CN102242870A - Duffing-based detection device and method for distributed optical fiber pipeline leakage - Google Patents

Duffing-based detection device and method for distributed optical fiber pipeline leakage Download PDF

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CN102242870A
CN102242870A CN2011101696011A CN201110169601A CN102242870A CN 102242870 A CN102242870 A CN 102242870A CN 2011101696011 A CN2011101696011 A CN 2011101696011A CN 201110169601 A CN201110169601 A CN 201110169601A CN 102242870 A CN102242870 A CN 102242870A
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fiber
input end
light source
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CN102242870B (en
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冯健
刘金海
张化光
马大中
张红娜
李健
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Northeastern University China
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Abstract

The invention provides a duffing-based detection device and method for a distributed optical fiber pipeline leakage, belonging to the technical field of fluid pipeline leakage detection. The device comprises a light source module, a fiber optic interferometer module, a photoelectric detection module, a data acquisition module and a PC (personal computer) machine. The detection method comprises the following steps: 1, a laser light is generated; 2, the fiber optic interferometer module detects a vibration signal along the pipeline; 3, the photoelectric detection module receives the optical signal transmitted by the fiber optic interferometer module, transforms the optical signal into an electric signal and amplifies and outputs the optical signal; 4, the data acquisition module receives the electric signal outputted by the photoelectric detection module and carries out a filtering process and an A/D conversion on the electric signal; and 5, the PC machine starts detecting. The invention has advantages that: a chaotic oscillator based detection algorithm is applied to the distributed optical fiber pipeline leakage detection device and method; since the algorithm has strong noise suppression capacity and signal frequency selection performance, the requirement of the signal-to-noise-ratio of the detection signal can be obviously reduced.

Description

Detect the device and method of the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator
Technical field
The invention belongs to fluid line leak detection technology field, particularly a kind of device and method that detects the leakage of distribution type fiber-optic pipeline based on Du Fen oscillator (Duffing).
Background technique
Pipeline transport is being brought into play more and more important effect as one of five big carriers of running neck and neck with railway, highway, aviation, water transport in national defense industry and national economy.Along with rapid development of economy for over ten years, the fluid line leak detection technology also has significant progress, multiple pipeline leakage detection method occurred.
The method of fluid-transporting tubing Leak testtion and location roughly is divided into two classes, manages detection method in outer detection method and the pipe.Manage outer detection method and directly detect pipeline external environment condition and tube wall situation, for example pipeline external monitoring detection method, oily quick cable, detection fiber etc.Detection method is also referred to as computer pipeline monitoring (Computational Pipeline Monitor in the pipe, CPM), it is used instrument and apparatus the pipe interior Operational Limits is detected, then with the input data of pipe interior Operational Limits (for example pressure, flow and temperature etc.) as the monitoring of computer pipeline, whether the variation that physical parameters such as the flow that causes according to leakage, pressure take place draws pipeline by inference computer and manual analysis and leaks.
In recent years, along with the continuous development of optical fiber technology, optical fiber sensing technology also begins to be applied to pipeline leakage testing.Distribution type fiber-optic pipe detection technology utilizes optical fiber as sensor fluid line oscillating signal on the way, not only can detect the situation that leakage takes place pipeline, and can carry out early warning to the pipeline harm pipeline incident that takes place along the line.Distribution type fiber-optic fluid line leakage monitoring technology has very high requirement for testing precision and sensitivity.When the big and leakage rate of background noise hour, the signal that distribution type fiber-optic fluid line leakage monitoring system records shows as the detection problem of the weak periodic signal under the strong noise background.
Summary of the invention
At the deficiency that prior art exists, the invention provides a kind of device and method that detects the leakage of distribution type fiber-optic pipeline based on Du Fen oscillator (Duffing).
Apparatus of the present invention comprise light source module, fibre optic interferometer module, photodetection module, data acquisition module and PC;
Light source module: light source module comprises laser, light source driving circuit and light source protection circuit, the input end of the output termination light source protection circuit of light source driving circuit wherein, and the output terminal of light source protection circuit is as the output terminal of light source module.
