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CN109084816A - A kind of anti-polarization decay alarm algorithm of Fibre Optical Sensor signal - Google Patents

A kind of anti-polarization decay alarm algorithm of Fibre Optical Sensor signal Download PDF

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CN109084816A
CN109084816A CN201810548215.5A CN201810548215A CN109084816A CN 109084816 A CN109084816 A CN 109084816A CN 201810548215 A CN201810548215 A CN 201810548215A CN 109084816 A CN109084816 A CN 109084816A
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signal
phase
light intensity
signals
interference
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CN109084816B (en
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王青
孙峰
孙一峰
任仲杰
蒲涛
王敏
姜坤
崔珂
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Nanjing University of Science and Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
    • G01D5/35322—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with one loop with several directions of circulation of the light, e.g. Sagnac interferometer

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

本发明公开了一种光纤光栅传感信号的抗偏振衰落方法及报警算法，首先使用三态偏振分集接收器接收两相邻光纤光栅反射回来的干涉信号，将偏振态不确定的干涉信号分成三路，再由系统的信号发生器调制形成每路三组移相光强信号。然后通过每路的三组移相光强信号在一段采样时间中相互比较求解三路移相光强信号干涉对比度的大小，确定三路移相光强信号中对比度最好的一路，再结合三步移相算法进行光纤传感器振动的相位解调。然后采用离散差分算法处理相位信号序列并设定报警的阈值，统计差分后离散差分信号超过阈值的数目判断是否报警。该判定干涉信号对比度的方法实时性强，准确性高；报警算法监测动态信号变化能力强、精度较高、抗环境干扰能力强。

The invention discloses an anti-polarization fading method and an alarm algorithm of a fiber grating sensing signal. First, a three-state polarization diversity receiver is used to receive the interference signals reflected by two adjacent fiber gratings, and the interference signals with uncertain polarization states are divided into three channels, and then modulated by the signal generator of the system to form three groups of phase-shifted light intensity signals for each channel. Then, by comparing the three groups of phase-shifting light intensity signals of each channel in a period of sampling time, the size of the interference contrast of the three phase-shifting light intensity signals is determined, and the best contrast among the three phase-shifting light intensity signals is determined, and then combined with the three Phase-shifting algorithm for phase demodulation of optical fiber sensor vibration. Then use the discrete difference algorithm to process the phase signal sequence and set the threshold value of the alarm. After the difference is counted, the number of discrete difference signals exceeding the threshold value is used to judge whether to alarm or not. The method for judging the contrast of interference signals has strong real-time performance and high accuracy; the alarm algorithm has strong ability to monitor dynamic signal changes, high precision, and strong ability to resist environmental interference.

Description

A kind of anti-polarization decay alarm algorithm of Fibre Optical Sensor signal
Technical field
The invention belongs to technical field of optical fiber sensing, and in particular to a kind of anti-polarization decay alarm calculation of Fibre Optical Sensor signal Method.
Background technique
In China, with the deep implementation of policies of reform and opening to the outside world, wealth of society high speed increases, and compatriots are equally to the need of safety Ask higher and higher, more and more extensively.State's inner perimeter security product recent years will keep fast-developing situation, and development potentiality is huge Greatly.
It is compared with traditional electronic sensor, fiber-optic grating sensor fibre optical sensor has size small, light-weight, cost Many advantages, such as cheap, electromagnetism interference, high sensitivity is securely and reliably, corrosion-resistant, can carry out distributed measurement, be easy to networking, It has been widely used for temperature, vibration, the measurement of the parameters such as stress.
In actual operation, the signal that system is received from sensor fibre include invasion vibration signal, disturbing signal and Noise signal.The three kind signal parsers common to the alarm decision of three kinds of signals are respectively as follows: statistic algorithm, comentropy algorithm With fft analysis algorithm.
Statistic algorithm mainly from signal amplitude and invades signal and noise signal in terms of signal duration two to distinguish.When External force is on sensor fibre, and the invasion signal amplitude that system receives has significant change, and the duration is relatively long, and Noise signal amplitude is relatively small, and the amplitude duration is long.The algorithm key is that reasonable pulse lower threshold is arranged, if Threshold value is reasonable, can effectively distinguish three kinds of signals.To obtain reasonable lower threshold, needs to carry out a large amount of field test, obtain Proficiency data, and then analyze and obtain relatively reasonable threshold value；Comentropy is one that metric amount size is used in information theory Concept, information content is bigger, and entropy is also bigger.Can be with comentropy come gauge signal, the semaphore of statistics gatherer is each The distribution situation in section, and then the comentropy of the signal can be calculated, entropy is bigger, and signal information contained amount is also more.It is logical The comentropy of signal is crossed, i.e. information content contained by the signal, as the foundation for determining invasion.Statistic algorithm and comentropy algorithm are all It is to be analyzed in time domain, wherein statistic algorithm is more to be counted for the pulse shape of unlike signal, and comentropy is then Be to be obtained according to the probability distribution in signal difference section, direct relation had no between sampled value, distinguish invasion signal and Effect is more preferable in disturbing signal；FFT is fast discrete Fourier transformation, signal can be transformed from the time domain to frequency domain, work as signal When time domain is difficult to differentiate its feature, transforms to and be then easy to distinguish on frequency domain.
