CN109682321A - Distributed strain sensor-based system and its measurement method based on adaptive reference compensation - Google Patents
Distributed strain sensor-based system and its measurement method based on adaptive reference compensation Download PDFInfo
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- CN109682321A CN109682321A CN201910001805.0A CN201910001805A CN109682321A CN 109682321 A CN109682321 A CN 109682321A CN 201910001805 A CN201910001805 A CN 201910001805A CN 109682321 A CN109682321 A CN 109682321A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
Abstract
It include light source module, pulse modulation module, circulator, straining sensing optical cable, coherent reception module, signal processing module and adaptive equalization module the invention discloses a kind of distributed strain sensor-based system based on adaptive reference compensation and its measurement method, the system.For this system in such a way that coherent phase demodulates, Real-time demodulation goes out the phase information of each point in straining sensing optical cable.Contain strain sensing optical fiber and reference optical fiber in the straining sensing optical cable of special package, by reference to the phase change in optical fiber, the real-time compensation of phase noise caused by temperature drift and laser frequency drift is carried out to strain sensor fibre.In order to realize high-precision phase compensation, this system carries out real-time tracing and adaptive phase compensation using phase information of the self-adapting compensation method to reference optical fiber.Compared with prior art, which can effectively inhibit temperature drift and laser light source phase jitter, realize high-precision distributed strain sensing.
Description
Technical field
The invention belongs to sensory field of optic fibre, answer more particularly, to a kind of distribution based on adaptive reference compensation
Become sensor-based system and its measurement method.
Background technique
China is an earthquake-prone countries, and seismic activity area is numerous, and macroseism takes place frequently in history, and macroseism is to our people
Cause serious life and property loss.Earthquake rule is studied, the certainty omen of earthquake is found, realizes accurately earthquake prediction
It is current Important Problems urgently to be solved.LI Si guang academician once pointed out: the generation of earthquake is mainly since crustal movement is in rock
In layer contradiction between caused crustal stress and rock resistivity gradually develop and intensify as a result, being seen to crustal stress
Survey, find out the related property of crustal stress, feature and the mode of action and changing rule, be possible to earthquake occur place,
The judgement of time, frequency and the intensity science of making.Therefore, high-precision crust deformation, geostress survey instrument are to realize that earthquake is pre-
Survey the key equipment and research emphasis of forecast.
Currently, earth stress observation instrument mainly includes the flexible deformeter of chamber being erected in cavern and is mounted on rock stratum
Drilling strain gauge in drilling.Deformeter stretch mainly by distance between the good baseline rod of length stabilisation and two foundation piers
Compare the observation for realizing stratum strain.However, existing flexible deformeter generally require longer baseline rod realize it is highly sensitive
Strain detection, therefore the construction cost installed is higher.Different-direction borehole strain meter is become by the diameter of measurement drilling different directions
Change, realizes the detection strained to acline.It stretches deformeter relative to chamber, drilling strain gauge is without digging large-sized mountain
Hole, therefore installation cost is lower, but drilling strain gauge is only suitable for the opposite measure of the change of crustal stress.If deformeter peace simultaneously
Dress mode is unreasonable, and fixed point position is wriggled, and a variety of unpredictable factors such as cement and expanded, long variation of bar can all make to see
Various forms of long period noises are mixed into measured data, it is difficult to realize long-term accurate earth stress observation.And existing electricity
Deformeter can only carry out the crustal strain measurement of single-point, therefore there is the deficiency of " unchanged at survey, at change do not survey ", grind in earthquake prediction
The reservoir stress information of some keys may be missed in studying carefully.
Fibre strain instrument has the characteristics that electromagnetism interference, electrical isolation, passive, in the long-term observation of field complex environment
With peculiar advantage.Therefore, it is answered based on fibre optic interferometer, fiber bragg grating and the isostructural optical fiber of fiber-grating laser
Become instrument to quickly grow in recent years.However, optical fiber is answered since the characteristic of optical fiber itself is easy to be influenced by temperature change
The long-time stability of change instrument are always the critical issue in practical application.Meanwhile being based on fibre optic interferometer and fiber grating laser
Device is also difficult to carry out the cascade multiplexing of large capacity, realizes large-scale landform stress measurement.Therefore, a wide range of, high-precision light
Fine distribution method for measuring stress is still problem in science urgently to be resolved.
