Data acquisition method, distributed optical fiber sensing system and optical signal processing method

Abstract

The present application provides a data acquisition method, a distributed optical fiber sensing system and an optical signal processing method. The data acquisition method is applied to a distributed optical fiber sensing system, and includes: controlling a laser to emit a continuous optical signal, and dividing the continuous optical signal into a first branch and a second branch; modulating and peak power amplifying the continuous optical signal of the first branch, and injecting the continuous optical signal that has completed modulation and peak power amplification into the optical fiber to be tested; performing distributed amplification and optical power amplification on the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal; processing the first scattered light signal and the continuous optical signal of the second branch to obtain a first polarized electrical signal and a second polarized electrical signal; real-time acquisition of the first polarized electrical signal and the second polarized electrical signal; converting the first polarized electrical signal into a first complex array, and converting the second polarized electrical signal into a second complex array. The present application can solve the problem of optical signal attenuation caused by long-distance transmission.

Description

Technical Field

[0001] The present application relates to the field of optical fiber technology, and in particular to a data acquisition method, a distributed optical fiber sensing system and an optical signal processing method. Background Art

[0002] In distributed fiber optic sensing systems, optical fiber as a sensing unit has the characteristics of small size, anti-electromagnetic interference, and easy deployment. In recent years, it has been widely used in perimeter security monitoring, oil and gas pipeline leakage monitoring, submarine cable monitoring, anchor damage monitoring, overhead power line dancing, ice monitoring, etc. Existing long-distance distributed fiber optic sensing systems usually use different technical means, such as erbium-doped fiber optical amplification technology, forward distributed Raman amplification technology, bidirectional distributed Raman amplification technology, and remote pump amplification technology, to detect acoustic vibration signals around long-distance optical fibers.

[0003] However, in long-distance optical fiber transmission, it is difficult for the existing systems to effectively deal with problems such as signal attenuation and noise interference. Summary of the invention

[0004] The present invention proposes a data acquisition method, a distributed optical fiber sensing system and an optical signal processing method to solve the problems that the systems in the prior art are difficult to effectively deal with signal attenuation and noise interference in long-distance optical fiber transmission.

[0005] The technical solution of the present invention is as follows: a data acquisition method is applied to a distributed optical fiber sensing system, wherein the distributed optical fiber sensing system includes a laser, and the laser is used to emit a continuous optical signal into the optical fiber to be tested; the method includes: controlling the laser to emit a continuous optical signal, and dividing the continuous optical signal into a first branch and a second branch; modulating and peak power amplifying the continuous optical signal of the first branch, and injecting the continuous optical signal that has completed modulation and peak power amplification into the optical fiber to be tested; performing distributed amplification and optical power amplification on the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal; processing the first scattered light signal and the continuous optical signal of the second branch to obtain a first polarized electrical signal and a second polarized electrical signal, wherein the polarization state of the first polarized electrical signal and the polarization state of the second polarized electrical signal are perpendicular to each other; collecting the first polarized electrical signal and the second polarized electrical signal in real time; converting the first polarized electrical signal into a first complex array, and converting the second polarized electrical signal into a second complex array.

[0006] Compared with the related art, the embodiments of the present application have at least the following advantages:

[0007] The present application first divides the continuous optical signal emitted by the laser into a first branch and a second branch, modulates and peak-power-amplifies the continuous optical signal of the first branch, and then injects it into the optical fiber to be tested, and then performs distributed amplification and optical power amplification on the backward Rayleigh scattered optical signal generated by the optical fiber to be tested to enhance the transmission capacity of the optical signal. After processing the first scattered light signal and the continuous optical signal of the second branch, a first polarized electrical signal and a second polarized electrical signal with polarization states perpendicular to each other are obtained. This eliminates the correlation interference between the polarization states of the optical signal during transmission. At the same time, since there is a difference between the fading position corresponding to the polarization state of the first polarized electrical signal and the fading position corresponding to the polarization state of the second polarized electrical signal, when the two fading positions are different, they can compensate each other, thereby suppressing the fading of the optical signal.

[0008] In some embodiments, the first scattered light signal and the continuous light signal of the second branch are processed to obtain a first polarized electric signal and a second polarized electric signal, including: performing polarization state processing on the first scattered light signal to obtain a first light signal and a second light signal, wherein the polarization state of the first light signal and the polarization state of the second light signal are perpendicular to each other; performing polarization state processing on the continuous light signal of the second branch to obtain a third light signal and a fourth light signal, wherein the polarization state of the first light signal is the same as the polarization state of the third light signal, and the polarization state of the second light signal is the same as the polarization state of the fourth light signal; performing heterodyne detection and photoelectric conversion processing on the first light signal and the third light signal to obtain the first polarized electric signal; performing heterodyne detection and photoelectric conversion processing on the second light signal and the fourth light signal to obtain the second polarized electric signal.