Chinese patent " optical fiber grating sensing modulation-demo-demodulation method and device based on phase shift signal modulation " (CN107290042A) in, when signal system demodulates light intensity phase, the interference light intensity that directly acquisition is spread out of from 3 port of circulator is believed The solution for number carrying out three step phase-shifting methods, then obtains the phase information of interference signal after unpacking.In the process, by fiber grating Group return interference light intensity signal polarization direction be it is uncertain, the feelings that will lead to difference in signal strength are directly received by detector Condition, light intensity signal can not be acquired when serious influences subsequent demodulating process.
Summary of the invention
The purpose of the present invention is to provide a kind of anti-polarization decay alarm algorithms of Fibre Optical Sensor signal, solve data and adopt Collection module receives the weak disadvantage of interference light intensity signal of circulator output, realizes and adopt to uncertain polarization state interference signal Collection；Simplify and realize that strong real-time, environment resistant interference performance be strong, the higher alarm algorithm of accuracy.
The technical solution for realizing the aim of the invention is as follows: a kind of anti-polarization decay alarm algorithm of Fibre Optical Sensor signal, Method and step is as follows:
Step 1 opens laser light source, and emergent light is made successively to pass through isolator, photoswitch and phase-modulator.Wherein, believe Number generator is connect with photoswitch and phase-modulator respectively, is generated pulse signal effect in photoswitch by signal generator, is produced Raw continuous light pulse, acts on phase-modulator, generates continuous phase impulse modulation.Form phase modulated laser pulse light Beam；The 1st port for entering circulator by the laser pulse light beam of phase-modulation enters the optical fiber of welding by its 2nd port Grating group.Fiber grating group can incude the vibration signal of environment, and when pulsed light beam is not through sharing the same light in fiber grating group When fine grating, there is partial pulse light beam to return to circulator, the signal of adjacent two fiber gratings reflection generates dry in circulator It relates to, then exports interference signal from the 3rd port of circulator.
Interference light intensity signal I (t) expression formula that step 2, two neighboring fiber grating generate is as follows:
Wherein, phase is closed For initial phase,For drift about phase,Indicate vibration signal phase, A, B is constant.It is generated for phase-modulator0、Three road light intensity signals phase intervals, substitute intoIt obtains Xin tri- road interference light intensity signal I (n) such as following formula:
That is:
The uncertain interference signal of polarization state being emitted from 3 port of circulator is received using three state polarization diversity receiver, And it is divided into tri- road interference signal of Xin, it all include three groups of above-mentioned interference light intensity signals per interference signal all the way；Three tunnels are dry It relates to signal and is converted to three tunnel light intensity electric signals, data collecting module collected light intensity electric signal by three photodetectors, and incite somebody to action It is sent into data processing module；Data processing module is finally obtained by the delay of calibration phase modulated signal and reception signal Two neighboring fiber grating generates three tunnels totally nine groups of phase shift light intensity signal I after interfering11、I12、I13、I21、I22、I23、I31、 I32、I33。
Step 3, three groups of phase shift light intensity signals for setting the first via are respectively I11, I12, I13, then | I11-I12| it is B1[cos(θ) + sin (θ)], | I11-I13| it is 2B1Sin (θ), | I12-I13| it is B1[cos(θ)-sin(θ)]；Will | I11-I12|, | I11-I13|, | I12-I13| in maximal term be denoted as Imax1；The I on the second tunnel is found out in the same waymax2And the I on third roadmax3。
Under synchronization, Imax1、Imax2And Imax3Three is simultaneously Bi[cos(θ)+sin(θ)]、 2BiSin (θ) or Bi In [cos (θ)-sin (θ)] a certain item (wherein i=1,2 or 3)；At a time, if Imax1、Imax2And Imax3Respectively B1 [cos(θ)+sin(θ)]、B2[cos(θ)+sin(θ)]、 B3[cos (θ)+sin (θ)], then compare Imax1、Imax2And Imax3It is big Small you can get it B1、B2、B3Size；B under different moments can be compared in the same wayiThe size of value, by BiIt is worth maximum Signal is determined as the maximum phase shift light intensity signal all the way of contrast all the way.
