Rapid demodulation method, device and system for optical frequency domain reflection multi-channel sensing

Abstract

The invention discloses a fast demodulation device for optical frequency domain reflection multi-channel sensing. The fast demodulation device comprises a CPU chip and a GPU chip which are connected. The CPU chip comprises a first cache unit and a plurality of second cache units, one second cache unit corresponds to one group of reference signals, the first cache unit is used for storing the measurement signals, and each second cache unit is used for storing each group of reference signals; the GPU chip comprises a plurality of cross-correlation demodulation modules, one cross-correlation demodulation module corresponds to one sensing optical fiber, and each cross-correlation demodulation module is used for performing cross-correlation demodulation on the measurement signal and each group of reference signals so as to obtain wavelength drift data of each sensing optical fiber. The rapid demodulation device can improve the timeliness of optical frequency domain reflection multi-optical-path signal demodulation.

Description

Technical Field

[0001] The present invention relates to optical frequency domain reflection technology, and in particular to a fast demodulation method, device and system for optical frequency domain reflection multi-path sensing. Background Art

[0002] With the rapid development of optical fiber communication technology, optical fiber sensing technology has quickly become an important component of sensing technology. Compared with traditional sensing technology, optical fiber sensing technology has many advantages, such as high sensitivity, electrical insulation, ability to be used in high and low temperature environments, corrosion resistance, and electromagnetic interference resistance, which has attracted extensive attention from researchers.

[0003] Optical Frequency Domain Reflectometry (OFDR) is a fiber optic sensing and measurement technology. Its working principle is to use the Rayleigh backscattering phenomenon when light propagates in the optical fiber, and to detect the changes in physical parameters along the optical fiber, such as temperature and strain, by analyzing the frequency changes of the optical signal emitted by the light source in the optical fiber. It plays an important role in national and civil perimeter security monitoring, oil and gas pipeline monitoring, wind turbine health monitoring, deep sea and submarine earthquake monitoring, etc.

[0004] In order to realize signal collection of multiple sensing optical fibers, the Chinese patent with patent application number CN202210554559.3 discloses that in an optical frequency domain reflectometer, the signals of different sensing optical fibers can be distinguished according to the unique Rayleigh scattered light between each sensing optical fiber, and a coupler is used instead of an optical switch to realize parallel collection of multi-channel data, and then the wavelength drift spectrum of each sensing optical fiber is demodulated through a cross-correlation algorithm to realize multi-channel sensing.

[0005] However, the computer demodulates the signals output by each sensing optical fiber on the optical frequency domain reflectometer in sequence, that is, the computer first performs cross-correlation demodulation on the reference signal and the measurement signal output by the first sensing optical fiber to obtain the wavelength drift spectrum of the first sensing optical fiber, and then performs cross-correlation demodulation on the reference signal and the measurement signal output by the second sensing optical fiber to obtain the wavelength drift spectrum of the second sensing optical fiber... and so on, until the wavelength drift spectra of all sensing optical fibers are obtained. The cross-correlation demodulation of different sensing optical fibers is not performed simultaneously, which seriously affects the timeliness of signal demodulation. Summary of the invention

[0006] In order to solve the above-mentioned deficiencies of the prior art, the present invention provides a fast demodulation device for optical frequency domain reflection multi-path sensing, which can improve the timeliness of optical frequency domain reflection multi-path signal demodulation.

[0007] The present invention provides a fast demodulation method and system based on the fast demodulation device.

[0008] The technical problem to be solved by the present invention is achieved through the following technical solutions: A fast demodulation device for optical frequency domain reflection multi-path sensing is used for cross-correlation demodulation of a multi-path optical fiber sensing module, wherein the multi-path optical fiber sensing module comprises a plurality of sensing optical fibers arranged in parallel; the fast demodulation device comprises: Connected CPU chip and GPU chip; The CPU chip includes a cache module and a parsing module, the cache module is used to store measurement signals and multiple groups of reference signals, one group of reference signals corresponds to one sensing optical fiber, the measurement signal corresponds to all sensing optical fibers, and the parsing module is used to parse the wavelength drift data of each sensing optical fiber to obtain the wavelength drift spectrum of each sensing optical fiber; The GPU chip includes a plurality of cross-correlation demodulation modules, one cross-correlation demodulation module corresponds to one sensing optical fiber, and each cross-correlation demodulation module is used to perform cross-correlation demodulation on the measurement signal and each group of reference signals respectively to obtain wavelength drift data of each sensing optical fiber.

[0009] Furthermore, the cache module includes a first cache unit and a plurality of second cache units, one second cache unit corresponds to a group of reference signals, the first cache unit is used to store the measurement signal, and each second cache unit is used to store each group of reference signals.

