Optical fiber signal processing device and method and distributed optical fiber temperature measurement system

Abstract

The invention relates to the technical field of optical sensing, in particular to an optical fiber signal processing device and method and a distributed optical fiber temperature measurement system.The device comprises a signal acquisition module, an analog-to-digital conversion module and a signal processing module, and the signal acquisition module comprises a photoelectric conversion unit and a signal amplification circuit; the signal processing module comprises a denoising unit and a temperature processing unit; the photoelectric conversion unit is used for converting the optical fiber signal into a current signal; the signal amplification circuit is used for converting the current signal into a voltage signal and carrying out signal amplification to obtain an amplified electric signal; the analog-to-digital conversion module is used for converting the amplified electric signal into a digital signal; the denoising unit is used for performing superposition denoising and wavelet filtering on the digital signal to obtain a target signal; the temperature processing unit is used for obtaining temperature values corresponding to different positions along the temperature measuring optical fiber according to the target signal; the device can well improve the stability and reliability of Stokes and anti-Stokes signals, and ensures the temperature measurement precision.

Description

Technical Field

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

[0002] With the development of science and technology and the improvement of people's quality of life, the importance of temperature monitoring in the fields of industry, transportation, urban pipelines, building safety, etc. is becoming more and more obvious. Traditional temperature sensors generally work based on electrical signals, and have the advantages of high temperature measurement accuracy, simple operation, and low price. They are widely used in many fields. However, in temperature measurement environments such as long distances (more than several kilometers), strong electromagnetic interference, and flammable and explosive environments, this type of temperature sensor cannot meet the measurement requirements. Therefore, the Distributed Optical Fiber Temperature Sensor (Distributed Optical Fiber Temperature Sensor) that uses the Raman effect for temperature measurement came into being.

[0003] However, in the existing distributed optical fiber temperature measurement process, the signal-to-noise ratio of the optical fiber signal (Raman scattering signal, i.e., Stokes light signal and anti-Stokes light signal) is relatively low, resulting in some useful temperature values ​​being submerged in the noise, which in turn leads to low accuracy of distributed optical fiber temperature measurement, bringing adverse effects on temperature monitoring. Summary of the invention

[0004] The present invention provides an optical fiber signal processing device, method and distributed optical fiber temperature measurement system to solve the problem that part of the useful temperature value of the optical fiber signal (Raman scattering signal) is submerged in the existing distributed optical fiber temperature measurement process, thereby resulting in low distributed optical fiber temperature measurement accuracy.

[0005] The present invention provides an optical fiber signal processing device, the device comprising: a signal acquisition module, an analog-to-digital conversion module, and a signal processing module, the signal acquisition module comprising a photoelectric conversion unit and a signal amplification circuit, the signal processing module comprising: a denoising unit and a temperature processing unit;

[0006] The photoelectric conversion unit is used to convert the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal; the signal amplification circuit is used to convert the current signal into a voltage signal, and amplify the signal to obtain an amplified electrical signal; the analog-to-digital conversion module is used to convert the amplified electrical signal into a digital signal; the denoising unit is used to perform superposition denoising and wavelet filtering on the digital signal to obtain a target signal; the temperature processing unit is used to obtain the temperature values ​​corresponding to different positions along the temperature measurement optical fiber according to the target signal.

[0007] In one embodiment of the present invention, the photoelectric conversion unit is an avalanche photodiode, the signal amplification circuit includes a pseudo differential amplification circuit, the cathode of the avalanche photodiode is connected to a preset first bias voltage device, the anode of the avalanche photodiode is connected to the pseudo differential amplification circuit, and the pseudo differential amplification circuit is used to convert the current signal output by the avalanche photodiode into a voltage signal and perform signal amplification;

[0008] The pseudo differential amplifier circuit includes: a proportional operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a reference voltage device; the positive electrode of the avalanche photodiode is connected to the inverting input terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is grounded, the inverting input terminal of the proportional operational amplifier is also connected to one end of the first resistor, the other end of the first resistor is connected to the output terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is also connected to one end of the second resistor, the other end of the second resistor is connected to the reference voltage device, the output terminal of the proportional operational amplifier is also connected to one end of the third resistor, the other end of the third resistor is the positive voltage output terminal of the pseudo differential amplifier circuit, the end of the second resistor away from the proportional operational amplifier is also connected to one end of the fourth resistor, and the other end of the fourth resistor is the negative voltage output terminal of the pseudo differential amplifier circuit.

[0009] In one embodiment of the present invention, the signal amplifying circuit further includes a plurality of differential amplifying circuits, and the plurality of differential amplifying circuits are arranged in sequence;

[0010] The positive voltage input terminal of the first differential amplifier circuit is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the negative voltage input terminal of the first differential amplifier circuit is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, and the first differential amplifier circuit is connected to the remaining differential amplifier circuits in sequence to complete signal amplification and obtain an amplified electrical signal.

[0011] In one embodiment of the present invention, the plurality of differential amplifier circuits include: a first-stage differential amplifier circuit, a second-stage differential amplifier circuit, and a third-stage differential amplifier circuit, and the pseudo differential amplifier circuit, the first-stage differential amplifier circuit, the second-stage differential amplifier circuit, the third-stage differential amplifier circuit, and the analog-to-digital conversion module are connected in sequence;

[0012] The first-stage differential amplifier circuit includes: a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second operational amplifier, a first intermediate resistor, a second intermediate resistor, and a second bias voltage device;

[0013] One end of the fifth resistor is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the other end of the fifth resistor is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, one end of the sixth resistor is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the other end of the sixth resistor is connected to the inverting input terminal of the first operational amplifier, one end of the seventh resistor is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, the other end of the seventh resistor is connected to the positive input terminal of the first operational amplifier, the negative voltage output terminal of the first operational amplifier, the first intermediate resistor, the second intermediate resistor, and the positive input terminal of the first operational amplifier are connected. The voltage output ends are connected in sequence, one end of the first intermediate resistor close to the second intermediate resistor is connected to the inverting input end of the second operational amplifier, the non-inverting input end of the second operational amplifier is connected to the second bias voltage device, and the output end of the second operational amplifier is connected to the bias voltage input end of the first operational amplifier to complete signal noise reduction and amplification; one end of the eighth resistor is connected to the sixth resistor, the other end of the eighth resistor is connected to the negative voltage output end of the first operational amplifier, one end of the ninth resistor is connected to the seventh resistor, and the other end of the ninth resistor is connected to the positive voltage output end of the first operational amplifier.

[0014] In one embodiment of the present invention, the signal amplification circuit further includes: a bias circuit, the output voltage of which is adjustable; the output end of the bias circuit is connected to the three-stage differential amplifier circuit to adjust the amplified electrical signal output by the three-stage differential amplifier circuit.