Step 4, the selection maximum light intensity signal of phase shift all the way of contrast are denoted as I1、I2、I3, then carry out three step phase-shifting methods Phase signal is solved and unpacks to obtain, phase signal contains the information of phase in time domain, and phase signal carries out forward difference meter Calculation obtains discrete differential signal, the discrete differential signal reaction change information of phase signal, wherein the signal segment changed greatly Show that there are disturbing signals in environment；The discrete differential signal under various environment, which is calculated, by acquisition carries out signal threshold value Tmin's Setting, statistics of the data discrete differential signal of progress beyond threshold point quantity that will acquire in a period of time, when passing through threshold It alarms when the quantity overrate of value point.
Compared with prior art, the present invention its remarkable advantage is:
(1) the uncertain interference signal of polarization state exported from circulator is obtained using three state polarization diversity receiver, it is real The reception to the interference signal is showed, has made receiving end that can receive the uncertain interference signal of polarization state.
(2) it is compared to each other in one section of sampling time using per three groups of phase shift light intensity signals all the way, by comparing identical multiply The light intensity peak factor of the method factor has determined the strongest phase shift light intensity signal all the way of contrast in three road signals.Acquired phase shift Light intensity signal be three road signals in subsequent calculating it is best all the way, and algorithm is easy, real-time is high, stability is strong.
(3) the discrete differential signal obtained through three step phase-shifting methods is handled by difference operator, obtains characterization phase signal The fairly obvious data of change rate, to judge to provide to calculate with the presence or absence of alarm factors in environment above to count with visually obvious According to.The timeliness of system can be met with discrete differential algorithm, quickly handle phase signal sequence.
(4) it is able to satisfy in use process according to the setting that the discrete differential signal acquired under different situations carries out threshold value to report The accurate judgement of alert signal can exclude the influence of ambient noise again, ensure that the accuracy of system reduces rate of false alarm.
(5) passed through using threshold value count legally constituted authority meter discrete differential signal pass through the number of threshold value can be to avoid enumerative mixed Confuse, number is passed through by the threshold value set in a period of time and carries out alarm decision, the method can pass through setting triggering alarm The specified sensitivity passed through quantity and effectively control alarm.
Detailed description of the invention
Fig. 1 is a kind of system structure diagram of the anti-polarization decay alarm algorithm of Fibre Optical Sensor signal of the invention.
Fig. 2 is the system flow chart of algorithm.
Fig. 3 be in the present invention three state polarization diversity receiver receive certain all the way in interference signal by signal generator tune System three groups of phase intervals be0、Interference light intensity signal graph.
Fig. 4 is in the present invention by certain phase shift light intensity signal all the way | I11-I12|, | I11-I13|, | I12-I13| middle maximal term It is denoted as Imax1, the I of other two-way is found out in the same waymax2And Imax3The comparison figure of latter three.
After Fig. 5 is judges the light intensity signal of phase shift all the way that contrast is best in three tunnel phase shift light intensity signals in the present invention, Three step phase-shifting methods are used to restore the phase signal figure after phase information unpacks.
Fig. 6 is the discrete differential signal graph for preferably obtaining contrast after phase signal series processing all the way in the present invention.
Specific embodiment
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, right with reference to the accompanying drawings of the specification A specific embodiment of the invention is described in detail.
The present invention is at Chinese patent " optical fiber grating sensing modulation-demo-demodulation method and device based on phase shift signal modulation " (CN107290042A) it on the basis of, is connect before using three step phase-shifting method demodulation phase signals using three state polarization diversity receiver The uncertain interference signal of polarization state is received, is divided into behind three tunnels by judging that phase shift contrast of the light signal intensity is optimal true all the way Determine the best light intensity signal of phase shift all the way of signal strength and carries out subsequent demodulation work.The road phase shift light intensity signal is used into three steps Forward difference processing is carried out again after phase-shifting method demodulation, the final discrete differential signal obtained in time domain, according to discrete differential Signal given threshold simultaneously judges alert if.