[0010] Furthermore, the GPU chip further includes an FFT operation module, which is used to perform a fast Fourier transform on the measurement signal and each group of reference signals to convert the reference signal and each group of measurement signals from the time domain to the distance domain; each cross-correlation demodulation module includes: A sliding window value taking unit, used for slidingly taking values ​​of respective measurement signals and reference signals according to a preset window length, so as to obtain a plurality of sets of window data, wherein a set of window data corresponds to a spatial position on the sensing optical fiber; A plurality of IFFT operation units, one IFFT operation unit corresponds to a group of window data, and each IFFT operation unit is used to perform an inverse fast Fourier transform on a measurement signal and a reference signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from a distance domain to a frequency domain; A plurality of cross-correlation operation units, one cross-correlation operation unit corresponds to a group of window data, and each cross-correlation operation unit is used to perform cross-correlation operation on the measurement signal and the reference signal in each group of window data to obtain the wavelength drift data of each spatial position on the sensing optical fiber.

[0011] Furthermore, the cross-correlation function adopted by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

[0012] Furthermore, the GPU chip includes multiple stream processors, each stream processor includes multiple thread blocks, and each thread block includes multiple threads.

[0013] A fast demodulation method for optical frequency domain reflection multi-path sensing is used for cross-correlation demodulation of a multi-path optical fiber sensing module, wherein the multi-path optical fiber sensing module comprises a plurality of sensing optical fibers arranged in parallel; the fast demodulation method comprises the following steps: Step 100: constructing a plurality of cross-correlation demodulation modules in the GPU chip according to the data volume of each sensing optical fiber, wherein one cross-correlation demodulation module corresponds to one sensing optical fiber; Step 200: The CPU chip sequentially acquires multiple groups of reference signals, and transmits each group of reference signals to the GPU chip after storing them, wherein one group of reference signals corresponds to one sensing optical fiber; Step 300: The GPU chip saves each group of reference signals into a corresponding cross-correlation demodulation module; Step 400: the CPU chip simultaneously acquires measurement signals of all sensing optical fibers, and transmits the measurement signals to the GPU chip after storing them; Step 500: The GPU chip saves the measurement signal to each cross-correlation demodulation module simultaneously; Step 600: Each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein to obtain wavelength drift data of each sensing optical fiber; Step 700: the GPU chip transmits the wavelength drift data of each sensing optical fiber to the CPU chip; Step 800: The CPU chip analyzes the wavelength drift data of each sensing optical fiber to obtain the wavelength drift spectrum of each sensing optical fiber.

[0014] Furthermore, in step 100, according to the amount of data of each sensing optical fiber, a first cache unit and multiple second cache units are constructed in the CPU chip, one second cache unit corresponds to a group of reference signals, and the first cache unit corresponds to the measurement signal; in step 200, the CPU chip saves each group of reference signals into the corresponding second cache unit, and in step 400, the CPU chip saves the measurement signal into the first cache unit.

[0015] Further, in step 300, before the GPU chip saves each group of reference signals into the corresponding cross-correlation demodulation module, the FFT operation module is used to perform fast Fourier transform on each group of reference signals, so as to convert each group of reference signals from the time domain to the distance domain; and, in step 500, before the GPU chip saves the measurement signals into each cross-correlation demodulation module at the same time, the FFT operation module is used to perform fast Fourier transform on the measurement signals, so as to convert the measurement signals from the time domain to the distance domain; In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein to obtain the wavelength drift data of each sensing optical fiber in the following steps: Step 610: Sliding and sampling the mixed measurement signal and the reference signal stored respectively according to the preset window length to obtain multiple groups of window data, where one group of window data corresponds to a spatial position on the sensing optical fiber; Step 620: construct multiple IFFT operation units and multiple cross-correlation operation units according to the data amount of each group of window data, one IFFT operation unit and one cross-correlation operation unit corresponding to one group of window data; Step 630: Each IFFT operation unit performs an inverse Fourier operation on the reference signal and the measurement signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from the distance domain to the frequency domain; Step 640: Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and the reference signal in each group of window data to obtain the wavelength drift data of each spatial position on the sensing optical fiber.

[0016] Furthermore, the cross-correlation function adopted by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

[0017] An optical frequency domain reflection multi-channel sensing system comprises a data acquisition device, an optical frequency domain reflectometer, an optical fiber coupler, a multi-channel optical fiber sensing module and the above-mentioned fast demodulation device, wherein the multi-channel optical fiber sensing module comprises a plurality of sensing optical fibers arranged in parallel, the optical frequency domain reflectometer is respectively connected to each sensing optical fiber through the optical fiber coupler, and the fast demodulation device is connected to the optical frequency domain reflectometer.

[0018] The present invention has the following beneficial effects: the fast demodulation device of the present invention is based on the cooperation of a CPU chip and a GPU chip, the CPU chip is responsible for front-end data preprocessing and data caching and back-end data parsing, the GPU chip is responsible for intermediate data demodulation operations, and at the same time, the parallel processing capability of the GPU chip is utilized to construct a plurality of cross-correlation demodulation modules in the GPU chip, one cross-correlation demodulation module is specifically responsible for the cross-correlation demodulation of a sensing optical fiber, so that the cross-correlation demodulation of each sensing optical fiber can be performed simultaneously, greatly improving the timeliness of demodulation of multi-optical path signals reflected in the optical frequency domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the optical frequency domain reflection multi-path sensing system provided by the present invention.