The fibre optic interferometer module: the fibre optic interferometer module is made up of laser, optical isolators, Fiber Optic Coupler, Single Mode Fiber, guiding fiber and optical circulator.Wherein laser is to be used for lasing device; Optical isolators can be realized the forward transmitted of optical signal, suppresses backlight simultaneously, has nonreversibility, can solve the problem of light reflection in the light path, is used to protect light source; Fiber Optic Coupler is two, can be divided into two or more light outputs to one or more light inputs, be used to transmit and distribute the passive device of optical signal, one of them Fiber Optic Coupler will be as being divided into the light splitter of two-beam from the laser that laser is propagated, and another Fiber Optic Coupler is used for forming interference signal and sends signal to guiding fiber; Single Mode Fiber be along pipe laying as measuring fiber, be used to detect pipeline oscillating signal on the way; Optical circulator only allows the incident light non-reciprocal device that reflected light is exported from the another port from determining the port input of certain port, and optical circulator can be avoided the loss through the Coupler generation.
Wherein the input end of optical isolators is as the input end of fibre optic interferometer module, the output terminal of optical isolators is connected with Coupler, the output terminal of Fiber Optic Coupler connects the head end of two Single Mode Fiber, two parallel connections of Single Mode Fiber, the end of Single Mode Fiber connects the input end of Fiber Optic Coupler, in addition when the stressed difference of measuring fiber is propagated vibration round about, Fiber Optic Coupler is two, the input end of a Fiber Optic Coupler becomes output terminal at this moment, this moment, the output terminal of Fiber Optic Coupler was connected with the input end of optical circulator, optical circulator output is connected with one tunnel input of photodetection module, the output terminal of another Fiber Optic Coupler connects guiding fiber, and the end of guiding fiber connects other one road input end of photodetection module;
The photodetection module, finish the function that light converts electricity to and electrical signal is amplified, the photodetection module comprises and converts optical signal to the device photoelectric prober of electrical signal and the amplification circuit that electrical signal is amplified, the photodetection module has two-way received signal end, wherein one the tunnel receive the signal that the guiding fiber propagation is come, other one the tunnel receives optical circulator propagates the signal of coming.
Data acquisition module, comprise eliminator and data collecting card, the input end of eliminator is as the input end of data acquisition module, and the output terminal of eliminator connects the input end of data collecting card, and data collecting card carries out data the A/D conversion and exports PC to.
The output terminal of light source module connects the input end of the optical isolators of fibre optic interferometer module in this device, the output terminal of guiding fiber connects one road input end of photodetection module in the fibre optic interferometer module, the output terminal of optical circulator is connected with other one tunnel input of photodetection module in the fibre optic interferometer module, the output terminal of photodetection module connects the input end of data acquisition module, the output of data acquisition module is connected to PC, carries out the test and the processing of signal.
The present invention as development platform, finishes signal to the reading of computer with LabVIEW, and finishes and use the detection that the Duffing chaology realizes signal, judges leakage situation by the variation of output phase trajectory figure, and realizes the location.
Laser process isolator that is sent by the single longitudinal mode narrow cable and wide optical fiber laser among the present invention and Fiber Optic Coupler are divided into the equal two-beam ripple of light intensity and propagate in two Single Mode Fiber, end at optical fiber transducer, be that Fiber Optic Coupler goes out to form interference signal, two bundle coherent light light intensity are respectively I 1, I 2, Δ S (t) is that two bundle coherent light waves modulation are poor,
Figure BDA0000070252260000021
Be the phase difference of two bundle coherent light waveses, the light intensity I after two bundle coherent light waveses are interfered is
Figure BDA0000070252260000022
If I hFor being input to the total light intensity in two measuring fibers; λ is the mixing efficiency of two coherent lights, and the light intensity I (t) after then two bundle coherent light waveses are interfered has
Figure BDA0000070252260000023
Only consider to exchange light intensity, and convert electrical signal to by the optical signal of photoelectric detector, K is a photoelectric conversion factors, and λ is the mixing efficiency of two coherent lights, and the of ac i (t) of photoelectric current is
Figure BDA0000070252260000031
Pipeline leaks, when being subjected to pipeline oscillating signal along the line, test optical fibre cables does the time spent, two measuring fibers in the optical cable all can produce ess-strain, therefore the two bundle coherent lights of propagating in two sensor fibres can produce phase change, thereby influence the variation of light intensity, finally cause the variation of photodetector output current signal.Therefore we can detect distribution type fiber-optic by the variation of photodetector output light intensity and are oscillating signal on the way, thereby realize that pipe leakage detects in real time.
