CN109217919A - Based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method - Google Patents
Based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- 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
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- H04B10/524—Pulse modulation
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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
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- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
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Abstract
The present invention provides one kind to be based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method.Phase sensitivity type optical time domain reflectometer includes generation device and detection device；Generation device includes laser source, acousto-optic modulator, arbitrary-function generator and the first erbium-doped fiber amplifier；Detection device includes circulator, the second erbium-doped fiber amplifier and photodetector.Above-mentioned phase sensitivity type optical time domain reflectometer and measurement method change the strategy that traditional time domain relationship type Φ-OTDR only carries out one-dimensional correlation operation in the time domain, time domain-airspace two-dimensional matrix is constituted with the time-domain signal of point of proximity, two dimensional image matching operation is carried out on time domain-airspace to two two-dimensional matrixes of two-frequency signal, it can be substantially reduced the related operation requirement long to time domain window with this, improve the temporal resolution of sensor-based system.
Description
Technical field
Embodiments of the present invention are related to field of sensing technologies, more specifically, embodiments of the present invention are related to a kind of base
In the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method.
Background technique
Relative to other distributed sensing technologies, the phase sensitivity type optical time domain reflectometer (Φ-based on Rayleigh scattering effect
OTDR) technology has the advantages that structure is simple, high sensitivity.The technology by into optical fiber inject narrow linewidth laser pulse,
The interference superposed signal of the backward Rayleigh scattering light in half pulse width is obtained, this interference superposed signal is to ambient temperature or strain
Change extremely sensitive.The Strength Changes of echo-signal show that the response sensitivity of temperature or strain is able to reach mK and n ε
Magnitude.
Φ-OTDR technique difficult point is the quantitative measurment to temperature or strain.Time domain correlation can be achieved on quantitative survey
A kind of technology of amount.Existing time domain correlation is by injecting the pulse pair of certain frequency difference into testing fiber, when obtaining two
Domain signal obtains the time delay of two time-domain signals, is become according to temperature or strain by carrying out time domain relevant calculation to this two bars
Change amount and the relationship temperature of two pulse pair frequency differences or the variable quantity of strain, to realize the quantitative survey to temperature or strain
Amount.Existing time domain correlation needs to accumulate a large amount of data, to need in longer phase to obtain high measurement accuracy
It closes and carries out relevant calculation on window.The length of associated window determines the temporal resolution of the sensor.Therefore, longer associated window is led
The temporal resolution of this method has been caused to decline；Moreover, the rate of change of temperature or strain is considered constant in associated window
, this allows for the measurement that this method is not suitable for the Dynamic Signal of variable Rate variation.
Summary of the invention
In the present context, embodiments of the present invention are intended to provide a kind of based on the matched phase sensitivity type light in time domain-airspace
Domain reflectometer and measurement method, to solve existing for existing time domain relationship type Φ-OTDR, temporal resolution is poor, is not suitable for becoming
The problem of measurement of the Dynamic Signal of rate variation.
In the first aspect of embodiment of the present invention, when providing a kind of phase sensitivity type light matched based on time domain-airspace
Domain reflectometer, including generation device and detection device；The generation device includes laser source, acousto-optic modulator, arbitrary function hair
Raw device and the first erbium-doped fiber amplifier；The detection device includes circulator, the second erbium-doped fiber amplifier and photodetection
Device；The continuous light of the laser source output is modulated to pulsed light by the acousto-optic modulator, so that described in process of each period
Acousto-optic modulator modulates two pulses, and the frequency of two pulses is respectively first frequency and second frequency, wherein described
Meaning function generator is exported for generating preset square-wave signal to the acousto-optic modulator；The arteries and veins of the acousto-optic modulator output
It washes off via after first erbium-doped fiber amplifier amplification, again through in circulator injection testing fiber；The light to be measured
Backward Rayleigh scattering echo-signal in fibre is exported through the circulator to second erbium-doped fiber amplifier, by described second
It is detected after erbium-doped fiber amplifier amplification by the photodetector；Wherein, it is modulated by the acousto-optic modulator adjacent
Time interval between pulse is greater than propagation time of the light in the testing fiber.
It further, further include filter, the filter is set to second erbium-doped fiber amplifier and the photoelectricity
Between detector, for filtering out the spontaneous emission noise of second erbium-doped fiber amplifier.
Further, the filter is realized using fiber bragg grating (FBG).