[0020] Figure 2 This is a schematic structural diagram of the optical frequency domain reflectometer provided by the present invention.

[0021] Figure 3 This is a schematic structural diagram of the fast demodulation device provided by the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the cross-correlation demodulation module in the fast demodulation device provided by the present invention.

[0023] Figure 5 A block diagram of the steps of the fast demodulation method provided by the present invention.

[0024] Figure 6 This is a block diagram of the steps of the cross-correlation demodulation algorithm in the fast demodulation device provided by the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Embodiment 1 like Figure 1 As shown, an optical frequency domain reflection multi-channel sensing system includes a data acquisition device 2, an optical frequency domain reflectometer 3, a first optical fiber coupler 4, a multi-channel optical fiber sensing module 5 and a fast demodulation device 1, wherein the multi-channel optical fiber sensing module 5 includes a plurality of sensing optical fibers 51 arranged in parallel, the optical frequency domain reflectometer 3 is respectively connected to each sensing optical fiber 51 through the first optical fiber coupler 4, the data acquisition device 2 is connected to the optical frequency domain reflectometer 3, and the data acquisition device 2 is connected to the fast demodulation device 1.

[0030] During operation, the measuring optical signal emitted by the optical frequency domain reflectometer 3 is divided into multiple paths by the first optical fiber coupler 4, and each path of the measuring optical signal enters each sensing optical fiber 51 respectively. The Rayleigh scattered light generated by each sensing optical fiber 51 is aggregated by the first optical fiber coupler 4 and input into the optical frequency domain reflectometer 3. The optical frequency domain reflectometer 3 converts the Rayleigh scattered light into a beat frequency signal and outputs it to the data acquisition device 2. The data acquisition device 2 collects the beat frequency signal, obtains a reference signal and a measurement signal, and outputs them to the fast demodulation device 1. The fast demodulation device 1 performs cross-correlation demodulation on the reference signal and the measurement signal, and finally obtains the wavelength drift spectrum of each sensing optical fiber 51.

[0031] In this embodiment, the first optical fiber coupler 4 is a 1*N coupler, which can be connected to at most N sensing optical fibers 51 at the same time, where N≥2.

[0032] like Figure 2As shown, the optical frequency domain reflectometer 3 includes a tunable laser 31, a second fiber coupler 32, an auxiliary interferometer arm, a main interferometer arm, a first photoelectric balance detector 314, a second photoelectric balance detector 315 and a third photoelectric balance detector 316. The tunable laser 31 is connected to the auxiliary interferometer arm and the main interferometer arm respectively through the second fiber coupler 32, the auxiliary interferometer arm is connected to the first photoelectric balance detector 314, the main interferometer arm is connected to the second photoelectric balance detector 315 and the third photoelectric balance detector 316 respectively, and the first photoelectric balance detector 314, the second photoelectric balance detector 315 and the third photoelectric balance detector 316 are all connected to the data acquisition device 2.

[0033] The auxiliary interference arm includes a first fiber circulator 33, a third fiber coupler 34, a delay fiber 35, a first Faraday rotator reflector 36 and a second Faraday rotator reflector 37. The first port of the first fiber circulator 33 is connected to the second fiber coupler 32, the second port of the first fiber circulator 33 is connected to the first port of the third fiber coupler 34, and the third port of the first fiber circulator 33 is connected to the first photoelectric balanced detector 314; the second port of the third fiber coupler 34 is connected to the first photoelectric balanced detector 314, the third port of the third fiber coupler 34 is connected to the first Faraday rotator reflector 36 via the delay fiber 35, and the fourth port of the third fiber coupler 34 is connected to the second Faraday rotator reflector 37.

[0034] The main interferometer arm includes a fourth fiber coupler 38, a polarization controller 39, a second fiber circulator 310, a fifth fiber coupler 311, a first polarization beam splitter 312 and a second polarization beam splitter 313. The first port of the fourth fiber coupler 38 is connected to the second fiber coupler 32, the second port of the fourth fiber coupler 38 is connected to the first port of the fifth fiber coupler 311 via the polarization controller 39, and the third port of the fourth fiber coupler 38 is connected to the first port of the second fiber circulator 310; the second port of the second fiber circulator 310 is connected to the first fiber coupler 4, and the third port of the second fiber circulator 310 is connected to the second port of the fifth fiber coupler 311; the third port of the fifth fiber coupler 311 is connected to the second photoelectric balanced detector 315 and the third photoelectric balanced detector 316 respectively via the first polarization beam splitter 312, and the fourth port of the fifth fiber coupler 311 is connected to the second photoelectric balanced detector 315 and the third photoelectric balanced detector 316 respectively via the second polarization beam splitter 313.

