CN109708742A - Distributed optical fiber vibration sensing system and its control method based on feature extraction - Google Patents
Distributed optical fiber vibration sensing system and its control method based on feature extraction Download PDFInfo
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- CN109708742A CN109708742A CN201811609794.6A CN201811609794A CN109708742A CN 109708742 A CN109708742 A CN 109708742A CN 201811609794 A CN201811609794 A CN 201811609794A CN 109708742 A CN109708742 A CN 109708742A
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Abstract
The present invention discloses a kind of distributed optical fiber vibration sensing system based on feature extraction, including signal control and extraction module, 22 × 2 couplers, 2 time delay optical fibers, 31 × 2 mechanical optical switches, time-sequence control module, three fiber port circulators and sensing optical path.Such system can be controlled by the switching sequence to mechanical optical switch, realize different light paths switching, and the extraction of vibration signal is realized based on signal characteristic extracting methods.Invention additionally discloses a kind of control methods of distributed optical fiber vibration sensing system based on feature extraction.
Description
Technical field
The invention belongs to Fibre Optical Sensor and sensor-based network technology field, in particular to a kind of distributed optical fiber sensing system.
Background technique
With the rapid development of the national economy, national Large Infrastructure Projects, boundary line, national defence emphasis facility, residential houses
It is urgent Deng the demand to perimeter security system, it is desirable that also higher and higher.All kinds of security and guard technology means are widely used.?
Some important regions, such as airport, military base, government, industrial park, prison, bank vault, museum, power plant, oil
Library, school etc., illegal invasion and various destructive activities in order to prevent, traditional precautionary measures are usually to take " people's air defense+object
It is anti-" combine behave.For many years, traditional perimeter security system solution is (infrared point-to-point to the scheme of penetrating, video monitoring side
Case, leakage cable scheme, vibration cable scheme, microwave relative shot program, fence, power grid etc.) it is done for social peace security
Due contribution is gone out, but has been limited by factors such as some objective technical conditions, there is also some defects.
Distributed optical fiber vibration sensing system using optical signal in a fiber backscatter signals come perceive extraneous vibration become
Change.Since the phase, intensity and polarization state of the light propagated in a fiber will receive the physical field that optical fiber edge is surveyed, for example, temperature,
The influence of pressure, vibration etc. can restore these physical quantitys by the parameter of detection light.Distributed Optical Fiber Sensing Techniques can
With real-time continuous perception and positioning optical fiber along the physical quantity surveyed.In technologies numerous at present, distributed vibration sensing system tool
Have over long distances, it is anti-interference, continuously perceive external information, monitoring and recognize invasion etc. performances, pass through control technology realize perception letter
Number transmission, networking, therefore show one's talent.However, being faced with a series of ask again during system is applied to engineering site
The performance indicators such as precision, distance sensing, rate of false alarm are had higher requirement by topic.
Summary of the invention
The purpose of the present invention is to provide a kind of distributed optical fiber vibration sensing system based on feature extraction and its control
Method can be controlled by the switching sequence to mechanical optical switch, realize different light paths switching, and be based on signal characteristic abstraction
The extraction of method realization vibration signal.
In order to achieve the above objectives, solution of the invention is:
A kind of distributed optical fiber vibration sensing system based on feature extraction, including signal control and extraction module, 22
× 2 couplers, 2 time delay optical fibers, 31 × 2 mechanical optical switches, time-sequence control module, three fiber port circulators and sensing
Optical path, wherein signal controls the input terminal that time-sequence control module is connect with the trigger signal output end of extraction module, the timing
Control module controls 31 × 2 mechanical optical switches according to the trigger signal that signal control is sent with extraction module；Institute
State the first, second input terminal that signal control is separately connected the first coupler with the light signal output end of extraction module, the first coupling
First output end of clutch connects the fixed port of the second mechanical optical switch, the second mechanical optical switch through the first time delay optical fiber
The second moved end connection third mechanical optical switch the second moved end, the first moved end of the second mechanical optical switch connects the second coupling
The second output terminal of clutch；First moved end of third mechanical optical switch connects the second moved end of the first mechanical optical switch, the
The fixed port of three mechanical optical switches connects the input terminal of three fiber port circulators, three fiber ports through the second time delay optical fiber
The first output end connection sensing optical path of circulator, the second output terminal of three fiber port circulators connect the defeated of the second coupler
Enter end, the first output end of the second coupler connects the first moved end of the first mechanical optical switch, the first mechanical optical switch
Fixed port connects the second output terminal of the first coupler.
