CN106656315A - Optical cable disturbance detection system and detection method based on fiber interference principle - Google Patents
Optical cable disturbance detection system and detection method based on fiber interference principle Download PDFInfo
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- CN106656315A CN106656315A CN201610842663.7A CN201610842663A CN106656315A CN 106656315 A CN106656315 A CN 106656315A CN 201610842663 A CN201610842663 A CN 201610842663A CN 106656315 A CN106656315 A CN 106656315A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/071—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2589—Bidirectional transmission
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/27—Arrangements for networking
- H04B10/272—Star-type networks or tree-type networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
Abstract
The invention provides an optical cable disturbance detection system and detection method based on a fiber interference principle. The method comprises steps that a laser device, an isolator, a 2*2 star-shaped coupler, a fiber loop, a photoelectric conversion module, a digital signal conversion module and a signal demodulation module are connected; light emitted by the laser device is divided by the 2*2 star-shaped coupler into two beams of coherent light having same light powers; the two beams of coherent light enter the fiber loop and are transmitted along the fiber loop in opposite directions, when the fiber loop is interfered by an external signal, light signals including the external interference signal returned by the 2*2 star-shaped coupler are received by the photoelectric conversion module, the light signals are converted into simulation electric signals, the simulation electric signals are converted through the digital signal conversion module into digital signals which are sent to the signal demodulation module for demodulation, and the position of the external interference signal is acquired to detect the optical cable path. The method is advantaged in that influence of external electromagnetic interference can be completely prevented, and the method further has properties of rapid response speed, accurate positioning and simple operation.
Description
Technical field
The present invention relates to communication technical field, more specifically, is related to a kind of optical cable based on fiber interference principle and disturbs
Detecting system and detection method.
Background technology
Fibre-optic telecommunication cable is the very important device of communication field, especially in Railway Communication field, be which carry
The transmission of the information such as various voices, data and image.Due to the current lightguide cable link stock number of China it is more huge so that
One complexity is become and large order to the maintenance and management of optical cable.
The existing optical cable for railway communication is laid using direct-buried mode mostly, but due to its use time length,
The not congruent reason of completion information, therefore there is a problem of that optic cable section pathway information is not complete or inaccurate, thus cause construction
Middle to dig disconnected optical cable, this phenomenon for playing communication disruption happens occasionally.Therefore, detect that optical cable disturbance is particularly important before construction.
Currently, optical cable Disturbance Detection rely primarily on reinforced-core in optical cable electrology characteristic realize, its general principle be by
The signal loading that signal generator sends detects on the ground the electromagnetism that heart yearn is sent on the reinforced-core of optical cable, then
Ripple.However, this optical cable Disturbance Detection mode is often present, response speed is slow, positioning precision is low, easily stupid by electromagnetic interference, instrument
The problems such as weight, complex operation.
The content of the invention
In view of the above problems, it is an object of the invention to provide a kind of optical cable Disturbance Detection system based on fiber interference principle
And detection method, have that response speed is slow, positioning precision is low to solve existing optical cable Disturbance Detection mode, easily receive electromagnetic interference
With the problem of complex operation.
The present invention provides a kind of optical cable Disturbance Detection system based on fiber interference principle, including laser instrument, isolator, 2
× 2 star-type couplers, optical fiber circuit, photoelectric conversion module, digital signal conversion module and signal demodulation module；Wherein, laser
Device is connected with isolator, for the optical signal that stable laser sends；Isolator is connected with 2 × 2 star-type couplers, for Jing
Optical signal after isolator is stable is divided into the beam coherent light of luminous power identical two；2 × 2 star-type couplers respectively with optical fiber circuit and
Photoelectric conversion module is connected；Wherein, optical fiber circuit described in the two beam coherent lights that 2 × 2 star-type couplers are separated, and in optical fiber circuit
Middle difference is each transmitted in opposite direction, and receives the optical signal that 2 × 2 star-type couplers are passed back by photoelectric conversion module；
Wherein, when optical fiber circuit is disturbed by external signal, photoelectric conversion module receives the optical signal comprising external interference signals, and
Convert optical signals to analog electrical signal；Digital signal conversion module is connected with photoelectric conversion module, for by analog electrical signal
Be converted to data signal；Signal demodulation module is used to be demodulated data signal, obtains the position of external interference signals, according to
Verify optical cable pathway in the position of the external interference signals of acquisition.
