CN205981438U - Distributed optical fiber sensing system - Google Patents
Distributed optical fiber sensing system Download PDFInfo
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- CN205981438U CN205981438U CN201620942411.7U CN201620942411U CN205981438U CN 205981438 U CN205981438 U CN 205981438U CN 201620942411 U CN201620942411 U CN 201620942411U CN 205981438 U CN205981438 U CN 205981438U
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Abstract
The utility model provides a distributed optical fiber sensing system, includes: ware, optical circulator, sensing fiber, beat frequency ware, photoelectric converter and detection locator are surely gone here and there to signal generator, light source, optical frequency comb generater, frequency sweep, positioning circuit in the detection locator carries out digital filtering through generating the different just digital band pass filter of zero lap of a plurality of frequency channels to the original data section that comes from a plurality of frequency sweeps detection light pulse, obtains sensing fiber's many reflectivity curves, disappear to decline to the reflectivity curve and handle, synthesize the reflectivity curves for many that are not had the decline of interference fading and polarization, do the phase place processing to synthesizing the reflectivity curve, obtain its phase place variance curve, according to the variance in the phase place variance curve shake judging of moving point and finally shaken moving point the position with the vibration wave form, the utility model discloses positioning accuracy is high, and vibration frequency response range is big, and the SNR of vibration wave form is high.
Description
Technical field
The utility model relates to a kind of technology of sensory field of optic fibre, specifically a kind of distributing optical fiber sensing system
System.
Background technology
Since 20 century 70 optical fiber are by utility model, optical fiber sensing technology also flourishes therewith.Except can
For remote high rate communication, optical fiber also possesses the ability of perception external physical parameter.Using this sensitive characteristic, grind
Study carefully a series of fiber optic sensing device of personnel's utility model.Wherein distributed optical fiber vibration sensor is grinding of recent years
Study carefully focus.It has a lot of advantages compared to traditional vibrating sensor, such as：Waterproof and dampproof；Electromagnetism interference；Using peace
Entirely；Most of all, having the ability of distributed sensing and remote recording.
At present using the most extensively, most study be distributed optical fiber sensing system based on optical time domain reflectometer because
The advantages of such system has compact conformation, demodulating algorithm is simple, positioning precision is high, signal to noise ratio is high.But have two great lack
Fall into：First, the frequency of vibration responsive bandwidth of system and distance sensing are contradiction.Because traditional dividing based on optical time domain reflectometer
The frequency response bandwidth of cloth optical fiber vibration sensing system is the half of system emission detection pulse frequency, and emission detection pulse
The inverse of frequency, that is, direct impulse transmission time interval it is necessary to come the time of transmission back, institute in whole section of sensor fibre more than light
Longer with sensor fibre length, vibratory response bandwidth is less, and vice versa.This defect seriously limits such distributed light
Fine vibration sensing system is in the application in altofrequency vibrating sensing field.2nd, the spatial resolution of system and maximum detectable range are
Contradiction.Want to obtain high spatial resolution, the persistent period of detecting optical pulses must be very short, and this leads to detecting optical pulses
Power is very low, and then limits detection range.
For the contradiction of frequency of vibration responsive bandwidth and distance sensing, there are several solutions as follows at present：Based on optical frequency
The distributed optical fiber vibration sensing system of domain reflectometer is although the frequency information of altofrequency vibration can be obtained, but cannot obtain
The time-domain information of vibration；Distributed optical fiber sensing system based on interferometer is although very big frequency of vibration response model can be obtained
Enclose, but such system has the shortcomings that demodulating algorithm complexity, positioning precision are poor；Knot is merged based on interferometer and optical time domain reflectometer
The distributed optical fiber sensing system of structure is although obtain the advantage of two class systems, but system becomes complicated, and sensor fibre
Need for loop configuration it is impossible to single-ended measurement；Based on the distributed sensing system of frequency multiplexing technique and optical time domain reflectometer, comprehensive
Close performance (spatial resolution, measurable range, signal to noise ratio) still to have much room for improvement.