[0015] In one embodiment of the present invention, the denoising unit includes: a first storage unit, a second storage unit, and a denoising processing unit;

[0016] The denoising processing unit is used to store the first received digital signal in the first storage unit, and store the second received digital signal in the second storage unit; when the next digital signal is received, the data in the first storage unit and the second storage unit are accumulated to obtain accumulated data; the data originally stored in the first storage unit and the second storage unit are cleared, and the accumulated data is stored in the first storage unit, and the next digital signal is stored in the second storage unit; when a preset number of digital signals are received, the accumulated data stored in the first storage unit is averaged to obtain an intermediate signal; and the target signal is obtained by performing wavelet filtering on the intermediate signal.

[0017] In one embodiment of the present invention, it further comprises: a temperature control module, the temperature control module comprising: a temperature monitoring unit and a cold and hot circulator;

[0018] The temperature monitoring unit is used to monitor the temperature of the photoelectric conversion unit and the signal amplification circuit, and when the temperature of the photoelectric conversion unit and / or the signal amplification circuit exceeds a preset temperature threshold range, a temperature increase signal or a temperature decrease signal is sent to the hot and cold circulator;

[0019] The hot and cold cycler is used to respond to the temperature increase signal and the temperature decrease signal to keep the temperature of the photoelectric conversion unit and the temperature of the signal amplification circuit within the temperature threshold range.

[0020] In one embodiment of the present invention, the temperature processing unit is specifically used to demodulate the target signal to obtain the signal strength reflected by the temperature measuring optical fiber; obtain the optical time domain reflection information of the temperature measuring optical fiber, and based on the signal strength and the optical time domain reflection information, obtain the temperature values ​​corresponding to different positions along the temperature measuring optical fiber.

[0021] The present invention also provides an optical fiber signal processing method based on the optical fiber signal processing device as described in any one of the above, the method comprising: converting the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal;

[0022] Converting the current signal into a voltage signal, and amplifying the signal to obtain an amplified electrical signal; converting the amplified electrical signal into a digital signal;

[0023] Performing superposition denoising and wavelet filtering on the digital signal to obtain a target signal;

[0024] According to the target signal, the temperature values ​​corresponding to different positions along the temperature measuring optical fiber are obtained.

[0025] The present invention also provides a distributed optical fiber temperature measurement system, comprising:

[0026] A distributed temperature measuring optical fiber and an optical fiber signal processing device as described in any one of the above items, wherein the distributed temperature measuring optical fiber is connected to the optical fiber signal processing device.

[0027] Beneficial effects of the present invention: The optical fiber signal processing device, method and distributed optical fiber temperature measurement system provided by the present invention are provided with a signal acquisition module, an analog-to-digital conversion module and a signal processing module. The signal acquisition module includes a photoelectric conversion unit and a signal amplification circuit. The signal processing module includes: a denoising unit and a temperature processing unit. The photoelectric conversion unit is used to convert the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal. The signal amplification circuit is used to convert the current signal into a voltage signal and perform signal amplification to obtain an amplified electrical signal. The analog-to-digital conversion module is used to convert the amplified electrical signal into a digital signal. The denoising unit is used to perform superposition denoising and wavelet filtering on the digital signal to obtain a target signal. The temperature processing unit is used to obtain the temperature values ​​corresponding to different positions along the temperature measurement optical fiber according to the target signal. The device can better realize the signal enhancement of the light signal, avoid the submersion of some useful temperature values, and effectively improve the accuracy of distributed optical fiber temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of an optical fiber signal processing device provided by an embodiment of the present invention;

[0029] Figure 2 It is a structural schematic diagram of a signal amplification circuit in an optical fiber signal processing device provided in one embodiment of the present invention;

[0030] Figure 3 A schematic diagram showing comparison of system signal-to-noise ratios corresponding to different accumulation times provided in an embodiment of the present invention;

[0031] Figure 4 A schematic flow chart of a method for processing optical fiber signals provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0034] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0035] In order to facilitate understanding of the optical fiber signal processing device, method and distributed optical fiber temperature measurement system provided by the present invention, some technical terms involved in the present invention are explained below.

[0036] Raman scattered light temperature-sensitive effect: After the light pulse is incident on the sensing fiber, the propagation of photons in the fiber is affected by factors such as fiber density, stress, doping, temperature, bending deformation, etc., and part of the scattered light will propagate in the opposite direction of the incident light, which is called backscattered light. The detection light enters the fiber and generates spontaneous Raman scattering during the transmission process. The backward anti-Stokes light generated is sensitive to temperature, that is, it increases with increasing temperature. Combined with optical time domain reflection technology for spatial positioning, and by analyzing and comparing the backward Raman scattering signal, the temperature value corresponding to any point along the fiber can be obtained. This enables real-time distributed monitoring of the temperature value of the target object.

[0037] Optical Time Domain Reflectometry: When light is transmitted in an optical fiber, the scattered light will return to the optical fiber entrance. By recording the time from the injection to the return of the light, the transmission length of the light in the optical fiber can be calculated, thereby accurately locating the location of the temperature change.

[0038] APD detector: APD detector, also known as avalanche photodiode, is a photovoltaic device with internal gain. It uses the directional motion of photogenerated carriers in a strong electric field to produce an avalanche effect. Photogenerated electrons or holes with very high kinetic energy collide with lattice atoms, causing the lattice atoms to produce secondary electrons. The secondary electrons and hole pairs gain enough kinetic energy under the action of the electric field, and ionize the lattice atoms to produce new electron-hole pairs. This process continues like an "avalanche". Such multiple collisions produce a chain reaction, resulting in an avalanche-like multiplication of carriers.

[0039] FPGA: The full name of FPGA is Field-Programmable Gate Array, which is translated into Chinese as Field Programmable Gate Array. FPGA chip is a universal digital chip that has the function of simulating most digital logic chips. FPGA is a product further developed on the basis of programmable devices such as PAL (Programmable Array Logic), GAL (General Array Logic), EPLD (Erasable Programmable Logic Device). It appeared as a semi-custom circuit in the field of Application Specific Integrated Circuit (ASIC), which not only solves the shortcomings of customized circuits, but also overcomes the shortcomings of the limited number of gate circuits of the original programmable devices.

[0040] MCU: Definition of MCU chip MCU chip refers to microcontroller unit, also known as single-chip microcomputer or single-chip microcomputer, which appropriately reduces the frequency and specifications of the central processing unit, and integrates peripheral interfaces such as memory, counter, USB (universal serial bus), A / D conversion (analog-to-digital conversion), UART (universal asynchronous receiver / transmitter), PLC (programmable logic controller), DMA (direct memory access), and even LCD drive circuit on a single chip to form a chip-level computer. It can perform different combination controls for different application scenarios, so MCU chip is a single-chip microcomputer chip.