Summary of the invention
Aiming at the above defects or improvement requirements of the prior art, the present invention provides a kind of based on adaptive reference compensation
Distributed strain sensor-based system and its measurement method, it is intended to solve existing fiber sensor-based system measurement be easily affected by temperature, range
The small and not high problem of precision.
To achieve the above object, according to one aspect of the present invention, a kind of point based on adaptive reference compensation is provided
Cloth strain sensing system, comprising:
Light source module, for generating the continuous narrow-linewidth laser probe light of two-way and local oscillator light；
Pulse modulation module, input terminal are connect with light source module output end, for carrying out continuous narrow linewidth probe light
Impulse modulation and shift frequency export short-pulse laser sequence；
Circulator, input terminal are connect with pulse modulation module output end, are dissipated for realizing short light pulse sequence with multiple
Penetrate light sequence transmitted in both directions in sensor fibre；
Straining sensing optical cable, inscription have scattering enhancing point, and input terminal is connect with pulse modulation module output end, output end
It is connect with the first output end of circulator, short-pulse laser sequence goes out multiple scattering light sequences by scattering enhancing point scattering；
Coherent reception module, one input terminal are connected with the local oscillator light output end of light source module, another input terminal with
The second output terminal of circulator connects, to make local oscillator light and the scattering interference of light form light beat signal, and frequently by multiple photo-beats
Signal is converted into electric signal, exports multiple beat frequency sequences；
Signal processing module, input terminal are connect with the output end of coherent reception module, to demodulate phase in beat frequency sequence
Phase difference between adjacent beat signal, obtains phase difference sequence；
Adaptive equalization module, input terminal are connected with the output end of signal processing module, to strain sensing phase
Carry out adaptive reference compensation.
The present invention is detected using the coherent phase of straining sensing optical cable, realizes highly sensitive distributed strain measurement.It adopts
With the adaptive Phase Compensation System based on reference sensor, reduces and intersect spirit with straining because of system shot noise and fiber optic temperature
Sensitivity bring low-frequency noise.Thus overcome existing fibre optic strain sensor multiplexing capacity small, the degree of intersection of temperature and strain
Height, low-frequency noise is larger, zero float stability it is poor the defects of, realize high-precision, large-scale distributed strain sensing.
Further, straining sensing optical cable includes:
Microstructured optical fibers have inscribed multiple equidistant scatterings enhancing points on microstructured optical fibers, for enhancing in single mode optical fiber
Backward Rayleigh scattering；
Package metals casing forms sensing optic cable to encapsulating microstructure optical fiber, and carries out hot biography to microstructured optical fibers
It leads；
Fiber clamp, microstructured optical fibers to be fixed in metal sleeve, fiber clamp is applied prestressing force.
Further, microstructured optical fibers doubling is encapsulated in metal sleeve, wherein one section of optical fiber is as strain sensing optical fiber,
It is fixed on metal sleeve by way of metallization welding, length changes with the strain of metal sleeve；Another section of optical fiber
It as reference optical fiber, is loosely placed on metal sleeve, is not influenced by metal sleeve strain.
Further, the scattering enhancing point number on two sections of microstructured optical fibers of doubling is identical, and enhances each scattering
Point marks one by one, guarantees being aligned one by one by head and the tail sequence for the scattering enhancing point on two sections of optical fiber of encapsulation.
Further, adaptive equalization module includes:
The output end of sef-adapting filter, input terminal and signal processing module connects, for carrying out certainly to fixed phase
Adaptive filtering, the adaptive penalty coefficient for adjusting phase fluctuation caused by temperature drift and laser frequency drift；Adaptive filter
Wave device can also carry out gradient estimation and Estimation of Mean to fixed phase and strain sensing phase, if the gradient of strain sensing phase is big
In the average gradient of fixed phase, then Estimation of Mean can be carried out to strain sensing phase and fixed phase, from strain sensing phase
In subtract equal value difference between the two, then carry out adaptive equalization, finally add equal value difference in compensation phase；It is wherein adaptive
The step-length of filter is square of the ratio of adaptive equalization strain sensing phase and fixed phase；
The output end of subtracter, input terminal and sef-adapting filter connects, for that will adjust after reference compensation phase
Position is subtracted from strain sensing phase, realizes the adaptive equalization of Low frequency phase noise.