Step 1, in conjunction with Fig. 1, a kind of system building of the anti-polarization decay alarm algorithm of Fibre Optical Sensor signal is as follows:
The output end of laser light source is connected with the input terminal of isolator, the output end of isolator is then connected into photoswitch Input terminal, the output end of photoswitch is connected with the input terminal of phase-modulator, then phase-modulator output end and annular No. 1 port of device is connected.For circulator, by its No. 2 port welding optic fibre grating groups, by its No. 3 ports and three state polarization point Collect the input terminal connection of receiver, three output ends of three state polarization diversity receiver are defeated with three photodetectors respectively Enter end to be connected, the output end of three photodetectors is connect with the input terminal of data acquisition module jointly, finally acquires data The output end of module and the input terminal of data processing module connect.Wherein the output end of signal generator respectively with photoswitch and phase The control port of position modulator is connected, and regulates and controls the action time of the two.
Laser light source 1 is opened, the light that laser light source issues successively passes through isolator 2, photoswitch 3 and phase-modulator 4.Its In, signal generator 7 is connect with photoswitch 3 and phase-modulator 4 respectively, by signal generator 7 generate pulse signal effect in Photoswitch 3 generates continuous light pulse, acts on phase-modulator 4, generates continuous phase impulse modulation.It is formed phase modulated Laser pulse light beam；The 1st port for entering circulator 5 by the laser pulse light beam of phase-modulation, by its 2nd port into Enter the optical fiber of welding optic fibre grating group 6.When fiber grating 6 induction vibration of group, pulsed light beam is penetrated in fiber grating group 6 not When with fiber grating, there is partial pulse light beam to return to circulator 5.The interference is received using three state polarization diversity receiver 8 Signal, and the interference signal that polarization state portion determines is divided by three tunnels by the three state polarization diversity receiver 8, it is formed altogether newly Three road interference signals.Interference signal is converted to three tunnel light intensity electric signals by photodetector 9.The acquisition of data acquisition module 10 comes From 9 light intensity electric signals, it is finally sent to data processing module 11.Fiber grating group can incude the vibration signal of environment, and When pulsed light beam is through different fiber gratings in fiber grating group, there is partial pulse light beam to return to circulator, adjacent two The signal of fiber grating reflection generates interference in circulator.
Each fiber grating interval holding in step 2, the fiber grating group of circulator welding is identical, according to data processing mould Three tunnels that block generates every two adjacent fiber grating totally nine groups of phase shift light intensity signals, will be different by the data structure of setting Phase shift light intensity signal is distinguish, it is ensured that is not mixed mutually between each signal, is not interfered with each other.What two neighboring fiber grating generated Interference light intensity signal I (t) expression formula is as follows:
Wherein, phase is closed For initial phase,For drift about phase,Indicate vibration signal phase, A, B is constant；It is generated for phase-modulator0、The phase intervals of three road light intensity signals substitute intoIt obtains new Three road interference light intensity signal I (n) such as following formula:
That is:
I (n) is received using three state polarization diversity receiver, since the polarization state of interfering beam during this is uncertain, in It is to receive the uncertain interference signal of polarization state being emitted from 3 port of circulator using three state polarization diversity receiver and be divided into three Road then receives the uncertain interference letter of three groups of polarization states of three state polarization classification receiver output using three photodetectors Number, ensure that three photodetectors at least 1 can receive the resolving that interference signal carries out next step in this way. Collected interference signal is converted to three tunnel light intensity electric signals, data collecting module collected light intensity telecommunications by photodetector simultaneously Number, finally it is sent to data processing module；Data processing module passes through calibration phase modulated signal and receives the delay of signal, It obtains and generates three tunnels totally nine groups of phase shift light intensity signal I after two neighboring fiber grating interferes11、I12、I13、I21、I22、I23、 I31、I32、I33, wherein three groups of phase shift light intensity signals are as shown in Figure 3 in the first via.