When taking place to leak, measuring fiber produces ess-strain, cause this place's fiber phase modulation, the signal that produces modulation is propagated to the sensor two ends simultaneously, and process Coupler c1, optical circulator e2, a photodetector f2 returned data are gathered signal processing, and an other light path is passed through guiding fiber, photodetector f1 sends back data acquisition signal and handles, by the time difference of two ends vibration detection signal, can calculate accurately and leak the position that takes place, ranging formula can be expressed as
X = L w - v ( t 2 - t 1 - L w v ) 2 - - - ( 7 )
In the formula, X is the distance of leakage point to head end; L wBe the duct length that detects; t 1Detect the time of pipeline leakage signal for the sensor head end; t 2Detect the time of pipeline leakage signal for transducer tip; V is the velocity of propagation of light wave in optical fiber.
At the high request of distribution type fiber-optic pipeline leakage testing device to sensitivity and precision, the present invention proposes Duffing oscillator detection algorithm is applied among the present invention.When the big and leakage rate of background noise hour, the signal that the present invention records shows as the problem of the Detection of Weak Signals under the very noisy.Because chaos system has robustness and periodic signal is had receptance noise in critical phase transformation place, that is to say, in critical phase transformation place, even very strong noise can not make chaos system undergo phase transition yet, the Duffing oscillator system is only to the periodic signal sensitivity consistent with forced frequency of the present invention in addition, and for the signal of other frequencies, even frequency is very high, signal is very strong very inresponsive yet, this moment, the signal different with forced frequency was equivalent to noise, and chaos system is only to the periodic signal sensitivity identical with forced frequency.As long as the frequency of oscillating signal was identical when we set the forced frequency of Duffing oscillator system with leakage, we can get rid of the signal and the interference of noise of other frequencies, can effectively improve the signal to noise ratio of device.
The Duffing oscillator as detecting universal model is
Figure BDA0000070252260000033
In the formula, k is a damping ratio; F is a cycle driving force amplitude; ω is the driving force angular frequency, and x (t) is output.
As k fixedly the time, the state of Duffing system clocklike changes with hormetic variation.When f is 0, finally be parked in one of two saddle points (± 1,0) mutually; F hour, near some periodic vibration two saddle points mutually; When f increased slightly, frequency division appearred in periodic vibration, and when f continued to increase the interval that surpasses between three singular points, chaos state appearred in the vibration that jumps of can moving back between these singular points; Further increase f to the chaos critical value, large scale periodic motion state occurs.
The threshold value R of chaos (ω), the expression threshold value is f below d, the critical driving force value that chaos state changes to the large scale periodic state just appears.K is a damping ratio, and f is a cycle driving force amplitude, the span of Chaotic Threshold R (ω)=f/k:
(1) as f/k＞0
f k > 4 cosh ( πω 2 ) 3 2 πω - - - ( 9 )
Change to the large scale periodic state by chaos state.
(2) as f/k＜0
- 4 cosh ( &pi;&omega; 2 ) 3 2 &pi;&omega; < f k < 4 cosh ( &pi;&omega; 2 ) 3 2 &pi;&omega; - - - ( 10 )
Change to the large scale periodic state by chaos state.