[0035] When in use, the swept-frequency light emitted by the tunable laser 31 passes through the second fiber coupler 32 and is split at a ratio of 1:99, wherein 1% of the swept-frequency light enters the auxiliary interference arm, and the other 99% of the swept-frequency light enters the main interference arm; the swept-frequency light in the auxiliary interference arm is divided into two beams after passing through the first fiber circulator 33 and the third fiber coupler 34, wherein one of the swept-frequency light beams passes through the delay fiber 35 and reaches the first Faraday rotator reflector 36, and the other swept-frequency light beam directly reaches the second Faraday rotator reflector 37; the two swept-frequency light beams are respectively reflected by the first Faraday rotator reflector 36 and the second Faraday rotator reflector 37, and then return to the third fiber coupler 34 along the original path to generate a first beat-frequency interference light, which is finally input into the first photoelectric balance detector 314 for photoelectric signal conversion to form a first beat-frequency interference light. frequency signal; the swept-frequency light in the main interference arm is split by the fourth optical fiber coupler 38, and one beam of swept-frequency light passes through the polarization controller 39 to enter the fifth optical fiber coupler 311, and the other beam of swept-frequency light passes through the second optical fiber circulator 310 and enters the first optical fiber coupler 4, and after forming Rayleigh scattered light in each sensing optical fiber 51, it passes through the second optical fiber circulator 310 and enters the fifth optical fiber coupler 311, and the Rayleigh scattered light and the swept-frequency light generate a second beat frequency interference light in the fifth optical fiber coupler 311, and the second beat frequency interference light is split by the fifth optical fiber coupler 311, and then polarized by the first polarization beam splitter 312 and the second polarization beam splitter 313 respectively, and finally input into the second photoelectric balance detector 315 and the third photoelectric balance detector 316 for photoelectric signal conversion to form a second beat frequency signal.

[0036] The data acquisition device 2 uses the first beat frequency signal as a sampling clock signal to acquire the second beat frequency signal to obtain time domain data of the reference signal and the measurement signal. When the measurement parameters such as temperature and strain in the target environment do not change, the time domain data acquired by the data acquisition device 2 is the reference signal. When the measurement parameters such as temperature and strain in the target environment change, the time domain data acquired by the data acquisition device 2 is the measurement signal.

[0037] Embodiment 2 like Figure 3 As shown, a fast demodulation device 1 for optical frequency domain reflection multi-path sensing is used in the optical frequency domain reflection multi-path sensing system described in Example 1 to perform cross-correlation demodulation on the multi-path optical fiber sensing module 5; the fast demodulation device 1 includes a CPU chip and a GPU chip connected to each other.

[0038] In this embodiment, the CPU chip and the GPU chip are connected via a PCIE bus, and the CPU chip and the data acquisition device 2 are connected via a PCI bus.

[0039] The CPU chip includes a cache module and a parsing module, wherein the cache module is used to store measurement signals and multiple groups of reference signals, wherein one group of reference signals corresponds to one sensing optical fiber 51, and the measurement signal corresponds to all sensing optical fibers 51, and the parsing module is used to parse the wavelength drift data of each sensing optical fiber 51 to obtain the wavelength drift spectrum of each sensing optical fiber 51; The GPU chip includes a plurality of cross-correlation demodulation modules, one cross-correlation demodulation module corresponds to one sensing optical fiber 51 , and each cross-correlation demodulation module is used to perform cross-correlation demodulation on the measurement signal and each group of reference signals respectively to obtain wavelength drift data of each sensing optical fiber 51 .

[0040] The fast demodulation device 1 of the present invention is based on the cooperation of a CPU chip and a GPU chip. The CPU chip is responsible for front-end data preprocessing and data caching and back-end data parsing, and the GPU chip is responsible for intermediate data demodulation operations. At the same time, the parallel processing capability of the GPU chip is utilized to construct multiple cross-correlation demodulation modules in the GPU chip. One cross-correlation demodulation module is specifically responsible for the cross-correlation demodulation of a sensing optical fiber 51, so that the cross-correlation demodulation of each sensing optical fiber 51 can be performed simultaneously, greatly improving the timeliness of demodulation of multi-optical path signals reflected in the optical frequency domain.

[0041] It is particularly noted that when the optical frequency domain reflectometer 3 collects the second beat frequency signals of each sensing optical fiber 51, each sensing optical fiber 51 is connected to the first optical fiber coupler 4 in sequence, so that the Rayleigh scattered light of each sensing optical fiber 51 is received in sequence through the first optical fiber coupler 4. Therefore, there are multiple groups of reference signals collected by the data acquisition device 2, and each group of reference signals only includes the reference signal of one sensing optical fiber 51; and when the optical frequency domain reflectometer 3 collects the measurement signals of each sensing optical fiber 51, all the sensing optical fibers 51 are connected to the first optical fiber coupler 4 at the same time, so that the Rayleigh scattered light of all the sensing optical fibers 51 is received through the first optical fiber coupler 4 at the same time. Therefore, there is only one group of measurement signals collected by the data acquisition device 2, and the group of measurement signals simultaneously includes the measurement signals of all the sensing optical fibers 51.

[0042] Preferably, the cache module comprises a first cache unit and a plurality of second cache units, one second cache unit corresponds to a group of reference signals, the first cache unit is used to store the measurement signal, and each second cache unit is used to store each group of reference signals.