The length of above-mentioned second time delay optical fiber is greater than the length of the first time delay optical fiber.
Above-mentioned signal control includes light source pulse control module, light-pulse generator, photoelectric conversion module, AD turns with extraction module
Change the mold block, feature extraction and vibration locating module and user's interactive display module, wherein light source pulse control module is periodically
Electric impulse signal is issued, driving pulse light source is provided among pulsed optical signals to optical path；Photoelectric conversion module is received from optical path
The backscatter signals of return, feeding AD conversion module is converted to digital signal after being converted to electric signal, is then sent into use simultaneously
In family interactive display module and feature extraction and vibration locating module, to carry out the real-time display of waveform and the feature of vibrating intruding
It extracts and positions.
Based on the control method of the distributed optical fiber vibration sensing system as previously described based on feature extraction, light source pulse
Control module issues a pulse triggering signal at the kT moment, gives light-pulse generator and time-sequence control module respectively, and k is integer；
Light-pulse generator receives the optical signal of one fixed pulse width of sending after trigger signal, this optical signal enters the first coupling
It is divided into two parts after clutch, a part enters in the first time delay optical fiber, subsequently into the second mechanical optical switch, another part
It is directly entered the first mechanical optical switch；
Time-sequence control module is sent out respectively after the synchronous triggering signal that the kT moment receives the sending of light source pulse control module
The control signal of 3 mechanical optical switches out, thus the on-off of 3 mechanical optical switches of control.
The switching sequence of above-mentioned 3 mechanical optical switches is:
During kT~kT+t1, the fixed port of the first mechanical optical switch and the second moved end are straight-through, the second mechanical light
The fixed port of switch and the second moved end are straight-through, and the first moved end of third mechanical optical switch and fixed port are straight-through；
During kT+t1~kT+t2, the fixed port of the first mechanical optical switch and the first moved end are straight-through, and second is mechanical
The fixed port of formula photoswitch and the second moved end are straight-through, and the second moved end of third mechanical optical switch and fixed port are straight-through；
During kT+t2~kT+t3, the fixed port of the first mechanical optical switch and the first moved end are straight-through, and second is mechanical
The fixed port of formula photoswitch and the first moved end are straight-through, and the fixed port of third mechanical optical switch and first/second moved end are straight
It is logical.
After adopting the above scheme, improvement of the invention is:
(1) present invention is dropped compared with nowadays popular φ-OTDR scheme using broadband SLED as system source significantly
Low system cost；
(2) present invention is combined using three mechanical optical switches with three fiber port circulators, by constantly changing machine
The switching sequence of tool formula photoswitch is dexterously coupled into two-beam among one sensor fibre, avoids using coupler coupling
Close bring 3db loss；
(3) compared with the sagnac interference scheme with traditional based on rayleigh scattering, guaranteeing positioning accuracy and spatial discrimination
While rate, theoretical space dynamic range of the invention and sensitivity can be extended to 2 times of traditional scheme.
Detailed description of the invention
Fig. 1 is overall structure figure of the invention；
Fig. 2 is the structure chart of signal control and extraction module in the present invention；
Fig. 3 is signal flow schematic diagram.
Specific embodiment
Below with reference to attached drawing, technical solution of the present invention and beneficial effect are described in detail.
