CN107560710A - A kind of three-dimensional vibrating signal antinoise method towards Φ OTDR techniques - Google Patents
A kind of three-dimensional vibrating signal antinoise method towards Φ OTDR techniques Download PDFInfo
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Abstract
The invention discloses a kind of three-dimensional vibrating signal antinoise method towards Φ OTDR techniques.The denoising method of the present invention is to carry out denoising for two noise likes, in terms of the denoising of coherent noise, because coherent noise is regular in time domain, therefore the method for the present invention is desirable to be finally reached with the function of periodic transformation and carry out coherent noise one effective counteracting by establishing one.In terms of the denoising of random noise, the smooth Wiener-Hopf equation filtering algorithm of adding window of the invention, it is ensured that got a promotion while signal to noise ratio and signal effective range.Comprise the following steps that：Step 1: determine the average signal-to-noise ratio and signal effective range of primary signal；Step 2: the filtering and noise reduction of coherent noise；Step 3: the filtering and noise reduction of random noise.
Description
Technical field
The present invention relates to a kind of three-dimensional vibrating signal antinoise method towards Φ-OTDR technique, belong to fully distributed fiber
Field of signal processing in sensing technology.
Background technology
Along with the fast development of optical fiber communication technology, optical fiber sensing technology obtained in recent years further investigation and it is extensive
Health monitoring problem applied to multiple fields.The one kind of distributed optical fiber sensing technology as optical fiber sensing technology, because
Its good distributed nature is more and more widely paid attention to.Distributed optical fiber sensing technology can be divided into from principle
Three major types, it is Brillouin scattering, Rayleigh scattering, Raman scattering respectively.Brillouin scattering is mainly to monitor deformation and temperature, is drawn
Graceful scattering is mainly monitoring temperature, and Rayleigh scattering is mainly monitoring vibration.Method based on Rayleigh scattering monitoring vibration has
A lot, wherein coherent light time domain reflection technology (Ф-OTDR) is a kind of than more typical and relative maturity of detection vibration signal
Method, therefore present invention is generally directed to the signal of Φ-OTDR technique collection to be studied.
The signal of Φ-OTDR technique collection is a three-dimensional vibrating signal, therefore the filtering and noise reduction of signal is treated as
To the underlying issue entirely studied.The good and bad method of evaluation signal has a lot, such as：Signal to noise ratio, signal intensity, the bit error rate,
Transmission rate etc..But in these above-mentioned evaluation methods, have plenty of the evaluation for signal of communication, have plenty of and received for single-point
The evaluation of voice/vibration data of collection, they are not for the method for Φ-OTDR technique data, it is therefore desirable to which one meets
The evaluation index of Φ-OTDR technique.Three length, time and amplitude information are included based on the Φ-OTDR vibration datas monitored,
Signal, is divided into two parts and is studied by present invention the advantages of combining the above method and actual conditions, a part be " when it is m-
The estimation of signal to noise ratio in amplitude " plane, another part are the useful signal length ranges in " length-amplitude " plane.
, it is necessary to carry out the research of an entirety to denoising method on the basis of evaluation index is determined.In practical application
In, the vibration of optical fiber sensing is conducted by object to be detected to come, therefore noisy research theory, noise can for combination
To be divided into coherent noise and random noise.The appearance of coherent noise in time has regularity, is mainly conducted through including medium
Sound wave, face ripple, the more subwaves etc. come.Random noise does not have certain rule, is typically caused by surrounding environment, such as the rustle of leaves in the wind,
People and animals walk about, systematic error etc..For the denoising method of coherent noise, have：It is bandpass filtering method, f-k converter techniques, small echo, fuzzy
The method of differentiation etc..But the above-mentioned denoising method for coherent noise, have plenty of and directly cut off in time domain, had plenty of in frequency
Directly cut off on domain, also have plenty of it is similar with the filtering and noise reduction method of random noise, they not for coherent noise spy
Point is handled.Have for the denoising method of random noise：Fitting of a polynomial, KL conversion, SVD is decomposed, time-frequency division handles, be small
The modes such as ripple filtering.Above-mentioned Noise Filter method, which has plenty of, lays particular emphasis on signal smoothing, has plenty of and focuses on improving signal letter
Make an uproar and compare, have plenty of the separation for laying particular emphasis on signal and noise, but these methods can not balance above-mentioned two well and evaluate and refer to
Relation between mark, it is impossible to ensure signal to noise ratio and signal effective range while improve.Therefore for the three-dimensional of Φ-OTDR technique collection
The filtering and noise reduction problem of vibration signal, become the Important Problems of experts and scholars' concern.