Distribution type fiber-optic fluid line Leak testtion model based on the Duffing oscillator is as follows:
Figure BDA0000070252260000043
Wherein z (t) is a signal to be detected, at first with driving force f cBe arranged on the driving force f of critical chaotic state correspondence dThe place, be in the chaos threshold state as shown in Figure 4 this moment.When same frequency measured signal input system, when promptly distribution type fiber-optic fluid line leak detection system had leakage, the phase trajectory of system changed periodic state rapidly over to, as shown in Figure 5.Do not have when leakage, measured signal does not contain the same frequency periodic signal, only has noise, and system is in chaos state.Can judge the periodic signal that whether contains in the input measured signal with the driving signal same frequency according to the variation of system's phase trajectory thus, leakage situation that can the test fluid pipe-line system.
If measured signal z (t)=f cCos (ω t+ θ) is as the perturbation of periodic force, wherein f cBe the driving force amplitude of measured signal, ω is the frequency of measured signal, and θ is the initial phase angle of measured signal, and the total periodic force A (t) in the Duffing equation becomes
Figure BDA0000070252260000044
In the formula (12),
Figure BDA0000070252260000045
Be the phase place of periodic signal to be measured, f wBe total driving force amplitude,
Figure BDA0000070252260000046
f w = f d 2 + f d f c cos &theta; + f c 2 - - - ( 13 )
If f c=f d, then
Figure BDA0000070252260000048
Influence can ignore.
If the amplitude of further fluid line leak detection system signal, then begin to regulate (reducing) driving force value f, reenter chaos state up to system, write down hormetic value f ' this moment, the difference of the driving force f that this value is corresponding with the chaos threshold state is periodic signal amplitude to be measured, and the amplitude of periodic signal promptly to be measured is f c=f d-f '.
The present invention is based on the detecting method of the leakage of Duffing oscillator phase trajectory detection distribution type fiber-optic pipeline, step is as follows:
Step 1, the at first driving of laser process circuit of light sources produce laser, send the fibre optic interferometer module to by light source protection circuit;
Step 2, detect pipeline oscillating signal on the way by the fibre optic interferometer module, the vibration letter is propagated in opposite direction, one road oscillating signal returns along Fiber Optic Coupler, and other one road oscillating signal returns along guiding fiber, gives the photodetection module respectively and carries out photodetection;
Step 3, photodetection module receive the optical signal that the fibre optic interferometer module sends, and convert optical signal to electrical signal, and optical signal is amplified output;
Step 4, data acquisition module receive the electrical signal of photodetection module output, and electrical signal is carried out Shelving, and carry out the A/D conversion, and the signal after will changing at last sends PC to and handles;
Step 5, PC adopt Duffing chaos phase trajectory method to detect gathering the signal that comes, variation by phase trajectory, a situation arises to observe leak condition, when not taking place to leak, phase trajectory is in critical chaotic state, in case leak, phase trajectory transition at once is to the large scale periodic state, can judge leakage thus, and position by relevant location algorithm;
Step 6, this detection are cycle detection, constantly repeating step 2-step 5.
Advantage of the present invention: the detection algorithm of chaotic oscillator is applied to distribution type fiber-optic fluid line leak detecting device and method, because the characteristic that it has extremely strong noise inhibiting ability and signal frequency selection can significantly reduce the requirement to the testing signal signal to noise ratio.
Description of drawings
Fig. 1 is the structured flowchart that installs among the present invention;
Fig. 2 is light source driving circuit figure among the present invention;
Fig. 3 is a photodetection module circuit diagram among the present invention;
Fig. 4 is data acquisition module eliminator figure among the present invention;
Fig. 5 is the phase trajectory figure that chaos system is in the chaos threshold state among the present invention;
Fig. 6 is the phase trajectory figure that chaos system is in the large scale periodic state among the present invention;
Fig. 7 is the chaos threshold state phase trajectory figure that the present invention adds noise signal;
Fig. 8 is a kind of method flow diagram that detects the leakage of distribution type fiber-optic pipeline based on Duffing oscillator phase trajectory of the present invention;
Embodiment
The present invention is described in detail with Figure of description in conjunction with specific embodiments.