As shown in Figure 1, the present invention provides a kind of low-loss high sensitivity distributed optical fiber vibration biography based on feature extraction
Sensing system, comprising: signal control and extraction module, 22 × 2 couplers；2 time delay optical fibers；31 × 2 mechanical optical switches；
Time-sequence control module；Three fiber port circulators；And sensing optical path；Wherein, the trigger signal of signal control and extraction module
Output end connects the input terminal of time-sequence control module, the touching that the time-sequence control module is sent according to signal control with extraction module
Signalling controls 31 × 2 mechanical optical switches；The signal control is connect with the light signal output end of extraction module
The first input end of coupler 1, the first output end of coupler 1 connect the fixing end of mechanical optical switch 2 through time delay optical fiber 1
Mouthful, the first moved end of the first moved end connection mechanical optical switch 3 of mechanical optical switch 2, the second moved end of mechanical optical switch 2
Connect the second output terminal of coupler 2；First moved end of the second moved end connection mechanical optical switch 1 of mechanical optical switch 3, machine
The fixed port of tool formula photoswitch 3 connects the input terminal of three fiber port circulators, three fiber port circulators through time delay optical fiber 2
The connection of port 2 sensing optical path, the ports 3 of three fiber port circulators connects the input terminal of coupler 2, the first of coupler 2
Output end connects the second moved end of mechanical optical switch 1, and the second of the fixed port connection coupler 1 of mechanical optical switch 1 is defeated
Enter end, and the second output terminal connection signal of coupler 1 controls and extraction module.
In the present embodiment, the pulse signal that light source issues is divided into the equal two parts of power after coupler 1, so
Circulator is finally subsequently entered successively by 1*2 mechanical optical switch 3 at regular intervals between afterwards.In order to guarantee that speed is slower
That a part of light there is no the entrance of back rayleigh scattering light when passing through 1*2 mechanical optical switch 3 completely just, in entire optical path
1*2 mechanical optical switch 1 and 1*2 mechanical optical switch 2.So the length of time delay optical fiber 2 has to be larger than the length of time delay optical fiber 1
Degree, to guarantee the interference condition of light.
As shown in Fig. 2, being the internal structure of signal control and extraction module, comprising: light source pulse control module；Pulsed light
Source；Photoelectric conversion module；AD conversion module；Feature extraction and vibration locating module；User's interactive display module.Light source pulse control
Issue to molding block period an electric impulse signal, control light-pulse generator synchronously issue among periodic optical pulse to optical path into
Row sensing；Then, the rayleigh scattering signal backwards returned from optical path enters photoelectric conversion module and is converted to electric signal；It connects down
Come, above electrical signal is converted into digital signal in AD conversion module, then simultaneously be sent to user's interactive display module and
In feature extraction and vibration locating module, to carry out the real-time display of waveform and the feature extraction and positioning of vibrating intruding, specifically
For, feature extraction and vibration locating module are used to classify to signal according to the feature of signal, and it finds out disturbance point and positions,
And user's interactive display module is used to provide visualization interface for user and set system parameter, such as pulse width,
Sample rate etc..
Specific work process is as follows: light source pulse control module issues a pulse-triggered letter at kT (k the is integer) moment
Number, light-pulse generator and time-sequence control module are given respectively.
Light-pulse generator receives the optical signal of one fixed pulse width of sending after trigger signal, this optical signal enters coupler
It is divided into two parts after 1, a part enters in time delay optical fiber 1, and subsequently into 1 port of mechanical optical switch 2, another part is straight
Tap into 1 port into mechanical optical switch 1.
Time-sequence control module is sent out respectively after the synchronous triggering signal that the kT moment receives the sending of light source pulse control module
The control signal of three mechanical optical switches out, thus the on-off of three mechanical optical switches of control.
For mechanical optical switch under the action of above-mentioned control sequential, photoelectric conversion module may finally receive 4 differences
The Rayleigh scattering signal in path, is respectively as follows: as shown in Figure 3
1) coupler 1-- time delay optical fiber 1--1*2 mechanical optical switch 2--1*2 mechanical optical switch 3-- time delay optical fiber 2-
-- sensing optical path -- three fiber port circulators -- the coupler 2--1*2 mechanical optical switch 2-- delay of three fiber port circulators
Optical fiber 1-- coupler 1；
2) coupler 1-- time delay optical fiber 1--1*2 mechanical optical switch 2--1*2 mechanical optical switch 3-- time delay optical fiber 2-
-- sensing optical path -- three fiber port circulators -- the coupler 2--1*2 mechanical optical switch 1-- coupling of three fiber port circulators
Device 1；3) 2-three fiber port of coupler 1--1*2 mechanical optical switch 1--1*2 mechanical optical switch 3-- time delay optical fiber annular
Device -- sensing optical path -- three fiber port circulators -- coupler 2--1*2 mechanical optical switch 2-- time delay optical fiber 1-- coupler
1；
4) 2-three fiber port of coupler 1--1*2 mechanical optical switch 1--1*2 mechanical optical switch 3-- time delay optical fiber
Circulator -- sensing optical path -- three fiber port circulators -- coupler 2--1*2 mechanical optical switch 1-- coupler 1；
In above-mentioned 4 optical paths, since by optical path 2, as the light path of optical path 3, the signal of optical path 2 and optical path 3 exists
In coupler 1 occur light etc. journeys interference.Therefore, the vibration signal sensed in optical path can pass through the letter in optical path 2 and optical path 3
Number interference extracts.