In the second aspect of embodiment of the present invention, when providing a kind of phase sensitivity type light matched based on time domain-airspace
The measurement method of domain reflectometer, the measurement method are based on anti-based on the matched phase sensitivity type optical time domain in time domain-airspace as described above
Meter is penetrated to realize；The measurement method includes: two pulses modulating each period by the acousto-optic modulator as one
Group pulse pair；Multiple groups pulse pair is generated by the generation device, successively testing fiber is squeezed into through the detection device, by described
Photodetector in detection device receives the corresponding backward Rayleigh scattering echo-signal of the multiple groups pulse pair, wherein described
The corresponding backward Rayleigh scattering echo-signal of multiple groups pulse pair includes each pulse in the multiple groups pulse in the light to be measured
Backward Rayleigh scattering echo-signal in fine each position；Based on the received in the multiple groups pulse pair with first frequency arteries and veins
Corresponding backward Rayleigh scattering echo-signal is rushed, the first time domain-spatial feature figure is obtained；Based on the received with the multiple groups pulse
Centering has the corresponding backward Rayleigh scattering echo-signal of pulse of second frequency, obtains the second time domain-spatial feature figure；Its
In, the first time domain-spatial feature figure and the second time domain-spatial feature figure are sat with the position on testing fiber for the first dimension
It marks, be two-dimensional coordinate, with the photodetector received signal intensity with the signal reception time of the photodetector
Or signal amplitude is third dimension coordinate；The reference data region of predetermined size is chosen in the first time domain-spatial feature figure,
The corresponding matched data region in the reference data region is determined in the second time domain-spatial feature figure, calculates the reference
Data area and displacement of the matched data region on two-dimensional coordinate, when determining described first according to the displacement
Time delay between domain-spatial feature figure and the second time domain-spatial feature figure；According to the first frequency and the second frequency
Frequency difference and the time delay between rate calculate the temperature changing speed or strain variation speed of the testing fiber；Root
According to the temperature changing speed or the product of strain variation speed and corresponding time of measuring, determine the testing fiber described right
Answer the temperature variation or strain variation amount in time of measuring.
Further, the reference data region includes preset first position in the first time domain-spatial feature figure
The data point of the predefined size neighborhood of point；Determine that the reference data region is corresponding in the second time domain-spatial feature figure
The step of matched data region include: in the second time domain-spatial feature figure, by with the preset first position point
The data point of the predefined size neighborhood of the identical second position point of one-dimensional coordinate is formed by data area as number to be matched
According to region；The second dimension reference axis by data area to be matched along the second time domain-spatial feature figure moves, and is moved through
The difference matrix between resulting data area to be matched and the reference data region is moved in journey every time, and calculates each institute
The quadratic sum of all elements of the difference matrix obtained；Determine that the quadratic sum of all elements of the difference matrix in moving process is minimum
When corresponding difference matrix, using the corresponding data area to be matched of the difference matrix as the matched data region.
Further, the strain variation speed of the testing fiber obtains in the following way: calculating according to the following formula
The strain knots modification of the testing fiber corresponding to time delay calculated:
Wherein, Δ v indicates the frequency difference between the first frequency and second frequency, and v indicates light wave fundamental frequency, pεIndicate bullet light
Coefficient, Δ ε indicate the strain knots modification of the testing fiber corresponding to time delay calculated, KεIndicate the coefficient of strain；
The ratio between the strain knots modification of the testing fiber according to corresponding to time delay calculated and time delay calculated, are obtained
Obtain the strain variation speed of the testing fiber.
Further, the temperature changing speed of the testing fiber obtains in the following way: calculating according to the following formula
The temperature knots modification of the testing fiber corresponding to time delay calculated:
Wherein, Δ v indicates the frequency difference between the first frequency and second frequency, and v indicates that light wave fundamental frequency, ξ indicate hot light
Coefficient, α indicate that thermal expansion coefficient, Δ T indicate the temperature knots modification of the testing fiber corresponding to time delay calculated,
KTIndicate temperature coefficient；The temperature knots modification of the testing fiber according to corresponding to time delay calculated with it is calculated
The ratio between time delay obtains the temperature changing speed of the testing fiber.
According to the present invention embodiment based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace and measurement method,
That it changes the strategy that traditional time domain relationship type Φ-OTDR only carries out one-dimensional correlation operation in the time domain, with point of proximity when
Domain signal constitutes time domain-airspace two-dimensional matrix, and two dimensional image is carried out on time domain-airspace to two two-dimensional matrixes of two-frequency signal
Matching operation can be substantially reduced the related operation requirement long to time domain window with this, improve the temporal resolution of sensor-based system.