It is another aspect of this invention to provide that providing a kind of distributed strain sensor-based system based on adaptive reference compensation
Measurement method, including probe light through frequency displacement and is modulated into multiple short pulse sequences, and each short pulse sequence is in strain sensing
Short pulse subsequence, the backscattering light pulse subsequence of return and local oscillator light are formed through multiple scatterings enhancing point reflection in optical cable
It interferes to form beat frequency optical signal subsequence into coherent reception module, beat frequency optical signal subsequence is divided into the sub- sequence of strain sensing
Subsequence two parts are arranged and are referred to, the phase information of corresponding each strain sensing point and reference point is obtained by relevant detection,
The phase information of each strain sensing point and reference point is input in adaptive equalization module, will be adjusted by adaptive equalization
Reference compensation phase afterwards is subtracted from strain sensing phase, obtains adaptive equalization strain sensing phase.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, can obtain down and show
Beneficial effect:
1, it using the distributed coherent phase demodulation techniques compensated based on adaptive reference, may be implemented highly sensitive, big
The strain measurement in a distributed manner of range effectively solves the problems, such as that there are sensing measurement blind areas for existing single-point deformeter；
2, special package is carried out to microstructured optical fibers, sensor fibre is compensated by reference to optical fiber, can effectively be dropped
It is low because fiber optic temperature and strain cross sensitivity caused by measurement error；
3, it realizes that high-precision adaptive low-frequency noise compensates using Avaptive filtering system, effectively improves the drift of system
Stability realizes accurately strain measurement steady in a long-term.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the distributed strain sensor-based system provided by the invention based on adaptive reference compensation；
Fig. 2 is straining sensing optical cable structural schematic diagram provided by the invention；
Fig. 3 is the structural schematic diagram of adaptive noise reduction system provided by the invention；
Fig. 4 is the received sensing beat frequency subsequence of signal processing module and when with reference to beat frequency subsequence in the embodiment of the present invention
Domain figure；
Fig. 5 is the fixed phase that signal processing module exports in the embodiment of the present invention, strain sensing phase, and adaptive
The phase change time-domain diagram of the compensation phase of compensating module output；
Fig. 6 is the fixed phase that signal processing module exports in the embodiment of the present invention, strain sensing phase and adaptive
The phase noise power density figure of the compensation phase of compensating module output.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
Fig. 1 is the distributive fiber optic strain sensor-based system schematic diagram provided by the invention based on adaptive reference compensation, point
Cloth strain sensing system includes light source module 1, and light source module 1 is for generating the continuous narrow-linewidth laser of two-way, two-way output
Light is connected with pulse modulation module 2 and coherent reception module 5 respectively.Pulse generating module 2, input terminal and light source module 1
Output end connection, is modulated to short-pulse laser sequence for the continuous narrow-linewidth laser of the first via, and generate certain frequency displacement, pulse tune
The output end of molding block 2 is connect with the port a of circulator 3, and the port b of circulator 3 and the straining sensing optical cable 4 of special package connect
It connects.Therefore, the short-pulse laser sequence generated by pulse generating module 2 after circulator 3 is injected into straining sensing optical cable 4,
It is reflected by straining sensing optical cable 4, the second output of coherent reception module 5 is then returned by the port c of circulator 3
End.The output end of coherent reception module 5 is connect with the input terminal of signal processing module 6.It is reflected from straining sensing optical cable 4
Light is scattered, in coherent reception module 5, interference is carried out with the continuous narrow-linewidth laser in the second road that light source module 1 issues and is superimposed, shape
At beat frequency subsequence.Signal processing module 6 is determined each in straining sensing optical cable 4 by receiving time of beat frequency subsequence
Then the position of strain sensing point and reference point carries out phase demodulating to these beat frequency subsequences again and recovers each strain sensing
The phase information of point and reference point.The transducing signal for the strain sensing point that signal processing module 6 obtains and the reference letter of reference point
It number is input in adaptive equalization module 7, adaptive equalization module 7 carries out transducing signal according to the phase value of reference signal
Adaptive noise reduction eliminates Low frequency phase noise caused by drifting about in transducing signal due to temperature fluctuation and laser frequency.