Under the action of mechanical optical switch controls signal, during kT~kT+t1,1 He of port of mechanical optical switch 1
Port 3 is straight-through, and the port 1 and port 3 of mechanical optical switch 2 are straight-through, and the port 2 and port 1 of mechanical optical switch 3 are straight-through；
During kT+t1~kT+t2, the port 1 and port 2 of mechanical optical switch 1 are straight-through, the end of mechanical optical switch 2
Mouth 1 and port 3 are straight-through, and the port 3 and port 1 of mechanical optical switch 3 are straight-through；
During kT+t2~kT+t3, the port 1 and port 2 of mechanical optical switch 1 are straight-through, the end of mechanical optical switch 2
Mouth 1 and port 2 are straight-through, and the port 1 and port 2 (or port 3) of mechanical optical switch 3 are straight-through.
For mechanical optical switch under the action of above-mentioned control sequential, photoelectric conversion module may finally receive 4 differences
The Rayleigh scattering signal in path, in 4 optical paths, have two optical paths occur light etc. journeys interference.Therefore, the vibration in optical path is sensed
Signal can be extracted by signal interference.
The above examples only illustrate the technical idea of the present invention, and this does not limit the scope of protection of the present invention, all
According to the technical idea provided by the invention, any changes made on the basis of the technical scheme each falls within the scope of the present invention
Within.
Claims (5)
1. a kind of distributed optical fiber vibration sensing system based on feature extraction, it is characterised in that: control and extract including signal
Module, 22 × 2 couplers, 2 time delay optical fibers, 31 × 2 mechanical optical switches, time-sequence control module, three fiber port rings
Shape device and sensing optical path, wherein signal controls the input that time-sequence control module is connect with the trigger signal output end of extraction module
End, the trigger signal that the time-sequence control module is sent according to signal control with extraction module is to 31 × 2 mechanical optical switches
It is controlled；It is first, second defeated to be separately connected the first coupler for the light signal output end of signal control and extraction module
Entering end, the first output end of the first coupler connects the fixed port of the second mechanical optical switch through the first time delay optical fiber, and second
Second moved end of the second moved end connection third mechanical optical switch of mechanical optical switch, the first of the second mechanical optical switch are dynamic
The second output terminal of the second coupler of end connection；First moved end of third mechanical optical switch connects the first mechanical optical switch
Second moved end, the fixed port of third mechanical optical switch connect the input of three fiber port circulators through the second time delay optical fiber
End, the first output end connection sensing optical path of three fiber port circulators, the second output terminal connection of three fiber port circulators
The input terminal of second coupler, the first moved end of the first output end the first mechanical optical switch of connection of the second coupler, first
The fixed port of mechanical optical switch connects the second output terminal of the first coupler.
2. as described in claim 1 based on the distributed optical fiber vibration sensing system of feature extraction, it is characterised in that: described
The length of two time delay optical fibers is greater than the length of the first time delay optical fiber.
3. as described in claim 1 based on the distributed optical fiber vibration sensing system of feature extraction, it is characterised in that: the letter
Number control and extraction module include that light source pulse control module, light-pulse generator, photoelectric conversion module, AD conversion module, feature mention
Take and vibrate locating module and user's interactive display module, wherein light source pulse control module periodically sends out electric pulse letter
Number, driving pulse light source is provided among pulsed optical signals to optical path；What photoelectric conversion module reception was returned from optical path dissipates backwards
Signal is penetrated, feeding AD conversion module is converted to digital signal after being converted to electric signal, is then sent into user's interaction display mould simultaneously
In block and feature extraction and vibration locating module, to carry out the real-time display of waveform and the feature extraction and positioning of vibrating intruding.