[0041] A / D converter: An electronic component that converts analog signals into digital signals. A common analog-to-digital converter converts an input voltage signal into an output digital signal. Since the digital signal itself has no practical meaning and only represents a relative size, any analog-to-digital converter requires a reference analog quantity as a conversion standard. The more common reference standard is the maximum convertible signal size, and the output digital quantity represents the size of the input signal relative to the reference signal. The most important parameter of an analog-to-digital converter is the accuracy of the conversion, which is usually expressed by the number of bits of the output digital signal. The more bits of the digital signal that the converter can accurately output, the stronger the converter's ability to distinguish the input signal, and the better the performance of the converter.

[0042] Combine the following Figures 1 to 4 , the optical fiber signal processing device, method and distributed optical fiber temperature measurement system provided by the present invention are explained.

[0043] See also Figure 1 , Figure 1 A schematic diagram of the structure of an optical fiber signal processing device provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the device comprises:

[0044] A signal acquisition module, an analog-to-digital conversion module, and a signal processing module, wherein the signal acquisition module includes a photoelectric conversion unit and a signal amplification circuit, and the signal processing module includes: a denoising unit and a temperature processing unit;

[0045] The photoelectric conversion unit is used to convert the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal, and the optical fiber signal includes a Stokes optical signal and an anti-Stokes optical signal; the signal amplification circuit is used to convert the current signal into a voltage signal, and perform signal amplification to obtain an amplified electrical signal; the analog-to-digital conversion module is used to convert the amplified electrical signal into a digital signal; the denoising unit is used to perform superposition denoising and wavelet filtering on the digital signal to obtain a target signal; the temperature processing unit is used to obtain the temperature values ​​corresponding to different positions along the temperature measurement optical fiber according to the target signal.

[0046] Wherein, the photoelectric conversion unit, the signal amplification circuit, the analog-to-digital conversion module, the denoising unit, and the temperature processing unit are connected in sequence.

[0047] It should be noted that, in the above embodiments, by providing the above modules and units, the optical fiber signal can be amplified better to avoid the useful temperature information in the signal from being submerged, and the temperature conversion efficiency and accuracy are higher.

[0048] It should also be noted that by performing superposition denoising and wavelet filtering on the digital signal, a relatively stable target signal can be obtained.

[0049] It should be mentioned that the signal acquisition module, analog-to-digital conversion module, and signal processing module in the above embodiments are all integrated in a small constant temperature box, so as to ensure the stability and accuracy of the optical fiber signal processing process.

[0050] Please refer to Figure 2 In some embodiments, the photoelectric conversion unit is an avalanche photodiode, and the signal amplification circuit includes a pseudo-differential amplifier circuit. The cathode of the avalanche photodiode is connected to a preset first bias voltage device, and the anode of the avalanche photodiode is connected to the pseudo-differential amplifier circuit. The pseudo-differential amplifier circuit is used to convert the current signal output by the avalanche photodiode into a voltage signal and perform signal amplification.

[0051] It should be noted that the temperature measuring optical fiber is connected to the photosensitive area of ​​the avalanche photodiode to input the optical fiber signal / optical signal into the avalanche photodiode. The avalanche photodiode converts the optical fiber signal into a current signal under the bias voltage applied by the first bias voltage device VIBAS.

[0052] The pseudo differential amplifier circuit includes: a proportional operational amplifier, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a reference voltage device; the positive electrode of the avalanche photodiode is connected to the inverting input terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is grounded, the inverting input terminal of the proportional operational amplifier is also connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the output terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is also connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the reference voltage device, the output terminal of the proportional operational amplifier is also connected to one end of the third resistor R3, the other end of the third resistor R3 is the positive voltage output terminal of the pseudo differential amplifier circuit, the end of the second resistor R2 away from the proportional operational amplifier is also connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is the negative voltage output terminal of the pseudo differential amplifier circuit. Figure 2 The operational amplifier in the pseudo-differential amplifier circuit is the proportional operational amplifier.

[0053] It should be noted that the voltage at the reverse input terminal of the proportional operational amplifier is equal to the voltage at the non-inverting input terminal. The first resistor R1 is also connected in parallel with a capacitor, and a grounding capacitor is also connected between the non-inverting input terminal of the proportional operational amplifier and the ground to enhance the safety of the entire circuit.

[0054] It should be mentioned that if the inverting input terminal of the proportional operational amplifier is directly grounded, U i ( Figure 2 Middle I 光 The corresponding voltage value, I 光 Refers to the reverse current generated by the avalanche photodiode under the bias voltage applied by the first bias voltage device) increases, U i =V + (Voltage at the non-inverting input of the proportional operational amplifier) ​​-V - (the voltage value of the inverting input terminal of the proportional operational amplifier), VOUT (the voltage value of the positive voltage output terminal of the pseudo differential amplifier circuit) is amplified to be close to the positive rail of the power supply (such as +3.3V, etc.). By setting different first resistors R1R1, the voltage V - , thereby reducing U i , until V + Basically equal to V -However, since the inverting input of the proportional operational amplifier is directly grounded, the output voltage VOUT will always be close to the positive rail of the power supply +3.3V. The differential output voltage of the proportional operational amplifier is ΔOUT0 = VOUT-VOUTN, which is about 1.47V. Among them, VOUT refers to the voltage value of the positive voltage output terminal of the proportional operational amplifier, and VOUTN refers to the voltage value of the negative voltage output terminal of the pseudo differential amplifier circuit. Similarly, for the case of a voltage signal input to the inverting input terminal of the proportional operational amplifier, when V + >V - When ΔOUT0 is about 1.47V, when V + <V - , VOUT will always be close to the negative rail of the power supply, that is, 0V, but due to the presence of a clamping circuit inside the proportional operational amplifier, the VOUT voltage cannot be lower than 0.6V, so ΔOUT0 is about -1.23V. It can be seen from the above theoretical derivation that if different voltage signals are input to the inverting input terminal of the proportional operational amplifier, a voltage output signal with a corresponding amplification factor cannot be obtained. Therefore, in the above embodiment, a current signal is input to the inverting input terminal of the proportional operational amplifier to convert the current signal into a voltage signal and amplify it.

[0055] In some embodiments, the signal amplification circuit further includes a plurality of differential amplification circuits, and the plurality of differential amplification circuits are arranged in sequence;

[0056] The positive voltage input terminal of the first differential amplifier circuit is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the negative voltage input terminal of the first differential amplifier circuit is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, and the first differential amplifier circuit is connected to the remaining differential amplifier circuits in sequence to complete signal amplification and obtain an amplified electrical signal.