The content of the invention
In order to overcome the shortcomings of above-mentioned technology, the invention provides a kind of three-dimensional vibrating signal towards Φ-OTDR technique
Denoising method.
In terms of the denoising of coherent noise, because coherent noise is regular in time domain, therefore the method for the present invention
It is desirable to be finally reached with the function of periodic transformation and carry out coherent noise one effective counteracting by establishing one.
In terms of the denoising of random noise, adding window of the invention is smooth-Wiener-Hopf equation filtering algorithm, it is ensured that signal to noise ratio and signal are effective
Got a promotion while scope.
The present invention provides a kind of three-dimensional vibrating signal antinoise method towards Φ-OTDR technique, main including following several
Step：
Step 1: determine the average signal-to-noise ratio and signal effective range of primary signal；
Step 2: the filtering and noise reduction of coherent noise；
Step 3: the filtering and noise reduction of random noise；
The advantage of the invention is that：
(1) the present invention is in order to adapt to reference needs of the Φ-OTDR technique in actual conditions, and present invention employs signal to noise ratio
With signal effective range two indices as judgment criteria.
(2) the present invention utilizes five interpolation of Emmett and Berlin to suppress the coherent noise of multiple points in effective range
Noise is combined mode and generates periodic noise in time domain, effectively inhibits coherent noise.
(3) the present invention is smooth using Wiener-Hopf equation combined window for signal to noise ratio and signal effective range the two indexs
Filtering method carry out Removing Random No, the signal to noise ratio and signal effective range of signal can be improved simultaneously.
Brief description of the drawings
Fig. 1 is algorithm flow chart in the present invention；
Fig. 2 is original clear signal oscillogram in the present invention；
Fig. 3 is original small-signal oscillogram in the present invention；
Fig. 4 generates coherent noise for five interpolation methods of Emmett in the present invention；
Fig. 5 generates coherent noise method for Berlin noise in the present invention；
Fig. 6 is the method that interpolation and Berlin are combined in the present invention.
Embodiment
The present invention is described in detail with reference to the accompanying drawings and examples.
A kind of three-dimensional vibrating signal antinoise method towards Φ-OTDR technique provided by the invention, system block diagram such as Fig. 1 institutes
Show, it is as follows to specifically include step：
Step 1: determine the average signal-to-noise ratio and signal effective range of primary signal.
Signal to noise ratio, English name are called SNR or S/N (SIGNAL-NOISE RATIO), also known as signal to noise ratio.Refer to one
The ratio of signal and noise in electronic equipment or electronic system.The measurement unit of signal to noise ratio is dB, its computational methods such as formula
(1) shown in.
The effective power of wherein Ps and Pn difference representation signals and noise.Because what instrument and equipment finally monitored is all electricity
Signal, therefore signal to noise ratio can also be converted into the ratio of voltage magnitude, as shown in formula (2).
Signal effective range, refer under the premise of ensureing that signal to noise ratio is effective in " when m- amplitude " plane, in " length-width
Maximum effective distance in degree " plane.
Step 2: the filtering and noise reduction of coherent noise.
In order to remove coherent noise, the method that the tradition that the present invention does not use directly is cut off, but establish a time domain
On periodic function, in order that this function is applied to the denoising situation in multiple length points, therefore establish the step of coherent noise
It is rapid as follows：
(1) is a cycle signal in time domain because of coherent noise, therefore firstly the need of determination period of a function.
(2) for multiple numerical points are generated during the sampling period, logarithm value point carries out five interpolation methods of Emmett.
(3) noise as steps 2 have one it is apparent the problem of, exactly local maximin is all in integer
Position, a kind of improved method is exactly to use gradient noise, that is, Berlin noise.
(4) interpolation Berlin noise is the combination of both above noise, thus above the problem of solve.
(5) is function obtained above, and overlapping n cycle, n such as formula (3) are shown repeatedly.
(6) removes to preferably adapt to the coherent noise in the range of actual induction in multiple " time~amplitude " planes,
To the function tried to achieve above, plus an auto-adaptive parameter, i+ △ i, △ i scope take 1~19, then take SNR=min [SNR
(i)], wherein i=1,2 ..., 20.