4. based on the control method of the distributed optical fiber vibration sensing system as claimed in claim 3 based on feature extraction,
Be characterized in that: light source pulse control module issues a pulse triggering signal at the kT moment, gives light-pulse generator and timing respectively
Control module, k are integer；
Light-pulse generator receives the optical signal of one fixed pulse width of sending after trigger signal, this optical signal enters the first coupler
After be divided into two parts, a part enters in the first time delay optical fiber, and subsequently into the second mechanical optical switch, another part is direct
Into the first mechanical optical switch；
Time-sequence control module issues 3 after the synchronous triggering signal that the kT moment receives the sending of light source pulse control module respectively
The control signal of a mechanical optical switch, thus the on-off of 3 mechanical optical switches of control.
5. control method as claimed in claim 4, it is characterised in that: the switching sequence of 3 mechanical optical switches is:
During kT~kT+t1, the fixed port of the first mechanical optical switch and the second moved end are straight-through, the second mechanical optical switch
Fixed port and the second moved end it is straight-through, the first moved end of third mechanical optical switch and fixed port are straight-through；
During kT+t1~kT+t2, the fixed port of the first mechanical optical switch and the first moved end are straight-through, the second mechanical light
The fixed port of switch and the second moved end are straight-through, and the second moved end of third mechanical optical switch and fixed port are straight-through；
During kT+t2~kT+t3, the fixed port of the first mechanical optical switch and the first moved end are straight-through, the second mechanical light
The fixed port of switch and the first moved end are straight-through, and the fixed port of third mechanical optical switch and first/second moved end are straight-through.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111811551A (en) * | 2020-07-07 | 2020-10-23 | 中国南方电网有限责任公司超高压输电公司昆明局 | Low-loss polarization interference type ultra-high voltage direct current control protection system OTDR device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101487723A (en) * | 2009-03-02 | 2009-07-22 | 北京航空航天大学 | Optical fiber distributed perturbation sensor based on Sagnac interferometer |
| CN104198030A (en) * | 2014-08-29 | 2014-12-10 | 中国石油天然气股份有限公司 | Multi-channel vibration detection method based on coherent Rayleigh scattering and detection system thereof |
| RU2549540C1 (en) * | 2013-12-24 | 2015-04-27 | Федеральное государственное бюджетное учреждение науки "Институт океанологии им. П.П. Ширшова Российской академии наук" (ИО РАН) | Apparatus for monitoring state of long pipelines, including underwater pipelines |
| CN107421570A (en) * | 2017-07-20 | 2017-12-01 | 全球能源互联网研究院 | A kind of multi-functional distribution type optical fiber sensing equipment |
| CN108254064A (en) * | 2018-04-23 | 2018-07-06 | 南京曦光信息科技有限公司 | A kind of optical fiber vibration sensing detection method and device |
-
2018
- 2018-12-27 CN CN201811609794.6A patent/CN109708742B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101487723A (en) * | 2009-03-02 | 2009-07-22 | 北京航空航天大学 | Optical fiber distributed perturbation sensor based on Sagnac interferometer |
| RU2549540C1 (en) * | 2013-12-24 | 2015-04-27 | Федеральное государственное бюджетное учреждение науки "Институт океанологии им. П.П. Ширшова Российской академии наук" (ИО РАН) | Apparatus for monitoring state of long pipelines, including underwater pipelines |
| CN104198030A (en) * | 2014-08-29 | 2014-12-10 | 中国石油天然气股份有限公司 | Multi-channel vibration detection method based on coherent Rayleigh scattering and detection system thereof |
| CN107421570A (en) * | 2017-07-20 | 2017-12-01 | 全球能源互联网研究院 | A kind of multi-functional distribution type optical fiber sensing equipment |
| CN108254064A (en) * | 2018-04-23 | 2018-07-06 | 南京曦光信息科技有限公司 | A kind of optical fiber vibration sensing detection method and device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111811551A (en) * | 2020-07-07 | 2020-10-23 | 中国南方电网有限责任公司超高压输电公司昆明局 | Low-loss polarization interference type ultra-high voltage direct current control protection system OTDR device |
| CN111811551B (en) * | 2020-07-07 | 2021-12-21 | 中国南方电网有限责任公司超高压输电公司昆明局 | Low-loss polarization interference type ultra-high voltage direct current control protection system OTDR device |
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