Fig. 1 is the structured flowchart of the device of a kind of leakage that detects the distribution type fiber-optic pipeline based on Du Fen oscillator (Duffing) of the present invention.Comprise light source module, fibre optic interferometer module, photodetection module, data acquisition module and PC;
Light source module: light source module comprises laser, light source driving circuit, light source protection circuit, the input end of the output termination light source protection circuit of light source driving circuit wherein, and the output terminal of light source protection circuit is as the output terminal of light source module.
The drive circuit of light source as shown in Figure 2, D2 is a laser diode among the figure, D1 is a monitor diode, the luminous power of D2 output is monitored by monitor diode D1, and by monitor photodiode the power signal of the light of D2 output is converted to current signal.The current signal of monitor diode output is converted to voltage signal through potentiometer R5 and resistance R 7 again, voltage signal compares by the value that operational amplifier A R1 in the feedback loop and voltage comparator AR2 set, and then the size of the driving current of control triode Q1 adjusting D2 output, realized the automatic control of laser output power.
The fibre optic interferometer module: the fibre optic interferometer module is made up of laser a, optical isolators b, Fiber Optic Coupler c1, c2, Single Mode Fiber d1, d2, optical circulator e1.Wherein laser a is used for lasing device; Optical isolators b can realize the forward transmitted of optical signal, suppresses backlight simultaneously, has nonreversibility, can solve the problem of light reflection in the light path, is used to protect light source; Fiber Optic Coupler c1, c2 can be divided into two or more light outputs to one or more light inputs, be used to transmit and distribute the passive device of optical signal, wherein c1 will be as being divided into the light splitter of two-beam from the laser that laser is propagated, and c2 is used for forming interference signal and sends signal to guiding fiber d3; Single Mode Fiber d1, d2 be along pipe laying as measuring fiber, be used to detect pipeline oscillating signal on the way; Reflected light is from the non-reciprocal device of another port output from determining the port input for optical circulator e1, the incident light that only allows certain port, and optical circulator can be avoided the loss that produces through Coupler.
Wherein the input end of optical isolators b is as the input end of fibre optic interferometer, the output terminal of optical isolators b is connected with Coupler c1, the output terminal of Coupler c1 connects Single Mode Fiber d1, the head end of d2, two Single Mode Fiber d1, d2 is parallel to be connected, the end of Single Mode Fiber connects the input end of Coupler c2, in addition when the stressed difference of measuring fiber is propagated vibration round about, the input end of Coupler c1 becomes output terminal at this moment, this moment, the output terminal of Coupler c1 was connected with the input end of optical circulator e1, optical circulator e1 output is connected with other one tunnel input of photodetector module, the output terminal of Coupler c2 connects guiding fiber d3, the end of guiding fiber d3 connects one road input end of photodetection module, each device connect and compose the fibre optic interferometer module.
The photodetection module, finish the function that light converts electricity to and electrical signal is amplified, module comprises device photoelectric prober f1, the f2 that optical signal is converted to electrical signal, and the amplification circuit that electrical signal is amplified, the photodetection module has two-way received signal end among the present invention, wherein one the tunnel receive the signal that guiding fiber d3 propagation is come, other one the tunnel receives optical circulator propagates the signal of coming.
The photodetection modular circuit is connected to the inverting input of operational amplifier A 1 and A2 with two identical PIN photodiodes as shown in Figure 3, and the output terminal with A1 and A2 is connected respectively on the in-phase input end and inverting input of difference amplifier A3 again.When prober is subjected to the influence generation undesired signal of external environment, what these 2 operational amplifiers of A1 and A2 produced will be that phase place is identical, amplitude is identical, the common mode signal of time synchronization, after the input end of difference amplifier A3 receives common mode signal, can be with the common mode signal filtering, thereby improved signal to noise ratio, reached and eliminate the purpose of external environment the detection circuit influence.