[0043] The fast demodulation device 1 of the present invention constructs the first cache unit and multiple second cache units in the CPU chip. One second cache unit specifically stores the reference signal of a sensing optical fiber 51, and the first cache unit simultaneously stores the measurement signals of all sensing optical fibers 51. Each cache unit uses a dedicated transmission channel to transmit data with the GPU chip to improve the efficiency of data transmission between the CPU chip and the GPU chip.

[0044] When constructing the first cache unit and multiple second cache units, first, according to the number of the sensing optical fibers 51, the same number of second cache units are constructed in the cache of the CPU chip, and then, according to the amount of data of each sensing optical fiber 51, a cache space of corresponding size is configured for each second cache unit, and finally, the first cache unit is constructed with the remaining cache space in the cache.

[0045] In order to improve the spatial resolution of wavelength drift demodulation, this embodiment uses a sliding window cross-correlation algorithm to perform cross-correlation demodulation on the measurement signal and each group of reference signals respectively.

[0046] The GPU chip further includes an FFT operation module, which is used to perform a fast Fourier transform on the measurement signal and each group of reference signals to convert the reference signal and each group of measurement signals from the time domain to the distance domain.

[0047] Since each group of reference signals only needs to be collected once when the sensor system is set up, and the measurement signal needs to be collected multiple times at preset time intervals when the sensor system is working to monitor the real-time changes of measurement parameters such as temperature and strain in the target environment, the fast demodulation device 1 of the present invention does not construct a special FFT operation module for the reference signal in the GPU chip, but adopts a solution in which the measurement signal and the reference signal share an FFT operation module to save the computing power resources of the GPU chip.

[0048] The GPU chip includes a plurality of stream processors, each stream processor includes a plurality of thread blocks, each thread block includes a plurality of threads, and the threads are the basic computing units of the GPU chip.

[0049] When constructing the FFT operation module and multiple cross-correlation demodulation modules, first, according to the number of the sensing optical fibers 51, the same number of cross-correlation demodulation modules are constructed in the GPU chip, and then, according to the data volume of each sensing optical fiber 51 and the parameter volume of the sliding window cross-correlation algorithm, a corresponding number of stream processors are configured for each cross-correlation demodulation module, wherein each cross-correlation demodulation module is configured with multiple stream processors, and finally, the FFT operation module is constructed with the remaining stream processors in the GPU chip.

[0050] like Figure 4 As shown, each cross-correlation demodulation module includes: A sliding window value taking unit, used to slide and take values ​​of respective measurement signals and reference signals according to a preset window length, so as to obtain multiple sets of window data, wherein one set of window data corresponds to a spatial position on the sensing optical fiber 51; A plurality of IFFT operation units, one IFFT operation unit corresponds to a group of window data, and each IFFT operation unit is used to perform an inverse fast Fourier transform on a measurement signal and a reference signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from a distance domain to a frequency domain; There are multiple cross-correlation operation units, one cross-correlation operation unit corresponds to a group of window data, and each cross-correlation operation unit is used to perform cross-correlation operation on the measurement signal and the reference signal in each group of window data to obtain the wavelength drift data of each spatial position on the sensing optical fiber 51.

[0051] The fast demodulation device 1 of the present invention utilizes the parallel processing capability of the GPU chip to construct multiple IFFT operation units and multiple cross-correlation operation units in each cross-correlation demodulation module. One IFFT operation unit is specifically responsible for the fast inverse Fourier transform of a group of window data, and one cross-correlation operation unit is specifically responsible for the cross-correlation operation of a group of window data, so that the cross-correlation demodulation of each spatial position on the sensing optical fiber 51 can be performed simultaneously, which greatly improves the timeliness of the demodulation of the optical frequency domain reflection multi-path signal, and only one cross-correlation demodulation cycle is required to complete the cross-correlation demodulation operation of all spatial positions on all sensing optical fibers 51.

[0052] When constructing multiple IFFT operation units and multiple cross-correlation operation units, first, according to the number of windows slidably intercepted by the sliding window value taking unit, the same number of IFFT operation units and cross-correlation operation units are constructed in each cross-correlation demodulation module, and then, according to the data amount of each window data and the parameter amount of the IFFT function and the cross-correlation function, a corresponding number of thread blocks are configured for each IFFT operation unit and each cross-correlation operation unit in the stream processor of each cross-correlation demodulation module, wherein each IFFT operation unit and each cross-correlation operation unit are configured with multiple thread blocks.

[0053] Preferably, the cross-correlation function adopted by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

[0054] In this embodiment, the FFT function used by the FFT operation module and the IFFT function used by the IFFT operation unit are both library functions provided by the GPU chip.

[0055] Embodiment 3 A fast demodulation method for optical frequency domain reflection multi-path sensing is used in the optical frequency domain reflection multi-path sensing system described in Example 1 to perform cross-correlation demodulation on the multi-path optical fiber sensing module 5; Figure 5 As shown, the fast demodulation method comprises the following steps: Step 100 : constructing a plurality of cross-correlation demodulation modules in the GPU chip according to the data volume of each sensing optical fiber 51 , wherein one cross-correlation demodulation module corresponds to one sensing optical fiber 51 .