Utility model content
This utility model is limited to distance sensing, and the invasion adopting for prior art more direct impulse tranmitting frequency
Position algorithm is based on intensity demodulation, cannot eliminate polarization decay and interference fading noise, easily while its signal to noise ratio is relatively low
Make the defects such as the vibrational waveform information error that phase demodulating goes out, propose a kind of distributed optical fiber sensing system, by producing optical frequency
Rate combs signal, and combination can disappear the phase demodulation algorithm of interference fading and polarization decay, eliminates on the reflectance curve of sensor fibre
Pole weak reflection spot, improve signal to noise ratio and positioning precision；Frequency of vibration responsive bandwidth is expanded at double by frequency multiplexing technique,
The sweep light pulse of transmitting solves spatial resolution and the contradiction of detection range.
This utility model is achieved through the following technical solutions：
This utility model is related to a kind of distributed optical fiber sensing system, including：Signal generator, light source, optical frequency comb life
Grow up to be a useful person, frequency sweep is cut string device, optical circulator, sensor fibre, beat frequency device, optical-electrical converter and detected localizer, wherein：Signal occurs
Device respectively cut with frequency sweep string device, optical frequency comb maker and detection localizer be connected, light source respectively with optical frequency comb maker
It is connected with beat frequency device, the outfan of optical frequency comb maker cuts string with frequency sweep, and device is connected, circulator and sensor fibre are sequentially connected,
The outfan of sensor fibre is sequentially connected with circulator, beat frequency device and optical-electrical converter, the outfan of optical-electrical converter and detection
Localizer is connected.
Described signal generator includes：Arbitrarily signal generating device and two radio frequency signal amplifiers, wherein：Two radio frequencies
Signal amplifier is connected with two output channels of arbitrarily signal generating device respectively.
One passage of described arbitrarily signal generating device repeats to export frequency sweep rf pulse sequence, and another passage exports
Single frequency sinusoidal ripple signal.
Described frequency sweep rf pulse sequence includes：Multiple time intervals, same pulse width, different and non-overlapping of waiting
The frequency sweep RF pulse signal of swept frequency range.
The product of described time interval and the number of frequency sweep RF pulse signal is equal to light in sensor fibre back and forth
Transmission time.
Described light source includes：Narrow cable and wide optical fiber laser, fiber coupler and the Polarization Controller being sequentially connected.
Preferably, the splitting ratio of described fiber coupler is 90: 10.
Described optical frequency comb maker includes：Direct voltage source and photomodulator, wherein：Direct voltage source adjustment input
The DC offset voltage of photomodulator, and produce optical frequency comb signal.
Described photomodulator is light intensity modulator or optical phase modulator.
Described frequency sweep is cut string device and is included：Connected acousto-optic modulator/single side-band modulator and EDFA Erbium-Doped Fiber Amplifier.
Described sensor fibre is Single mode communication optical fiber.
Described beat frequency device is 50: 50 fiber couplers.
Described optical-electrical converter is balanced detector.
Described detection localizer includes：Connected data collecting card and positioning circuit, wherein：Data collecting card is to input
The signal of telecommunication sampled, by initial data input positioning circuit carry out phase demodulating.
Technique effect
Compared with prior art, this utility model can obtain high spatial resolution and long detection range simultaneously, expands at double
The responsive bandwidth of frequency of vibration, and can effectively eliminate the pole weakness on reflectance curve, and then eliminate phase demodulating mistake,
Reach the purpose improving signal to noise ratio, accurate detection and positioning oscillation point.
Brief description
Fig. 1 is distributed optical fiber sensing system schematic diagram；
Fig. 2 is the time-frequency curve of frequency sweep detecting optical pulses signal；
Fig. 3 is the vibrational waveform figure in the oscillation point detected in embodiment 1；
In figure：1 is arbitrarily signal generating device, 2,3 is radio frequency signal amplifiers, 4 is narrow cable and wide optical fiber laser, 5 is light
Fine bonder, 6 be Polarization Controller, 7 be direct voltage source, 8 be photomodulator, 9 be acousto-optic modulator, 10 put for erbium-doped fiber
Big device, 11 be optical circulator, 12 be sensor fibre, 13 be 50: 50 fiber couplers, 14 be balanced detector, 15 adopt for data
Truck, 16 be positioning circuit.
