously based on Sagnac interferometer.
Embodiment 2
The multipoint disturbance positioning method of the optical fiber distributed perturbation sensor of the present embodiment comprises the single Sagnac type interferometer based on shown in Fig. 1, taking 3 disturbances simultaneously as example, i.e. and 3 disturbance f
1(t), f
2and f (t)
3(t) occur simultaneously.
F
1(t), f
2(t) phase place causing changes cotype (1) and (2), supposes disturbing signal f
3(t) phase place causing is:
In formula, C
krepresent f
3(t) amplitude, ω
k" represent f
3(t) angular frequency,
represent f
3(t) initial phase, Q is f
3(t) quantity of frequency content component.
F
1(t), f
2(t) disturbance location is along counterclockwise and being clockwise expressed as cotype (3)-(6), f to the travel-time of detector
3(t) disturbance location is along being expressed as to the travel-time of detector counterclockwise and clockwise:
In formula, z
3corresponding f
3(t) disturbance location is to the distance of reference position, τ
5, τ
6be respectively f
3(t) travel-time of detector is arrived in the disturbance at disturbance occurrence positions place along counterclockwise and clockwise direction.
The signal receiving at detector place is:
The signal that detector is received carries out pre-service: filtering DC terms, then ask for K by the method that peak-to-peak value is asked in segmentation
1i
0eliminate because the interference signal visibility that luminous power fluctuates and signal polarization induction decline causes changes, can obtain
(21)
To formula (21) application trigonometric function phase extraction algorithms, can obtain:
By formula (1), (2), (3)-(6), (17)-(19) substitutions (22), can obtain:
Formula (23) is used and poor eliminate indigestion formula, can be obtained:
The quantity of supposing the composition that frequency is identical is P, and formula (24) can be reduced to:
(25)
Wherein, the composition that frequency is identical can be expressed as:
Wherein,
Taking t as variable, formula (25) is carried out respectively to frequency domain amplitude analysis of spectrum and phase spectral analysis, obviously, in formula (25), each at least can obtain two equations, be not difficult the coldest days of the year end equation, in these nine equations, comprise A
i,
b
j,
c
k,
z
1, z
2and z
3totally nine unknown numbers.To these nine equations simultaneousness system of equations, easily prove that the Jacobian matrix of this system of equations is not degenerated, obvious solving equation group can extract the position z of three disturbances
1, z
2and z
3.In the process of Simultaneous Equations, need to carry out simple classification and discuss, repeat no more herein.
Above embodiment is only for illustrating the present invention; and be not limitation of the present invention; the those of ordinary skill in relevant technologies field; without departing from the spirit and scope of the present invention; can also make a variety of changes and modification; therefore all technical schemes that are equal to also belong to category of the present invention, and scope of patent protection of the present invention should be defined by the claims.
Claims (8)
1. a multipoint disturbance positioning method, is characterized in that, the method comprising the steps of:
S1. signal detector being received carries out pre-service, extracts the phase information of described signal;
S2. phase information step S1 being obtained is carried out frequency domain amplitude analysis of spectrum and phase spectral analysis, extracts amplitude and phase information under each frequency content, the position of reduction disturbing signal.
2. multipoint disturbance positioning method as claimed in claim 1, is characterized in that, the pre-service in step S1 further comprises step:
The DC terms of signal described in S1.1 filtering;
The visibility that S1.2 eliminates described signal by anti-polarization decay method and light power stabilising control method changes;
S1.3 asks for the intensity signal of step S1.2 two interference signals after treatment by asking for the method for peak-to-peak value;
S1.4 extracts phase information from described intensity signal.
3. multipoint disturbance positioning method as claimed in claim 1, is characterized in that, the pre-service in step S1 further comprises step:
The DC terms of signal described in S1.1 filtering;
The method that S1.2 asks for peak-to-peak value by segmentation is asked for the intensity signal of described signal;
S1.3 extracts phase information from described intensity signal.