[0009] In some embodiments, the real-time acquisition of the first polarization electrical signal and the second polarization electrical signal includes: filtering the first polarization electrical signal and the second polarization electrical signal respectively; and real-time acquisition of the first polarization electrical signal and the second polarization electrical signal after filtering.

[0010] In some embodiments, converting the first polarization electric signal into a first complex array, and converting the second polarization electric signal into a second complex array, includes: converting the first polarization electric signal into a first digital signal, and demodulating and filtering the first digital signal to obtain the first complex array; converting the second polarization electric signal into a second digital signal, and demodulating and filtering the second digital signal to obtain the second complex array.

[0011] In some embodiments, the modulating and peak power amplifying the continuous optical signal of the first branch, and injecting the modulated and peak power amplified continuous optical signal into the optical fiber to be tested, includes: modulating the continuous optical signal of the first branch into a pulsed optical signal; peak power amplifying the pulsed optical signal; and injecting the peak power amplified pulsed optical signal into the optical fiber to be tested.

[0012] In some embodiments, the distributed optical fiber sensing system further includes a Raman amplifier; the distributed amplification and optical power amplification of the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal includes: controlling the Raman amplifier to emit a Raman light signal; based on the Raman light signal, distributed amplifying the backward Rayleigh scattered light signal generated in the optical fiber to be tested; filtering out the Raman light signal in the backward Rayleigh scattered light signal that has completed distributed amplification, wherein the backward Rayleigh scattered light signal is generated by the optical fiber to be tested under the action of the pulse light signal that has completed peak power amplification and the Raman light signal; and optical power amplifying the backward Rayleigh scattered light signal that has completed Raman light signal filtering to obtain the first scattered light signal.

[0013] An embodiment of the present application also provides a distributed optical fiber sensing system including: a laser, an optical fiber coupler, a first processing device, an optical fiber to be tested, a second processing device and a data acquisition device; wherein the laser is used to emit a continuous optical signal; the optical fiber coupler is used to receive the continuous optical signal and divide the continuous optical signal into a first branch and a second branch; the first processing device is used to modulate and peak power amplify the continuous optical signal of the first branch, and then inject the continuous optical signal that has completed the modulation and peak power amplification into the optical fiber to be tested, and then perform distributed amplification and optical power amplification on the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal; the second processing device is used to process the first scattered light signal and the continuous optical signal of the second branch to obtain a first polarized electrical signal and a second polarized electrical signal, wherein the polarization state of the first polarized electrical signal and the polarization state of the second polarized electrical signal are perpendicular to each other; the data acquisition device is used to collect the first polarized electrical signal and the second polarized electrical signal in real time, and convert the first polarized electrical signal into a first complex array, and convert the second polarized electrical signal into a second complex array.

[0014] An embodiment of the present application also provides an optical signal processing method, the method comprising: obtaining a first complex array and a second complex array, wherein the first complex array and the second complex array are obtained based on the data acquisition method as described above; performing rotation vector and sliding average processing on the first complex array to obtain a first array; performing rotation vector and sliding average processing on the second complex array to obtain a second array; adding the first array and the second array to obtain a third complex array; calculating amplitude data and phase data of the third complex array; and determining position information of an external vibration source based on the phase data.

[0015] In some embodiments, performing rotation vector and sliding average processing on the first complex array to obtain the first array includes: performing normalized complex conjugate processing on the first complex array to obtain the second array; performing Fourier transform processing on the second array to obtain the third array; multiplying the third array and a preset array to obtain the fourth array; performing inverse Fourier transform processing on the fourth array to obtain the first array; performing rotation vector and sliding average processing on the second complex array to obtain the first array includes: performing normalized complex conjugate processing on the second complex array to obtain the fifth array; performing Fourier transform processing on the fifth array to obtain the sixth array; multiplying the sixth array and the preset array to obtain the seventh array; performing inverse Fourier transform processing on the seventh array to obtain the second array.