Furthermore it is preferred that structure be：Digital signal conversion module include be sequentially connected preamplifier, amplifier, mould/
Number converter；Wherein, preamplifier is connected with photoelectric conversion module, for the analog telecommunications exported to photoelectric conversion module
Number pre-amplification is carried out, again amplified device is amplified the analog electrical signal of Jing pre-amplifications；A/D converter is used for after amplification
Analog electrical signal is converted to data signal.
On the other hand, the present invention provides a kind of optical cable disturbance detecting method based on fiber interference principle, using above-mentioned
Optical cable Disturbance Detection is carried out based on the optical cable Disturbance Detection system of fiber interference principle, the method includes：By laser instrument, isolation
Device, 2 × 2 star-type couplers, optical fiber circuit, photoelectric conversion module, digital signal conversion module and signal demodulation module are entered respectively
Row connection；The a branch of light path Jing after isolator is stable that laser instrument sends is divided into luminous power identical two by 2 × 2 star-type couplers
Beam coherent light；Two beam coherent lights enter optical fiber circuit, and each transmit in opposite direction respectively in optical fiber circuit, work as optical fiber
When loop is disturbed by external signal, photoelectric conversion module is received in the optical signal that 2 × 2 star-type couplers are passed back comprising outside
Interference signal, and the optical signal comprising external interference signals is converted into analog electrical signal；Photoelectric conversion module will be changed
Analog electrical signal sends digital signal conversion module to, and analog electrical signal is converted to data signal by digital signal conversion module；
Digital signal conversion module sends the data signal changed to signal demodulation module, and signal demodulation module is entered to data signal
Row demodulation, obtains the position of external interference signals, and according to the position of the external interference signals for obtaining optical cable pathway is verified.
By above-mentioned, the optical cable Disturbance Detection system based on fiber interference principle and detection method that the present invention is provided
Using the optical characteristics of optical signal, can fundamentally prevent the impact of external electromagnetic interference, and fast response time, positioning are accurate
Really, simple to operate, when optical cable Disturbance Detection is carried out, workmen need to only pass through the position that subterranean cable is found by tapping ground
Put, so as to verify the path of optical cable.
Description of the drawings
It is of the invention by reference to the content of the explanation below in conjunction with accompanying drawing, and with being more fully understood to the present invention
Other purposes and result will be more apparent and should be readily appreciated that.In the accompanying drawings：
Fig. 1 is the structural representation of the optical cable Disturbance Detection system based on fiber interference principle according to the embodiment of the present invention
Figure；
Fig. 2 is that the tested optical cable of the optical cable Disturbance Detection system based on fiber interference principle according to the embodiment of the present invention connects
Enter the structural representation of optical fiber loop；
Fig. 3 is the demodulation flow process of 3 × 3 star-type couplers according to the embodiment of the present invention；
Fig. 4 is the structural representation of the optical cable Disturbance Detection system based on fiber interference principle according to the embodiment of the present invention one
Figure；
Fig. 5 is the matrix diagram of the external disturbance point according to the embodiment of the present invention；
Fig. 6 is according to the LED intensity display data figure under the effect of the external disturbance point of the embodiment of the present invention；
Fig. 7 is the curve map of the active position with LED output intensities of the external disturbance point according to the embodiment of the present invention；
Fig. 8 is the corresponding diagram of the optical cable depth of burying according to the embodiment of the present invention and LED output intensities.