[0057] It should be noted that, by providing the above-mentioned multiple differential amplifier circuits, the signal output by the pseudo differential amplifier circuit can be amplified step by step, which has higher safety and stronger stability.

[0058] In some embodiments, the multiple differential amplifier circuits include: a first-stage differential amplifier circuit, a second-stage differential amplifier circuit, and a third-stage differential amplifier circuit, and the pseudo-differential amplifier circuit, the first-stage differential amplifier circuit, the second-stage differential amplifier circuit, the third-stage differential amplifier circuit, and the analog-to-digital conversion module are connected in sequence.

[0059] The first-stage differential amplifier circuit includes: a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a first operational amplifier, a second operational amplifier, a first intermediate resistor, a second intermediate resistor, and a second bias voltage device.

[0060] One end of the fifth resistor R5 is connected to the positive voltage output end of the pseudo differential amplifier circuit, the other end of the fifth resistor R5 is connected to the negative voltage output end of the pseudo differential amplifier circuit, one end of the sixth resistor R6 is connected to the positive voltage output end of the pseudo differential amplifier circuit, the other end of the sixth resistor R6 is connected to the inverting input end of the first operational amplifier, one end of the seventh resistor R7 is connected to the negative voltage output end of the pseudo differential amplifier circuit, the other end of the seventh resistor R7 is connected to the positive input end of the first operational amplifier, the negative voltage output end of the first operational amplifier, the first intermediate resistor, the second intermediate resistor, and the positive input end of the first operational amplifier are connected. The voltage output terminals are connected in sequence, one end of the first intermediate resistor close to the second intermediate resistor is connected to the inverting input terminal of the second operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the second bias voltage device, and the output terminal of the second operational amplifier is connected to the bias voltage input terminal of the first operational amplifier to complete signal noise reduction and amplification; one end of the eighth resistor R8 is connected to the sixth resistor R6, and the other end of the eighth resistor R8 is connected to the negative voltage output terminal of the first operational amplifier, one end of the ninth resistor R9 is connected to the seventh resistor R7, and the other end of the ninth resistor R9 is connected to the positive voltage output terminal of the first operational amplifier. The positive voltage output terminal of the first operational amplifier is the positive voltage output terminal of the first differential amplifier circuit, and the negative voltage output terminal of the first operational amplifier is the negative voltage output terminal of the first differential amplifier circuit. Figure 2 The larger operational amplifier in the first differential amplifier circuit is the first operational amplifier, and the smaller operational amplifier is the second operational amplifier.

[0061] It should be noted that the secondary differential amplifier circuit includes: a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third operational amplifier, a fourth operational amplifier, a third intermediate resistor, a fourth intermediate resistor, and a third bias voltage device.

[0062] One end of the tenth resistor R10 is connected to the negative voltage output terminal of the first operational amplifier, and the other end of the tenth resistor R10 is connected to the inverting input terminal of the third operational amplifier; one end of the eleventh resistor R11 is connected to the positive voltage output terminal of the first operational amplifier, and the other end of the eleventh resistor R11 is connected to the non-inverting input terminal of the third operational amplifier; one end of the twelfth resistor R12 is connected to the inverting input terminal of the third operational amplifier, and the other end of the twelfth resistor R12 is connected to the negative voltage output terminal of the third operational amplifier; one end of the thirteenth resistor R13 is connected to the inverting input terminal of the third operational amplifier, and the other end of the twelfth resistor R13 is connected to the negative voltage output terminal of the third operational amplifier; The positive input terminal of the amplifier is connected, and the other end of the thirteenth resistor R13 is connected to the positive voltage output terminal of the third operational amplifier; the negative voltage output terminal of the third operational amplifier, the third intermediate resistor, the fourth intermediate resistor, and the positive voltage output terminal of the third operational amplifier are connected in sequence, and the inverting input terminal of the fourth operational amplifier is connected to one end of the third intermediate resistor close to the fourth intermediate resistor; the positive input terminal of the fourth operational amplifier is connected to the third bias voltage device, and the output terminal of the fourth operational amplifier is connected to the bias voltage input terminal of the third operational amplifier to complete signal noise reduction and amplification. The positive voltage output terminal of the third operational amplifier is the positive voltage output terminal of the secondary differential amplifier circuit, and the negative voltage output terminal of the third operational amplifier is the negative voltage output terminal of the secondary differential amplifier circuit.

[0063] Figure 2 The larger operational amplifier in the secondary differential amplifier circuit is the third operational amplifier, and the smaller operational amplifier is the fourth operational amplifier.

[0064] It should be noted that the three-stage differential amplifier circuit includes: a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a fifth operational amplifier, a sixth operational amplifier, a fifth intermediate resistor, a sixth intermediate resistor, and a fourth bias voltage device.

[0065] One end of the fourteenth resistor R14 is connected to the negative voltage output end of the secondary differential amplifier circuit, and the other end of the fourteenth resistor R14 is connected to the inverting input end of the fifth operational amplifier; one end of the fifteenth resistor R15 is connected to the positive voltage output end of the secondary differential amplifier circuit, and the other end of the fifteenth resistor R15 is connected to the non-inverting input end of the fifth operational amplifier; one end of the sixteenth resistor R16 is connected to the inverting input end of the fifth operational amplifier, and the other end of the sixteenth resistor R16 is connected to the negative voltage output end of the fifth operational amplifier; one end of the seventeenth resistor R17 is connected to the non-inverting input end of the fifth operational amplifier, and the other end of the seventeenth resistor R17 is connected to the positive voltage output end of the fifth operational amplifier; one end of the eighteenth resistor R18 is connected to the non-inverting input end of the fifth operational amplifier, and the other end of the eighteenth resistor R18 is grounded. The negative voltage output terminal of the fifth operational amplifier, the fifth intermediate resistor, the sixth intermediate resistor, and the positive voltage output terminal of the fifth operational amplifier are connected in sequence; the inverting input terminal of the sixth operational amplifier is connected to one end of the fifth intermediate resistor close to the sixth intermediate resistor, and the non-inverting input terminal of the sixth operational amplifier is connected to the fourth bias voltage device; the output terminal of the sixth operational amplifier is connected to the bias voltage input terminal of the fifth operational amplifier to complete signal noise reduction and amplification. The positive voltage output terminal of the fifth operational amplifier is the positive voltage output terminal of the three-stage differential amplifier circuit, and the negative voltage output terminal of the fifth operational amplifier is the negative voltage output terminal of the three-stage differential amplifier circuit. The positive voltage output terminal of the three-stage differential amplifier circuit is connected to the positive voltage input terminal of the analog-to-digital conversion module (ADC), and the negative voltage output terminal of the three-stage differential amplifier circuit is connected to the negative voltage input terminal of the analog-to-digital conversion module. Figure 2 AINN is the positive voltage input terminal of the analog-to-digital conversion module, and AINP is the negative voltage input terminal of the analog-to-digital conversion module.