Specifically, as shown in Fig. 2, straining sensing optical cable 4 includes microstructured optical fibers 41, by ultraviolet laser in single mode optical fiber
The scattering enhancing point composition of 5m, overall length 570m, corresponding strain sensing optical fiber 44 and reference light are divided between upper inscription 112
Fibre 45 enhances point containing 56 scatterings respectively, and guarantees a scattering enhancing point of n-th (n=1,2,3, N) and 2N+1-n
(n=1,2,3, N) a scattering enhances point alignment, is then encapsulated in metal sleeve 46.Scattering enhancing point is for enhancing
Backward Rayleigh scattering in single mode optical fiber improves the signal-to-noise ratio of scattering light.Wherein each scattering of strain sensing optical fiber 44 enhances point
It is all fixed on metal sleeve 46 by fiber clamp 42, and is applied with certain prestressing force.And reference optical fiber 45 is then completely loose
It is placed in metal sleeve 46 with relaxing.Therefore, when effects of strain is on metal sleeve 46, strain sensing optical fiber 44 can be with metal
Casing 46 generates strain, and reference optical fiber 45 is then entirely unaffected by.And strain sensing optical fiber 44 and reference optical fiber 45 are then in
In the same temperature environment, therefore effective temperature-compensating may be implemented.
In the embodiment of distributed strain sensor-based system provided by the invention, the short pulse that pulse modulation module 2 exports swashs
The duration of light sequence, each short light pulse isTwo adjacent applied in short pulse intervalsWherein, n is optical fiber pack
Rate is penetrated, l is two scattering enhancing points the distance between 43 in microstructured optical fibers 41, and c is the light velocity, and L is the total of microstructured optical fibers 41
Length.Since the time interval of two adjacent short-pulse lasers is come greater than maximum of the short-pulse laser in micro-structure sensing optic cable
The transmission back time, therefore will not be overlapped between each reflected light signal sequence.And the duration of short-pulse laser is less than phase
The transmission time back and forth of neighbour's scattering enhancing point, so the pulse signal of each scattering enhancing point will not weigh in reflected light signal sequence
It is folded, therefore according to the difference of reflection light pulse transmission time, it can precisely determine each scattering enhancing position.
In embodiment provided by the invention, the optical maser wavelength that light source module 1 issues is 1550.7nm, into impulse modulation mould
Block 2 and the two-way laser intensity ratio for entering relevant receiving module 5 are 90:10.Light pulse occurs the short pulse that module 2 generates and continues
Time was 30 nanoseconds, and the pulse spacing is 1 microsecond, and the frequency displacement of 200MHz can be added to laser pulse.Contain in relevant receiving module 5
There are 2 × 2 couplers that a splitting ratio is 50:50 and the balanced detector that bandwidth is 800MHz.Signal processing module 6 samples
Rate is 2G/s, resolution ratio 8bit.
Fig. 3 is the functional block diagram of the adaptive equalization module 7 of the embodiment of the present invention.It include one in adaptive equalization module 7
A subtracter 71 and sef-adapting filter 72.The ginseng of the strain sensing signal and reference optical fiber that are exported from signal processing module
Signal is examined to be separately input in adaptive equalization module 7, sef-adapting filter 71 is first filtered reference signal, then with answer
Become transducing signal to subtract each other, obtains compensated signal output.Then according to the value of current compensation output, to sef-adapting filter
System function be updated, realize high-precision adaptive equalization.