The system flow chart of step 3, as shown in connection with fig. 2 algorithm, if the phase shift light intensity signal of the first via is respectively I11, I12, I13, then | I11-I12| it is B1[cos (θ)+sin (θ)], | I11-I13| it is 2B1Sin (θ), | I12-I13| it is B1[cos(θ)- sin(θ)].If the phase shift light intensity signal on the second tunnel is respectively I21, I22, I23, then | I21-I22| it is B2[cos (θ)+sin (θ)], | I21-I23| it is 2B2Sin (θ), | I22-I23| it is B2[cos(θ)-sin(θ)].If the phase shift light intensity signal on third road is respectively I31, I32, I33, then | I31-I32| it is B3[cos (θ)+sin (θ)], | I31-I33| it is 2S3Sin (θ), | I32-I33| it is B3[cos(θ)- sin(θ)].Will | I11-I12|, | I11-I13|, | I12-I13| in maximal term be denoted as Imax1, will | I21-I22|, | I21-I23|, | I22-I23| in maximal term be denoted as Imax2, will | I31-I32|, | I31-I33|, | I32-I33| in maximal term be denoted as Imax3.Same It inscribes for the moment, Imax1、 Imax2And Imax3Three is simultaneously Bi[cos(θ)+sin(θ)]、2BiSin (θ) or Bi[cos(θ)-sin (θ)] in a certain item (wherein i=1,2 or 3).Such as at a time, Imax1、Imax2And Imax3Respectively B1[cos(θ)+ sin(θ)]、B2[cos(θ)+sin/(θ)]、B3[cos (θ)+sin (θ)], then compare Imax1、Imax2And Imax3Size can obtain B out1、B2、B3Size；B under different moments can be compared in the same wayiThe size of value, by BiIt is worth maximum signal all the way It is determined as the maximum phase shift light intensity signal all the way of contrast.Wherein, certain two adjacent three tunnel phase shift light intensity signal of fiber grating compares Process is as shown in Figure 4 according to above-mentioned steps.
Step 4, the selection maximum light intensity signal of phase shift all the way of contrast are denoted as I1、I2、I3, then carry out as described in following formula The phase solution of three step phase-shifting methods:
The phase signal θ that will be obtained after the phase unwrapping acquired in time domain.Wherein, the phase signal θ such as Fig. 5 institute recovered Show.The phase signal θ of a period of time acquisition sequence constituted is set as array { xn, define difference operator Δ: Δ xn= xn+1-xnFor the forward difference at n, the phase signal sequence acquired is subjected to forward-difference operator processing and obtains discrete differential Signal, a certain segment difference sub-signal are as shown in Figure 6.The signal reaction change information of phase signal sequence, wherein changing greatly Signal segment show that there are disturbing signals in environment.The phase signal sequence under varying environment is acquired, phase signal sequence is poor Discrete differential signal is obtained after dividing processing and sets suitable threshold value Tmin, exclude the influence of slight perturbations in environment, reduce system Rate of false alarm counts the number that differential signal in a period of time exceeds threshold value after given threshold, when the number beyond threshold value is more Triggering alarm.
Embodiment 1
In conjunction with Fig. 1 to Fig. 6, a kind of anti-polarization decay alarm algorithm of Fibre Optical Sensor signal, experiment tests certain optical fiber light The vibration information of gate sensor, two grating fibers spacing are 24m, sampling time 22s, laser pulse period and phase-modulation arteries and veins The frequency of punching is 1MHz, and the pulse width of phase-modulation is 160ns in a cycle, selects light intensity signal and alarm algorithm real Existing step are as follows:
Step 1, in conjunction with Fig. 1, open laser light source 1 and simultaneously allow tester near the optical fiber of welding fiber grating group 6 It walks about, so that 6 induction vibration of fiber grating group, the light that laser light source 1 issues successively passes through isolator 2, photoswitch 3 and phase tune Device 4 processed, signal generator 7 generate the high-speed pulse signal that frequency is 1MHz, act on photoswitch 3, generate continuous laser arteries and veins Punching, while the phase-modulation of pi/2 being provided between providing to phase-modulator 4, phase modulated laser pulse light beam is formed, is passed through The laser pulse light beam of phase-modulation enters the 1st port of circulator 5, and the light of welding optic fibre grating group 6 is entered by the 2nd port Fibre generates interference signal after the reflection of fiber grating group 6 in circulator 5, and photoelectric converter 8 receives interference signal.Data Acquisition module 9 acquires the light intensity electric signal generated by photoelectric converter 8, and is sent to data acquisition module 10, data acquisition Module 10 transmits a signal to data processing module 11, and data processing module is by calibration phase modulated signal and receives signal Delay, to obtain three tunnel phase shift light intensity signals.