Detailed description of the invention
The following detailed description is read with reference to the accompanying drawings, above-mentioned and other mesh of exemplary embodiment of the invention
, feature and advantage will become prone to understand.In the accompanying drawings, if showing by way of example rather than limitation of the invention
Dry embodiment, in which:
Fig. 1 be show embodiment according to the present invention based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace
Light channel structure schematic diagram；
Fig. 2 be show embodiment according to the present invention based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace
The flow chart of one exemplary process of measurement method；
Fig. 3 is a flow chart that may be handled for showing the step S250 in Fig. 2；
Fig. 4 is to show time domain-airspace matching method schematic diagram.
In the accompanying drawings, identical or corresponding label indicates identical or corresponding part.
Specific embodiment
The principle and spirit of the invention are described below with reference to several illustrative embodiments.It should be appreciated that providing this
A little embodiments are used for the purpose of making those skilled in the art can better understand that realizing the present invention in turn, and be not with any
Mode limits the scope of the invention.On the contrary, these embodiments are provided so that this disclosure will be more thorough and complete, and energy
It is enough that the scope of the present disclosure is completely communicated to those skilled in the art.
Embodiment according to the present invention proposes a kind of based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace
With measurement method.
Herein, it is to be understood that any number of elements in attached drawing be used to example rather than limit and it is any
Name is only used for distinguishing, without any restrictions meaning.
Below with reference to several representative embodiments of the invention, the principle and spirit of the present invention are explained in detail.
Exemplary means
The embodiment provides one kind to be based on matched phase sensitivity type (i.e. phase-sensitive) optical time domain in time domain-airspace
Reflectometer (OTDR, Optical Time Domain Reflectometer), including generation device and detection device；The production
Generating apparatus includes laser source, acousto-optic modulator, arbitrary-function generator and the first erbium-doped fiber amplifier；The detection device packet
Include circulator, the second erbium-doped fiber amplifier and photodetector；The continuous light of the laser source output passes through the acousto-optic tune
Device processed is modulated to pulsed light, so that each period modulates two pulses, the frequency of two pulses by the acousto-optic modulator
Rate is respectively first frequency and second frequency, wherein the arbitrary-function generator is for generating preset square-wave signal output
To the acousto-optic modulator；The pulsed light of acousto-optic modulator output via after first erbium-doped fiber amplifier amplification,
Again through in circulator injection testing fiber；Backward Rayleigh scattering echo-signal in the testing fiber is through the circulator
Output is visited after second erbium-doped fiber amplifier amplification by the photodetector to second erbium-doped fiber amplifier
It surveys；Wherein, the time interval between adjacent pulse modulated by the acousto-optic modulator is greater than light in the testing fiber
In propagation time.
Fig. 1 show it is of the invention based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace, including generation device and
Detection device.
As shown in Figure 1, generation device includes laser source (LASER shown in FIG. 1) 1-1, acousto-optic modulator (AOM) 1-2, appoints
Anticipate function generator (AFG) 1-3 and the first erbium-doped fiber amplifier (EDFA1 shown in FIG. 1) 1-4.
Detection device includes circulator 1-5, the second erbium-doped fiber amplifier (EDFA2 shown in FIG. 1) 1-6 and photodetection
Device (PD) 1-7.
The continuous light of laser source 1-1 output is modulated to pulsed light by acousto-optic modulator 1-2, so that each period passes through sound
Optical modulator 1-2 modulates two pulses, and the frequency of two pulses is respectively first frequency and second frequency, wherein any
Function generator 1-3 is exported for generating preset square-wave signal to acousto-optic modulator 1-4.Preset square-wave signal for example can be with
Rule of thumb it is arranged, or can also be arranged by the method for test, which is not described herein again.
Wherein, the output light wavelength of laser 1-1 is, for example, 1550.09nm.Each of modulated by acousto-optic modulator 1-2
Pulse width is, for example, 20ns, and peak power is, for example, 1W.
In addition, the frequency difference between first frequency and second frequency is, for example, preset value, for example, first frequency is equal to f0, and
Second frequency is equal to f0+ Δ f, then the frequency difference between two pulses that each period modulates by acousto-optic modulator 1-2 is Δ
f。
Acousto-optic modulator 1-2 is the continuous light modulation that exports laser 1-1 into pulsed light.
Acousto-optic modulator 1-2 output pulsed light via the first erbium-doped fiber amplifier 1-4 amplification after, again through circulator 1-
In 5 injection testing fibers.
Backward Rayleigh scattering echo-signal in testing fiber is exported through circulator 1-5 to the second erbium-doped fiber amplifier 1-
6, it is detected after the second erbium-doped fiber amplifier 1-6 amplification by photodetector 1-7.