[0016] In some embodiments, the calculation of the amplitude data and phase data of the third complex array includes: performing modulo processing on the third complex array to obtain an eighth array, and performing phase processing on the third complex array to obtain a ninth array, wherein one dimension of the third complex array is a time dimension and the other dimension is a space dimension; in the time dimension, slicing the eighth array based on a preset slice length to obtain a plurality of slice arrays; based on the plurality of slice arrays, determining a value array, wherein the data in the value array represents the subscript value of the largest data among a plurality of data corresponding to the smallest time dimension in the slice array; and selecting data in the ninth array that matches each data in the value array to obtain the phase data.

[0017] Compared with the prior art, the embodiments of the present application have at least the following advantages:

[0018] The present application performs Fourier transform processing on the second array, and then performs inverse Fourier transform processing on the fourth array to obtain the first array. Data processing in the time domain can be converted into data processing in the frequency domain, thereby improving the efficiency of data processing. At the same time, based on the phase data, the data with obvious changes in the phase data is analyzed, so that the position information of the external vibration source can be accurately determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a step flow chart of a data collection method according to one embodiment of the present application.

[0020] Figure 2 It is a schematic diagram of the structure of a distributed optical fiber sensing system according to one embodiment of the present application.

[0021] Figure 3 It is a schematic diagram of an intensity curve of an embodiment of the present application.

[0022] Figure 4 It is a flowchart of the steps of an optical signal processing method according to one embodiment of the present application.

[0023] Figure 5 It is a schematic diagram of a positioning curve according to an embodiment of the present application.

[0024] Figure 6 It is a schematic diagram of a vibration curve and a vibration amplitude spectrum of an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the implementation methods of the present application and the features in the implementation methods can be combined with each other without conflict.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present application. The described implementations are only part of the implementations of the present application, rather than all of the implementations.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0028] It should be further noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0029] In this application, "at least one" means one or more, and "more" means two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0030] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0031] In distributed fiber optic sensing systems, optical fiber as a sensing unit has the characteristics of small size, anti-electromagnetic interference, and easy deployment. In recent years, it has been widely used in perimeter security monitoring, oil and gas pipeline leakage monitoring, submarine cable monitoring, anchor damage monitoring, overhead power line dancing, ice monitoring, etc. Existing long-distance distributed fiber optic sensing systems usually use different technical means, such as erbium-doped fiber optical amplification technology, forward distributed Raman amplification technology, bidirectional distributed Raman amplification technology, and remote pump amplification technology, to detect acoustic vibration signals around long-distance optical fibers.

[0032] However, in long-distance optical fiber transmission, it is difficult for the existing systems to effectively deal with problems such as signal attenuation and noise interference.

[0033] Based on this, please combine Figure 1 , which is a flow chart of the steps of the data acquisition method provided in this application. The data acquisition method is applied to a distributed optical fiber sensing system. For the specific structure of the distributed optical fiber sensing system, please refer to Figure 2The distributed optical fiber sensing system includes a laser, which is used to emit a continuous optical signal into the optical fiber to be tested. The laser can be a narrow linewidth laser, and the optical fiber to be tested is a single-mode communication optical fiber. In this embodiment, the narrow linewidth laser can emit a continuous optical signal with a wavelength of 1550nm. Since the output optical signal of the narrow linewidth fiber laser has a very narrow spectral linewidth, it can ensure that the optical signal will not have frequency diffusion and intermodulation interference during transmission, which helps to improve the stability and transmission quality of the optical signal.

[0034] The specific steps are as follows:

[0035] Step 101: Control a laser to emit a continuous optical signal, and divide the continuous optical signal into a first branch and a second branch.

[0036] In this embodiment, the distributed optical fiber sensing system further includes an optical fiber coupler. The distributed optical fiber sensing system controls the narrow linewidth laser to emit a continuous optical signal, and controls the optical fiber coupler to divide the continuous optical signal into a first branch and a second branch.

[0037] Specifically, the fiber coupler receives the continuous optical signal output by the narrow linewidth laser and divides it into two paths, and the power ratio of the two continuous optical signals is 90: 10. In other embodiments, the power ratio of the two continuous optical signals can also be 50:50, which is not limited in this application.

[0038] Using a single-port coupler with a power ratio of 90:10, the signal can be split into two branch signals of different strengths, while using a four-port coupler with a power ratio of 50:50, the two signals can be combined into an output signal of average strength.

[0039] Step 102: modulate and peak-power amplify the continuous optical signal of the first branch, and inject the modulated and peak-power amplified continuous optical signal into the optical fiber to be tested.

[0040] In this embodiment, the distributed optical fiber sensing system further includes a first processing device, which is used to modulate the continuous optical signal of the first branch into a pulse optical signal, perform peak power amplification on the pulse optical signal, and inject the pulse optical signal after peak power amplification into the optical fiber to be tested.