Specific embodiment
The specific embodiment of the present invention is described in detail below with reference to accompanying drawing.
Have that response speed is slow, positioning precision is low for aforementioned existing optical cable Disturbance Detection mode, easily receive electromagnetic interference
With the problem of complex operation, optical cable Disturbance Detection system and detection method of the present invention based on fiber interference principle is by laser
Device, isolator, star-type coupler, optical fiber circuit, photoelectric conversion module, digital signal conversion module and signal demodulation module composition
One integrates transmission and the detecting system that demodulates of signal, so as to detect to optical cable disturbance and fast response time, fixed
Level is standby, simple to operate, and when optical cable Disturbance Detection is carried out, user of service only need to can find subterranean cable by tapping ground
Position, so as to verify the path of optical cable.
In order to illustrate the optical cable Disturbance Detection system based on fiber interference principle of present invention offer, Fig. 1 shows basis
The structure of the optical cable Disturbance Detection system based on fiber interference principle of the embodiment of the present invention.
As shown in figure 1, the present invention provide the optical cable Disturbance Detection system based on fiber interference principle include laser instrument 1,
Isolator 2,2 × 2 star-type couplers 3, optical fiber circuit 4, photoelectric conversion module 5, digital signal conversion module 6 and signal solution mode transfer
Block 7.Wherein, laser instrument 1 is connected with isolator 2, for the optical signal that stable laser 1 sends；The star coupling of isolator 2 and 2 × 2
Clutch 3 is connected, for being divided into the beam coherent light of luminous power identical two to the optical signal Jing after isolator 2 is stable.Need explanation
It is that isolator 2 is arranged between the star-type coupler 3 of laser instrument 1 and 2 × 2, its purpose is to prevent from from 2 × 2 stars coupling
The light of device reflection produces impact to laser instrument 1, to ensure stablizing for laser instrument 1.
2 × 2 star-type couplers 3 are connected respectively with optical fiber circuit 4 and photoelectric conversion module 5；Wherein, 2 × 2 star-type coupler
The 3 two beam coherent lights for separating enter optical fiber circuit 4, and each transmit in opposite direction, and pass through respectively in optical fiber circuit 4
Photoelectric conversion module 5 receives the optical signal that 2 × 2 star-type couplers 3 are passed back；Wherein, disturbed by external signal in optical fiber circuit 4
When, photoelectric conversion module 5 receives the optical signal comprising external interference signals, and converts optical signals to analog electrical signal；Numeral
Signal conversion module 6 is connected with photoelectric conversion module 5, for analog electrical signal to be converted into data signal；Signal demodulation module 7
For data signal to be demodulated, the position of external interference signals is obtained, visited according to the position of the external interference signals for obtaining
Mingguang City's cable pathway.
Specifically, digital signal conversion module includes preamplifier, amplifier, the A/D converter (figure being sequentially connected
In it is not shown)；Wherein, preamplifier is connected with photoelectric conversion module, for the simulation exported to photoelectric conversion module
Electric signal carries out pre-amplification, and again amplified device is amplified the analog electrical signal of Jing pre-amplifications；A/D converter is used to amplify
Analog electrical signal afterwards is converted to data signal.
With reference to Fig. 1, in an example of the present invention, laser instrument sends a branch of light path, through 2 × 2 star-type coupler quilts
It is divided into the beam coherent light of luminous power identical two.As shown in two opposite arrows in Fig. 1, this two beams coherent light enters optical fiber circuit
Afterwards, transmit respectively along contrary direction, according to the interference theory of light, this two-beam meets that frequency is identical, direction of vibration is identical,
The constant interference condition of phase difference, therefore, interference is produced inside optical fiber circuit, interference fringe is formed, when the external world does not interfere with
During signal, interference is stable, and when optical fiber circuit is subject to external signal interference, (arrow in Fig. 1 perpendicular to optical fiber circuit 4 is
Interference signal) when, interference fringe can then send out change (i.e. this two beams coherent light can produce phase difference).By photoelectric conversion module 5
The optical signal comprising external interference signals is received, and the optical signal is converted into analog electrical signal, data signal is then passed through again
The analog electrical signal is converted to data signal by modular converter, finally by the above-mentioned phase difference of signal demodulation module from data signal
In demodulate, so as to obtain the position of external interference signals, carried out point by the position to acquired external interference signals
Analysis, just can verify optical cable pathway.