Wherein, the time interval between adjacent pulse modulated by acousto-optic modulator 1-2 is greater than light in testing fiber
In propagation time.
In addition, as shown in Figure 1, first end of the pulsed light through circulator 1-5 exported from the first erbium-doped fiber amplifier 1-4
Mouth 1 enters circulator 1-5, then from the output of the second port 2 of circulator 1-5 into testing fiber；After testing fiber return
Enter circulator 1-5, then the third port from circulator 1-5 through the second port 2 of circulator 1-5 to Rayleigh scattering echo-signal
3 outputs to the second erbium-doped fiber amplifier 1-6.
As an example, in detection device can also include filter, filter be set to the second erbium-doped fiber amplifier 1-6 with
Between photodetector 1-7, for filtering out the spontaneous emission noise of the second erbium-doped fiber amplifier 1-6.
As an example, filter can for example be realized using optical fiber bragg grating FBG.
Illustrative methods
The embodiments of the present invention also provide a kind of measurements based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace
Method, the measurement method are based on realizing based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace as described above；The survey
Amount method includes: two pulses modulating each period by the acousto-optic modulator as a set of pulses pair；Pass through institute
It states generation device and generates multiple groups pulse pair, successively testing fiber is squeezed into through the detection device, by the light in the detection device
Electric explorer receives the corresponding backward Rayleigh scattering echo-signal of the multiple groups pulse pair, wherein the multiple groups pulse pair is corresponding
Backward Rayleigh scattering echo-signal include each pulse in the multiple groups pulse in the testing fiber each position after
To Rayleigh scattering echo-signal；It is corresponding with having the pulse of first frequency in the multiple groups pulse pair backward auspicious based on the received
Sharp scatter echo signal obtains the first time domain-spatial feature figure；Based on the received in the multiple groups pulse pair have second frequency
The corresponding backward Rayleigh scattering echo-signal of the pulse of rate obtains the second time domain-spatial feature figure；Wherein, first time domain-
Spatial feature figure and the second time domain-spatial feature figure with the position on testing fiber are one-dimensional coordinate, with the photodetection
The signal reception time of device is two-dimensional coordinate, using the photodetector received signal intensity or signal amplitude as the third dimension
Coordinate；The reference data region that predetermined size is chosen in the first time domain-spatial feature figure, in the second time domain-sky
The corresponding matched data region in the reference data region is determined in characteristic of field figure, calculates the reference data region and the matching
Displacement of the data area on two-dimensional coordinate, to determine the first time domain-spatial feature figure and institute according to the displacement
State the time delay between the second time domain-spatial feature figure；According between the first frequency and second frequency frequency difference and
The time delay calculates the temperature changing speed or strain variation speed of the testing fiber；According to the temperature change speed
The product of degree or strain variation speed and corresponding time of measuring, determines temperature of the testing fiber in the corresponding time of measuring
Spend variable quantity or strain variation amount.
Fig. 2 schematically shows according to the anti-based on the matched phase sensitivity type optical time domain in time domain-airspace of the embodiment of the present disclosure
Penetrate a kind of illustrative process flow 200 of the measurement method of meter.
In the measurement method, two pulses that each period is modulated by acousto-optic modulator 1-2 are as one group of arteries and veins
Punching pair.As described above, the frequency of two pulses of the set of pulses centering in each period is for example respectively f0And f0+ Δ f, then
Frequency difference between two pulses of every group pulse centering is Δ f.
As shown in Fig. 2, generating multiple groups pulse pair in step S210 by generation device, successively being squeezed into through detection device
Testing fiber receives the corresponding backward Rayleigh scattering echo-signal of multiple groups pulse pair by the photodetector 1-7 in detection device,
Wherein, the corresponding backward Rayleigh scattering echo-signal of multiple groups pulse pair includes that each pulse in multiple groups pulse is each in testing fiber
Backward Rayleigh scattering echo-signal on position.
In step S220, based on the received with there is the corresponding backward Rayleigh of the pulse of first frequency in multiple groups pulse pair
Scatter echo signal obtains the first time domain-spatial feature figure；And based on the received in multiple groups pulse pair have second frequency
The corresponding backward Rayleigh scattering echo-signal of pulse, obtain the second time domain-spatial feature figure.
Wherein, the first time domain-spatial feature figure and the second time domain-spatial feature figure are with the position on testing fiber for first
It ties up coordinate, be two-dimensional coordinate with the signal reception time of photodetector 1-7, strong with photodetector 1-7 received signal
Degree or signal amplitude are third dimension coordinate.For example, the first, second, and third dimension coordinate can be sat with the X in XYZ coordinate system respectively
Mark, Y coordinate and Z coordinate indicate.