[0066] Figure 2 The larger operational amplifier in the three-stage differential amplifier circuit is the fifth operational amplifier, and the smaller operational amplifier is the sixth operational amplifier.

[0067] In some embodiments, the signal amplification circuit further includes: a bias circuit, the output voltage of which is adjustable; the output end of the bias circuit is connected to the three-stage differential amplifier circuit to adjust the amplified electrical signal output by the three-stage differential amplifier circuit.

[0068] It should be noted that by setting the bias circuit, it is possible to facilitate adjustment of the amplified electrical signal output by the three-stage differential amplifier circuit, so that the three-stage differential amplifier circuit outputs an electrical signal of a corresponding amplification factor with higher accuracy and greater adjustability.

[0069] The bias circuit includes: a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a potentiometer RJ, a twenty-third resistor R23, a power supply, and a seventh operational amplifier.

[0070] One end of the nineteenth resistor R19 is connected to the inverting input terminal of the fifth operational amplifier, the other end of the nineteenth resistor R19 is connected to the twentieth resistor R20, and the end of the twentieth resistor R20 away from the nineteenth resistor R19 is connected to the output terminal of the seventh operational amplifier; the twenty-first resistor R21 is connected to the output terminal of the seventh operational amplifier, and the end of the twenty-first resistor R21 away from the twentieth resistor R20 is connected to the twenty-second resistor R22, and the twenty-second resistor R22 is grounded. One end of the twenty-third resistor R23 is connected to the power supply, the other end of the twenty-third resistor R23 is connected to the first fixed end of the potentiometer RJ, the second fixed end of the potentiometer RJ is grounded, and the sliding end of the potentiometer RJ is connected to the non-inverting input terminal of the seventh operational amplifier. By adopting the above-mentioned bias circuit, the adjustment of the amplified electrical signal output by the three-stage differential amplifier circuit can be realized more flexibly. Figure 2 The operational amplifier connected to the potentiometer RJ is the seventh operational amplifier. The power supply can be 3.3V.

[0071] It should be noted that Figure 2 The resistance values ​​of the resistors are exemplarily described in the figure. The first resistor R1 can be 20K (kilo-ohms), and the second resistor R2 can be any value, such as 25Ω (ohms). The third resistor R3 and the fourth resistor R4 can be 25Ω, the fifth resistor R5 can be 470Ω, the sixth resistor R6, the seventh resistor R7, the tenth resistor R10, the eleventh resistor R11, the fourteenth resistor R14, and the fifteenth resistor R15 can be 145Ω, the eighth resistor R8, the ninth resistor R9, the twelfth resistor R12, the thirteenth resistor R13, the sixteenth resistor R16, the seventeenth resistor R17, the eighteenth resistor R18, and the nineteenth resistor R19 can be 680Ω, the twentieth resistor R20 can be 10K, the twenty-first resistor R21 and the twenty-second resistor R22 can be 400Ω, and the twenty-third resistor R23 can be 5.1K. Figure 2 The 2.5K resistors in the figure represent the intermediate resistors. Figure 2 FB+ in the figure indicates the positive terminal in the feedback loop, and FB- indicates the negative terminal in the feedback loop. OUT+ indicates the positive voltage output terminal, and OUT- indicates the negative voltage output terminal.

[0072] In order to ensure the signal amplification accuracy of the above-mentioned differential amplifier circuits at each level, the signal amplification accuracy of the differential amplifier circuits at each level is verified by combining theoretical analysis with actual measurement.

[0073] About theoretical analysis:

[0074] The output of the first-stage differential amplifier circuit:

[0075] ΔOUT1=VOUT1 + -VOUT1 -

[0076] =-ΔOUT0*Af=-(VOUT-VOUTN)*(R8 / R6)=4.689*(VOUTN-VOUT);

[0077] Where VOUT1 + Represents the output of the positive voltage output terminal of the first differential amplifier circuit, VOUT1 - It represents the output of the negative voltage output terminal of the first-stage differential amplifier circuit, and Af represents the amplification factor of the differential amplifier circuit.

[0078] The output of the secondary differential amplifier circuit:

[0079] ΔOUT2=VOUT2 + -VOUT2 - =-ΔOUT1*Af=-21.986*(VOUTN-VOUT);

[0080] Where VOUT2 + Represents the output of the positive voltage output terminal of the secondary differential amplifier circuit, VOUT2 - Represents the output of the negative voltage output terminal of the secondary differential amplifier circuit.

[0081] Output of the three-stage differential amplifier circuit:

[0082] ΔOUT3=VOUT3 + -VOUT3 -

[0083] =-ΔOUT2*Af+[-(V 偏 -0)*R15 / R18]=103.095*(VOUTN-VOUT)-V 偏 ;

[0084] Where VOUT3 + Represents the output of the positive voltage output terminal of the three-stage differential amplifier circuit, VOUT3 - Represents the output of the negative voltage output terminal of the three-stage differential amplifier circuit, V 偏 Represents the output voltage of the bias circuit.

[0085] In addition, let the center bias voltage of each differential amplifier circuit (such as the voltage of the second bias voltage device in the first differential amplifier circuit, the third bias voltage device in the second differential amplifier circuit, and the fourth bias voltage device in the third differential amplifier circuit) be Vocm, and each output voltage VOUT be + -Vocm=Vocm-VOUT - , VOUT + Represents the output of the positive voltage output terminal of the differential amplifier circuit, VOUT - Represents the output of the negative voltage output terminal of the differential amplifier circuit, then:

[0086] VOUT1 + =Vocm+0.5*(VOUTN-VOUT)*4.689=Vocm+2.345*(VOUTN-VOUT);

[0087] VOUT1 - =Vocm-0.5*(VOUTN-VOUT)*4.689=Vocm-2.345*(VOUTN-VOUT);

[0088] VOUT2 + =Vocm+0.5*(VOUT1 - -VOUT1 + )*4.689

[0089] =Vocm-10.993*(VOUTN-VOUT);

[0090] VOUT2 - =Vocm-0.5*(VOUT1 - -VOUT1 + )*4.689

[0091] =Vocm+10.993*(VOUTN-VOUT);

[0092] VOUT3 + =Vocm+0.5*(VOUT2 - -VOUT2 + )*4.689-0.5*V 偏

[0093] =Vocm+51.546*(VOUTN-VOUT)-0.5*V 偏 ;

[0094] VOUT3 - =Vocm-0.5*(VOUT2 - -VOUT2 +)*4.689+0.5*V 偏

[0095] =Vocm-51.546*(VOUTN-VOUT)+0.5*V 偏 ;