4. multipoint disturbance positioning method as claimed in claim 3, is characterized in that, also comprises step after step S1.1, before S1.2:
S1.11 amplifies and filtering processing step S1.1 signal after treatment.
5. multipoint disturbance positioning method as claimed in claim 3, is characterized in that, in step S1.3, the method for extracting phase information is that trigonometric function phase extraction method or phase place produce carrier modulation.
6. multipoint disturbance positioning method as claimed in claim 5, is characterized in that, the phase information of extracting is:
·
·
·
Wherein, A
i, B
j, C
krepresent respectively the amplitude under the different angular frequencies of multiple disturbances, ω
i, ω '
j, ω
k n' represent respectively the angular frequency of multiple disturbances,
represent respectively the initial phase under the different angular frequencies of multiple disturbances, c is the light velocity in vacuum, the refractive index that n is sensor fibre, and L is the distance of coupling mechanism apart from reference position, the length that D is fiber optic loop, z
1, z
2and z
ncorresponding multiple disturbance locations are to the distance of described reference position respectively.
7. multipoint disturbance positioning method as claimed in claim 1, is characterized in that, in step S2, extract after the amplitude and phase information under each frequency content, and the system of equations of the incoherent equation composition of simultaneous, and solve described system of equations, obtain the position of disturbing signal.
8. the multipoint disturbance positioning method as described in claim 1-7 any one, is characterized in that, the optical fiber distributed perturbation sensor of the method based on single Sagnac type interferometer.
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| CN104764472B (en) * | 2015-04-16 | 2017-04-12 | 武汉理工光科股份有限公司 | Pipeline monitoring system and method based on optical time domain reflection detection technology |
| CN105277272A (en) * | 2015-10-25 | 2016-01-27 | 复旦大学 | Distributed optical fiber vibration sensing multi-point disturbance localization algorithm |
| CN107014409B (en) * | 2017-03-26 | 2019-05-28 | 天津大学 | A kind of long range optical frequency domain reflection-based optical fiber Distributed Multi destabilization sensing method |
| DE102017216666A1 (en) * | 2017-09-20 | 2019-03-21 | Dr. Johannes Heidenhain Gmbh | Position measuring device and method for operating a position measuring device |
| CN108803018B (en) * | 2018-08-15 | 2020-09-08 | 重庆理工大学 | Method for reconstructing longitudinal refractive index distribution of optical waveguide |
| CN109489800A (en) * | 2018-12-14 | 2019-03-19 | 广东世港信息科技有限公司 | A kind of disturbance event recognition methods in distribution optic cable vibration safety pre-warning system |
| CN112285770B (en) * | 2020-10-28 | 2021-07-06 | 重庆大学 | Seismic wave phase spectrum disturbance method based on real number wavelet transformation |
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| US5402231A (en) * | 1992-08-24 | 1995-03-28 | Mcdonnell Douglas Corporation | Distributed sagnac sensor systems |
| CN1862239A (en) * | 2006-06-15 | 2006-11-15 | 华中科技大学 | Distributed optical fiber vibration sensing method and apparatus thereof |
| CN100437050C (en) * | 2006-11-15 | 2008-11-26 | 北京航空航天大学 | Distribution type fiber-optic vibration sensor |
| CN101487723A (en) * | 2009-03-02 | 2009-07-22 | 北京航空航天大学 | Optical fiber distributed perturbation sensor based on Sagnac interferometer |
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| US7305153B2 (en) * | 2005-06-21 | 2007-12-04 | Litton Systems, Inc. | Multi wavelength sensor array |
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| CN1862239A (en) * | 2006-06-15 | 2006-11-15 | 华中科技大学 | Distributed optical fiber vibration sensing method and apparatus thereof |
| CN100437050C (en) * | 2006-11-15 | 2008-11-26 | 北京航空航天大学 | Distribution type fiber-optic vibration sensor |
| CN101487723A (en) * | 2009-03-02 | 2009-07-22 | 北京航空航天大学 | Optical fiber distributed perturbation sensor based on Sagnac interferometer |
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