Data acquisition module, comprise eliminator and data collecting card, the input end of eliminator is as the input end of data acquisition module, and the output terminal of eliminator connects the input end of data collecting card, and data collecting card carries out data the A/D conversion and exports PC to.
Eliminator as shown in Figure 4, generally the frequency range of the oscillating signal of pipe leakage is 100～2000Hz, the frequency ratio that counts the score is the 44.74 frequency dividing ratio scopes that therefore provide according to the data of chip MAX266, should select immediately 43.96, requires F this moment 0, F 2, F 3, F 4, F 5Be low level, require F 1Be high level.Next the mode of operation for chip MAX266 is provided with, and wherein MODE3 can freely adjust CF center frequency, meets the demands.The mode of operation of MAX266 is by the realization that is provided with to pin SIA, SA/B and SIB.IO mouth that can external one 8051 single-chip microcomputer is to F 0～F 5High-low level and mode of operation be provided with.Select R 1=R 3=1.5k Ω, R 2=R 4=10k Ω.After circuit structure was determined, the filter characteristics of wave filter was only relevant with clock frequency.
A kind ofly detect the method for the leakage of distribution type fiber-optic pipeline based on Du Fen oscillator (Duffing), step is as follows:
Step 1, the at first driving of laser process circuit of light sources; produce laser; send the fibre optic interferometer module to by light source protection circuit; adopt among the present invention and can guarantee that laser has fabulous coherence's single longitudinal mode narrow cable and wide optical fiber laser; the drive circuit of light source as shown in Figure 2, D2 is a laser diode among the figure, D1 is a monitor diode; the luminous power of D2 output is monitored by monitor diode D1, and by monitor photodiode the power signal of the light of D2 output is converted to current signal.The current signal of monitor diode output is converted to voltage signal through potentiometer R5 and resistance R 7 again, voltage signal compares by the value that operational amplifier A R1 in the feedback loop and voltage comparator AR2 set, and then the size of the driving current of control triode Q1 adjusting D2 output, realized the automatic control of laser output power.Semiconductor laser is not strong for the ability to bear of surge, and electric current that produces when opening and turning off power supply and voltage etc. take place often for the surge of semiconductor laser.For this surge, the switch that contact resistance is very little is in parallel with semiconductor laser, and when semiconductor laser started, with switch on, power work disconnected power supply after stable more by the time, and this method is very effective for eliminating surge.
Step 2, detect pipeline oscillating signal on the way by fibre optic interferometer, the vibration letter is propagated in opposite direction, and one road oscillating signal returns along Coupler c1, and other one road oscillating signal returns along guiding fiber d3, gives the photodetection module respectively and carries out photodetection.
Step 3, photodetection module receive the optical signal that fibre optic interferometer sends, convert optical signal to electrical signal, and optical signal is amplified output, photodetection module amplification circuit as shown in Figure 3, two identical PIN photodiodes are connected to the inverting input of operational amplifier A 1 and A2, and the output terminal with A1 and A2 is connected respectively on the in-phase input end and inverting input of difference amplifier A3 again.When prober is subjected to the influence generation undesired signal of external environment, what these 2 operational amplifiers of A1 and A2 produced will be that phase place is identical, amplitude is identical, the common mode signal of time synchronization, after the input end of difference amplifier A3 receives common mode signal, can be with the common mode signal filtering, thereby improved signal to noise ratio, reached and eliminate the purpose of external environment the detection circuit influence.
Step 4, data acquisition module receives the electrical signal of photodetection module output, electrical signal is carried out Shelving, and carry out the A/D conversion, signal after will changing at last sends PC to and handles, the PCI-6251 data collecting card that wherein adopts company of American National instrument company (NI) to produce is finished, eliminator as shown in Figure 4, generally the frequency range of the oscillating signal of pipe leakage is 100～2000Hz, the frequency ratio that counts the score is the 44.74 frequency dividing ratio scopes that therefore provide according to the data of chip MAX266, should select immediately 43.96, require F this moment 0, F 2, F 3, F 4, F 5Be low level, require F 1Be high level.Next the mode of operation for chip MAX266 is provided with, and wherein MODE3 can freely adjust CF center frequency, meets the demands.The mode of operation of MAX266 is by the realization that is provided with to pin SIA, SA/B and SIB.IO mouth that can external one 8051 single-chip microcomputer is to F 0～F 5High-low level and mode of operation be provided with.Select R 1=R 3=1.5k Ω, R 2=R 4=10k Ω.After circuit structure was determined, the filter characteristics of wave filter was only relevant with clock frequency.