[0056] In step 100, a first cache unit and a plurality of second cache units are constructed in the CPU chip according to the data volume of each sensing optical fiber 51, wherein one second cache unit corresponds to a set of reference signals, and the first cache unit corresponds to the measurement signal.

[0057] When constructing the first cache unit and multiple second cache units, first, according to the number of the sensing optical fibers 51, the same number of second cache units are constructed in the cache of the CPU chip, and then, according to the amount of data of each sensing optical fiber 51, a cache space of corresponding size is configured for each second cache unit, and finally, the first cache unit is constructed with the remaining cache space in the cache.

[0058] Step 200 : The CPU chip sequentially acquires multiple groups of reference signals, and transmits each group of reference signals to the GPU chip after storing them. One group of reference signals corresponds to one sensing optical fiber 51 .

[0059] In step 200, when the measurement parameters such as temperature and strain in the target environment do not change, the first sensing optical fiber 51 is first connected to the first port of the first optical fiber coupler 4, and the connections between the other sensing optical fibers 51 and the first optical fiber coupler 4 are disconnected. The optical frequency domain reflectometer 3 receives the Rayleigh scattered light of the first sensing optical fiber 51 through the first optical fiber coupler 4, and outputs a second beat frequency signal to the data acquisition device 2, so that the data acquisition device 2 can collect and obtain a first group of reference signals. Then, the second sensing optical fiber 51 is connected to the second port of the first optical fiber coupler 4, and the connections between the other sensing optical fibers 51 and the first optical fiber coupler 4 are disconnected. The optical frequency domain reflectometer 3 receives the Rayleigh scattered light of the second sensing optical fiber 51 through the first optical fiber coupler 4, and outputs a second beat frequency signal to the data acquisition device 2, so that the data acquisition device 2 can collect and obtain a second group of reference signals... and so on, until the data acquisition device 2 collects and obtains the reference signals of each sensing optical fiber 51 in sequence and transmits them to the CPU chip. After performing preprocessing such as filtering on each group of reference signals, the CPU chip saves each group of reference signals in a corresponding second cache unit, and then transmits each group of reference signals to the GPU chip.

[0060] Step 300: The GPU chip saves each group of reference signals into a corresponding cross-correlation demodulation module.

[0061] In step 300, each cross-correlation demodulation module is configured with multiple stream processors, each stream processor has a certain memory space, and together they constitute the common memory of each cross-correlation demodulation module; each group of reference signals is saved in the common memory of the corresponding cross-correlation demodulation module.

[0062] Step 400: The CPU chip simultaneously acquires the measurement signals of all the sensing optical fibers 51, and transmits the measurement signals to the GPU chip after storing them.

[0063] In step 400, all the sensing optical fibers 51 are first connected to the first optical fiber coupler 4. The connection port of each sensing optical fiber 51 on the first optical fiber coupler 4 is the same as the connection port when the reference signal is collected in step 200. When the measurement parameters such as temperature and strain in the target environment change, the optical frequency domain reflectometer 3 simultaneously receives the Rayleigh scattered light of all the sensing optical fibers 51 through the first optical fiber coupler 4, and outputs the second beat frequency signal to the data acquisition device 2, so that the data acquisition device 2 can collect the measurement signal and transmit it to the CPU chip. After preprocessing the measurement signal such as filtering, the CPU chip saves the measurement signal to the first cache unit, and then transmits the measurement signal to the GPU chip.

[0064] Step 500: The GPU chip saves the measurement signal to each cross-correlation demodulation module simultaneously.

[0065] In step 500, the measurement signal is saved in the common display memory of each cross-correlation demodulation module; since the measurement signal includes the measurement signals of all sensing optical fibers 51 at the same time, the measurement signals saved by the GPU chip in each cross-correlation demodulation module are all identical and complete.

[0066] Step 600 : Each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein, so as to obtain the wavelength drift data of each sensing optical fiber 51 .

[0067] In step 600, although the measurement signal includes the measurement signals of all the sensing fibers 51 at the same time, due to the uniqueness of Rayleigh scattered light, when performing cross-correlation demodulation, only part of the measurement signal that comes from the same sensing fiber 51 as the reference signal will show correlation, while part of the measurement signal that comes from different sensing fibers 51 will not show any correlation. Therefore, only the measurement signal and the reference signal from the same sensing fiber 51 can be demodulated to obtain the wavelength drift data through correlation.

[0068] Step 700: The GPU chip transmits the wavelength drift data of each sensing optical fiber 51 to the CPU chip.

[0069] Step 800 : the CPU chip analyzes the wavelength drift data of each sensing optical fiber 51 to obtain the wavelength drift spectrum of each sensing optical fiber 51 .

[0070] In order to improve the spatial resolution of wavelength drift demodulation, this embodiment uses a sliding window cross-correlation algorithm to perform cross-correlation demodulation on the measurement signal and each group of reference signals respectively.

