Sensing fiber Raman temperature measurement method, sensor, electronic equipment and storage medium

Abstract

The invention relates to the technical field of sensing optical fibers, and discloses a sensing optical fiber Raman temperature measurement method, a sensor, electronic equipment and a storage medium, and the method comprises the steps: obtaining target electric signals corresponding to three parts of backward Raman scattering light; wherein the two parts of the backward Raman scattering light are obtained by injecting two intensity modulation chirped pulse signals into the sensing optical fiber respectively, the other part of the backward Raman scattering light is obtained by injecting an intensity modulation constant signal into the sensing optical fiber, and the intensity modulation chirped pulse signals are frequency sweeping signals comprising a direct-current component and an alternating-current component; aC components corresponding to the two intensity modulation chirped pulse signals are respectively an intensity modulation sine function signal and an intensity modulation cosine function signal having a 90-degree phase difference with the intensity modulation sine function signal; and demodulating temperature information along the sensing optical fiber based on the target electric signal. According to the invention, the response time of Raman temperature detection of the sensing fiber can be reduced.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and more specifically, to an optical fiber sensing Raman temperature measurement method, a sensor, an electronic device, and a storage medium. Background Art

[0002] The Raman Distributed Temperature Sensing (RDTS) system with intensity modulated chirped pulse compression is a system that uses chirped pulse amplification (CPA) to enhance pulse energy and monitors temperature through Raman distributed fiber temperature sensing technology. In the RDTS system with intensity modulated chirped pulse compression, the intensity modulated chirped pulse light signal is injected into the sensing fiber, and then the back Raman scattered light generated by them is collected and analyzed. The back Raman scattered light includes anti-Stokes Raman Scattering (ASR) and Stokes Raman Scattering (SR). The intensity of anti-Stokes light is related to temperature, while the amplitude of Stokes light is almost unaffected by temperature. Therefore, by obtaining the ratio of anti-Stokes light to Stokes light, the temperature information along the fiber can be obtained.

[0003] The intensity modulated chirped pulse compression RDTS system in the related art generates four intensity modulated chirped pulse signals and outputs them to the sensing fiber. After spontaneous Raman scattering, anti-Stokes light and Stokes light are generated at each position of the sensing fiber. The corresponding electrical signal is obtained by the photoelectric detection module. Four parts of Raman scattering light intensity data are obtained according to the electrical signal, and then the temperature data along the optical fiber is obtained through matched filtering and demodulation calculation. The four swept frequency signals are used as a group to demodulate the temperature curve, which has problems such as long response time and needs further improvement and optimization. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a sensing fiber Raman temperature measurement method, a sensor, an electronic device and a storage medium to improve or alleviate at least one of the above problems.

[0005] In a first aspect, the present application provides a sensing optical fiber Raman temperature measurement method, comprising: obtaining target electrical signals corresponding to three parts of back Raman scattered light respectively; wherein two parts of back Raman scattered light are obtained by respectively injecting two intensity modulated chirped pulse signals into the sensing optical fiber, and the remaining part of back Raman scattered light is obtained by injecting an intensity modulated constant signal into the sensing optical fiber, the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are respectively an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal; and temperature information along the sensing optical fiber is demodulated based on the target electrical signal.

[0006] In the above scheme, the RDTS system based on two intensity modulated chirped pulse signals and one intensity modulated constant signal has fewer sweeping signals than the RDTS system using four sine and cosine wave sweeping signals in the prior art, so the response time for demodulating the temperature curve is faster, which has a speed performance advantage.

[0007] As an optional method, the temperature information along the sensing optical fiber is demodulated based on the target electrical signal, including: synthesizing the target electrical signal into a complex signal according to the Euler formula; performing matched filtering on the complex signal to obtain a processed OTDR signal; and obtaining the temperature information along the sensing optical fiber by demodulating and calculating the processed OTDR signal.

[0008] In the above scheme, two intensity modulated chirped pulse signals and a target electrical signal corresponding to an intensity modulated constant signal are synthesized into a complex signal in the form of Euler's formula through simple basic operations, so that the real part of the complex signal only includes the wave signal of the cosine symbol part, and the imaginary part only includes the wave signal of the sine symbol part. After the complex signal is synthesized, a matched filter is used to match filter the complex signal to obtain a processed OTDR signal. By demodulating and calculating the processed OTDR signal, the temperature information along the sensing optical fiber is obtained.

[0009] As an optional method, the two intensity modulated chirped pulse signals and the intensity modulated constant signal are respectively amplified before being injected into the sensing optical fiber, wherein the acquisition of the target electrical signals corresponding to the three parts of back Raman scattered light includes: receiving the first original electrical signal and the second original electrical signal corresponding to the two intensity modulated chirped pulse signals; multiplying the first original electrical signal and the second original electrical signal by the corresponding correction factors respectively to obtain the corrected first target electrical signal and the second target electrical signal, wherein the target electrical signals include the first target electrical signal, the second target electrical signal and the third target electrical signal corresponding to the intensity modulated constant signal.