Specific embodiment
Below embodiment of the present utility model is elaborated, the present embodiment is being front with technical solutions of the utility model
Put and implemented, give detailed embodiment and specific operating process, but protection domain of the present utility model does not limit
In following embodiments.
Embodiment 1
As shown in figure 1, the present embodiment includes：Signal generator, light source, optical frequency comb maker, frequency sweep cut string device, the ring of light
Shape device 11, sensor fibre 12, beat frequency device, optical-electrical converter and detection localizer, wherein：Signal generator cuts string with frequency sweep respectively
Device, optical frequency comb maker and detection localizer are connected；Light source is connected with optical frequency comb maker and beat frequency device respectively；Optical frequency
Rate comb maker cuts string device input optical frequency comb signal to frequency sweep, and frequency sweep cuts the frequency sweep detecting optical pulses string that string device output is amplified,
Input through a port of optical circulator 11 and exported to sensor fibre 12 by b port；The Rayleigh that sensor fibre 12 produces is dorsad
The b port through optical circulator 11 for the scattered light inputs optical circulator 11 and inputs beat frequency device, with reference light in beat frequency device by c port
Middle beat frequency, the beat frequency optical signal input optical-electrical converter of generation；The outfan of optical-electrical converter is connected with detection localizer.
Described signal generator includes：Arbitrarily signal generating device 1 and two radio frequency signal amplifiers 2,3, wherein：Two
Radio frequency signal amplifiers 2,3 are connected with two output channels of arbitrarily signal generating device 1 respectively.
One passage of described arbitrarily signal generating device 1 repeats to export frequency sweep rf pulse sequence, and another passage is defeated
Go out single frequency sinusoidal ripple signal.
Number of repetition L=16 of the described frequency sweep rf pulse sequence repeating to export, including：N=5 is waited time interval
T (20 μ s), same pulse width τP(2 μ s), different and non-overlapping swept frequency range：150～170MHz, 170～190MHz,
The frequency sweep RF pulse signal of 190～210MHz, 210～230MHz and 230～250MHz.
Described time interval T is equal to light in sensor fibre 12 with the product NT of number N of frequency sweep RF pulse signal
Transmission time back and forth, i.e. 100 μ s.
The frequency of described single frequency sinusoidal ripple signal is 100MHz.
Described light source includes：Narrow cable and wide optical fiber laser 4, fiber coupler 5 and the Polarization Controller 6 being sequentially connected.
The splitting ratio of described fiber coupler 5 is 90: 10.
The live width of described narrow cable and wide optical fiber laser 4 is 1kHz.
Described optical frequency comb maker includes：Direct voltage source 7 and photomodulator 8, wherein：Direct voltage source 7 adjusts
The DC offset voltage of input photomodulator 8, and produce optical frequency comb signal.
Described optical frequency comb signal is the 2M+1=detecting light and the generation of single frequency sinusoidal ripple signal of input photomodulator 8
The optical frequency comb signal of 3 light frequency compositions, wherein：M is the sideband exponent number that photomodulator 8 produces.
Described photomodulator 8 is light intensity modulator.
Described frequency sweep is cut string device and is included：Connected acousto-optic modulator 9 and EDFA Erbium-Doped Fiber Amplifier 10.
As shown in Fig. 2 described frequency sweep cuts the time interval T=20 μ s of the frequency sweep detecting optical pulses string of string device output, arteries and veins
Rush width τP=2 μ s, swept frequency range F1 be 50～70MHz, 70～90MHz, 90～110MHz, 110～130MHz, 130～
150MHz, F2 are 150～170MHz, 170～190MHz, 190～210MHz, 210～230MHz, 230～250MHz, and F3 is
250～270MHz, 270～290MHz, 290～310MHz, 310～330MHz, 330～350MHz.
Described sensor fibre 12 is Single mode communication optical fiber, and total length is 10km.
Described beat frequency device is 50: 50 fiber couplers 13.
Described optical-electrical converter is balanced detector 14.
The a width of 400MHz of band of described balanced detector 14.