Step 5, with LabVIEW as development platform, finish signal to the reading of PC, and finish and use the detection that the Duffing chaology realizes system signal, by the variation of output phase trajectory figure, judge leakage situation, and realize the location.Software module adopts Duffing chaos phase trajectory method to detect gathering the signal that comes, variation by phase trajectory, a situation arises to observe leak condition, when not taking place to leak, phase trajectory is in critical chaotic state, in case leak, phase trajectory transition at once is to the large scale periodic state, can judge leakage thus, and position by relevant location algorithm.
It is as follows wherein to detect the small-signal step based on Duffing oscillator phase trajectory method:
(1), regulates the driving force amplitude, observe phase trajectory figure, when driving force amplitude f=0.72562, be in critical chaotic state, and use the Melnikov method to calculate the threshold value R (ω)=0.7530 of gained, the value that the driving force amplitude of the chaos phenomenon of actual appearance that hence one can see that is calculated gained than Melnikov method is little, is illustrated in figure 5 as the phase trajectory figure of system's critical chaotic state;
(2), input measured signal f cCos ω t, system's transition is the large scale periodic state, the system of being illustrated in figure 6 as is in the phase trajectory figure of system of large scale periodic state, this moment regulating system driving force amplitude f, when system comes back to critical chaotic state, driving force amplitude f '=0.72561 of system, then the amplitude f of measured signal c=f d-f '=0.00001.Learn that by simulation result the detectable minimum threshold of system is 10 -5, i.e. 10lg 0.00001=-50dB and at present in the micro-signal Detection range has only-10dB with the lowest signal-to-noise thresholding of time domain approach processing signals.Therefore can illustrate that it is feasible adopting Duffing phase trajectory method to detect faint sinusoidal signal.
(3), add white Gaussian noise, observe the variation of phase trajectory figure, Fig. 7 is 0 for adding average, the critical chaotic state phase trajectory figure of system when variance is 0.1 white Gaussian noise.By phase trajectory figure as can be seen; noise makes phase trajectory become coarse, many " burrs " occurred around the phase trajectory ring, but the existence of noise does not change the state of phase trajectory; therefore Duffing phase trajectory method is for the sinusoidal signal sensitivity, and has robustness for noise.
(4), found through experiments when adding the different sinusoidal signal of frequency, significant change does not take place in system, can infer thus, phase trajectory is for the sinusoidal signal sensitivity identical with the driving force signal frequency, for the signal of other frequencies, even frequency is very high, signal is very strong very inresponsive yet.
Step 6, this detection are cycle detection, constantly repeating step 2-step 5.
By analyzing the faint sinusoidal signal of distributed as can be known fluid pipe leakage real-time detection apparatus output, adopt Duffing oscillator phase trajectory method that it is detected, when the big and leakage rate of the background noise of device hour, the signal that the present invention records shows as the problem of the Detection of Weak Signals under the very noisy.Adopt Duffing oscillator phase trajectory method as can be seen by above-mentioned analysis, detection can reach-50dB with the lowest signal-to-noise threshold value of the small-signal of driving force same frequency, therefore adopt Duffing oscillator phase trajectory method to detect the faint sinusoidal signal that distributed fluid pipe leakage real-time detection apparatus is exported, can effectively improve the signal to noise ratio of device.