[0010] In theory, there is a certain relationship between the peak values ​​of intensity modulated chirped pulse signals. However, since the optical amplification module amplifies pulses of different modulation shapes inconsistently, the original theoretical peak value relationship is distorted after the swept-frequency pulse lights of different shapes are amplified, and the final temperature curve will produce a large distortion. In the above scheme, the correction factor is used to correct the amplitude of the second original electrical signal corresponding to the collected back Raman scattered light, which can greatly suppress the problem of temperature curve distortion caused by amplitude distortion.

[0011] As an optional manner, the correction factor is calculated by determining the correction factor as the quotient of a first average power ratio of the two intensity modulated chirped pulse signals before signal amplification and a second average power ratio of the two intensity modulated chirped pulse signals after signal amplification.

[0012] In the above scheme, the amplitude of the target electrical signal is corrected by using the power ratio relationship of the intensity modulated chirped pulse signal before and after amplification, which can better suppress the problem of temperature curve distortion caused by amplitude distortion.

[0013] As an optional manner, the expression of the intensity modulated constant signal and the two intensity modulated chirped pulse signals is: I1(t)=C, Or, I1(t) = C, Or, I1(t) = C,

[0014] Or, I1(t) = C,

[0015] Among them, I1(t) is the intensity modulated constant signal, I2(t) and I3(t) are two intensity modulated chirped pulse signals respectively, w(t) is the window function, f0 is the sweep center frequency, k is the frequency modulation rate, A, B, C are constants and A≥B>0, C>0.

[0016] In the above scheme, the expressions of an intensity modulated constant signal and two intensity modulated chirped pulse signals include the above four different combinations that are essentially different. Using any one of the combinations or other modified forms of swept frequency signals that do not deviate from the essence of any one of the combinations, the temperature curve can be demodulated using the temperature measurement method provided in the present application. In addition, adding a window function to the intensity modulated chirped pulse signal can further improve the sidelobe suppression ratio, so that the temperature accuracy of the final demodulated temperature curve is higher.

[0017] In a second aspect, the present application provides a sensing fiber Raman temperature measurement sensor, comprising: a signal generating module, used to generate two intensity modulated chirped pulse signals and an intensity modulated constant signal, wherein the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are respectively an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal; an optical detection and acquisition module, used to acquire three parts of back Raman scattered light generated after the two intensity modulated chirped pulse signals and the intensity modulated constant signal are injected into the sensing fiber and Raman scattered, and convert the back Raman scattered light into a corresponding target electrical signal; a signal processing module, used to execute the sensing fiber Raman temperature measurement method described in the first aspect.

[0018] In the above scheme, the RDTS system based on two intensity modulated chirped pulse signals and one intensity modulated constant signal has fewer sweeping signals than the RDTS system using four sine and cosine wave sweeping signals in the prior art, so the response time for demodulating the temperature curve is faster, which has a speed performance advantage.

[0019] As an optional manner, the signal generating module includes a signal generator and a frequency sweeping signal generating module, and the frequency sweeping signal generating module generates the intensity modulated chirped pulse signal and the intensity modulated constant signal under the drive of the signal generator; wherein the frequency sweeping signal generating module is a directly modulated laser.

[0020] As an optional method, it also includes: an optical amplification module, which is used to amplify the intensity modulated chirped pulse signal and the intensity modulated constant signal output by the signal generating module; a wavelength division multiplexer, which is used to inject the amplified intensity modulated chirped pulse signal and the intensity modulated constant signal into the sensing optical fiber respectively, and receive the back Raman scattered light; a correction calculation module, which is used to determine the quotient of the first average power ratio corresponding to the two intensity modulated chirped pulse signals before signal amplification and the second average power ratio corresponding to the two intensity modulated chirped pulse signals after signal amplification as the correction factor; wherein the optical detection and acquisition module is used to receive the first original electrical signal and the second original electrical signal corresponding to the two intensity modulated chirped pulse signals, and the third target electrical signal corresponding to the intensity modulated constant signal; the signal processing module is used to correct the second original electrical signal according to the correction factor to obtain a corrected second target electrical signal, and the target electrical signal includes the first original electrical signal, the second target electrical signal and the third target electrical signal corresponding to the intensity modulated constant signal.

[0021] In the above scheme, the optical amplifier module can enhance the intensity of the optical signal and improve the stability and measurement accuracy of the RDTS system. The wavelength division multiplexer is used to transmit the sweep signal to the sensing optical fiber, so that the sensing optical fiber Raman temperature sensor can perform temperature detection normally. The correction calculation module calculates the correction factor for the amplitude correction of the target electrical signal, which is beneficial to improve the accuracy of the temperature sensor.

[0022] In a third aspect, the present application provides a computer program product, comprising computer program instructions, wherein when the computer program instructions are read and executed by a processor, the method described in the first aspect is executed.