Described detection localizer includes：Connected data collecting card 15 and positioning circuit 16, wherein：Data collecting card 15
The signal of telecommunication of input is sampled, initial data is inputted positioning circuit 16 and carries out phase demodulating.
Sample rate t of described data collecting card 15sFor 1GSa/s, resolution is 8bit.
The present embodiment is related to the detection localization method based on said system, comprises the following steps：
The initial data from NL frequency sweep detecting optical pulses that data collecting card 15 is sampled by step 1, positioning circuit 16
Section labelling in chronological order, that is,：{xn(k)；K=1 ..., K }；N=1 ..., NL, wherein：K is to detect light arteries and veins from 1 frequency sweep
The data volume of the initial data of punching；And produce that 2M+1 frequency range be different and non-overlapping digital band-pass filter { hn,m(k)；K=
1,…,K}；N=1 ..., NL；M=1 ..., 2M+1, the initial data section after labelling is divided into 2M+1 sub- data segment rower again
Note, that is,：{xn,m(k)；K=1 ..., K }；N=1 ..., NL；L=1 ..., 2M+1.
Step 2, the individual sub- data segment of NL (2M+1) and each self-corresponding digital matched filter that previous step is obtained
{hn,m(k)；K=1 ..., K }；N=1 ..., NL；M=1 ..., 2M+1 make computing cross-correlation, obtain the NL (2M of sensor fibre 12
+ 1) bar reflectance curve.
The expression formula of described reflectance curve is
Wherein：κ is index, and * represents conjugation, and the reflectance obtaining is plural number.
Interference fading and polarization decay are existed on described reflectance curve.
Due to the time interval T between two adjacent detecting optical pulses, much smaller than NT, that is, it is less than light in sensor fibre 12
Middle maximum transmission time back and forth, so the rayleigh backscattering of two adjacent detecting optical pulses is just to have one in time
Duan Chonghe's.But be because that the frequency of two adjacent detecting optical pulses is different, corresponding matched filter is also different, so can
To suppress the back-reflection signal of unmatched detecting optical pulses therewith with band filter and matched filter, reach and separate the back of the body
Purpose to scattered light signal.
Step 3, fetch from be labeled as 1 frequency sweep detecting optical pulses reflectance curve { R1,m(k)；K=1 ..., K }；M=1 ...,
The conjugation of 2M+1As reference, it is multiplied with other reflectance curves, obtain NL (2M+1)
The reflectance curve of bar phase RZ：
Step 4, the reflectance curve of the phase RZ that previous step is obtained make average calculating operation, obtain NL bar and no interfere declining
The integrated reflectance curve falling with polarization decay：
Step 5, take the phase term of the NL bar integrated reflectance curve that previous step obtains, obtain NL bar phase curve：
{φn(k)=angle [rn(k)]；K=1 ..., K }；N=1 ..., NL.
Step 3～5 are explained as follows：As a example when n=1,2M+1 bar reflectance curve { R1,m(k)；K=1 ..., K }；m
=1 ..., 2M+1 demodulate 2M+1 part of the rayleigh backscattering light from same frequency sweep detecting optical pulses, and this 2M+1 bar is anti-
Penetrate and serious interference fading and polarization decay point are all existed on rate curve, the modulus value very little of the reflectance of these decline points, it is subject to
Influence of noise, the phase demodulating of these points can malfunction.But because the frequency of this 2M+1 part is different, this 2M+1 bar
Reflectance curve is also different, and the pole weakness that is, interference fading and polarization decay lead to is on this 2M+1 bar reflectance curve
Position is also different.Average calculating operation is done to this 2M+1 bar reflectance curve and just can eliminate these pole weakness, thus eliminating this
The phase demodulating mistake occurring on a little points.But because reflectance is plural number, from the knowledge of complex addition, plural number is added
The modulus value of result not necessarily becomes big, diminishes sometimes.In order that the modulus value after reflectance is added maximizes, need first rotary reflection
Rate, makes their angle be zeroed, is then added again.
Step 6, the NL bar phase curve time delay D unit that previous step is obtained, then by the phase curve before and after time shift
Make difference, obtain NL bar differenced phase plot：{Δφn(k)=φn(k)-φn(k-D)；K=1 ..., K }；N=1 ..., NL.