To constitute optical fiber circuit as shown in Figure 1, can find out according to fiber core identification in optical cable place to be measured machine room corresponding
Optical cable is standby fine, and using ring flange loopback is carried out, the optical fiber circuit needed for so as to form test.And in order to realize to tested optical cable
Optical cable Disturbance Detection, Fig. 2 shows the optical cable Disturbance Detection system based on fiber interference principle according to embodiments of the present invention
The structure of tested optical cable incoming fiber optic loop.
As shown in Fig. 2 certain root optical cable to be measured between AB two places is represented with heavy line, in A ground machine room selects the optical cable
This two optical fiber are accessed two output ports of 2 × 2 star-type couplers by ring flange and wire jumper, in B by two standby fibre a and b
Ground machine room finds out corresponding two standby fibres according to fiber core identification, and by ring flange loopback is directly carried out.Thus, using optical cable to be measured
In two standby fibres define optical fiber circuits needed for Fig. 1.
On the other hand, the present invention also provides a kind of optical cable disturbance detecting method based on fiber interference principle, and it is utilized
State carries out optical cable Disturbance Detection based on the optical cable Disturbance Detection system of fiber interference principle, and the method specifically includes following steps：
1st, by laser instrument, isolator, 2 × 2 star-type couplers, optical fiber circuit, photoelectric conversion module, data signal modulus of conversion
Block and signal demodulation module are attached respectively；
2nd, that a branch of light path Jing after isolator is stable that laser instrument sends is divided into luminous power is identical for 2 × 2 star-type couplers
Two beam coherent lights；
3rd, two beam coherent lights enter optical fiber circuit, and each transmit in opposite direction respectively in optical fiber circuit, work as light
When fine loop is disturbed by external signal, photoelectric conversion module is received in the optical signal that 2 × 2 star-type couplers are passed back comprising outer
Portion's interference signal, and the optical signal comprising external interference signals is converted into analog electrical signal；
4th, photoelectric conversion module sends the analog electrical signal changed to digital signal conversion module, data signal conversion
Analog electrical signal is converted to data signal by module；
5th, digital signal conversion module sends the data signal changed to signal demodulation module, signal demodulation module pair
Data signal is demodulated, and obtains the position of external interference signals, and according to the position of the external interference signals for obtaining optical cable is verified
Pathway.
Wherein, when optical fiber circuit is disturbed by external signal, two beam coherent lights produce phase difference in optical fiber circuit, lead to
The corresponding relation set up between external interference signals and phase difference is crossed, and phase difference is demodulated by signal demodulation module；According to
The phase difference for being demodulated, by calculating or lookup table mode the position of external interference signals is obtained.Wherein, external interference signals exist
Loss in optical fiber circuit is directly proportional to transmission path, and when outside interference signal intensity is constant, phase difference value is bigger, outward
The intensity of portion's interference signal is stronger.
Specifically, light wave transmission in length is for the optical fiber of l can produce phase delay.Therefore, the variable quantity of phase place can use
Following formula are indicated：
Φ=β × l (2)
Wherein, β is light wave propagation constant in a fiber, and l is fiber lengths, and Δ l is the variable quantity of fiber lengths l；N is
Fiber core refractive index, Δ n is the variable quantity of fiber core refractive index n；Δ α is the variable quantity of fiber core radius α.In above formula,Table
Show that the long and slender long l of sense light is micro- and become the phase difference for causing, referred to as strain effect；It is micro- for sensor fibre fiber core refractive index
The phase difference that change causes, referred to as elasto-optical effect；Become the phase difference for causing for sensor fibre core diameter is micro-, referred to as
For poisson effect, impact of the poisson effect to ΔΦ is minimum, typically ignores.