Step 2 keeps each fiber grating interval holding in the fiber grating group of circulator welding identical and is 24m.It is dry Relate to light intensity signal I (n) such as following formula:
That is:
I (n) is received using three state polarization diversity receiver, while photodetector is converted to collected interference signal Three tunnel light intensity electric signals, the data collecting module collected light intensity electric signal, are finally sent to data processing module.Data processing Module obtains after two neighboring fiber grating interferes by the delay of calibration phase modulated signal and reception signal and generates three Lu Gongjiu group phase shift light intensity signal I11、I12、I13、I21、I22、I23、I31、 I32、I33。
Step 3, the phase shift light intensity signal I by the first via11, I12, I13It indicates, three groups of phase shift light intensity signals locally put Big figure as shown in figure 3, in figure three kinds not synteny respectively represent three groups of phase shift light intensity signals that phase intervals are pi/2.It counts respectively Calculate | I11-I12|、|I11-I13|、|I12-I13|.Next will find out | I11-I12|、|I11-I13|、||I12-I13| in maximum Item is denoted as Imax1.The corresponding I in the second tunnel is found out in the same waymax2I corresponding with third roadmax3, three kinds of line styles in Fig. 4 The curve of drafting has respectively represented Imax1、Imax2、Imax3.As can be seen from the figure Imax3Representative phase shift light intensity signal all the way Contrast is maximum, the I in this segment signalmax1、Imax2And Imax3Maximum value be respectively 37,78,183；Mean value is respectively 22.3684,46.9813,110.0440.According to the choosing method of phase shift light intensity signal in three tunnels described previously, I is selectedmax3It represents The light intensity signal of phase shift all the way carry out subsequent phase resolving, data of the road the Gu Jiangci signal as later period resolving phase.
Step 4 chooses Imax3It is representative all the way in three groups of phase shift light intensity signals be denoted as I respectively1、I2、I3, this is comparison Spend strongest phase shift light intensity signal all the way.The resolving of phase is carried out then according to three step Phase-shifting algorithms, three step phase-shifting method such as following formulas:
The phase signal that will be obtained after the phase unwrapping acquired in time domain.Wherein, the phase signal recovered such as Fig. 5 institute Show.By a period of time, the phase signal sequence of acquisition is set as array { xn, define difference operator Δ: Δ xn=xn+1-xnFor at n Forward difference, by the phase signal sequence acquired carry out forward-difference operator processing obtain discrete differential signal.The signal is anti- The change information of phase signal sequence is answered, wherein the signal segment changed greatly shows that there are disturbing signals in environment.
The phase signal sequence under varying environment is acquired, suitable threshold value will be set after the processing of phase signal differential of sequence Tmin, the setting of threshold value should exclude the influence of slight perturbations in environment, reduce system rate of false alarm.The number that will be acquired in a period of time Exceed threshold point quantity statistics according to a signal is carried out, alarms when passing through the quantity overrate of threshold point.Fig. 6 institute It is shown as phase signal sequence carrying out the discrete differential signal obtained after forward difference processing, is illustrated as sensor-based system someone nearby The test signal walked about can acquire various ambient noise signals and defined alarm signal in actual samples, according to multiple groups The threshold value of signal setting alarm is acquired, such as the low alarm setting threshold value in embodiment can be selected as ± 0.5, count difference later Signal exceeds the number of threshold value, sets nominal threshold value according to ideal system sensitivity requirement and passes through quantity, when one section Between statistics pass through quantity a little compared with load quantity, judge whether to alarm.
The present embodiment realizes the measurement to phase oscillation signal by a series of measure.The discrete differential finally acquired Signal graph, fluctuation larger part be test man across optical fiber when generate, the amplitude of discrete differential signal and test man it is practical walk emotionally Condition is coincide, and the vibration signal for reflecting that the fiber grating signal is chosen and alarm algorithm accurately detects in working range becomes Change, shows that this method real-time height, strong operability, measurement accuracy is higher, environment resistant interference performance is strong.