[0041] Specifically, the first processing device includes an acousto-optic modulator and a first erbium-doped fiber amplifier. The acousto-optic modulator is used to modulate the continuous light signal of the first branch into a pulse light signal. In this embodiment, when the power ratio of the continuous light signals of the two branches output by the fiber coupler is 90:10, the acousto-optic modulator receives a light signal whose power ratio of the continuous light signal output by the fiber coupler is 90. The acousto-optic modulator can also be replaced with an electro-optic modulator or a high-speed optical switch. The first erbium-doped fiber amplifier is used to amplify the peak power of the pulse light signal. And the first erbium-doped fiber amplifier injects the continuous light signal that has completed the modulation and peak power amplification into the optical fiber to be tested.

[0042] Step 103: Perform distributed amplification and optical power amplification on the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal.

[0043] In this embodiment, the first processing device further includes an optical circulator, a wavelength division multiplexer, a Raman amplifier and a second erbium-doped fiber amplifier. The optical circulator is used to receive the continuous optical signal that has completed modulation and peak power amplification sent by the first erbium-doped fiber amplifier, and transmit the continuous optical signal that has completed modulation and peak power amplification to the optical fiber to be tested. The distributed optical fiber sensing system controls the Raman amplifier to emit a Raman optical signal.

[0044] The wavelength division multiplexer is used to perform distributed amplification on the backscattered Rayleigh light signal generated in the optical fiber to be tested through the Raman light signal output by the Raman amplifier, and then filter out the Raman light signal in the backscattered Rayleigh light signal that has completed distributed amplification. Among them, the backscattered Rayleigh light signal is generated by the optical fiber to be tested under the action of the pulse light signal that has completed peak power amplification and the Raman light signal, and the pulse light signal that has completed peak power amplification is the light signal injected into the optical fiber to be tested via the optical circulator and the wavelength division multiplexer.

[0045] In this embodiment, the Raman amplifier amplifies the optical signal by means of Raman scattering. Due to the existence of Raman gain, a higher gain than that of the optical fiber amplifier can be achieved.

[0046] Furthermore, the optical circulator is also used to inject the backward Rayleigh scattered light signal after Raman optical signal filtering into the second erbium-doped fiber amplifier. In this embodiment, the optical circulator includes three ports. The first port of the optical circulator is used to receive the pulsed light signal after peak power amplification transmitted by the first erbium-doped fiber amplifier. The second port of the optical circulator is used to transmit the pulsed light signal after peak power amplification transmitted by the first erbium-doped fiber amplifier to the optical fiber to be tested, and then receive the backward Rayleigh scattered light signal after Raman optical signal filtering. The third port of the optical circulator is used to transmit the backward Rayleigh scattered light signal after Raman optical signal filtering to the next component.

[0047] The second erbium-doped fiber amplifier is used to amplify the optical power of the backward Rayleigh scattered light signal after the Raman light signal is filtered out, so as to obtain the first scattered light signal.

[0048] In this embodiment, by using a wavelength division multiplexer and a Raman amplifier, the pulse light signal and the Raman light signal that have completed peak power amplification can be injected into the optical fiber to be tested, thereby realizing distributed measurement, and after the distributed amplification is completed, the Raman light signal in the backward Rayleigh scattered light signal that has completed distributed amplification is filtered out by the wavelength division multiplexer to avoid affecting subsequent signal detection and acquisition, thereby improving the acquisition accuracy of the frequency information of each point along the optical fiber to be tested, which helps to improve the accuracy and reliability of the distributed optical fiber sensing device.

[0049] Step 104: After processing the first scattered light signal and the continuous light signal of the second branch, a first polarized electric signal and a second polarized electric signal are obtained, wherein the polarization state of the first polarized electric signal and the polarization state of the second polarized electric signal are perpendicular to each other.

[0050] In this embodiment, the first polarized electrical signal corresponds to an electrical signal of P polarized light, and the second polarized electrical signal corresponds to an electrical signal of S polarized light.

[0051] The distributed optical fiber sensing system also includes a second processing device, and the second processing device includes a polarization controller. Specifically, the polarization controller is controlled to process the polarization state of the first scattered light signal to obtain a first light signal and a second light signal, wherein the polarization state of the first light signal and the polarization state of the second light signal are perpendicular to each other. The polarization controller is controlled to process the polarization state of the continuous light signal of the second branch to obtain a third light signal and a fourth light signal, wherein the polarization state of the first light signal is the same as the polarization state of the third light signal, and the polarization state of the second light signal is the same as the polarization state of the fourth light signal.