Wherein, the position on testing fiber corresponding to received backward Rayleigh scattering echo-signal can be according to such as lower section
Formula determines: for each pulse in multiple groups pulse pair, the sending time of the pulse is known and is denoted as t0, photodetector
The backward Rayleigh scattering echo-signal corresponding duration for the pulse that 1-11 is received is, for example, from t1To t2(that is, from t1
Moment initially receives the backward Rayleigh scattering echo-signal of the pulse, t2Reception terminates), then by t1What reception arrived
That start position of signal strength (or signal amplitude) as testing fiber position, by t2That signal that reception arrives is strong
Spend the final position (such as fiber lengths L) of (or signal amplitude) as testing fiber position.If by the starting point of testing fiber position
Position is as 0 point, then Wherein, c indicates light in a fiber
Transmission speed.
In step S230, the reference data region of predetermined size is chosen in the first time domain-spatial feature figure, second
The corresponding matched data region in the reference data region is determined in time domain-spatial feature figure.
As an example, reference data region includes the predetermined of preset first position point in the first time domain-spatial feature figure
The data point of big small neighbourhood.
The step of corresponding matched data region in the reference data region is determined in the second time domain-spatial feature figure is for example
Including step S310-S330 shown in Fig. 3.
The processing of above-mentioned steps S310-S330 is described in conjunction with Fig. 4.
Fig. 4 gives time domain-airspace matching method schematic diagram.It is f that left figure in Fig. 4, which shows optical frequency,0Detecting optical pulses
The received signal strength figure (example as the first time domain-spatial feature figure) in constant temperature variation, right figure shows optical frequency
For f0The detecting optical pulses of+Δ f constant temperature change when received signal strength figure (as the second time domain-spatial feature figure
Example).
It should be noted that the first time domain-spatial feature figure and the second time domain-spatial feature figure are used two in Fig. 4
The form for tieing up figure indicates, that is to say, that in Fig. 4, abscissa indicates the position on testing fiber, and ordinate indicates photodetection
Device 1-11 receive after to the corresponding receiving time of Rayleigh scattering echo-signal, and photodetector 1-11 received signal intensity
Or signal amplitude then uses brightness of image or gray scale to indicate that (i.e. different signal strengths or signal amplitude are presented as not in Fig. 4
With the point of brightness or different gray scales).
For example, it is assumed that the coordinate of preset first position point is (xP, yP, zP), that is, the first of preset first position point tie up,
Two-dimensional coordinate is (xP, yP), it is assumed that predefined size neighborhood is with the point (xP, yP) centered on ZW×tWThe rectangle of size is (wherein,
ZWFor the size on one-dimensional coordinate, tWFor the size on two-dimensional coordinate).In other words, the preset first position point (xP,
yP) predefined size neighborhood in data point composed by data area be one-dimensional coordinate
In range, two-dimensional coordinateRegion composed by data in range.As shown in figure 4, first
M in time domain-spatial feature figure (left figure) indicates reference data region.
In step s310, in the second time domain-spatial feature figure, by the one-dimensional coordinate with preset first position point
The data point of the predefined size neighborhood of identical second position point is formed by data area as data area to be matched.
Wherein the initial position of second position point selected in the second frequency domain-spatial feature figure can be and above-mentioned
Identical any point (the x of one-dimensional coordinate of first position point in one frequency domain-spatial feature figurep, y 'p), that is to say, that second
The one-dimensional coordinate of the initial position of location point is equal to the one-dimensional coordinate x of first position pointp, and the initial bit of second position point
The two-dimensional coordinate y ' setpIt can be with the two-dimensional coordinate y of first position pointPDifference, can also be identical.In this way, data to be matched
One-dimensional coordinate in region i.e. the second time domain-spatial feature figureIn range, two-dimensional coordinateRegion S composed by data in range.
In step s 320, the two-dimensional coordinates by data area to be matched along the second time domain-spatial feature figure (are schemed
Time shaft in 4) it is mobile, it obtains and is moved between resulting data area to be matched and reference data region every time in moving process
Difference matrix, and calculate every time resulting difference matrix all elements quadratic sum.That is, in the second frequency domain-sky
After the initial position for selecting second position point in characteristic of field figure, by enabling, the one-dimensional coordinate of second position point is constant, changes
The mode of two-dimensional coordinate moves second position point, thus to obtain it is each it is mobile after data area to be matched, and then obtain
Corresponding difference matrix.