[0071] Preferably, in step 100, while constructing a plurality of cross-correlation demodulation modules, an FFT operation module is also constructed in the CPU chip; Figure 6 As shown, in step 300, before the GPU chip saves each group of reference signals into the corresponding cross-correlation demodulation module, it first uses the FFT operation module to perform fast Fourier transform on each group of reference signals to convert each group of reference signals from the time domain to the distance domain; in step 500, before the GPU chip saves the measurement signals into each cross-correlation demodulation module at the same time, it first uses the FFT operation module to perform fast Fourier transform on the measurement signals to convert the measurement signals from the time domain to the distance domain.

[0072] The FFT function used by the FFT operation module is a library function provided by the GPU chip.

[0073] Among them, when constructing the FFT operation module and multiple cross-correlation demodulation modules, first, according to the number of the sensing optical fibers 51, the same number of cross-correlation demodulation modules are constructed in the GPU chip, and then according to the data volume of each sensing optical fiber 51 and the parameter volume of the cross-correlation algorithm, a corresponding number of stream processors are configured for each cross-correlation demodulation module, wherein each cross-correlation demodulation module is configured with multiple stream processors, and finally the FFT operation module is constructed with the remaining stream processors in the GPU chip.

[0074] In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein to obtain the wavelength drift data of each sensing optical fiber 51 in the following steps: Step 610 : According to a preset window length, sliding values ​​are taken on the mixed measurement signal and the reference signal respectively stored to obtain multiple groups of window data, where one group of window data corresponds to a spatial position on the sensing optical fiber 51 .

[0075] In step 610, since the measurement signals and reference signals stored in each cross-correlation demodulation module have been converted from the time domain to the distance domain by fast Fourier transform in advance, the data length of the measurement signals and reference signals corresponds to the spatial length of the sensing optical fiber 51, and the data positions of the measurement signals and reference signals also correspond to the spatial positions of the sensing optical fiber 51. It can be understood that one data point of the measurement signal and reference signal corresponds to one Rayleigh scattering point of the sensing optical fiber 51. Sliding the mixed measurement signal and reference signal is equivalent to dividing the sensing optical fiber 51 into multiple sections according to a preset unit length (i.e., window length), and the measurement signal and reference signal of each section length on the sensing optical fiber 51 form a set of window data.

[0076] The shorter the window length is, the higher the spatial resolution of the final wavelength shift demodulation is.

[0077] Step 620: construct multiple IFFT operation units and multiple cross-correlation operation units according to the data amount of each group of window data, and one IFFT operation unit and one cross-correlation operation unit correspond to one group of window data.

[0078] In step 620, when constructing multiple IFFT operation units and multiple cross-correlation operation units, first, according to the number of windows slidably intercepted by the sliding window value taking unit, the same number of IFFT operation units and cross-correlation operation units are constructed in each cross-correlation demodulation module, and then, according to the data amount of each window data and the parameter amount of the IFFT function and the cross-correlation function, a corresponding number of thread blocks are configured for each IFFT operation unit and each cross-correlation operation unit in the stream processor of each cross-correlation demodulation module, wherein each IFFT operation unit and each cross-correlation operation unit are configured with multiple thread blocks.

[0079] Step 630: Each IFFT operation unit performs an inverse Fourier operation on the reference signal and the measurement signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from the distance domain to the frequency domain.

[0080] In step 630, the IFFT function used by the IFFT operation unit is a library function provided by the GPU chip.

[0081] Step 640 : Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and the reference signal in each group of window data, so as to obtain the wavelength drift data of each spatial position on the sensing optical fiber 51 .

[0082] In step 640, the cross-correlation function used by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention rather than to limit them. Although the embodiments of the present invention have been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the embodiments of the present invention can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fast demodulation device for optical frequency domain reflection multi-path sensing, characterized in that: Used to perform cross-correlation demodulation on a multi-channel optical fiber sensing module, wherein the multi-channel optical fiber sensing module includes a plurality of sensing optical fibers arranged in parallel; the fast demodulation device includes: Connected CPU chip and GPU chip; The CPU chip includes a cache module and a parsing module, the cache module is used to store measurement signals and multiple groups of reference signals, one group of reference signals corresponds to one sensing optical fiber, the measurement signal corresponds to all sensing optical fibers, and the parsing module is used to parse the wavelength drift data of each sensing optical fiber to obtain the wavelength drift spectrum of each sensing optical fiber; The GPU chip includes a plurality of cross-correlation demodulation modules, one cross-correlation demodulation module corresponds to one sensing optical fiber, and each cross-correlation demodulation module is used to perform cross-correlation demodulation on the measurement signal and each group of reference signals respectively to obtain wavelength drift data of each sensing optical fiber.

2. The fast demodulation device according to claim 1, characterized in that: The cache module includes a first cache unit and a plurality of second cache units, one second cache unit corresponds to a group of reference signals, the first cache unit is used to store the measurement signal, and each second cache unit is used to store each group of reference signals.