(7) can be removed before and after coherent noise to the data of " time~amplitude " plane in effective range herein
Signal-to-noise ratio data analysis.
Step 3: the filtering and noise reduction of random noise.
After being suppressed to coherent noise, in terms of denoising is also filtered to random noise, to be mainly directed to " long
Degree~amplitude " and " time~amplitude " two class plane are studied.Therefore the filtering method that the present invention uses also fully takes into account
The characteristics of two class planes.Comprise the following steps that：
(1) time of signals is designated as t, and length is designated as l, and actual signal output is denoted as y (t, l).
(2) is denoted as x in the suppression noise output of " time~amplitude " plane1(t), in the suppression of " length~amplitude " plane
Noise output processed is denoted as x2(l)。
(3).x1And x (t)2(t) Wiener-Hopf equation distribution is all obeyed, standard Wiener-Hopf equation refers to that it is 0 to obey average, and variance is
T/l normal distribution.
(4) it is m sampled point that, which sets window width,.
(5) carries out window smoothing processing in two class planes, i.e., to take the average of each amplitude according to window, and
Deploy respectively in two class planes.
Embodiment one
The present invention is described in detail with reference to the accompanying drawings and examples.
A kind of three-dimensional vibrating signal antinoise method towards Φ-OTDR technique provided by the invention, specifically includes step such as
Under：
Step 1: determine the average signal-to-noise ratio and signal effective range of primary signal.
The signal sent from vibration source, three-dimensional vibrating signal is converted to, can be most strong from certain point on optical fiber, signal can be along light
Fibre gradually weakens to both ends, therefore the present invention respectively substantially locate and waveform at weak output signal by the number of winning the confidence, hence it is evident that waveform such as Fig. 2 institutes of place
Show, faint place's waveform is as shown in Figure 3.Signal is substantially located, and the signal virtual value of waveform is 314mV, and noise virtual value is 101mV,
Signal to noise ratio is 9.97dB.At weak output signal, the signal and noise of waveform are not too much easily differentiated.
Step 2: the filtering and noise reduction of coherent noise.
In order to remove coherent noise, the method that the tradition that the present invention does not use directly is cut off, but establish a time domain
On periodic function, in order that this function is applied to the denoising situation in multiple length points, therefore establish the step of coherent noise
It is rapid as follows：
(1) because coherent noise be a cycle signal in time domain, therefore firstly the need of determine period of a function, one
As need according to sample frequency design the sampling period, according to the sample frequency of Φ-OTDR technology typically in 200Hz~20KHz
, it is therefore desirable to the cycle of reference is that 20 sampled points are more suitable.
(2) carries out five interpolation methods of Emmett during the sampling period with 10 numerical points of generation, logarithm value point.
Effect is as shown in Figure 4.
(3) noise as steps 2 have one it is apparent the problem of, exactly local maximin is all in integer
Position, a kind of improved method is exactly to use gradient noise, that is, Berlin noise.Effect is as shown in Figure 5.
(4) interpolation Berlin noise is the combination of both above noise, thus above the problem of solve.Effect is such as
Shown in Fig. 6.
(5) is function obtained above, repeatedly the overlapping n cycle, sampling period 4000Hz, storage time 2.5s,
Therefore number of cycles is 5000.
(6) removes to preferably adapt to the coherent noise in the range of actual induction in multiple " time~amplitude " planes,
To the function tried to achieve above, plus an auto-adaptive parameter, i+ △ i, △ i scope take 1~19, then take SNR=min [SNR
(i)], wherein i=1,2 ..., 20.It is optimum efficiency through overtesting i=11.
(7) can be removed coherent noise to the data of 17 in 42 to 58 meters " time~amplitude " planes herein
Front and rear signal-to-noise ratio data analysis.The signal to noise ratio average value on 17 points obtained in data from 9.97dB lifted to
10.45dB。
Step 3: the filtering and noise reduction of random noise.
After being suppressed to coherent noise, in terms of denoising is also filtered to random noise, to be mainly directed to " long
Degree~amplitude " and " time~amplitude " two class plane are studied.Therefore the filtering method that the present invention uses also fully takes into account
The characteristics of two class planes.Comprise the following steps that：
(1) time of signals is designated as t, and length is designated as l, and actual signal output is denoted as y (t, l).Shared in notebook data
10000 sampled points, length are 100 meters, 1 meter of minimum interval.