[0096] On this basis, if Vocm is set to 0.95V, V 偏 =0.2V, I 光 is 0μA (microampere), then the theoretical output value of each level of differential amplifier circuit is VOUT1 + =0.95V, VOUT1 - =0.95V, VOUT2 + =0.95V, VOUT2 - =0.95V, VOUT3 + =0.85V, VOUT3 - =1.05V;

[0097] Similarly, due to the existence of R5, R1 is about 18.2KΩ. After amplification, the voltage ΔOUT3 input to the analog-to-digital converter does not exceed 1.8V, so VOUTN-VOUT≤0.0194V, leaving a certain margin, VOUTN-VOUT≤0.0182V, that is, I 光 The maximum value is ≤1μA. 光 When the maximum value of is ≤1μA, the theoretical output value of each differential amplifier circuit is VOUT1 + =2.01V, VOUT1 - =0.95V, VOUT2 + =0.95V, VOUT2 - =0.95V, VOUT3 + =0.85V, VOUT3 - =1.05V.

[0098] The above is I 光 The theoretical output values ​​of the differential amplifier circuits at different levels corresponding to different values ​​are adjusted on this basis. 光 , and the outputs of the differential amplifier circuits at each level were measured, and the measured output results were consistent with the above theoretical outputs. Therefore, the differential amplifier circuits at each level in the above embodiment can better meet the signal amplification requirements and have higher accuracy.

[0099] It should be noted that, since the amount of data required for temperature measurement by the distributed temperature measurement optical fiber is very large, the analog-to-digital conversion module in this embodiment uses a 12-bit high-speed dual-channel A / D (analog-to-digital) converter as an analog-to-digital converter for two APD signals (Stokes light and anti-Stokes light generated after Raman scattering are converted into current signals by avalanche photodiodes, and the current signals are converted and amplified into voltage signals by signal amplification circuits, and the voltage signals are APD signals), ensuring the acquisition speed of Stokes signals and anti-Stokes signals. The sampling rate of the analog-to-digital converter can be 250MSPS (million times per second), the signal-to-noise ratio can be 69.6dBFS (full-scale decibels), the input noise can be -149.9dBFS / Hz (full-scale decibels / Hertz), and the analog signal input range can be 1.4Vp-p (Peak-to-Peak Voltage, peak-to-peak voltage) to 2.0Vp-p.

[0100] In order to better improve the data processing performance of the optical fiber signal processing device, the signal processing module in this embodiment adopts FPGA, which has higher overall system speed, lower power consumption, smaller physical size, and better reliability.

[0101] The signal amplification circuit of the optical fiber signal processing device in the above embodiment can better realize the hierarchical amplification of the signal, thereby avoiding the partial useful temperature value in the noise of the optical fiber signal from being submerged, and facilitating the subsequent temperature value analysis. On this basis, in order to improve the accuracy of the subsequent temperature value analysis, this embodiment adopts a denoising unit to perform superposition denoising and wavelet filtering on the digital signal output by the analog-to-digital conversion module to remove the noise in the digital signal, thereby improving the accuracy of the temperature value analysis.

[0102] In some embodiments, the denoising unit includes: a first storage unit, a second storage unit, and a denoising processing unit.

[0103] The denoising processing unit is used to store the first received digital signal in the first storage unit, and store the second received digital signal in the second storage unit; when the next digital signal is received, the data in the first storage unit and the second storage unit are accumulated to obtain accumulated data; the data originally stored in the first storage unit and the second storage unit are cleared, and the accumulated data is stored in the first storage unit, and the next digital signal is stored in the second storage unit; when a preset number of digital signals are received, the accumulated data stored in the first storage unit is averaged to obtain an intermediate signal; and the target signal is obtained by performing wavelet filtering on the intermediate signal.

[0104] It should be noted that, in the above embodiment, the first storage unit is a RAM (random access memory), and the second storage unit is a memory (memory).

[0105] It should also be noted that the denoising processing unit is specifically used to first store the first digital signal in the cache, and then store the data in the cache in the RAM; when the second digital signal arrives, the second digital signal is stored in the cache, and then the data in the cache is extracted into the Memory; when the third digital signal arrives, the data in the RAM and the Memory are accumulated to obtain the accumulated data, the original data stored in the RAM and the Memory are cleared, and the accumulated data is stored in the RAM, and the third digital signal is stored in the Memory; when receiving the subsequent digital signals, its operation is consistent with the operation of receiving the third digital signal. Through the above operations, the accumulation of multiple digital signals is achieved. By averaging the final accumulated data, data denoising can be better achieved to improve the accuracy of optical fiber temperature measurement.

[0106] In addition, the above embodiment can effectively remove noise by performing wavelet filtering on the intermediate signal. The wavelet filtering steps include: performing wavelet decomposition on the signal to obtain different frequency sub-bands, each sub-band contains multiple wavelet coefficients, and the wavelet coefficients represent the components of the signal within a specific frequency range; filtering the wavelet coefficients according to a preset threshold range, such as setting the wavelet coefficients exceeding the threshold range to 0; performing time domain conversion on the filtered wavelet coefficients to complete data reconstruction and obtain the target signal.

[0107] In order to verify the effect of the above-mentioned superposition denoising, this embodiment uses FPGA software to perform timing verification on the above-mentioned superposition denoising steps. The verification results show that the above-mentioned accumulation and averaging steps can better achieve signal denoising with high reliability.

[0108] Figure 3 For a comparison diagram of the system signal-to-noise ratio corresponding to different accumulation times provided in an embodiment of the present invention, please refer to Figure 3 , Figure 3 The temperature value analysis results corresponding to three accumulation times are shown as examples. Figure 3 The first picture from top to bottom is the analysis result of the temperature value corresponding to 1000 accumulation times, that is, 1000 accumulations are performed to obtain the accumulated data, the accumulated data are averaged to obtain the intermediate signal, the intermediate signal is subjected to wavelet filtering to obtain the target signal, and the temperature value analysis is performed based on the target signal to obtain the temperature values ​​corresponding to different positions along the temperature measuring optical fiber. Figure 3 The second picture from top to bottom is the temperature analysis result corresponding to 5000 accumulation times. Figure 3The third picture from the top is the analysis result of the temperature value corresponding to 10,000 accumulation times. Figure 3 Temperature represents the temperature value, Length represents the fiber length, i.e. the different positions of the temperature measuring fiber, and m represents the unit meter. Figure 3 It can be seen that by increasing the number of superpositions, the signal-to-noise ratio can be improved, that is, the accuracy of the temperature value obtained by optical fiber temperature measurement can be effectively improved. Figure 3 In the first figure from top to bottom, the fluctuation range of the temperature value is ±9°C, in the second figure, the fluctuation range of the temperature value is ±2.5°C, and in the third figure, the fluctuation range of the temperature value is ±1.2°C. The fluctuation gradually decreases from top to bottom, and the obtained temperature value gradually becomes more accurate. Therefore, by increasing the number of superpositions (accumulated times), the accuracy of temperature measurement can be improved. It should be mentioned that the increase in the number of superpositions also brings about an increase in the temperature measurement time (the time to obtain the temperature value), such as the temperature measurement time corresponding to 1000 superpositions is 0.63s (seconds), the temperature measurement time corresponding to 5000 superpositions is 1.04s, and the temperature measurement time corresponding to 10000 superpositions is 2.14s. Therefore, in actual application, the number of superpositions can be adjusted according to actual conditions. The number of superpositions corresponds to the preset number of digital signals in the above embodiment.