3. The fast demodulation device according to claim 1, characterized in that: The GPU chip further includes an FFT operation module, which is used to perform a fast Fourier transform on the measurement signal and each group of reference signals to convert the reference signal and each group of measurement signals from the time domain to the distance domain; each cross-correlation demodulation module includes: A sliding window value taking unit, used for slidingly taking values ​​of respective measurement signals and reference signals according to a preset window length, so as to obtain a plurality of sets of window data, wherein a set of window data corresponds to a spatial position on the sensing optical fiber; A plurality of IFFT operation units, one IFFT operation unit corresponds to a group of window data, and each IFFT operation unit is used to perform an inverse fast Fourier transform on a measurement signal and a reference signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from a distance domain to a frequency domain; A plurality of cross-correlation operation units, one cross-correlation operation unit corresponds to a group of window data, and each cross-correlation operation unit is used to perform cross-correlation operation on the measurement signal and the reference signal in each group of window data to obtain the wavelength drift data of each spatial position on the sensing optical fiber.

4. The fast demodulation device according to claim 3, characterized in that: The cross-correlation function adopted by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

5. The fast demodulation device according to claim 1, characterized in that: The GPU chip includes multiple stream processors, each stream processor includes multiple thread blocks, and each thread block includes multiple threads.

6. A fast demodulation method for optical frequency domain reflectometry multi-path sensing, characterized in that: Used to perform cross-correlation demodulation on a multi-channel optical fiber sensing module, wherein the multi-channel optical fiber sensing module includes a plurality of sensing optical fibers arranged in parallel; the fast demodulation method includes the following steps: Step 100: constructing a plurality of cross-correlation demodulation modules in the GPU chip according to the data volume of each sensing optical fiber, wherein one cross-correlation demodulation module corresponds to one sensing optical fiber; Step 200: The CPU chip sequentially acquires multiple groups of reference signals, and transmits each group of reference signals to the GPU chip after storing them, wherein one group of reference signals corresponds to one sensing optical fiber; Step 300: The GPU chip saves each group of reference signals into a corresponding cross-correlation demodulation module; Step 400: the CPU chip simultaneously acquires measurement signals of all sensing optical fibers, and transmits the measurement signals to the GPU chip after storing them; Step 500: The GPU chip saves the measurement signal to each cross-correlation demodulation module simultaneously; Step 600: Each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein to obtain wavelength drift data of each sensing optical fiber; Step 700: the GPU chip transmits the wavelength drift data of each sensing optical fiber to the CPU chip; Step 800: The CPU chip analyzes the wavelength drift data of each sensing optical fiber to obtain the wavelength drift spectrum of each sensing optical fiber.

7. The fast demodulation method according to claim 6, characterized in that: In step 100, a first cache unit and multiple second cache units are constructed in the CPU chip according to the amount of data of each sensing optical fiber, one second cache unit corresponds to a group of reference signals, and the first cache unit corresponds to the measurement signal; in step 200, the CPU chip saves each group of reference signals into the corresponding second cache unit, and in step 400, the CPU chip saves the measurement signal into the first cache unit.

8. The fast demodulation method according to claim 6, characterized in that: In step 300, before the GPU chip saves each group of reference signals into the corresponding cross-correlation demodulation module, the FFT operation module is used to perform fast Fourier transform on each group of reference signals, so as to convert each group of reference signals from the time domain to the distance domain; and, in step 500, before the GPU chip saves the measurement signals into each cross-correlation demodulation module at the same time, the FFT operation module is used to perform fast Fourier transform on the measurement signals, so as to convert the measurement signals from the time domain to the distance domain; In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on the measurement signal and reference signal stored therein to obtain the wavelength drift data of each sensing optical fiber in the following steps: Step 610: Sliding and sampling the mixed measurement signal and the reference signal stored respectively according to the preset window length to obtain multiple groups of window data, where one group of window data corresponds to a spatial position on the sensing optical fiber; Step 620: construct multiple IFFT operation units and multiple cross-correlation operation units according to the data amount of each group of window data, one IFFT operation unit and one cross-correlation operation unit corresponding to one group of window data; Step 630: Each IFFT operation unit performs an inverse Fourier operation on the reference signal and the measurement signal in each group of window data, so as to convert the measurement signal and the reference signal in each group of window data from the distance domain to the frequency domain; Step 640: Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and the reference signal in each group of window data to obtain the wavelength drift data of each spatial position on the sensing optical fiber.

9. The fast demodulation method according to claim 8, characterized in that: The cross-correlation function adopted by the cross-correlation operation unit is as follows: Wherein, F(x) is the result of performing FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate after performing FFT operation on the measurement signal.

10. An optical frequency domain reflection multi-channel sensing system, further characterized in that it comprises a data acquisition device, an optical frequency domain reflectometer, an optical fiber coupler, a multi-channel optical fiber sensing module and the rapid demodulation device according to claim 1, wherein the multi-channel optical fiber sensing module comprises a plurality of sensing optical fibers arranged in parallel, the optical frequency domain reflectometer is respectively connected to each sensing optical fiber through the optical fiber coupler, and the rapid demodulation device is connected to the optical frequency domain reflectometer.

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