[0052] Further, the polarization controller is controlled to perform heterodyne detection and photoelectric conversion on the first optical signal and the third optical signal to obtain a first polarized electrical signal. The polarization controller is controlled to perform heterodyne detection and photoelectric conversion on the second optical signal and the fourth optical signal to obtain a second polarized electrical signal. Herein, heterodyne detection refers to processing optical signals using optical frequency coherent detection technology, wherein the optical frequency coherent detection technology is based on the principle of mixing coherent reference light and incident signal light on a photosensitive surface.

[0053] In this embodiment, the polarization controller includes two receiving ends and two output ends, one receiving end is used to receive the first scattered light signal output by the first processing device, and the other output end is used to receive the continuous light signal of the second branch. Then, the polarization controller processes the first scattered light signal and the continuous light signal of the second branch to obtain a first polarized electrical signal and a second polarized electrical signal. The first polarized electrical signal is output from one output end of the polarization controller, and the second polarized electrical signal is output from the other output end of the polarization controller.

[0054] It should be noted that, since the polarization state of the P polarized light and the polarization state of the S polarized light are perpendicular to each other, the related interference between the polarization states of the optical signal during transmission can be eliminated. At the same time, since the fading position corresponding to the polarization state of the first polarized electrical signal and the fading position corresponding to the polarization state of the second polarized electrical signal are different, when the two fading positions are different, they can compensate each other, thereby suppressing the fading of the optical signal.

[0055] Step 105: convert the first polarization electrical signal into a first complex number array, convert the second polarization electrical signal into a second complex number array, and collect the first complex number array and the second complex number array in real time.

[0056] In some embodiments, the second processing device further includes a first filter, a second filter and a data acquisition device, wherein the first filter and the second filter are both bandpass filters. The first filter receives a first polarization electrical signal output from one output end of the polarization controller, and the second filter receives a second polarization electrical signal output from another output end of the polarization controller. The first filter is used to filter the first polarization electrical signal and input the filtered first polarization electrical signal to the data acquisition device. The second filter is used to filter the second polarization electrical signal and input the filtered second polarization electrical signal to the data acquisition device.

[0057] In this embodiment, the first polarization electrical signal is converted into a first digital signal, and the first digital signal is demodulated and filtered to obtain a first complex array. The second polarization electrical signal is converted into a second digital signal, and the second digital signal is demodulated and filtered to obtain a second complex array. After the first digital signal and the second digital signal are demodulated, the signals are changed from the original real number signals to complex number signals, i.e., vector signals. In other words, the data in the first complex array and the second complex array represent vector data.

[0058] In this embodiment, the data acquisition device is also used to generate a trigger signal and control the first processing device based on the trigger signal. For example, when the data acquisition device generates a trigger signal with an output frequency of f1, the first processing device will start to modulate the continuous optical signal of the first branch and amplify the peak power after receiving the trigger signal. Subsequently, the first complex array and the second complex array are analyzed and processed to obtain the position information of the external vibration source.

[0059] In some embodiments, the data acquisition device is used to demodulate the first complex array and the second complex array to obtain an amplitude signal and a phase signal, and determine the position information of the external vibration source based on the amplitude signal and the phase signal. Figure 3 , which is the intensity curve matching the amplitude signal when the length of the optical fiber to be tested is 99 km. The front end of the intensity curve is the gain of the signal by the Raman amplifier. It can be seen that the detection length of the system can be significantly extended.

[0060] The steps of determining the position information of the external vibration source based on the amplitude signal and the phase signal will be described in detail below. To avoid repetition, they will not be repeated here.

[0061] Compared with the prior art, the embodiments of the present application have at least the following advantages:

[0062] On the one hand, the first processing device injects the continuous optical signal that has completed modulation and peak power amplification into the optical fiber to be tested, which can realize the monitoring of the optical fiber to be tested, and then performs distributed amplification and optical power amplification on the backward Rayleigh scattered light signal in the optical fiber to be tested to obtain the first scattered light signal, which can extend the monitoring distance and improve the signal quality, thereby realizing high-resolution distributed sensing and accurately locating abnormal phenomena such as vibration in the optical fiber to be tested. On the other hand, the polarization controller processes the polarization state of the received continuous optical signal to suppress the attenuation of the optical signal. At the same time, the first filter and the second filter filter the optical signal transmitted by the polarization controller, and then the polarization electrical signal is converted into a complex array by the data acquisition device. It is convenient for subsequent analysis of the complex array to obtain accurate position information of the external vibration source.