In embodiment provided by the invention, light pulse modulator 2 can give signal while modulating short-pulse laser sequence
Processing module 6 sends trigger signal, realizes acquisition and the pulse laser sequence synchronization of beat frequency sequence.Coherent reception module 6 receives
To beat frequency sequence can indicate in chronological order are as follows: { xm}；M=1,2,3 ..., M.Each short light pulse is injected into sensing optic cable
After 4,112 scatterings enhancing point in sensing optic cable 4, which can reflect, generates 112 reflection light pulse signal subsequences.Wherein preceding 56
A scattering light pulse beat frequency is the beat signal of strain sensing fiber reflection, can be marked in chronological order are as follows: { xms(k)；K=
1,2,…56}.N number of scattering light pulse beat frequency is the beat signal of reference optical fiber reflection afterwards, can be marked in chronological order are as follows:
{xmr(k)；K=1,2 ... 56 }.It is two neighboring in strain sensing optical fiber 44 to dissipate when generating certain strain on sensing optic cable 4
Penetrating the distance between enhancing point can change, therefore the light beat signal x that two scattering enhancing point reflections are returnedms(k) and
xms(k+1) phase difference between will change, and reference section { xmr(k) } it will not then be influenced by straining.And when sensing
When the temperature of optical cable 4 changes, temperature can be influenced simultaneously between the beat signal on strain sensing optical fiber and reference optical fiber
Phase difference, therefore real-time phase can be carried out to strain transducing signal using the phase change on the reference optical fiber of same position
Position noise compensation.Fig. 4 is the beat frequency subsequence time-domain diagram received in signal processing module 6, wherein preceding 56 beat signals are
Strain sensing beat frequency subsequence { xms(k) }, rear 56 beat signals are with reference to beat frequency subsequence { xmr(k) }, and k-th is answered
Become sensing beat frequency xms(k) beat frequency x is referred to N+1-k (N=56)ms(N+1-k) corresponding.Signal processing module 6 passes through phase
It demodulates strain sensing beat frequency sequence { xmsAnd with reference to beat frequency sequence { xmrRevert to each scattering enhancing point on microstructured optical fibers
Between phase changeWithSensing phase sequence after resolvingAnd reference
Phase sequenceIt is input in self-reference compensating module 7, self-reference compensating module 7 is according to fixed phase sequenceIt is rightCarry out real-time phase compensation, adaptive equalization the following steps are included:
(1) according to strain sensing phase subsequenceNumber, be arranged 55 16 rank FIR (Finite Impulse
Response has limit for length's unit impulse response) adaptive filter system function { wi(j)；I=1,2 ..., M；J=1,2 ...,
55；}；Initial system function { w0(j) }=0；
(2) judge whether fixed phase subsequence i is greater than 16, if so, entering step (3), otherwise, phase compensation is enabled to export{wi(j) }=0；I=i+1；It repeats step (2)；
(3) judge strain sensing phaseWithGradient difference whether be greater than with reference to subsequenceAverage gradient, if so, to strain sensing phaseAnd fixed phaseCarry out office
Portion's Estimation of Mean, and obtain local mean value difference A (ij)；Otherwise, A (ij)=0 is enabled；
(4) to fixed phase subsequenceIn j-th of fixed phaseAccording to current filter
Wave device system function wi(j) FIR filtering is carried out, is obtained filtered with reference to output
(5) by strain sensing phaseIt subtracts filtered with reference to outputCompensation after obtaining phase compensation is defeated
Out
(6) it is exported according to compensationWith fixed phaseRatio square setting adaptive step
μ；
(7) it is exported according to adaptive step μ and compensationUpdate the system function w of sef-adapting filteri+1
(j)；
(8) judge whether phase order j is equal to N-1, if so, entering step (9), otherwise, enable j=j+1, repeat step
(3)~(7)；
(9) phase subsequence i=i+1 is enabled, step (3)~(8) are repeated；
(10) according to j-th of compensation phase output with reference to thermal compensation signal in i=1Intensity obtain j-th
Strain variation suffered by sensing point.
The present embodiment realizes the distributed strain sensing of 5m spatial resolution in 570m length.Fig. 5 is implementation of the present invention
The time domain wave pattern of strain sensing phase, fixed phase and compensation output phase in example when j=55.Fig. 6 is of the invention real
Apply strain sensing phase, fixed phase and the power spectral density for compensating output phase when j=55 in example.It can be seen that being based on
The adaptive equalization system of fixed phase is obviously inhibited relative to traditional Phase Demodulation Method of Optic, system drift, low frequency phase
Noise reduces 40dB.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (8)
1. a kind of distributed strain sensor-based system based on adaptive reference compensation characterized by comprising
Light source module (1), for generating the continuous narrow-linewidth laser probe light of two-way and local oscillator light；
Pulse modulation module (2), input terminal are connect with the light source module (1) output end, are used for the continuous narrow linewidth
Probe light carries out impulse modulation and shift frequency, exports short-pulse laser sequence；
Circulator (3), input terminal are connect with the pulse modulation module (2) output end, for realizing short light pulse sequence with
It is multiple to penetrate light sequence transmitted in both directions in sensor fibre；
Straining sensing optical cable (4), inscription have scattering enhancing point, and input terminal is connect with the pulse modulation module (2) output end,
Output end is connect with the first output end of circulator (3), and the short-pulse laser sequence goes out multiple dissipate by scattering enhancing point scattering
Penetrate light sequence；
Coherent reception module (5), one input terminal are connected with the local oscillator light output end of the light source module (1), another is defeated
Enter end to connect with the second output terminal of the circulator (3), to make local oscillator light and the scattering interference of light form light beat signal, and
Electric signal is converted by multiple smooth beat signals, exports multiple beat frequency sequences；
Signal processing module (6), input terminal are connect with the output end of coherent reception module (5), to demodulate in beat frequency sequence
Phase difference between adjacent beat signal, obtains phase difference sequence；
Adaptive equalization module (7), input terminal are connect with the output end of signal processing module (6), for strain sensing phase
Position carries out adaptive reference compensation.