Assume sensor fibre uniform stressed, obtained under strain effect and elasto-optical effect effect according to contingency theory, optical fiber
The variable quantity of phase place is：
In formula：P is external forces；μ is the Poisson constant of optical fiber；p11、p12For bullet light component of tensor；E is the bullet of optical fiber
Property modulus.Formula (3) is proved, in the case of sensor fibre uniform stressed, phase changing capacity is proportional to outer signals, vibration signal
P directly and dynamically can be modulated to the light phase ΔΦ in sensor fibre.
However, in actual applications, the impossible uniform stressed of optical fiber, it is assumed that the fiber lengths that external interference signals are applied to
For LS, sensor fibre total length is L, and Δ l represents that external interference signals effect causes the miniature deformation of optical fiber.
External signal P perceived by sensor fibre is characterized with sinusoidal signal.IfWherein P0For signal
Amplitude；ωaFor signal angular frequency.The phase of light wave formula of any time clockwise direction (CW) and counter clockwise direction (CCW) can
To be expressed as：
Wherein, β is light wave propagation constant in a fiber, and the fiber lengths that Ls is applied to for external interference signals, ε is just
Stain vector, P0For signal amplitude, n is optical fibre refractivity,
Wherein, μ for optical fiber Poisson constant, E for optical fiber elastic modelling quantity, k is light wave number in a vacuum, p11And p12
For strain-optical constant..
Phase difference (the double light velocity phase places of following titles that two beam coherent lights are produced in optical fiber circuit are obtained by formula (4), formula (5)
Difference change)For：
Wherein,The phase difference that two beam coherent lights are produced in the optical fiber circuit,For clockwise
Phase of light wave,For anticlockwise phase of light wave,For the phase difference that two beam coherent lights are produced in optical fiber circuit
Amplitude, ωaFor signal angular frequency, L is optical fiber total length, and t is time variable, and c is light wave velocity of wave.
δ β andIt is deployable respectively to be
In formula：β represents fiber waveguide constant in vacuum；k0For light wave number in a vacuum；C is light wave velocity of wave.By formula (6)-
Formula (8), it is established that external interference signals P changes with double light velocity phase differencesBetween corresponding relation.In light detection and signal
Processing module, only need to demodulate phase differenceExternal signal P can be reduced by calculating with the mode such as table look-up.Tapping letter
In the case that number P intensity is certain,Value is bigger, illustrates that external signal P that sensor fibre is perceived is stronger, and knocking P is in light
Loss when transmitting in cable surrounding environment is less.In limited region, it is believed that knocking P loss value in the environment
LossIt is directly proportional to transmission path M.
P=P-Loss (9)
Loss∝M (10)
By above-mentioned, when beating point is located at directly over the embedded point of optical cable, P values maximum.
In actual applications, it is possible to also need to Lian Duogen for fibre to detect optical fiber disturbance.Skilled person
All it should be understood that needing even how many standby fibres to be accomplished by the coupler with how many ports, therefore, in another example of the present invention
In, output end that can be by above-mentioned 2 × 2 star-type coupler through optical fiber circuit is connected with 3 × 3 star-type couplers, and 2 × 2
The optical signal with external interference signals of star-type coupler output (is divided into light through 3 × 3 star-type couplers by one dividing into three
Power identical three beams coherent light), 3 output ends of 3 × 3 star-type couplers are mutually 120 degree, and 3 road optical signals of output are passed through
Opto-electronic conversion, circuit amplify, AD samplings, are converted to data signal feeding signal demodulation module and are demodulated, you can demodulate phase
Potential difference.