[0023] In a fourth aspect, the present application provides an electronic device, comprising: a processor, a memory and a bus, wherein the processor and the memory communicate with each other through the bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the method described in the first aspect.

[0024] In a fifth aspect, the present application provides a computer-readable storage medium, comprising: the computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the method described in the first aspect.

[0025] Other features and advantages of the present application will be described in the subsequent description, and in part will become apparent from the description, or will be understood by implementing the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a process of a sensing optical fiber Raman temperature measurement method provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of the structure of a sensing optical fiber Raman temperature sensor provided in this application;

[0029] Figure 3 A schematic diagram of the structure of another sensing optical fiber Raman temperature measurement sensor provided in an embodiment of the present application;

[0030] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0032] It should be noted that all technical and scientific terms used in this document have the same meanings as those generally understood by technicians in the technical field to which this application belongs; the terms used in this document are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0034] To facilitate understanding, the technical solution provided in the embodiment of the present application is introduced below using the signal processing module in the intensity modulated chirped pulse compression RDTS system as an example of the execution body to introduce the application scenario of the sensing fiber Raman temperature measurement method provided in the embodiment of the present application.

[0035] Figure 1 A schematic diagram of a process of a sensing optical fiber Raman temperature measurement method provided in an embodiment of the present application, the method comprising the following steps:

[0036] Step S10: Obtain target electrical signals corresponding to three parts of backscattered Raman light respectively; wherein, two parts of backscattered Raman light are obtained by respectively injecting two intensity modulated chirped pulse signals into the sensing optical fiber, and the remaining part of backscattered Raman light is obtained by injecting an intensity modulated constant signal into the sensing optical fiber, the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are respectively an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal.

[0037] Chirped pulses are optical pulses whose frequency changes over time. For example, the frequency increases linearly from an initial value to a final value, forming a frequency-changing "sweep" signal. Chirped pulse signals can be linear frequency modulation (LFM) or nonlinear chirp (such as exponential chirp).

[0038] In the RDTS system, both anti-Stokes light and Stokes light are very weak. Therefore, in order to increase the sensing distance, high-power lasers or erbium-doped fiber amplifiers are usually used to enhance the optical power emitted into the sensing fiber. Increasing the pulse width can increase the optical power emitted into the sensing fiber, but the spatial resolution of the system will deteriorate as a result, because in traditional fiber-optic sensing systems, the spatial resolution is determined by the pulse width. The narrower the pulse width, the higher the spatial resolution. However, a narrower pulse width means reduced energy and a shorter transmission distance. Therefore, by increasing the peak energy of the pulse and narrowing its width, it is ensured that both long-distance detection and high resolution can be achieved. However, due to nonlinear effects, the input peak power cannot be increased indefinitely, which will deplete the pump power and reduce the signal-to-noise ratio. Therefore, there is a problem of mutual clamping of detection distance and spatial resolution in traditional fiber-optic sensing systems.

[0039] The signal amplitude spectrum obtained after matched filtering of the chirped pulse signal is approximately in the form of a Sinc function. The spatial resolution of the system is no longer limited by the pulse width, but is related to the bandwidth of the frequency sweep. This decouples the mutual restrictions between system indicators and enables the system to have both long-distance transmission and high spatial resolution performance. The spatial resolution in the frequency sweep system is expressed by the following formula:

[0040]

[0041] Where ΔZ is the spatial resolution, v g is the speed of light in the sensing fiber, and B is the sweep bandwidth. An intensity modulated constant signal and two intensity modulated chirped pulse signals are generated as a group at different times and input into the sensing fiber, and then their corresponding back Raman scattered light is collected respectively, and the optical signal is photoelectrically converted into the corresponding target electrical signal to facilitate subsequent analysis and processing. Among them, an intensity modulated constant signal is a constant, for example, I(t) = A, A is a positive real number, and I(t) is the intensity modulated constant signal; an intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an intensity modulated sinusoidal function signal, for example, I(t) = 1 + sin(2πf0t+πkt 2 ), f0 is the frequency sweep center frequency, k is the frequency modulation rate; the other intensity modulated chirped pulse signal is a frequency sweep signal including a DC component and an intensity modulated cosine function signal having a 90-degree phase difference with the intensity modulated sine function signal, for example, I(t)=1+cos(2πf0t+πkt 2 ). The embodiment of the present application does not specifically limit the expressions of one intensity modulated constant signal and two intensity modulated chirped pulse signals, and those skilled in the art may make adjustments according to actual conditions.

[0042] Step S20: Demodulate the temperature information along the sensing optical fiber based on the target electrical signal.

[0043] After acquiring the target electrical signal, a complex signal is synthesized according to the expression characteristics of the intensity modulated constant signal and the intensity modulated chirped pulse signal corresponding to the target electrical signal, and then matched filtering is performed. The intensity ratio of the anti-Stokes light and the Stokes light in the target electrical signal is used for temperature demodulation to calculate the temperature information along the sensing optical fiber.