Step 7, the NL bar differenced phase plot that previous step is obtained seek variance, obtain its phase variance curve：
If k=k in the phase variance curve that step 8 previous step obtains0The variance at place is more than 0.02, then this point is
Oscillation point, its position on sensor fibre 12 is：Wherein：C' is light spread speed in a fiber, tsFor number
According to the sample rate of capture card 15, k0For the corresponding index value in oscillation point；The NL bar that the vibrational waveform in oscillation point obtains for step 6 is poor
Divide k=k in phase curve0The new sequence of the differential phase composition at place：
The spatial resolution Δ z of the present embodiment is determined by the swept frequency range of frequency sweep detecting optical pulses, that is,Wherein：
γ is sweep velocity.
The frequency of vibration responsive bandwidth of the present embodiment is determined by the transmission time interval of frequency sweep detecting optical pulses, is 1/2T.
Compared to traditional scheme, N times of frequency of vibration responsive bandwidth increase in theory.
The present embodiment arranges an oscillation point, and at the 9.93km of sensor fibre 12, the single-frequency for 21kHz for the occurrence frequency is shaken
Dynamic, the vibration coverage in oscillation point is 10m.
In the present embodiment, K=100000, N=5, L=16, NL=80, M=1, D=100；Three digital band-pass filters
Frequency range bandwidth be respectively 50～150MHz, 150～250MHz and 250～350MHz；Then 80 frequency sweep detecting optical pulses
Initial data section is labeled as { x in chronological ordern(k)；K=1 ..., K }；N=1 ..., 80,80 × 3=240 subnumber being divided into
It is designated as { x according to segment markn,m(k)；K=1 ..., K }；N=1 ..., 80；M=1,2,3.
The reflectance curve that the present embodiment obtains is：
The reflectance curve of phase RZ isComprehensive
Reflectance curve isPhase curve is { φn(k)=angle [rn
(k)]；K=1 ..., 100000 }；N=1 ..., 80, differenced phase plot is { Δ φn(k)=φn(k)-φn(k-100)；K=
1,…,100000}；N=1 ..., 80, phase variance curve is
In phase variance curve, k0Variance at=99300 is more than 0.02, can determine that this point is oscillation point, oscillation point
Position on sensor fibre 12 isThis is matched with the vibration position setting.The vibration wave in oscillation point
Shape is { Δ φ98300(n)；N=1 ..., 80 }, as shown in figure 3, the signal to noise ratio of the vibrational waveform obtaining reaches 25dB.
The present embodiment breaches the restriction to frequency of vibration response range of the length of sensor fibre 12：Due to sensor fibre 12
Total length is 10km, and traditional based in the distributed optical fiber sensing system of optical time domain reflectometer, the vibration of maximum detection amount is frequently
Rate only has 5kHz, and the present embodiment successfully measures the frequency of vibration of 21kHz, and has high s/n ratio.
Claims (10)
1. a kind of distributed optical fiber sensing system is it is characterised in that include：Signal generator, light source, optical frequency comb maker,
Frequency sweep cuts string device, optical circulator, sensor fibre, beat frequency device, optical-electrical converter and detection localizer, wherein：Signal generator divides
Not do not cut string device, optical frequency comb maker and detection localizer to be connected with frequency sweep, light source respectively with optical frequency comb maker and bat
Frequency device is connected, and the outfan of optical frequency comb maker cuts string with frequency sweep, and device is connected, circulator and sensor fibre are sequentially connected, sensing
The outfan of optical fiber is sequentially connected with circulator, beat frequency device and optical-electrical converter, and the outfan of optical-electrical converter is positioned with detection
Device is connected.
2. distributed optical fiber sensing system according to claim 1, is characterized in that, described signal generator includes：Appoint
Meaning signal generator and two radio frequency signal amplifiers, wherein：Two radio frequency signal amplifiers respectively with arbitrarily signal generating device
Two output channels be connected.
3. distributed optical fiber sensing system according to claim 1, is characterized in that, described light source includes：It is sequentially connected
Narrow cable and wide optical fiber laser, fiber coupler and Polarization Controller.