Claims (7)

1.一种光纤传感信号的抗偏振衰落报警算法，其特征在于，方法步骤如下：1. a kind of anti-polarization fading alarm algorithm of optical fiber sensing signal, it is characterized in that, method step is as follows: 步骤1、打开激光光源，使出射光依次经过隔离器、光开关和相位调制器；其中，信号发生器分别与光开关和相位调制器连接，由信号发生器产生脉冲信号作用于光开关，产生连续光脉冲，作用于相位调制器，产生连续相位脉冲调制；形成经相位调制的激光脉冲光束，经过相位调制的激光脉冲光束进入环形器的第1端口，通过其第2端口进入熔接的光纤光栅组；光纤光栅组感应环境的振动信号，而当脉冲光束透过光纤光栅组中的不同光纤光栅时，均有部分脉冲光束返回环形器，相邻两光纤光栅反射的信号在环形器中产生干涉，接着从环形器第3端口输出干涉信号；Step 1. Turn on the laser light source, so that the outgoing light passes through the isolator, optical switch and phase modulator in sequence; wherein, the signal generator is connected to the optical switch and the phase modulator respectively, and the pulse signal generated by the signal generator acts on the optical switch to generate The continuous optical pulse acts on the phase modulator to generate continuous phase pulse modulation; a phase-modulated laser pulse beam is formed, and the phase-modulated laser pulse beam enters the first port of the circulator, and enters the fused fiber grating through its second port group; the fiber grating group senses the vibration signal of the environment, and when the pulse beam passes through different fiber gratings in the fiber grating group, part of the pulse beam returns to the circulator, and the signals reflected by two adjacent fiber gratings interfere in the circulator , and then output the interference signal from the third port of the circulator; 步骤2、相邻两个光纤光栅产生的干涉光强信号I(t)表达式如下：Step 2, the expression of the interference light intensity signal I(t) generated by two adjacent fiber gratings is as follows: 其中，合相位 为初始相，为漂移相，表示振动信号相，A、B均为常数；为相位调制器产生的0、三路光强信号的相位间隔，代入得到新的三路干涉光强信号I(n)如下式：Among them, the phase is the initial phase, is the drift phase, Indicates the vibration signal phase, A and B are constant; generated for the phase modulator 0, The phase interval of the three light intensity signals is substituted into The new three-way interference light intensity signal I(n) is obtained as follows: 即： which is: 采用三态偏振分集接收器接收从环形器3端口出射的偏振态不确定的干涉信号，并将其分成新的三路干涉信号，每一路干涉信号都包含三组上述的干涉光强信号；三路干涉信号通过三个光电探测器转换为三路光强电信号，数据采集模块采集光强电信号，并将其送入数据处理模块；数据处理模块通过标定相位调制信号和接收信号的延时，最终得到相邻两个光纤光栅发生干涉后产生三路共九组移相光强信号I11、I12、I13、I21、I22、I23、I31、I32、I33；The three-state polarization diversity receiver is used to receive the interference signal with uncertain polarization state emitted from the circulator 3 port, and divide it into new three-way interference signals, each of which contains three groups of the above-mentioned interference light intensity signals; One-way interference signals are converted into three-way light intensity electrical signals through three photodetectors, and the data acquisition module collects light intensity electrical signals and sends them to the data processing module; the data processing module calibrates the phase modulation signal and the delay of the received signal , and finally get three channels of nine sets of phase-shifted light intensity signals I 11 , I 12 , I 13 , I 21 , I 22 , I 23 , I 31 , I 32 , and I 33 after two adjacent fiber gratings interfere; 步骤3、设第一路的三组移相光强信号分别为I11，I12，I13，则|I11-I12|为B1[cos(θ)+sin(θ)]，|I11-I13|为2B1sin(θ)，|I12-I13|为B1[cos(θ)-sin(θ)]；将|I11-I12|，|I11-I13|，|I12-I13|中的最大项记作Imax1；以同样的方式求出第二路的Imax2及第三路的Imax3；Step 3. Let the three groups of phase-shifted light intensity signals of the first channel be I 11 , I 12 , and I 13 , then |I 11 -I 12 | is B 1 [cos(θ)+sin(θ)],| I 11 -I 13 | is 2B 1 sin(θ), |I 12 -I 13 | is B 1 [cos(θ)-sin(θ)]; |I 11 -I 12 |, |I 11 -I 13 |, the largest item in |I 12 -I 13 | is denoted as I max1 ; Find the I max2 of the second road and the I max3 of the third road in the same way; 在同一时刻下，Imax1、Imax2及Imax3三者同时为Bi[cos(θ)+sin(θ)]、2Bisin(θ)或Bi[cos(θ)+sin(θ)]中的某一项(其中i＝1，2或3)；在某一时刻，若Imax1、Imax2及Imax3分别为B1[cos(θ)+sin(θ)]、B2[cos(θ)+sin(θ)]、B3[cos(θ)+sin(θ)]，则比较Imax1、Imax2及Imax3的大小即可得出B1、B2、B3的大小；以同样的方式可以比较不同时刻下Bi值的大小，将Bi值最大的一路确定为对比度最大的一路移相光强信号；At the same moment, I max1 , I max2 and I max3 are Bi [ cos(θ)+sin(θ)], 2B i sin(θ) or B i [cos(θ)+sin(θ) ] (where i=1, 2 or 3); at a certain moment, if I max1 , I max2 and I max3 are B 1 [cos(θ)+sin(θ)], B 2 [ cos(θ)+sin(θ)], B 3 [cos(θ)+sin(θ)], then compare the size of I max1 , I max2 and I max3 to get B 1 , B 2 , B 3 Size; in the same way, the size of the Bi value at different times can be compared, and the path with the largest Bi value is determined as the path-shifted light intensity signal with the largest contrast; 步骤4、选取对比度最大的一路移相光强信号记作I1、I2、I3，再进行三步移相法的求解并解包得到相位信号，相位信号包含了时域上相位的信息，相位信号进行前向差分计算得到离散差分信号，离散差分信号反应了相位信号的变化信息，其中变化较大的信号段表明环境中存在扰动信号；通过采集计算各种环境下的离散差分信号进行信号阈值Tmin的设定，将一段时间内采集的数据进行一次离散差分信号超出阈值点数量的统计，当穿越阈值点的数量超过额定值时进行报警。