[0044] In the above scheme, the RDTS system based on two intensity modulated chirped pulse signals and one intensity modulated constant signal has fewer sweeping signals than the RDTS system using four sine and cosine wave sweeping signals in the prior art, so the response time for demodulating the temperature curve is faster, which has a speed performance advantage.

[0045] In some embodiments, step S20 includes:

[0046] S201: Synthesize the target electrical signal into a complex signal according to the Euler formula.

[0047] According to Euler's formula ix = cosx + isinx, and the target signal is synthesized into a complex signal. In order to make the synthesized complex signal finally be in the form of Euler's formula, a simple operation can be performed on the target electrical signal corresponding to an intensity modulated constant signal and two intensity modulated chirped pulse signals. The above three intensity modulated signals are A, 1+sin(2πf0t+πkt 2 )、1+cos(2πf0t+πkt 2 ) is used as an example to illustrate, let I1(t) = A, I2(t) = 1 + cos(2πf0t + πkt 2 ), I3(t)=1+sin(2πf0t+πkt 2 ), the synthesized complex signal I′(t)=AI′2(t)-I′1(t)+i(AI′3(t)-I′1(t)), wherein the third target electrical signal I′1(t) is a signal corresponding to I1(t), the first target electrical signal I′2(t) is a signal corresponding to I2(t), and the second target electrical signal I′3(t) is a signal corresponding to I3(t). In some embodiments, A may be 1.

[0048] Raman scattering in the sensing fiber can be regarded as a linear time-invariant process. Therefore, the convolution of the swept frequency optical signal on the fiber response is equal to the convolution of the synthetic complex signal on the fiber response. 2 )、1+cos(2πf0t+πkt 2) is used as an example to illustrate. In addition, let the positive real number A be equal to 1, then the synthesized complex signal is I′(t)=I′2(t)-I′1(t)+i(I′3(t)-I′1(t)), then the synthesized complex signal is equal to:

[0049]

[0050] Wherein, Y(t) represents the synthetic complex signal and h(t) represents the optical fiber response.

[0051] S202: Perform matched filtering on the complex signal to obtain a processed OTDR signal.

[0052] Use a matched filter to compress the pulse of Y(t) to obtain the processed OTDR signal:

[0053]

[0054] Where G(t) represents the processed OTDR signal, I * (-t) indicates a local matched filter.

[0055] Matched filter is a commonly used signal processing technique used to recover the original signal from the collected backscattered light signal and extract temperature information from it. The matched filter is designed to maximize the signal-to-noise ratio, thereby improving the quality and reliability of the signal.

[0056] S203: Demodulate and calculate the processed OTDR signal to obtain temperature information along the sensing optical fiber.

[0057] After the processed OTDR signal is calculated, the intensity ratio of the anti-Stokes light and the Stokes light is used for temperature demodulation to calculate the temperature information along the sensing optical fiber.

[0058] In the above scheme, two intensity modulated chirped pulse signals and a target electrical signal corresponding to an intensity modulated constant signal are synthesized into a complex signal in the form of Euler's formula through simple basic operations, so that the real part of the complex signal only includes the wave signal of the cosine symbol part, and the imaginary part only includes the wave signal of the sine symbol part. After the complex signal is synthesized, a matched filter is used to match filter the complex signal to obtain a processed OTDR signal. By demodulating and calculating the processed OTDR signal, the temperature information along the sensing optical fiber is obtained.

[0059] In some embodiments, the two intensity modulated chirped pulse signals and the intensity modulated constant signal are respectively amplified before being injected into the sensing optical fiber, wherein the step S10 of obtaining the target electrical signals corresponding to the three parts of back Raman scattered light respectively includes:

[0060] S101: Receive a first original electrical signal and a second original electrical signal corresponding to two intensity modulated chirped pulse signals.

[0061] S102: Correct the second original electrical signal according to the correction factor to obtain a corrected second target electrical signal, where the target electrical signal includes the first original electrical signal, the second target electrical signal, and a third target electrical signal corresponding to the intensity modulation constant signal.

[0062] Based on the above I2(t)=1+cos(2πf0t+πkt 2 ), I3(t)=1+sin(2πf0t+πkt 2 ) is used as an example to illustrate that the first original electrical signal and the second original electrical signal corresponding to the two intensity modulated chirped pulse signals are I″2(t) and I″3(t). The expression of the second target electrical signal I′3(t) obtained by correcting the second original electrical signal I″3(t) according to the correction factor is:

[0063]

[0064] Among them, factor is a correction factor, which is added in the signal processing process to correct the distortion amplitude. The correction factor is obtained by comparing the differences between each intensity modulated chirp pulse signal before and after amplification to compensate the swept frequency signal.

[0065] In theory, there is a certain relationship between the peak values ​​of intensity modulated chirped pulse signals. However, since the optical amplifier module amplifies pulses of different modulation shapes inconsistently, the original theoretical peak value relationship is distorted after the swept-frequency pulse lights of different shapes are amplified, and the final temperature curve will produce a large distortion. In the above scheme, the amplitude of the collected back Raman scattered light is corrected by using a correction factor based on the original electrical signal, which can greatly suppress the problem of temperature curve distortion caused by amplitude distortion.