[0109] It should be noted that, since the photoelectric conversion unit and the signal amplification circuit are more susceptible to the influence of temperature, when the temperature of the device changes, it is easy to affect the optical fiber temperature measurement accuracy. Therefore, in some embodiments, the optical fiber signal processing device further includes: a temperature control module, and the temperature control module includes: a temperature monitoring unit and a hot and cold circulator;

[0110] The temperature monitoring unit is used to monitor the temperature of the photoelectric conversion unit and the signal amplification circuit, and when the temperature of the photoelectric conversion unit and / or the signal amplification circuit exceeds a preset temperature threshold range, a temperature increase signal or a temperature decrease signal is sent to the hot and cold circulator;

[0111] The hot and cold cycler is used to respond to the temperature increase signal and the temperature decrease signal to keep the temperature of the photoelectric conversion unit and the temperature of the signal amplification circuit within the temperature threshold range.

[0112] Specifically, the hot and cold circulator is used to output a target voltage when receiving a temperature increase signal to put the hot and cold circulator in a heating state, and to output an inverted target voltage when receiving a temperature reduction signal to put the hot and cold circulator in a cooling state, thereby ensuring a constant temperature of the entire optical fiber signal processing device.

[0113] It should be noted that, in the above embodiments, by providing a temperature control module, the ambient temperature of the device can be kept in a constant temperature state to ensure that the signal is not affected by temperature drift, thereby ensuring the stability of the signal. In some embodiments, when it is detected that the actual temperature value of the photoelectric conversion unit and / or the signal amplification circuit is different from the preset temperature value, a temperature increase signal or a temperature decrease signal can be sent to the hot and cold circulator to achieve constant temperature control of the entire device.

[0114] It should be mentioned that in order to avoid the influence of the ambient temperature change on the measurement accuracy of the device, the present embodiment integrates the entire optical fiber signal processing device into a constant temperature box to ensure the accuracy of optical fiber temperature measurement.

[0115] In some embodiments, the temperature processing unit is specifically used to demodulate the target signal to obtain the signal intensity reflected by the temperature measuring optical fiber; obtain the optical time domain reflection information of the temperature measuring optical fiber, and obtain the temperature values ​​corresponding to different positions along the temperature measuring optical fiber based on the signal intensity and the optical time domain reflection information. Specifically, the target signal includes: a first signal obtained after the Stokes optical signal is processed as described above, and a second signal obtained after the anti-Stokes optical signal is processed as described above; based on the signal intensity change of the first signal, the signal intensity change of the second signal, and the optical time domain reflection information, the temperature values ​​corresponding to different positions along the temperature measuring optical fiber are obtained with high accuracy.

[0116] In addition, the optical fiber signal processing device also includes: an interface output module, which includes an Ethernet interface and an RS485 (a serial communication interface standard) interface. By providing an Ethernet interface and an RS485 interface, the analyzed temperature value and position data can be sent to the corresponding terminal. It should be mentioned that the RS485 interface adopts differential signal negative logic, and the logic "1" is represented by a voltage difference of + (2 to 6) V between the two lines; the logic "0" is represented by a voltage difference of - (2 to 6) V between the two lines. The interface signal level is relatively low, so it is not easy to damage the chip of the interface circuit, and the level is compatible with the TTL (transistor-transistor logic circuit) level, which can be easily connected to the TTL circuit.

[0117] It should be noted that the optical fiber signal processing device in the above embodiment integrates the light source, wavelength division, and related units of signal processing, which can effectively solve the problem that some useful temperature values ​​of the optical fiber signal (Raman scattering signal) are submerged in the existing distributed optical fiber temperature measurement process, thereby resulting in low accuracy of distributed optical fiber temperature measurement.

[0118] The optical fiber signal processing method provided by the present invention is described below. The optical fiber signal processing method described below and the optical fiber signal processing device described above can be referred to each other.

[0119] Please refer to Figure 4 The optical fiber signal processing method provided in this embodiment based on the optical fiber signal processing device as described in any one of the above items includes:

[0120] S410: Convert the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal, wherein the optical fiber signal includes a Stokes optical signal and an anti-Stokes optical signal.

[0121] S420: Convert the current signal into a voltage signal, and amplify the signal to obtain an amplified electrical signal; and convert the amplified electrical signal into a digital signal.

[0122] S430: Perform superposition denoising and wavelet filtering on the digital signal to obtain a target signal.

[0123] S440: According to the target signal, the temperature values ​​corresponding to different positions along the temperature measuring optical fiber are obtained. The optical fiber signal processing method in this embodiment can better enhance the signal of the optical fiber signal, avoid the submersion of some useful temperature values, effectively improve the accuracy of distributed optical fiber temperature measurement, and has low cost and strong feasibility.

[0124] This embodiment also provides a distributed optical fiber temperature measurement system, including:

[0125] A distributed temperature measurement optical fiber and an optical fiber signal processing device as described in any of the above items, wherein the distributed temperature measurement optical fiber is connected to the optical fiber signal processing device. The distributed optical fiber temperature measurement system in this embodiment can be applied to many application scenarios, such as temperature measurement environments with strong electromagnetic interference and flammable and explosive environments, to achieve high-precision optical fiber temperature measurement, low cost, and high flexibility.

[0126] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some implementations as replacements, the functions marked in the boxes can also occur in a different order than the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0127] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An optical fiber signal processing device, characterized in that: include: A signal acquisition module, an analog-to-digital conversion module, and a signal processing module, wherein the signal acquisition module includes a photoelectric conversion unit and a signal amplification circuit, and the signal processing module includes: a denoising unit and a temperature processing unit; The photoelectric conversion unit is used to convert the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal, and the optical fiber signal includes a Stokes optical signal and an anti-Stokes optical signal; the signal amplification circuit is used to convert the current signal into a voltage signal, and amplify the signal to obtain an amplified electrical signal; the analog-to-digital conversion module is used to convert the amplified electrical signal into a digital signal; the denoising unit is used to perform superposition denoising and wavelet filtering on the digital signal to obtain a target signal; the temperature processing unit is used to obtain the temperature values ​​corresponding to different positions along the temperature measurement optical fiber according to the target signal.