(2) is denoted as x in the suppression noise output of " time~amplitude " plane1(t), in the suppression of " length~amplitude " plane
Noise output processed is denoted as x2(l)。
(3).x1And x (t)2(t) Wiener-Hopf equation distribution is all obeyed.Calculation formula is as follows：
x1(t)~N (0, t), x2(l)~N (0, l)
(4) it is m=10 sampled point that, which sets window width,.
(5) carries out window smoothing processing in two class planes.Specific formula for calculation is as follows：
Analyzed in the data for filtering out coherent noise, the signal to noise ratio average value on the point of 17 obtained is from 10.45dB
11.56dB is lifted.It can observe that the scope of signal is expanded to 19 points simultaneously.
100 groups of Monitoring Datas are tested, it is consistent to have obtained effect with the effect described in embodiment one, is obtained
Conclusion is as follows：
Conclusion 1：In 100 groups of experiments, it is contemplated that the actual conditions that Φ-OTDR technique technology uses, the present invention use noise
It is correct than carrying out evaluation with signal effective range two indices；
Conclusion 2：In 100 groups of experiments, using the method for interpolation method combination Berlin noise, the denoising to coherent noise,
The signal to noise ratio within the scope of effective coverage can be effectively improved.
Conclusion 3：In 100 groups of experiments, using Wiener-Hopf equation combined window smothing filtering, random noise is carried out at denoising
Reason, can effectively improve the signal to noise ratio in signal effective range and effective range.
Test result indicates that the inventive method is applied to the filtering process of Φ-OTDR technique, it is the three-dimensional of Φ-OTDR technique
The filtering process of vibration signal provides a kind of effective way.
Claims (3)
1. a kind of three-dimensional vibrating signal antinoise method towards Φ-OTDR technique provided by the invention, system block diagram such as Fig. 1 institutes
Show, it is as follows to specifically include step：
Step 1: determine the average signal-to-noise ratio and signal effective range of primary signal；
Step 2: the filtering and noise reduction of coherent noise；
Step 3: the filtering and noise reduction of random noise.
2. optimization construction method according to claim 1, it is characterised in that：Step 2: the filtering and noise reduction of coherent noise.For
Removal coherent noise, the method that the tradition not used herein is directly cut off, but the periodic function established in a time domain,
In order that this function is applied to the denoising situation in multiple length points, thus it is as follows the step of establish coherent noise：
(1) is a cycle signal in time domain because of coherent noise, therefore firstly the need of determination period of a function.
(2) for multiple numerical points are generated during the sampling period, logarithm value point carries out five interpolation methods of Emmett.
(3) noise as steps 2 have one it is apparent the problem of, be exactly local maximin all in the position of integer,
A kind of improved method is exactly to use gradient noise, that is, Berlin noise.
(4) interpolation Berlin noise is the combination of both above noise, thus above the problem of solve.
(5) is function obtained above, and overlapping n cycle, n such as formula (3) are shown repeatedly.
(6) removes to preferably adapt to the coherent noise in the range of actual induction in multiple " time~amplitude " planes, to upper
The function that face is tried to achieve, plus an auto-adaptive parameter, i+ △ i, △ i scope take 1~19, then take SNR=min [SNR
(i)], wherein i=1,2 ..., 20.
(7) can be removed the letter before and after coherent noise to the data of " time~amplitude " plane in effective range herein
Make an uproar and compare data analysis.
3. optimization construction method according to claim 1, it is characterised in that：Step 3: the filtering and noise reduction of random noise.It is right
After coherent noise is suppressed, in terms of denoising is also filtered to random noise, mainly " length~amplitude " is directed to
" time~amplitude " two class plane is studied.Therefore the filtering method used herein has also fully taken into account two class planes
Feature.Comprise the following steps that：
(1) time of signals is designated as t, and length is designated as l, and actual signal output is denoted as y (t, l).
(2) is denoted as x in the suppression noise output of " time~amplitude " plane1(t), in the suppression noise of " length~amplitude " plane
Output is denoted as x2(l)。
(3).x1And x (t)2(t) Wiener-Hopf equation distribution is all obeyed, standard Wiener-Hopf equation refers to that it is 0 to obey average, and variance is t/l
Normal distribution.
(4) it is m sampled point that, which sets window width,.
(5) carries out window smoothing processing in two class planes, i.e., to take the average of each amplitude according to window, and two
Class plane is deployed respectively.
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Cited By (1)
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