[0066] In some embodiments, the correction factor is calculated by: determining the correction factor as the quotient of a first average power ratio of two intensity modulated chirped pulse signals before signal amplification and a second average power ratio of two intensity modulated chirped pulse signals after signal amplification.

[0067] Take I2(t) and I3(t) as an example to represent two intensity modulated chirped pulse signals, I″′2(t) and I″′3(t) represent the two intensity modulated chirped pulse signals after optical signal amplification, I″2(t) and I″3(t) represent the first original electrical signal and the second original electrical signal collected, P(I2(t)) and P(I3(t)) are the average optical powers corresponding to the two intensity modulated chirped pulse signals before optical signal amplification, and the first average power ratio k is: k can be understood as the amplitude relationship between the two intensity modulated chirped pulse signals before amplification in theory. After optical amplification, there is a certain degree of amplitude distortion. P(I″′2(t)) and P(I″′3(t)) are the average optical powers of the two intensity modulated chirped pulse signals after optical signal amplification. The second average power ratio k′ is: k′ can be understood as the actual amplitude relationship between the two intensity modulated chirped pulse signals after signal amplification, and the correction factor factor is calculated as follows:

[0068] Correspondingly, in step S102, the second original electrical signal is corrected according to the correction factor to obtain a corrected second target electrical signal: That is, I″3(t) is divided by factor to achieve correction of the second original electrical signal. Wherein, I′3(t) is the second target electrical signal obtained after the second original electrical signal is corrected.

[0069] Since the intensity of the pulse light is linearly related to the intensity of the collected first original electrical signal and the second original electrical signal, a correction factor factor is used for correction during the demodulation process. The corrected target electrical signal restores the intensity relationship corresponding to the original average power, and then the first original electrical signal I″2(t), the second target electrical signal I′3(t) and the third target electrical signal I′1(t) are synthesized into a complex signal, and the processed OTDR signal is obtained after matched filtering. Among them, in this embodiment, the first original electrical signal I″2(t) is the first target electrical signal I′2(t).

[0070] For example, theoretically, the sweep frequency amplitude of the first intensity modulated chirped pulse signal I2(t) is 1, and the sweep frequency amplitude of the second intensity modulated chirped pulse signal I3(t) is 2, that is, P(I2(t))=1, P(I3(t))=2, then After amplification, this relationship will be destroyed. For example, the sweeping light amplitude of the first intensity modulated chirped pulse signal I2(t) is amplified to 2, and the sweeping light amplitude of the second intensity modulated chirped pulse signal I3(t) is amplified to 8, that is, P(I″′2(t))=2, P(I″′3(t))=8, then Then we can get the correction factor Since the original electrical signal transmitted and collected through the sensing optical fiber is in direct proportion to P(I″′2(t)) and P(I″′3(t)), that is, P(I″2(t))=nP(I″′2(t)), P(I″3(t))=nP(I″′3(t)), where n is equal. Therefore, the corrected second target electrical signal can be obtained. At this time, the first original electrical signal I″2(t) and the second target electrical signal I′3(t) have restored an amplitude relationship of 1:2.

[0071] As an implementation manner, an optical power meter may be used to measure the average power of chirped pulse signals modulated with different intensities before and after optical amplification.

[0072] Compared with the traditional uncorrected processing flow, this embodiment can greatly suppress the problem of temperature curve distortion caused by amplitude distortion, improve the quality of matched filtering, and improve system performance.

[0073] In the above scheme, the amplitude of the second original electrical signal is corrected by using the power ratio relationship of the intensity modulated chirped pulse signal before and after amplification, which can better suppress the problem of temperature curve distortion caused by amplitude distortion.

[0074] In some embodiments, the expressions of the intensity modulated constant signal and the two intensity modulated chirped pulse signals are:

[0075] I1(t)=C,

[0076] or,

[0077] I1(t)=C,

[0078] or,

[0079] I1(t)=C,

[0080] or,

[0081] I1(t)=C,

[0082] Wherein, I1(t) is the intensity modulated constant signal, I2(t) and I3(t) are two intensity modulated chirped pulse signals, w(t) is a window function, f0 is the frequency sweep center frequency, k is the frequency modulation rate, A, B, C are constants and A≥B>0, C>0. Wherein, the window function w(t) can be a Hamming window, a Hanning window, a Blackman window, a Kaiser window, a Gaussian window, a triangular window, etc.