Wherein, by data area S to be matched along the second time domain-spatial feature figure two-dimensional coordinates (i.e. in Fig. 4 when
Between axis) mobile mode can be there are many implementation.
For example, data area S to be matched is mobile along the side (such as upside in Fig. 4) of above-mentioned time shaft, it moves every time
Dynamic step-length is preset value (can set, or be determined by the method for test based on experience value etc.), when being moved to image side
When boundary, returns initial position and moves data area S to be matched along the other side (downside in such as Fig. 4) of above-mentioned time shaft,
The step-length moved every time is still preset value, until being moved to boundary.A mobile step-length every time, obtains difference square described above
Battle array, and calculate the quadratic sum of all elements of difference matrix.
Or can successively move data area S to be matched (along time shaft) according to preset step-length from side boundary,
Until being moved to another lateral boundaries, and every time move a step-length when, obtain difference matrix described above, and calculate
The quadratic sum of all elements of difference matrix.
In step S330, determine corresponding when the quadratic sum minimum of all elements of the difference matrix in moving process
Difference matrix, using the corresponding data area to be matched of the difference matrix as matched data region.
Such as, it is assumed that entire moving process moves 100 times in total, has obtained 100 difference matrix, has selected this 100
That the smallest difference matrix of the quadratic sum of all elements in difference matrix, by the corresponding data area to be matched of the difference matrix
S is as matched data region.
Fig. 2 is returned to, as shown in Fig. 2, calculating reference data region and matched data region in the second dimension in step S240
Displacement on coordinate, to be determined between the first time domain-spatial feature figure and the second time domain-spatial feature figure according to the displacement
Time delay.
Wherein, reference data region for example can be according to respective with displacement of the matched data region on two-dimensional coordinate
The distance between central point calculates (can also be according to other methods), for example, the center position in reference data region is
(xP, yP), the center position in matched data region is (xP, y 'P), then reference data region and matched data region are second
The displacement tieed up on coordinate is y 'P-yP.That is, time delay is equal to y 'P-yP。
In step s 250, according to the frequency difference and time delay between first frequency and second frequency, light to be measured is calculated
Fine temperature changing speed or strain variation speed.
As an example, the strain variation speed of testing fiber can for example obtain in the following way:
The strain knots modification Δ ε of testing fiber corresponding to a calculating time delay calculated according to the following formula.
Formula one:
In formula one, Δ v indicates the frequency difference between first frequency and second frequency, and v indicates light wave fundamental frequency, pεIndicate bullet
Backscatter extinction logarithmic ratio, wherein v and pεFor known constant, Δ ε indicates that the strain of testing fiber corresponding to time delay calculated changes
Amount, KεIndicate the coefficient of strain, Kε=-1+pε。
In this way, obtained time delay τ and that strain knots modification Δ ε corresponding with time delay τ, then it can root
According to the ratio of the strain knots modification Δ ε and time delay τ calculated of testing fiber corresponding to time delay τ calculated
(as the first ratio) obtains the strain variation speed (being equal to above-mentioned first ratios delta ε/τ) of testing fiber.
In addition, as an example, the temperature changing speed of testing fiber can for example obtain in the following way:
The temperature knots modification Δ T of testing fiber corresponding to two calculating time delays calculated according to the following formula.
Formula two:
In formula two, Δ v indicates the frequency difference between first frequency and second frequency, and v indicates that light wave fundamental frequency, ξ indicate heat
Backscatter extinction logarithmic ratio, α indicate thermal expansion coefficient, wherein ξ and α be known constant, Δ T indicate corresponding to time delay calculated to
Survey the temperature knots modification of optical fiber, KTIndicate temperature coefficient, KT=-(ξ+α).
In this way, obtained time delay τ and that temperature knots modification Δ T corresponding with time delay τ, then it can root
According to the ratio of the temperature knots modification Δ T and time delay τ calculated of testing fiber corresponding to time delay τ calculated
(as the second ratio) obtains the temperature changing speed (being equal to above-mentioned second ratios delta T/ τ) of testing fiber.
In this way, after the temperature changing speed or strain variation speed for obtaining testing fiber by step S250,
In step S260, according to temperature changing speed or the product of strain variation speed and corresponding time of measuring, determine that testing fiber exists
Temperature variation (being equal to time of measuring multiplied by temperature changing speed Δ T/ τ) or strain variation amount in corresponding time of measuring
(being equal to time of measuring multiplied by strain variation speed Δ ε/τ).Time of measuring is, for example, to terminate from the measurement time started to measurement
This period of time of time, wherein the measurement time started is, for example, the transmission of the pulse of first sending in multiple groups pulse pair
Time, measurement end time are, for example, the sending time of the last one pulse issued in multiple groups pulse pair.