[0063] like Figure 4 As shown, the embodiment of the present application also provides a method for processing optical signals. The method can obtain accurate position information of the external vibration source after processing and analyzing the first complex array and the second complex array. According to different requirements, the order of the steps in the flowchart can be changed, and some steps can be omitted. The specific steps include:

[0064] Step 201: Obtain a first complex number array and a second complex number array.

[0065] The first complex number array and the second complex number array are acquired in real time based on the data acquisition method described above, and the data in the first complex number array and the second complex number array are both vector data.

[0066] Step 202: performing a rotation vector and a sliding average process on the first complex number array to obtain a first array, and performing a rotation vector and a sliding average process on the second complex number array to obtain a second array.

[0067] In some embodiments, the step of performing a rotation vector and a sliding average process on the first complex array to obtain the first array includes: performing a normalized complex conjugate process on the first complex array to obtain a second array. Performing a Fourier transform process on the second array to obtain a third array. Multiplying the third array and a preset array to obtain a fourth array. Performing an inverse Fourier transform process on the fourth array to obtain the first array.

[0068] The step of performing a rotation vector and a sliding average process on the second complex array to obtain the first array includes: performing a normalized complex conjugate process on the second complex array to obtain a fifth array. Performing a Fourier transform process on the fifth array to obtain a sixth array. Multiplying the sixth array and the preset array to obtain a seventh array. Performing an inverse Fourier transform process on the seventh array to obtain the second array.

[0069] The first array is obtained by performing rotation vector and sliding average processing on the first complex array as an example for explanation. The row data to be updated in the first complex array is multiplied by the adjacent previous row data and the data after normalized complex conjugation is used as the new row data to be updated, so as to obtain the second array. For example, the second row data in the first complex array is multiplied by the normalized complex conjugate of the first row data as the new second row data, and the third row data is multiplied by the normalized complex conjugate of the second row as the new third row data. After each row of data is updated, the second array is obtained. Then, each row of data in the second array is subjected to fast Fourier transform processing to obtain the third array.

[0070] Using a Hamming window with an array length of n, the Hamming window is padded with zeros to a preset length (denoted as points). Perform a fast Fourier transform on the data in the Hamming window to obtain a preset array. Multiply the third array and the preset array to obtain a fourth array. Perform an inverse Fourier transform on the fourth array to obtain the first array. Among them, the Hamming window can also be replaced by a Hanning window. The specific value of the preset length is set according to actual design requirements, and this application does not limit this.

[0071] It should be noted that the second array is first subjected to Fourier transform processing, and then the fourth array is subjected to inverse Fourier transform processing to obtain the first array. This can convert data processing in the time domain into data processing in the frequency domain, thereby improving the efficiency of data processing.

[0072] Step 203: Add the first array and the second array to obtain a third complex array.

[0073] Step 204: Calculate amplitude data and phase data of the third complex array.

[0074] In some embodiments, the third complex array is modulo processed to obtain an eighth array, and the third complex array is phase processed to obtain a ninth array, wherein one dimension of the third complex array is a time dimension and the other dimension is a space dimension.

[0075] Specifically, the third complex array is subjected to modulus processing, that is, the modulus value of each complex data in the third complex array is calculated. The modulus value represents the amplitude or intensity of each complex data in the third complex array. The third complex array is subjected to phase processing, that is, the third complex array is subjected to phase calculation, to obtain a ninth array.

[0076] In some embodiments, in the time dimension, the eighth array is sliced ​​based on a preset slice length to obtain multiple slice arrays. The step of obtaining the preset slice length includes: performing a slice operation on the eighth array with an interval length of L in the space dimension, and the number of slices is points / L rounded up. The values ​​of points and L can be set according to actual conditions.

[0077] In some embodiments, a value array is determined based on multiple slice arrays, wherein the data in the value array represents the subscript value of the largest data among multiple data corresponding to the smallest time dimension in a slice array.

[0078] In this embodiment, the minimum one-dimensional array in the time dimension of the eighth array in each slice length is calculated. Then the one-dimensional data is sliced ​​again, the subscript value of the maximum data in the one-dimensional array in each slice is obtained, and the subscript value is stored in the value array.

[0079] Furthermore, data in the ninth array that matches each data in the value array is selected to obtain phase data.

[0080] In this embodiment, the phase angle data corresponding to each data of the value array is extracted from the ninth array, and the phase calculation is performed on each phase angle data to obtain two-dimensional phase data.

[0081] Step 205: Determine the position information of the external vibration source based on the phase data.