Claims (6)

1. one kind is detected the device of the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator, and it is characterized in that: device comprises light source module, fibre optic interferometer module, photodetection module, data acquisition module and PC; Light source module comprises laser, light source driving circuit and light source protection circuit; The fibre optic interferometer module comprises laser, optical isolators, Fiber Optic Coupler, Single Mode Fiber, guiding fiber and optical circulator; The photodetection module comprises photodetector and amplification circuit; Data acquisition module comprises eliminator and data collecting card;
The output terminal of light source module connects the input end of the optical isolators of fibre optic interferometer module in this device, the output terminal of guiding fiber connects one road input end of photodetection module in the fibre optic interferometer module, the output terminal of optical circulator is connected with other one tunnel input of photodetection module in the fibre optic interferometer module, the output terminal of photodetection module connects the input end of data acquisition module, and the output of data acquisition module is connected to PC.
2. the device that detects the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator according to claim 1; it is characterized in that: the input end of the output termination light source protection circuit of light source driving circuit in the described light source module, the output terminal of light source protection circuit is as the output terminal of light source module.
3. the device that detects the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator according to claim 1, it is characterized in that: the input end of optical isolators is as the input end of fibre optic interferometer module in the described fibre optic interferometer module, the output terminal of optical isolators is connected with Coupler, the output terminal of Fiber Optic Coupler connects the head end of two Single Mode Fiber, two parallel connections of Single Mode Fiber, the end of Single Mode Fiber connects the input end of Fiber Optic Coupler, when the stressed difference of measuring fiber is propagated vibration round about, Fiber Optic Coupler is two, the input end of a Fiber Optic Coupler becomes output terminal at this moment, this moment, the output terminal of Fiber Optic Coupler was connected with the input end of optical circulator, optical circulator output is connected with one tunnel input of photodetection module, the output terminal of another Fiber Optic Coupler connects guiding fiber, and the end of guiding fiber connects other one road input end of photodetection module.
4. the device that detects the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator according to claim 1, it is characterized in that: described photodetection module comprises and converts optical signal to the device photoelectric prober of electrical signal and the amplification circuit that electrical signal is amplified, the photodetection module has two-way received signal end, wherein one the tunnel receive the signal that the guiding fiber propagation is come, other one the tunnel receives optical circulator propagates the signal of coming.
5. the device that detects the leakage of distribution type fiber-optic pipeline based on the Du Fen oscillator according to claim 1, it is characterized in that: the input end of eliminator is as the input end of data acquisition module in the described data acquisition module, the output terminal of eliminator connects the input end of data collecting card, and data collecting card carries out data the A/D conversion and exports PC to.
6. adopt the method for the device of the described leakage that detects the distribution type fiber-optic pipeline based on the Du Fen oscillator of claim 1, it is characterized in that: step is as follows:
The driving of step 1, laser process circuit of light sources produces laser, sends the fibre optic interferometer module to by light source protection circuit;
Step 2, detect pipeline oscillating signal on the way by the fibre optic interferometer module, the vibration letter is propagated in opposite direction, one road oscillating signal returns along Fiber Optic Coupler, and other one road oscillating signal returns along guiding fiber, gives the photodetection module respectively and carries out photodetection;
Step 3, photodetection module receive the optical signal that the fibre optic interferometer module sends, and convert optical signal to electrical signal, and optical signal is amplified output;
Step 4, data acquisition module receive the electrical signal of photodetection module output, and electrical signal is carried out Shelving, and carry out the A/D conversion, and the signal after will changing at last sends PC to and handles;
Step 5, PC adopt Du Fen oscillator chaos phase trajectory method to detect gathering the signal that comes, variation by phase trajectory, a situation arises to observe leak condition, when not taking place to leak, phase trajectory is in critical chaotic state, in case leak, phase trajectory transition at once is to the large scale periodic state, can judge leakage thus, and position by relevant location algorithm;
Step 6, this detection are cycle detection, constantly repeating step 2-step 5.
CN2011101696011A 2011-06-22 2011-06-22 Duffing-based detection device and method for distributed optical fiber pipeline leakage Expired - Fee Related CN102242870B (en)

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