As can be seen from the above description, the present invention in laser light source output laser optical frequency be it is scheduled, laser source output
Continuous light is modulated to pulsed light by acousto-optic modulator by arbitrary-function generator, and each periodic modulation goes out two pulses, simultaneously
The different amount of shift frequency respectively.Then power amplification is carried out to direct impulse light using erbium-doped fiber amplifier, is infused by circulator
Enter in testing fiber, may be implemented using testing fiber to the temperature and dynamic strain sensing in external environment.Backward Rayleigh dissipates
It penetrates signal to recycle via circulator, be filtered using fiber bragg grating, filter out the spontaneous emission noise of EDFA, then make
Electric signal is converted optical signals to photodetector.
Comprising the pulsed light that two optical frequencies are different in direct impulse each period, the time interval of two pulses is greater than light and exists
Propagation time in testing fiber.The echo-signal of each pulse represents the Rayleigh scattering information of different location in optical fiber, leads to
It crosses and is repeatedly detected, can be obtained in optical fiber each position Rayleigh scattering signal with ambient temperature or the change of strain.Fig. 4
Middle two width figure of left and right is respectively the different direct impulse received signal of two frequencies.Data processing i.e. will by matching primitives,
Calculate the time delay of two figures.
In the measurement method of the embodiment of the present invention, the demodulation of data uses time domain-airspace matching technique, i.e., using figure
As matching process obtains time delay, correct time retardation is obtained with this, while keeping high time resolution energy
Power.When demodulating the temperature or strain variation value of a certain position, the data point of spatial neighborhood at selection Fig. 4 left figure position or so
As pattern matrix M (i.e. reference data region), the rectangular area S in Fig. 4 right figure at same position is moved along time shaft, is moved
It will subtract each other to obtain difference matrix with the element of homography S during dynamic, calculate the quadratic sum of difference matrix all elements, record
The amount of movement of corresponding matrix S when quadratic sum minimum determines the time delay of two figures of left and right with this amount of movement, according to the time
Retardation and every group pulse obtain the pace of change of temperature or strain to the frequency difference between two pulses, and then are measured
Temperature or strain variation in time.
In addition, although describing the operation of the method for the present invention in the accompanying drawings with particular order, this do not require that or
Hint must execute these operations in this particular order, or have to carry out shown in whole operation be just able to achieve it is desired
As a result.Additionally or alternatively, it is convenient to omit multiple steps are merged into a step and executed by certain steps, and/or by one
Step is decomposed into execution of multiple steps.
Although detailed description of the preferred embodimentsthe spirit and principles of the present invention are described by reference to several, it should be appreciated that, this
It is not limited to the specific embodiments disclosed for invention, does not also mean that the feature in these aspects cannot to the division of various aspects
Combination is benefited to carry out, this to divide the convenience merely to statement.The present invention is directed to cover appended claims spirit and
Included various modifications and equivalent arrangements in range.
Claims (7)
1. being based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace, it is characterised in that including generation device and detection device；
The generation device includes laser source (1-1), acousto-optic modulator (1-2), arbitrary-function generator (1-3) and the first er-doped
Fiber amplifier (1-4)；
The detection device includes circulator (1-5), the second erbium-doped fiber amplifier (1-6) and photodetector (1-7)；
The continuous light of laser source (1-1) output is modulated to pulsed light by the acousto-optic modulator (1-2), so that each week
Phase modulates two pulses by the acousto-optic modulator (1-2), and the frequency of two pulses is respectively first frequency and second
Frequency, wherein the arbitrary-function generator (1-3) exports for generating preset square-wave signal to the acousto-optic modulator
(1-4)；
The pulsed light of the acousto-optic modulator (1-2) output is via after first erbium-doped fiber amplifier (1-4) amplification, again pass through
In circulator (1-5) the injection testing fiber；
Backward Rayleigh scattering echo-signal in the testing fiber is exported through the circulator (1-5) to the second er-doped light
Fiber amplifier (1-6) is detected after second erbium-doped fiber amplifier (1-6) amplification by the photodetector (1-7)；
Wherein, the time interval between adjacent pulse modulated by the acousto-optic modulator (1-2) be greater than light it is described to
Survey the propagation time in optical fiber.
2. according to claim 1 be based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace, it is characterised in that also wrap
Filter is included, the filter is set between second erbium-doped fiber amplifier (1-6) and the photodetector (1-7),
For filtering out the spontaneous emission noise of second erbium-doped fiber amplifier (1-6).