Wherein, Fig. 3 shows the demodulation flow process of 3 × 3 star-type couplers according to embodiments of the present invention.As shown in figure 3, will
3 road optical signals amplify through opto-electronic conversion, circuit and AD sample conversions are 3 railway digital signals, and 3 railway digital signals are poor
Point, the computing such as subtraction, multiplication, addition, integration and division, you can demodulate phase difference.
Specifically, if dual-beam phase difference variable is turned in the sensor fibre that causes of external signal PThen 3 railway digital signal
Si can be expressed as：
Wherein, di is the value of direct current component, and ai is the amplitude of AC portion.In formula：θ i are consolidating for 3 × 3 couplers introducing
Phase bit changes, and meets formula (12).
Si is passed through every straight and normalization process, obtains si：
It is poor to 3 railway digital signals (si i.e. after every straight and normalization) successively according to the flow process shown in Fig. 3
Point, the computing such as subtraction, multiplication, addition, integration, division, you can obtainBy SoutBy a high-pass filter
Flip-flop is filtered, demodulation result is finally given
In theory, when external forces are excessive,2 π can be can exceed that, now can be caused to transducing signal
Erroneous judgement.But in the practical application of optical cable Disturbance Detection, because external forces are intercepted through environment attenuation and cable protection layer,
The vibrations acted directly on optical fiber are atomic weak, general to excludeMore than the possibility of 2 π.Through many experiments, this deduction
It is verified.
In order to verify the feasibility of the optical cable disturbance detecting method based on fiber interference principle of present invention offer, Fig. 4 shows
The structure of the according to embodiments of the present invention one optical cable Disturbance Detection system based on fiber interference principle is gone out, using such as Fig. 4 institutes
The structure shown is detected to optical cable disturbance.
As shown in figure 4, optical cable is positioned on one piece of broad level land, two disk 20km bare fibres are distinguished by 10m jumping fibers
It is connected with tested optical cable two, and is isolated with ground by rubber blanket.Along tested optical cable pathway, every 1m by light-metering
Determine on cable a bit, totally 10 points；It is every to both sides respectively along perpendicular to the direction of tested optical cable pathway by this 10 points
Determine an application point every 2m, 110 application points are determined altogether, according to from top to bottom, order from left to right is write as percussion square
Battle array is as shown in Figure 5.By embedded processing platform, external interference signals are converted into LED intensity and are shown, it is most that LED is lighted
Lattice number is 40 lattice, and 40 lattice are representedIt has been more than 1.6 π.To keep the constancy of external interference signals, with the lead of mass M=2kg
Used as sign, (t is lead from contact to size P=8.85/tN of power to the impulsive force that block is produced from the height freely falling body of L=1m
Ground is to the time for stopping).In experiment, record LED intensity of 110 application points of the above under the external forces effect and show
Registration is according to as shown in Figure 6.
By the 7th row data instance of the matrix shown in Fig. 6, the curved line relation for obtaining active position with output intensity is as schemed
Shown in 7.Can see from Fig. 7 (longitudinal coordinate represents LED output intensities, and lateral coordinates represent the active position of external disturbance point)
Go out, when tapping apart from the nearest f6 points of tested optical cable, LED output intensities are maximum, can accurately judge that tested optical cable is located accordingly
Position.Observation LED intensity display data matrix, it can be seen that other 9 row data also substantially conform to the basic trend shown in Fig. 7.
The maximum each point of LED output intensities is determined, the pathway information of this section of 10m optical cable can be just detected.
It should be noted that in the present invention, the detectivity of photoelectric conversion module is -70dBm, when opto-electronic conversion mould
When block received optical power is more than -70dBm, display system can carry out corresponding response output.In actual environment, due to everywhere
The optical cable depth of burying may be different, and under the effect of same purpose power, LED outputs maximum can have differences, and Fig. 8 is illustrated not
With under the depth of burying, when application point is located at directly over optical cable pathway, the maximum of the LED output responses measured is tested.Wherein, it is horizontal
Coordinate represents the optical cable depth of burying, and ordinate represents LED output intensities, and due to this method measurement is relative maximum, optical cable
The difference of the depth of burying has no effect on the judgement to its pathway.