Step 4. Select the phase-shifted light intensity signal with the highest contrast and record it as I 1 , I 2 , and I 3 , and then solve it by the three-step phase-shift method and unpack it to obtain the phase signal. The phase signal contains the phase information in the time domain , the phase signal is calculated by forward difference to obtain a discrete differential signal, the discrete differential signal reflects the change information of the phase signal, and the signal segment with a large change indicates that there is a disturbance signal in the environment; by collecting and calculating the discrete differential signal in various environments The setting of the signal threshold T min is to count the data collected within a period of time for a discrete differential signal exceeding the threshold number, and when the number of crossing threshold points exceeds the rated value, an alarm will be issued. 2.根据权利要求1所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：所述步骤2中，采用三态偏振分集接收器接收由环形器3端口传输出来的不同偏振方向的干涉信号，再将其分成三路，使三态偏振分集接收器中三个偏振方向的接收器至少有1个能确保接收到干涉信号进行下一步的解算。2. the anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 1, is characterized in that: in described step 2, adopt three-state polarization diversity receiver to receive the different polarization direction that is transmitted by circulator 3 ports The interference signal is divided into three paths, so that at least one of the receivers in the three polarization directions in the three-state polarization diversity receiver can ensure that the interference signal is received for the next step of calculation. 3.根据权利要求1所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：所述步骤2中，各光纤光栅的间隔保持相同，根据数据处理模块将每两个相邻的光纤光栅产生的三路共九组移相光强信号，通过设定的数据结构将不同移相光强信号加以区分，确保各信号间不相互混杂、不相互干扰。3. the anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 1, is characterized in that: in described step 2, the interval of each fiber grating remains the same, according to data processing module every two adjacent optical fibers The three-way, nine groups of phase-shifted light intensity signals generated by the grating are distinguished by the set data structure to ensure that the signals are not mixed or interfered with each other. 4.根据权利要求1所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：所述步骤4中，根据三步移相算法，解得相位信号θ：4. The anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 1, is characterized in that: in described step 4, according to three-step phase-shifting algorithm, solve phase signal θ: 其中，对比度最大的一路信号中的三组移相光强信号依次为I1、I2、I3。Among them, the three groups of phase-shifted light intensity signals in one channel with the highest contrast are I 1 , I 2 , and I 3 in sequence. 5.根据权利要求1所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：所述步骤4中，将一段时间采集的相位信号θ构成的序列设为数组{xn}，定义差分算子Δ：Δxn＝xn+1-xn为在n处的前向差分，将相位信号序列进行前向差分算子处理获得离散差分信号，根据采集到的不同情况下的相位信号序列进行判断，最终设定报警阈值。5. the anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 1, is characterized in that: in described step 4, the sequence that the phase signal θ that collects for a period of time is formed is set as array {x n }, definition Difference operator Δ: Δx n = x n+1 -x n is the forward difference at n, and the phase signal sequence is processed by the forward difference operator to obtain a discrete difference signal. According to the collected phase signals in different situations The sequence is judged, and finally the alarm threshold is set. 6.根据权利要求5所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：采集不同环境下的相位信号序列，将相位信号序列差分处理后设定合适的阈值Tmin，排除环境中轻微扰动的影响、减少系统误报率，设定阈值后统计一段时间内离散差分信号超出阈值的个数，当超出阈值的个数较多时触发报警。6. The anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 5, characterized in that: the phase signal sequence under different environments is collected, and a suitable threshold Tmin is set after the phase signal sequence differential processing to exclude the environment The impact of slight disturbances in the medium and small disturbances, reducing the false alarm rate of the system, after setting the threshold, counting the number of discrete differential signals exceeding the threshold within a period of time, and triggering an alarm when the number of exceeding the threshold is large. 7.根据权利要求6所述的光纤传感信号的抗偏振衰落报警算法，其特征在于：超出阈值的个数是指差分数据超越阈值Tmin点的数量，所述达到报警的额定超越数量根据环境条件设定。7. the anti-polarization fading alarm algorithm of optical fiber sensing signal according to claim 6, it is characterized in that: the number exceeding threshold refers to the quantity of differential data surpassing threshold T min point, and the rated surpassing quantity that reaches warning according to Environmental condition setting.
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