3. according to claim 2 be based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace, which is characterized in that institute
Filter is stated to realize using fiber bragg grating (FBG).
4. the measurement method based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace, which is characterized in that the measurement method base
It is realized in of any of claims 1-3 based on the matched phase sensitivity type optical time domain reflectometer in time domain-airspace；The measurement
Method includes:
Two pulses that each period is modulated by the acousto-optic modulator (1-2) are as a set of pulses pair；
Multiple groups pulse pair is generated by the generation device, successively testing fiber is squeezed into through the detection device, by the detection
Photodetector (1-7) in device receives the corresponding backward Rayleigh scattering echo-signal of the multiple groups pulse pair, wherein described
The corresponding backward Rayleigh scattering echo-signal of multiple groups pulse pair includes each pulse in the multiple groups pulse in the light to be measured
Backward Rayleigh scattering echo-signal in fine each position；
Backward Rayleigh scattering echo-signal corresponding with having the pulse of first frequency in the multiple groups pulse pair based on the received,
Obtain the first time domain-spatial feature figure；
Backward Rayleigh scattering echo-signal corresponding with having the pulse of second frequency in the multiple groups pulse pair based on the received,
Obtain the second time domain-spatial feature figure；
Wherein, the first time domain-spatial feature figure and the second time domain-spatial feature figure are with the position on testing fiber for first
It ties up coordinate, be two-dimensional coordinate, with the photodetector (1-7) with the signal reception time of the photodetector (1-7)
Received signal intensity or signal amplitude are third dimension coordinate；
The reference data region of predetermined size is chosen in the first time domain-spatial feature figure,
The corresponding matched data region in the reference data region is determined in the second time domain-spatial feature figure,
The reference data region and displacement of the matched data region on two-dimensional coordinate are calculated, according to the displacement
Measure the time delay determined between the first time domain-spatial feature figure and the second time domain-spatial feature figure；
According to the frequency difference and the time delay between the first frequency and second frequency, the temperature of the testing fiber is calculated
Spend pace of change or strain variation speed；
According to the temperature changing speed or the product of strain variation speed and corresponding time of measuring, determine that the testing fiber exists
Temperature variation or strain variation amount in the corresponding time of measuring.
5. measurement method according to claim 4, which is characterized in that when the reference data region includes described first
The data point of the predefined size neighborhood of preset first position point in domain-spatial feature figure；
The step of corresponding matched data region in the reference data region is determined in the second time domain-spatial feature figure is wrapped
It includes:
In the second time domain-spatial feature figure, by identical with the one-dimensional coordinate of the preset first position point
The data point of the predefined size neighborhood of two location points is formed by data area as data area to be matched；
The second dimension reference axis by data area to be matched along the second time domain-spatial feature figure moves, and obtains moving process
In move difference matrix between resulting data area to be matched and the reference data region every time, and calculate gained every time
Difference matrix all elements quadratic sum；
Difference matrix corresponding when the quadratic sum minimum of all elements of the difference matrix in moving process is determined, by the difference
The corresponding data area to be matched of matrix is as the matched data region.
6. measurement method according to claim 4 or 5, which is characterized in that the strain variation speed of the testing fiber is logical
Under type such as is crossed to obtain:
The strain knots modification of the testing fiber corresponding to time delay calculated is calculated according to the following formula:
Wherein, Δ v indicates the frequency difference between the first frequency and second frequency, v
Indicate light wave fundamental frequency, pεIndicate that elasto-optical coefficient, Δ ε indicate the strain of the testing fiber corresponding to time delay calculated
Knots modification, KεIndicate the coefficient of strain；
The strain knots modification of the testing fiber according to corresponding to time delay calculated and time delay calculated it
Than obtaining the strain variation speed of the testing fiber.
7. the measurement method according to any one of claim 4-6, which is characterized in that the temperature change of the testing fiber
Speed obtains in the following way:
The temperature knots modification of the testing fiber corresponding to time delay calculated is calculated according to the following formula:
Wherein, Δ v indicates the frequency difference between the first frequency and second frequency, v
Indicate that light wave fundamental frequency, ξ indicate that thermo-optical coeffecient, α indicate that thermal expansion coefficient, Δ T indicate institute corresponding to time delay calculated
State the temperature knots modification of testing fiber, KTIndicate temperature coefficient；
The temperature knots modification of the testing fiber according to corresponding to time delay calculated and time delay calculated it
Than obtaining the temperature changing speed of the testing fiber.
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