2. distributed strain sensor-based system according to claim 1, which is characterized in that straining sensing optical cable (4) packet
It includes:
Microstructured optical fibers have inscribed multiple equidistant scatterings enhancing points on the microstructured optical fibers, for enhancing in single mode optical fiber
Backward Rayleigh scattering；
Metal sleeve forms sensing optic cable to encapsulating microstructure optical fiber, and carries out heat transfer to microstructured optical fibers；
Fiber clamp, the microstructured optical fibers to be fixed in the metal sleeve, the fiber clamp is applied pre- answer
Power.
3. distributed strain sensor-based system according to claim 2, which is characterized in that the microstructured optical fibers doubling encapsulation
In metal sleeve, wherein one section of optical fiber is fixed on metal sleeve by way of metallization welding as strain sensing optical fiber
On, length changes with the strain of metal sleeve；Another section of optical fiber is loosely placed on metal sleeve as reference optical fiber,
Length is not strained by metal sleeve and is changed.
4. according to distributed strain sensor-based system described in claim 2 and 3, which is characterized in that the strain sensing optical fiber and
The scattering enhancing point number of the reference optical fiber is identical, and marks one by one to each scattering enhancing point, guarantees on two sections of optical fiber
Scattering enhancing point is aligned one by one by head and the tail sequence.
5. distributed strain sensor-based system according to claim 1, which is characterized in that the adaptive equalization module (7)
Include:
Sef-adapting filter, input terminal are connect with the output end of signal processing module (6), adaptive for carrying out to fixed phase
It should filter, the adaptive penalty coefficient for adjusting phase fluctuation caused by temperature drift and laser frequency drift；
Subtracter, input terminal are connect with the output end of the sef-adapting filter, for that will adjust after fixed phase from
It is subtracted in strain sensing phase, realizes the adaptive equalization of Low frequency phase noise.
6. distributed strain sensor-based system according to claim 5, which is characterized in that the sef-adapting filter includes pair
Fixed phase and strain sensing phase carry out Estimation of Mean；
If the gradient of strain sensing phase is greater than the gradient of fixed phase, mean value is carried out to strain sensing phase and fixed phase
Estimation, subtracts the equal value difference of the strain sensing phase and fixed phase, then carry out adaptive equalization from strain sensing phase,
The equal value difference of the strain sensing phase and fixed phase is finally added in adaptive equalization strain sensing phase.
7. according to the distributed strain sensor-based system described in claim 5, which is characterized in that the step-length of the sef-adapting filter is
Square of the ratio of the adaptive equalization strain sensing phase and fixed phase.
8. a kind of measurement method of the distributed strain sensor-based system based on adaptive reference compensation, which is characterized in that the spy
Needle light is through frequency displacement and is modulated into multiple short pulse sequences, and each short pulse sequence increases in straining sensing optical cable through multiple scatterings
Strong point reflects to form short pulse subsequence, and the backscattering light pulse subsequence of return and the local oscillator light enter coherent reception mould
Block interferes to form beat frequency optical signal subsequence, and the beat frequency optical signal subsequence is divided into strain sensing subsequence and with reference to son
Sequence two parts obtain the phase information of corresponding each strain sensing point and reference point by relevant detection, described each to answer
The phase information for becoming sensing point and reference point is input in adaptive equalization module, by adaptive equalization by the ginseng after adjustment
It examines compensation phase to subtract from strain sensing phase, obtains adaptive equalization strain sensing phase.
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| WO2021017163A1 (en) * | 2019-08-01 | 2021-02-04 | 宁波飞芯电子科技有限公司 | Decoherence processing method and system, and coherent light receiving apparatus |
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| CN112923959A (en) * | 2021-01-27 | 2021-06-08 | 浙江大学 | System for improving sensing distance of phase-sensitive optical time domain reflectometer |
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