[0083] Assuming A=1, B=1, C=1, the synthetic complex signals corresponding to the above four different combinations of intensity modulated signals in the demodulation stage are: I′(t)=I′2(t)-I′1(t)+i(I′3(t)-I′1(t)), I′(t)=I′2(t)-I′1(t)-i(I′3(t)-I′1(t)), I′(t)=-I′2(t)+I′1(t)-i(I′3(t)-I′1(t)), I′(t)=-I′2(t)+I′1(t)-i(I′3(t)-I′1(t)), I′(t)=-I′2(t)+I′1(t)+i(I′3(t)-I′1(t)). Among them, I′1(t), I′2(t), and I′3(t) are the electrical signals collected after the three intensity modulated signals are injected into the sensing optical fiber and Raman scattering occurs. It should be noted that in other embodiments, A, B, and C can be other positive numbers as long as they can be calculated according to Euler's formula e ix =cosx+isinx, the target electrical signal can be synthesized into a complex signal that can be used for temperature demodulation analysis.

[0084] In the above scheme, the expressions of an intensity modulated constant signal and two intensity modulated chirped pulse signals include the above four different combinations that are essentially different. Using any one of the combinations or other modified forms of swept frequency signals that do not deviate from the essence of any one of the combinations, the temperature curve can be demodulated using the temperature measurement method provided in the present application. In addition, adding a window function to the intensity modulated chirped pulse signal can further improve the sidelobe suppression ratio, so that the temperature accuracy of the final demodulated temperature curve is higher.

[0085] like Figure 2 As shown, Figure 2 A schematic diagram of the structure of a sensing optical fiber Raman temperature sensor provided in this application, wherein the solid line represents optical fiber transmission, and the dotted line represents other modes such as electrical signal transmission and Ethernet transmission. The sensing optical fiber Raman temperature sensor includes:

[0086] The signal generating module 100 is used to generate two intensity modulated chirped pulse signals and an intensity modulated constant signal, wherein the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal.

[0087] The optical detection and acquisition module 200 is used to collect three parts of back Raman scattered light generated after two intensity modulated chirped pulse signals and an intensity modulated constant signal are injected into the sensing optical fiber and Raman scattered, and convert the back Raman scattered light into corresponding original electrical signals.

[0088] The signal processing module 300 is used to obtain a corresponding target electrical signal based on the original electrical signal, and to execute the sensing optical fiber Raman temperature measurement method described in any of the above method embodiments.

[0089] The implementation of the sensing fiber Raman temperature sensor is flexible, and those skilled in the art can adjust it according to the actual situation. For example, the signal generating module 100 can be compatible with a variety of optical path schemes for generating swept frequency light, including but not limited to the following schemes:

[0090] Method 1): Use a directly modulated laser (DML) to generate swept frequency light.

[0091] Method 2): Using continuous laser + acousto-optic modulator (AOM), the continuous laser emits continuous light, which is modulated by the AOM to generate swept frequency light.

[0092] Method 3): Using continuous laser + electro absorption modulator (EAM), the continuous laser emits continuous light, which is modulated by the EAM to generate swept frequency light.

[0093] Method 4): Using a continuous laser + an electro-optic modulator (EOM), the continuous laser emits continuous light, which is modulated by the EOM to generate a swept frequency light.

[0094] Method 5): Using continuous laser + semiconductor optical amplifier (Semiconductor Optical Amplifier, SOA), the continuous laser emits continuous light, the SOA is modulated to generate swept frequency light, and the SOA also has an amplification effect.

[0095] In the above scheme, the RDTS system based on two intensity modulated chirped pulse signals and one intensity modulated constant signal has fewer sweeping signals than the RDTS system using four sine and cosine wave sweeping signals in the prior art, so the response time for demodulating the temperature curve is faster, which has a speed performance advantage.

[0096] In some embodiments, reference Figure 3 , Figure 3A schematic diagram of the structure of another sensing fiber Raman temperature sensor provided in an embodiment of the present application, wherein the signal generating module 100 includes a signal generator 1001 and a frequency sweeping signal generating module 1002, and the frequency sweeping signal generating module 1002 generates an intensity modulated chirped pulse signal and an intensity modulated constant signal under the drive of the signal generator 1001; wherein the frequency sweeping signal generating module 1002 is a directly modulated laser.

[0097] In some embodiments, reference Figure 3 , the sensing optical fiber Raman temperature sensor also includes:

[0098] The optical amplifier module 400 is used to amplify the intensity modulated chirped pulse signal and the intensity modulated constant signal output by the signal generation module 100 .

[0099] The wavelength division multiplexer 500 is used to inject the amplified intensity modulated chirped pulse signal and the intensity modulated constant signal into the sensing optical fiber respectively, and receive the back Raman scattered light.

[0100] The correction calculation module 600 is used to determine the quotient of the first average power ratio corresponding to the two intensity modulated chirped pulse signals before signal amplification and the second average power ratio corresponding to the two intensity modulated chirped pulse signals after signal amplification as a correction factor; wherein the light detection and acquisition module 200 is used to receive the first original electrical signal and the second original electrical signal corresponding to the two intensity modulated chirped pulse signals, and the third target electrical signal corresponding to the intensity modulated constant signal; the signal processing module 300 is used to correct the second original electrical signal according to the correction factor to obtain a corrected second target electrical signal, and the target electrical signal includes the first original electrical signal, the second target electrical signal and the third target electrical signal corresponding to the intensity modulated constant signal.