By above-mentioned, using present invention offer the optical cable Disturbance Detection system based on fiber interference principle and detection
Method, by using the optical characteristics of optical signal, can fundamentally prevent the impact of external electromagnetic interference, and response speed
Hurry up, it is accurate positioning, simple to operate, when optical cable Disturbance Detection is carried out, workmen only need to can find ground by tapping ground
The position of lower optical cable, so as to verify the path of optical cable.
The optical cable based on fiber interference principle of the invention is described in an illustrative manner above with reference to accompanying drawing to disturb
Detecting system and detection method.It will be understood by those skilled in the art, however, that for the invention described above proposed based on optical fiber
The optical cable Disturbance Detection system of principle of interference and detection method, can be making various on the basis of without departing from present invention
Improve.Therefore, protection scope of the present invention should be determined by the content of appending claims.
Claims (10)
1. a kind of optical cable Disturbance Detection system based on fiber interference principle, including：Laser instrument, isolator, the coupling of 2 × 2 stars
Device, optical fiber circuit, photoelectric conversion module, digital signal conversion module and signal demodulation module；Wherein,
The laser instrument is connected with the isolator, for stablizing the optical signal that the laser instrument sends；
The isolator is connected with 2 × 2 star-type coupler, and for the optical signal to the isolator described in after stable light is divided into
The beam coherent light of power identical two；
2 × 2 star-type coupler is connected respectively with the optical fiber circuit and photoelectric conversion module；Wherein,
The two beam coherent lights that 2 × 2 star-type coupler is separated enter the optical fiber circuit, and distinguish in the optical fiber circuit
Each transmit in opposite direction, and the light letter that 2 × 2 star-type coupler is passed back is received by the photoelectric conversion module
Number；Wherein,
When the optical fiber circuit is disturbed by external signal, the photoelectric conversion module receives the light comprising external interference signals
Signal, and the optical signal is converted into analog electrical signal；
The digital signal conversion module is connected with the photoelectric conversion module, for the analog electrical signal to be converted into numeral
Signal；
The signal demodulation module is used to be demodulated the data signal, the position of external interference signals is obtained, according to obtaining
Verify optical cable pathway in the position of the external interference signals for taking.
2. the optical cable Disturbance Detection system of fiber interference principle is based on as claimed in claim 1, wherein,
The digital signal conversion module includes preamplifier, amplifier, the A/D converter being sequentially connected；Wherein,
The preamplifier is connected with the photoelectric conversion module, for the analog electrical signal exported to photoelectric conversion module
Pre-amplification is carried out, again amplifier described in Jing is amplified the analog electrical signal of Jing pre-amplifications；
The A/D converter is used to for the analog electrical signal after amplification to be converted to discrete data signal.
3. the optical cable Disturbance Detection system of fiber interference principle is based on as claimed in claim 1, wherein,
According to the fiber core identification of optical cable, ring is carried out for fibre by ring flange pair optical cable corresponding with the fiber core identification of the optical cable
Return, form optical fiber circuit.
4. a kind of optical cable disturbance detecting method based on fiber interference principle, utilizes as described in any one in claims 1 to 3
Optical cable Disturbance Detection is carried out based on the optical cable Disturbance Detection system of fiber interference principle, methods described includes：
By laser instrument, isolator, 2 × 2 star-type couplers, optical fiber circuit, photoelectric conversion module, digital signal conversion module and letter
Number demodulation module is attached respectively；
The a branch of light path Jing after isolator is stable that the laser instrument sends is divided into luminous power phase by 2 × 2 star-type coupler
Two same beam coherent lights；
The two beams coherent light enters the optical fiber circuit, and each passes in opposite direction respectively in the optical fiber circuit
Defeated, when the optical fiber circuit is disturbed by external signal, the photoelectric conversion module receives 2 × 2 star-type couplers and passes back
Optical signal in include external interference signals, and analog electrical signal will be converted to comprising the optical signal of external interference signals；
The photoelectric conversion module sends the analog electrical signal changed to digital signal conversion module, and the data signal turns
The analog electrical signal is converted to data signal by mold changing block；
The digital signal conversion module sends the data signal changed to the signal demodulation module, the signal demodulation
Module is demodulated to the data signal, obtains the position of external interference signals, according to the position of the external interference signals for obtaining
Put and verify optical cable pathway.
5. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 4, wherein,
When the optical fiber circuit is disturbed by external signal, the two beams coherent light produces phase place in the optical fiber circuit
Difference, by setting up the corresponding relation between external interference signals and the phase difference, and is demodulated by the signal demodulation module
Go out the phase difference；
According to the phase difference for being demodulated, the position of external interference signals is obtained by calculating or lookup table mode.
6. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 5, wherein,
Loss of the external interference signals in the optical fiber circuit is directly proportional to transmission path, in outside interference signal intensity
When constant, phase difference value is bigger, and the intensity of the external interference signals is stronger.
7. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 6, wherein, obtained by following formula
Take the phase difference that two beam coherent lights are produced in the optical fiber circuit：
Wherein,The phase difference that two beam coherent lights are produced in the optical fiber circuit,For clockwise light wave phase
Position,For anticlockwise phase of light wave,For the phase place spread that two beam coherent lights are produced in the optical fiber circuit
Value, ωaFor signal angular frequency, L is optical fiber total length, and t is time variable, and c is light wave velocity of wave.
8. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 7, wherein, respectively by following public affairs
Formula obtains the phase of light wave of clockwise and counterclockwise：
Wherein, β is light wave propagation constant in a fiber, and the fiber lengths that Ls is applied to for external interference signals, ε is normal strain
Vector, P0For signal amplitude, n is optical fibre refractivity,
Wherein, μ for optical fiber Poisson constant, E for optical fiber elastic modelling quantity, k is light wave number in a vacuum, p11And p12For strain
Optical constant.
9. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 8, wherein,
Output end of 2 × 2 star-type coupler through optical fiber circuit is connected with 3 × 3 star-type couplers, described 2 × 2
Star-type coupler output the optical signal with external interference signals through 3 × 3 star-type coupler by one dividing into three, it is described
3 output ends of 3 × 3 star-type couplers are mutually 120 degree, and 3 road optical signals of output are adopted through opto-electronic conversion, circuit amplification, AD
Sample, is converted to data signal feeding signal demodulation module and is demodulated, and obtains phase difference.
10. the optical cable disturbance detecting method of fiber interference principle is based on as claimed in claim 9, wherein,
3 road optical signals are amplified through opto-electronic conversion, circuit and AD sample conversions are 3 railway digital signals, by 3 railway digital letter
Difference, subtraction, multiplication, addition, integration and division arithmetic number are carried out, phase difference is obtained；Wherein, the 3 railway digital signal can be with
It is expressed as：
Wherein, di is the value of direct current component, and ai is the amplitude of AC portion,Produce in the optical fiber circuit for two beam coherent lights
Raw phase difference, θ i are the stationary phase change that coupler is introduced, and meet following formula：
I, j=1,2,3 and i ≠ j
The Si is passed through every straight and normalization process, obtains si；
Carry out difference, subtraction, multiplication, addition, integration and division arithmetic to si successively, and by high-pass filter filter direct current into
Point, obtain phase difference：
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| CN107645333A (en) * | 2017-11-22 | 2018-01-30 | 通号工程局集团北京研究设计实验中心有限公司 | A kind of separate type optical time domain reflectometer test device |
| CN110530498A (en) * | 2019-08-09 | 2019-12-03 | 国家电网有限公司 | Long range optical cable dynamic monitoring system |
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