[0082] Specifically, the least square method is used on the phase data in the time dimension to remove the smaller data in the data, and then the phase data is squared and calculated to obtain the positioning curve. If a more obvious bulge appears in the positioning curve, the data corresponding to the position of the bulge is the position information of the external vibration source.

[0083] When the length of the optical fiber to be tested is 99 km, a 20 m long optical fiber is wound around the piezoelectric ceramic at the tail end of the optical fiber to be tested, and an AC signal with a voltage amplitude of 20 V and a frequency of 10 Hz is applied to the piezoelectric ceramic. Then, the first complex array and the second complex array collected by the data collection method are processed by the optical signal processing method to obtain Figure 5 The positioning curve shown. It can be clearly seen from the positioning curve that there is an obvious peak at the tail end of the curve, and no false alarms due to coherent fading or polarization fading appear in other positions. Therefore, based on the distributed optical fiber sensing system, the first complex array and the second complex array are collected by the data acquisition method, and the first complex array and the second complex array are processed by the optical signal processing method, it can be verified that the distributed optical fiber sensing system can achieve fading suppression within a long-distance detection range.

[0084] Please combine again Figure 6 , the optical signal processing method is used to process the optical signal wrapped around the piezoelectric ceramic, and the vibration curve and vibration amplitude spectrum matching the phase data are obtained. From the figure, it can be seen that after being processed and restored by this method, the frequency of the phase signal obtained is consistent with the frequency applied to the piezoelectric ceramic, indicating that the optical signal processing method can linearly restore the vibration signal applied to the optical fiber by the outside world. Therefore, based on this method, the position information of the external vibration source can be accurately obtained.

[0085] Compared with the prior art, the embodiments of the present application have at least the following advantages:

[0086] On the one hand, the present application first performs Fourier transform processing on the second array, and then performs inverse Fourier transform processing on the fourth array to obtain the first array. Data processing in the time domain can be converted into data processing in the frequency domain, thereby improving the efficiency of data processing. On the other hand, by processing the phase data into a positioning curve, and then based on whether there is an obvious bulge in the positioning curve, the position information of the external vibration source can be quickly determined.

[0087] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application.

Claims

1. A data collection method, characterized in that: Applied to a distributed optical fiber sensing system, the distributed optical fiber sensing system includes a laser, and the laser is used to emit a continuous optical signal to the optical fiber to be tested; the method includes: Controlling the laser to emit a continuous optical signal, and dividing the continuous optical signal into a first branch and a second branch; Modulating and peak power amplifying the continuous optical signal of the first branch, and injecting the continuous optical signal that has completed modulation and peak power amplification into the optical fiber to be tested; Performing distributed amplification and optical power amplification on the backscattered Rayleigh light signal generated by the optical fiber to be tested to obtain a first scattered light signal; Performing polarization state processing on the first scattered light signal to obtain a first light signal and a second light signal, wherein the polarization state of the first light signal and the polarization state of the second light signal are perpendicular to each other; Performing polarization state processing on the continuous optical signal of the second branch to obtain a third optical signal and a fourth optical signal, wherein the polarization state of the first optical signal is the same as the polarization state of the third optical signal, and the polarization state of the second optical signal is the same as the polarization state of the fourth optical signal; After performing heterodyne detection and photoelectric conversion processing on the first optical signal and the third optical signal, a first polarized electrical signal is obtained; After performing heterodyne detection and photoelectric conversion processing on the second optical signal and the fourth optical signal, a second polarization electrical signal is obtained; collecting the first polarization electrical signal and the second polarization electrical signal in real time; The first polarization electric signal is converted into a first complex number array, and the second polarization electric signal is converted into a second complex number array.

2. The data collection method according to claim 1, characterized in that: The real-time acquisition of the first polarization electrical signal and the second polarization electrical signal comprises: performing filtering processing on the first polarization electrical signal and the second polarization electrical signal respectively; The first polarization electrical signal and the second polarization electrical signal after filtering are collected in real time.

3. The data collection method according to claim 1, characterized in that: The step of converting the first polarized electrical signal into a first complex array and converting the second polarized electrical signal into a second complex array comprises: Converting the first polarization electrical signal into a first digital signal, and performing demodulation and filtering on the first digital signal to obtain the first complex number array; The second polarization electrical signal is converted into a second digital signal, and the second digital signal is demodulated and filtered to obtain the second complex number array.