[0101] Driven by the signal generator 1001, the frequency sweep signal generating module 1002 generates an intensity modulated chirped pulse signal and an intensity modulated constant signal, which are amplified to below the nonlinear effect threshold by the optical amplifier module 400, and then injected into the sensing optical fiber after passing through the wavelength division multiplexer 500. The generated Stokes light and anti-Stokes light are returned through the 1650nm port (SR) and 1450nm port (ASR) of the wavelength division multiplexer 500 respectively, and are received by the optical detection and acquisition module 200 and complete the photoelectric conversion, and finally transmitted to the signal processing module 300 for the amplitude correction of the second original electrical signal mentioned above to obtain the corresponding target electrical signal, and then combined with the first original electrical signal and the third target electrical signal for complex signal synthesis, and then pulse compression is performed through the matched filter to achieve temperature demodulation.

[0102] The following is an example of a possible workflow of the sensing fiber Raman temperature sensor: the frequency sweep signal generating module 1002 is driven by the signal generator 1001 to generate one 1550nm intensity modulated chirped pulse signal. After the intensity modulated chirped pulse signal passes through the optical amplifier module 400, the optical signal amplitude is amplified, but amplitude distortion is generated at the same time. After being injected into the sensing fiber through the wavelength division multiplexer 500, Raman scattering occurs, generating 1450nm (ASR signal) and 1650nm (SR signal) scattering signals. The scattering signals return to the wavelength division multiplexer 500 and are divided into one 1450nm signal and one 1650nm signal. The two signals are received by the optical detection and acquisition module 200 respectively. Explanatory, one Raman scattering signal includes the above two signals.

[0103] When the above process is completed, the next intensity modulated chirped pulse signal or DC constant signal is sent to perform the above process. The two intensity modulated chirped pulse signals and one DC constant signal, a total of 3 in a group, complete the above process, which is equivalent to collecting a total of 6 signals (3 pairs of Stokes and anti-Stokes signals), which are adjusted in amplitude and processed in the subsequent signal process to obtain the final temperature information.

[0104] In the above scheme, the optical amplifier module 400 can enhance the intensity of the optical signal, improve the detection distance of the RDTS system, and help maintain the stability of the performance. The wavelength division multiplexer 500 is used to transmit the sweep signal to the sensing optical fiber, so that the sensing optical fiber Raman temperature sensor can perform temperature detection normally. The correction calculation module 600 can calculate the correction factor for the amplitude correction of the original electrical signal and obtain the corresponding target electrical signal. Through the correction processing, it is beneficial to improve the accuracy of the temperature sensor.

[0105] The present application provides a computer program product, including computer program instructions, which, when read and executed by a processor, execute the methods described in the above method embodiments.

[0106] Reference Figure 4 , Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application, wherein the electronic device includes a processor 401, a memory 402 and a bus 403, wherein the processor 401 and the memory 402 communicate with each other via the bus 403; the memory 402 stores program instructions that can be executed by the processor 401, and the processor 401 calls the program instructions to execute the methods described in the above-mentioned method embodiments.

[0107] The processor 401 includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor 401 can be a general-purpose processor, including a central processing unit (CPU), a micro control unit (MCU), a network processor (NP) or other conventional processors; it can also be a dedicated processor, including a neural network processor (NPU), a graphics processor (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. In addition, when there are multiple processors 401, some of them can be general-purpose processors and the other part can be dedicated processors.

[0108] The memory 402 includes one or more (only one is shown in the figure), which can be, but not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The processor 401 and other possible components can access the memory 402 and read and / or write data therein.

[0109] In particular, one or more computer program instructions may be stored in the memory 402, and the processor 401 may read and execute these computer program instructions to implement the weak password scanning behavior identification method provided in the embodiment of the present application.

[0110] The bus 403 includes one or more (only one is shown in the figure), which can be used to communicate directly or indirectly with other devices to interact with data. The bus 403 may include devices for wired wireless communication, such as optical fiber, serial peripheral interface (Serial Peripheral Interface, referred to as SPI) module, integrated circuit bus (Inter-Integrated Circuit, referred to as I2C), etc., and may also include devices for wireless communication, such as Bluetooth module, Wi-Fi module, mobile communication module (such as 4G, 5G module), etc.

[0111] Understandably, Figure 4 The structure shown is for illustration only. The electronic device may also include Figure 4 More or fewer components as shown, or with Figure 4 Different structures are shown. Figure 4 The components shown in the figure can be implemented by hardware, software or a combination thereof. The electronic device may be a physical device, such as a switch, a router, a server, a PC, etc., or a virtual device, such as a virtual machine, a virtualized container, etc. Moreover, the electronic device is not limited to a single device, but may also be a combination of multiple devices or an integrated environment composed of a large number of devices.

[0112] The present application provides a computer-readable storage medium, including: the computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the methods described in the above method embodiments.