2. The optical fiber signal processing device according to claim 1, characterized in that: The photoelectric conversion unit is an avalanche photodiode, the signal amplification circuit includes a pseudo differential amplification circuit, the cathode of the avalanche photodiode is connected to a preset first bias voltage device, the anode of the avalanche photodiode is connected to the pseudo differential amplification circuit, and the pseudo differential amplification circuit is used to convert the current signal output by the avalanche photodiode into a voltage signal and perform signal amplification; The pseudo differential amplifier circuit includes: a proportional operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a reference voltage device; the positive electrode of the avalanche photodiode is connected to the inverting input terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is grounded, the inverting input terminal of the proportional operational amplifier is also connected to one end of the first resistor, the other end of the first resistor is connected to the output terminal of the proportional operational amplifier, the non-inverting input terminal of the proportional operational amplifier is also connected to one end of the second resistor, the other end of the second resistor is connected to the reference voltage device, the output terminal of the proportional operational amplifier is also connected to one end of the third resistor, the other end of the third resistor is the positive voltage output terminal of the pseudo differential amplifier circuit, the end of the second resistor away from the proportional operational amplifier is also connected to one end of the fourth resistor, and the other end of the fourth resistor is the negative voltage output terminal of the pseudo differential amplifier circuit.

3. The optical fiber signal processing device according to claim 2, characterized in that: The signal amplifying circuit further comprises a plurality of differential amplifying circuits, and the plurality of differential amplifying circuits are arranged in sequence; The positive voltage input terminal of the first differential amplifier circuit is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the negative voltage input terminal of the first differential amplifier circuit is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, and the first differential amplifier circuit is connected to the remaining differential amplifier circuits in sequence to complete signal amplification and obtain an amplified electrical signal.

4. The optical fiber signal processing device according to claim 3, characterized in that: The plurality of differential amplifier circuits include: a primary differential amplifier circuit, a secondary differential amplifier circuit, and a tertiary differential amplifier circuit, and the pseudo differential amplifier circuit, the primary differential amplifier circuit, the secondary differential amplifier circuit, the tertiary differential amplifier circuit, and the analog-to-digital conversion module are connected in sequence; The first-stage differential amplifier circuit includes: a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a second operational amplifier, a first intermediate resistor, a second intermediate resistor, and a second bias voltage device; One end of the fifth resistor is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the other end of the fifth resistor is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, one end of the sixth resistor is connected to the positive voltage output terminal of the pseudo differential amplifier circuit, the other end of the sixth resistor is connected to the inverting input terminal of the first operational amplifier, one end of the seventh resistor is connected to the negative voltage output terminal of the pseudo differential amplifier circuit, the other end of the seventh resistor is connected to the positive input terminal of the first operational amplifier, the negative voltage output terminal of the first operational amplifier, the first intermediate resistor, the second intermediate resistor, and the positive input terminal of the first operational amplifier are connected. The voltage output ends are connected in sequence, one end of the first intermediate resistor close to the second intermediate resistor is connected to the inverting input end of the second operational amplifier, the non-inverting input end of the second operational amplifier is connected to the second bias voltage device, and the output end of the second operational amplifier is connected to the bias voltage input end of the first operational amplifier to complete signal noise reduction and amplification; one end of the eighth resistor is connected to the sixth resistor, the other end of the eighth resistor is connected to the negative voltage output end of the first operational amplifier, one end of the ninth resistor is connected to the seventh resistor, and the other end of the ninth resistor is connected to the positive voltage output end of the first operational amplifier.

5. The optical fiber signal processing device according to claim 4, characterized in that: The signal amplifying circuit further includes: a bias circuit, the output voltage of which is adjustable; the output end of the bias circuit is connected to the three-stage differential amplifying circuit to adjust the amplified electrical signal output by the three-stage differential amplifying circuit.

6. The optical fiber signal processing device according to claim 1, characterized in that: The denoising unit includes: a first storage unit, a second storage unit, and a denoising processing unit; The denoising processing unit is used to store the first received digital signal in the first storage unit, and store the second received digital signal in the second storage unit; when the next digital signal is received, the data in the first storage unit and the second storage unit are accumulated to obtain accumulated data; the data originally stored in the first storage unit and the second storage unit are cleared, and the accumulated data is stored in the first storage unit, and the next digital signal is stored in the second storage unit; when a preset number of digital signals are received, the accumulated data stored in the first storage unit is averaged to obtain an intermediate signal; and the target signal is obtained by performing wavelet filtering on the intermediate signal.

7. The optical fiber signal processing device according to claim 1, characterized in that: Also includes: A temperature control module, the temperature control module comprising: a temperature monitoring unit and a hot and cold circulator; The temperature monitoring unit is used to monitor the temperature of the photoelectric conversion unit and the signal amplification circuit, and when the temperature of the photoelectric conversion unit and / or the signal amplification circuit exceeds a preset temperature threshold range, a temperature increase signal or a temperature decrease signal is sent to the hot and cold circulator; The hot and cold cycler is used to respond to the temperature increase signal and the temperature decrease signal to keep the temperature of the photoelectric conversion unit and the temperature of the signal amplification circuit within the temperature threshold range.

8. The optical fiber signal processing device according to claim 1, characterized in that: The temperature processing unit is specifically used to demodulate the target signal to obtain the signal intensity reflected by the temperature measuring optical fiber; obtain the optical time domain reflection information of the temperature measuring optical fiber, and obtain the temperature values ​​corresponding to different positions along the temperature measuring optical fiber based on the signal intensity and the optical time domain reflection information.

9. A method for processing optical fiber signals based on the optical fiber signal processing device according to any one of claims 1 to 8, characterized in that: include: Converting the optical fiber signal reflected back by the distributed temperature measurement optical fiber into a current signal, wherein the optical fiber signal includes a Stokes optical signal and an anti-Stokes optical signal; Converting the current signal into a voltage signal, and amplifying the signal to obtain an amplified electrical signal; converting the amplified electrical signal into a digital signal; Performing superposition denoising and wavelet filtering on the digital signal to obtain a target signal; According to the target signal, the temperature values ​​corresponding to different positions along the temperature measuring optical fiber are obtained.

10. A distributed optical fiber temperature measurement system, characterized in that: include: A distributed temperature measuring optical fiber and an optical fiber signal processing device as described in any one of claims 1 to 8, wherein the distributed temperature measuring optical fiber is connected to the optical fiber signal processing device.

Images