4. The data collection method according to claim 1, characterized in that: The step of modulating and peak power amplifying the continuous optical signal of the first branch, and injecting the continuous optical signal after the modulation and peak power amplification into the optical fiber to be tested comprises: modulating the continuous optical signal of the first branch into a pulsed optical signal; Performing peak power amplification on the pulsed optical signal; The pulsed optical signal after peak power amplification is injected into the optical fiber to be tested.

5. The data collection method according to claim 4, characterized in that: The distributed optical fiber sensing system further includes a Raman amplifier; the backscattered Rayleigh light signal generated by the optical fiber to be tested is subjected to distributed amplification and optical power amplification to obtain a first scattered light signal, including: Controlling the Raman amplifier to emit a Raman optical signal; Performing distributed amplification on the backscattered Rayleigh light signal generated in the optical fiber to be tested based on the Raman light signal; Filtering out the Raman optical signal in the backscattered Rayleigh optical signal that has completed distributed amplification, wherein the backscattered Rayleigh optical signal is generated by the optical fiber to be tested under the action of the pulse optical signal that has completed peak power amplification and the Raman optical signal; The backscattered Rayleigh light signal after Raman light signal filtering is optically amplified to obtain the first scattered light signal.

6. A distributed optical fiber sensing system, characterized in that: include: A laser, a fiber coupler, a first processing device, an optical fiber to be tested, a second processing device and a data acquisition device; Wherein, the laser is used to emit a continuous light signal; The optical fiber coupler is used to receive the continuous optical signal and divide the continuous optical signal into a first branch and a second branch; The first processing device is used to modulate and peak power amplify the continuous optical signal of the first branch, and then inject the continuous optical signal that has completed modulation and peak power amplification into the optical fiber to be tested, and then perform distributed amplification and optical power amplification on the backward Rayleigh scattered light signal generated by the optical fiber to be tested to obtain a first scattered light signal; The second processing device is used to perform polarization state processing on the first scattered light signal to obtain a first light signal and a second light signal, and to perform polarization state processing on the continuous light signal of the second branch to obtain a third light signal and a fourth light signal, wherein the polarization state of the first light signal and the polarization state of the second light signal are perpendicular to each other, the polarization state of the first light signal and the polarization state of the third light signal are the same, and the polarization state of the second light signal and the polarization state of the fourth light signal are the same; and to obtain a first polarized electric signal after performing heterodyne detection and photoelectric conversion processing on the first light signal and the third light signal, and to obtain a second polarized electric signal after performing heterodyne detection and photoelectric conversion processing on the second light signal and the fourth light signal; The data acquisition device is used to acquire the first polarization electrical signal and the second polarization electrical signal in real time, and to convert the first polarization electrical signal into a first complex number array and convert the second polarization electrical signal into a second complex number array.

7. A method for processing an optical signal, characterized in that: The method comprises: Acquire a first complex number array and a second complex number array, wherein the first complex number array and the second complex number array are obtained based on the data acquisition method according to any one of claims 1 to 5; Performing vector rotation and sliding average processing on the first complex number array to obtain a first array; Performing vector rotation and sliding average processing on the second complex number array to obtain a second array; Add the first array and the second array to obtain a third complex array; Calculating amplitude data and phase data of the third complex number array; Based on the phase data, position information of the external vibration source is determined.

8. The optical signal processing method according to claim 7, characterized in that: The step of performing a rotation vector and a sliding average process on the first complex number array to obtain a first array includes: Performing normalized complex conjugate processing on the first complex number array to obtain a second array; Performing Fourier transform processing on the second array to obtain a third array; Multiplying the third array and the preset array to obtain a fourth array; Performing inverse Fourier transform processing on the fourth array to obtain the first array; The step of performing a rotation vector and a sliding average process on the second complex array to obtain a first array includes: Performing normalized complex conjugate processing on the second complex number array to obtain a fifth array; Performing Fourier transform processing on the fifth array to obtain a sixth array; Multiplying the sixth array and the preset array to obtain a seventh array; Perform inverse Fourier transform processing on the seventh array to obtain the second array.

9. The optical signal processing method according to claim 7, characterized in that: The calculating the amplitude data and the phase data of the third complex number array comprises: Performing modulo processing on the third complex array to obtain an eighth array, and performing phase processing on the third complex array to obtain a ninth array, wherein one dimension of the third complex array is a time dimension and another dimension is a space dimension; In the time dimension, slicing the eighth array based on a preset slice length to obtain a plurality of slice arrays; Based on the plurality of slice arrays, a value array is determined, wherein the data in the value array represents the subscript value of the largest data among the plurality of data corresponding to the smallest time dimension in the slice array; The data in the ninth array that matches each data in the value array is selected to obtain the phase data.

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