[0113] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0114] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0115] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0116] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A sensing optical fiber Raman temperature measurement method, characterized in that: include: Obtain target electrical signals corresponding to three parts of backscattered Raman light, respectively; wherein two parts of backscattered Raman light are obtained by respectively injecting two intensity modulated chirped pulse signals into a sensing optical fiber, and the remaining part of backscattered Raman light is obtained by injecting an intensity modulated constant signal into the sensing optical fiber, wherein the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are respectively an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal; The temperature information along the sensing optical fiber is demodulated based on the target electrical signal.

2. The method according to claim 1, characterized in that The step of demodulating the temperature information along the sensing optical fiber based on the target electrical signal comprises: According to Euler's formula, synthesize the target electrical signal into a complex signal; Performing matched filtering on the complex signal to obtain a processed OTDR signal; The temperature information along the sensing optical fiber is obtained by demodulating and calculating the processed OTDR signal.

3. The method according to claim 1, characterized in that The two intensity modulated chirped pulse signals and the intensity modulated constant signal are respectively amplified before being injected into the sensing optical fiber, wherein the target electrical signals corresponding to the three parts of backscattered Raman light are obtained, respectively, including: Receiving a first original electrical signal and a second original electrical signal corresponding to the two intensity modulated chirped pulse signals; The second original electrical signal is corrected according to the correction factor to obtain a corrected second target electrical signal, wherein the target electrical signal includes the first original electrical signal, the second target electrical signal and a third target electrical signal corresponding to the intensity modulation constant signal.

4. The method according to claim 3, characterized in that The correction factor is calculated by: determining the correction factor as the quotient of the first average power ratio of the two intensity modulated chirped pulse signals before signal amplification and the second average power ratio of the two intensity modulated chirped pulse signals after signal amplification.

5. The method according to any one of claims 1 to 4, characterized in that: The expressions of the intensity modulated constant signal and the two intensity modulated chirped pulse signals are: I1(t)=C, or, I1(t)=C, or, I1(t)=C, or, I1(t)=C, Among them, I1(t) is the intensity modulated constant signal, I2(t) and I3(t) are two intensity modulated chirped pulse signals respectively, w(t) is the window function, f0 is the sweep center frequency, k is the frequency modulation rate, A, B, C are constants and A≥B>0, C>0.

6. A sensing optical fiber Raman temperature sensor, characterized in that: include: A signal generating module, used for generating two intensity modulated chirped pulse signals and an intensity modulated constant signal, wherein the intensity modulated chirped pulse signal is a swept frequency signal including a DC component and an AC component, and the AC components corresponding to the two intensity modulated chirped pulse signals are respectively an intensity modulated sine function signal and an intensity modulated cosine function signal having a phase difference of 90 degrees with the intensity modulated sine function signal; An optical detection and acquisition module, used for acquiring three parts of back Raman scattered light generated after the two intensity modulated chirped pulse signals and the intensity modulated constant signal are injected into the sensing optical fiber and Raman scattered, and converting the back Raman scattered light into an original electrical signal; A signal processing module is used to obtain a corresponding target electrical signal based on the original electrical signal and to execute the sensing optical fiber Raman temperature measurement method according to any one of claims 1 to 5.

7. The sensing optical fiber Raman temperature sensor according to claim 6, characterized in that: The signal generating module comprises a signal generator and a frequency sweeping signal generating module, wherein the frequency sweeping signal generating module generates the intensity modulated chirped pulse signal and the intensity modulated constant signal under the driving of the signal generator; Wherein, the frequency sweep signal generating module is a directly modulated laser.

8. The sensing optical fiber Raman temperature sensor according to claim 6, characterized in that: Also includes: An optical amplification module, used for amplifying the intensity modulated chirped pulse signal and the intensity modulated constant signal output by the signal generation module; A wavelength division multiplexer, used for respectively injecting the amplified intensity modulated chirped pulse signal and the intensity modulated constant signal into the sensing optical fiber, and receiving the back Raman scattered light; A correction calculation module, used to determine the quotient of a first average power ratio of the two intensity modulated chirped pulse signals before signal amplification and a second average power ratio of the two intensity modulated chirped pulse signals after signal amplification as a correction factor; Among them, the optical detection and acquisition module is used to receive the first original electrical signal and the second original electrical signal corresponding to the two intensity modulated chirped pulse signals, and the third target electrical signal corresponding to the intensity modulated constant signal; the signal processing module is used to correct the second original electrical signal according to the correction factor to obtain a corrected second target electrical signal, and the target electrical signal includes the first original electrical signal, the second target electrical signal and the third target electrical signal corresponding to the intensity modulated constant signal.

9. An electronic device, characterized in that: include: A processor, a memory and a bus, wherein the processor and the memory communicate with each other via the bus; The memory stores program instructions executable by the processor, and the processor can execute the method according to any one of claims 1 to 5 by calling the program instructions.

10. A computer-readable storage medium, characterized in that: include: The computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the method according to any one of claims 1 to 5.

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