4. distributed optical fiber sensing system according to claim 1, is characterized in that, described optical frequency comb maker bag
Include：Direct voltage source and photomodulator.
5. distributed optical fiber sensing system according to claim 1, is characterized in that, described frequency sweep is cut string device and included：Phase
Acousto-optic modulator/single side-band modulator even and EDFA Erbium-Doped Fiber Amplifier.
6. distributed optical fiber sensing system according to claim 1, is characterized in that, described detection localizer includes：Phase
Data collecting card even and positioning circuit.
7. distributed optical fiber sensing system according to claim 3, is characterized in that, the splitting ratio of described fiber coupler
For 90:10.
8. distributed optical fiber sensing system according to claim 4, is characterized in that, described photomodulator is adjusted for light intensity
Device processed or optical phase modulator.
9. distributed optical fiber sensing system according to claim 1, is characterized in that, described sensor fibre is Single mode communication
Optical fiber.
10. distributed optical fiber sensing system according to claim 1, is characterized in that, described beat frequency device is 50:50 optical fiber
Bonder.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109974756A (en) * | 2019-04-11 | 2019-07-05 | 南京聚科光电技术有限公司 | Φ-the OTDR technique merged based on differential phase impulse ejection and time domain |
| CN112697181A (en) * | 2020-12-02 | 2021-04-23 | 广东工业大学 | Phase sensitive optical time domain reflection device and method based on frequency modulation |
| US11499849B2 (en) | 2019-06-28 | 2022-11-15 | Alcatel Submarine Networks | Method and apparatus for suppression of noise due to transmitted signal instability in a coherent fiber optical sensor system |
| US11828631B2 (en) | 2019-06-28 | 2023-11-28 | Alcatel Submarine Networks | Method and apparatus for suppression of noise due to local oscillator instability in a coherent fiber optical sensor |
| CN118013401A (en) * | 2024-04-10 | 2024-05-10 | 宁波联河光子技术有限公司 | DAS-based belt conveyor vibration false alarm suppression method |
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2016
- 2016-08-25 CN CN201620942411.7U patent/CN205981438U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109974756A (en) * | 2019-04-11 | 2019-07-05 | 南京聚科光电技术有限公司 | Φ-the OTDR technique merged based on differential phase impulse ejection and time domain |
| CN109974756B (en) * | 2019-04-11 | 2021-05-07 | 南京聚科光电技术有限公司 | phi-OTDR technology based on differential phase pulse emission and time domain combination |
| US11499849B2 (en) | 2019-06-28 | 2022-11-15 | Alcatel Submarine Networks | Method and apparatus for suppression of noise due to transmitted signal instability in a coherent fiber optical sensor system |
| US11828631B2 (en) | 2019-06-28 | 2023-11-28 | Alcatel Submarine Networks | Method and apparatus for suppression of noise due to local oscillator instability in a coherent fiber optical sensor |
| CN112697181A (en) * | 2020-12-02 | 2021-04-23 | 广东工业大学 | Phase sensitive optical time domain reflection device and method based on frequency modulation |
| CN118013401A (en) * | 2024-04-10 | 2024-05-10 | 宁波联河光子技术有限公司 | DAS-based belt conveyor vibration false alarm suppression method |
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Effective date of registration: 20190401 Address after: Room 105G, 199 GuoShoujing Road (Biological and Medical Innovation Building), Pudong New Area Free Trade Pilot Area, Shanghai, 200120 Co-patentee after: Liu Qingwen Patentee after: Shanghai Jiaotong University Intellectual Property Management Co., Ltd. Address before: 200240 No. 800, Dongchuan Road, Shanghai, Minhang District Patentee before: Shanghai Jiao Tong University |
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Effective date of registration: 20190828 Address after: Room 403, Building No. 555 Dongchuan Road, Minhang District, Shanghai, 200241 Patentee after: Park Niu (Shanghai) Technology Co., Ltd. Address before: Room 105G, 199 GuoShoujing Road (Biological and Medical Innovation Building), Pudong New Area Free Trade Pilot Area, Shanghai, 200120 Co-patentee before: Liu Qingwen Patentee before: Shanghai Jiaotong University Intellectual Property Management Co., Ltd. |
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