A fast demodulation method, device and system for optical frequency domain reflectometry multiplexing sensing

Abstract

The application discloses a kind of fast demodulation devices of optical frequency domain reflection multipath sensing, comprising: the CPU chip and GPU chip of being connected;The CPU chip includes first cache unit and a plurality of second cache units, a second cache unit corresponds to a group of reference signals, the first cache unit is used to save the measurement signal, each second cache unit is used to save each group of reference signals;The GPU chip includes a plurality of cross-correlation demodulation modules, a cross-correlation demodulation module corresponds to a sensing optical fiber, each cross-correlation demodulation module is used to respectively cross-correlation demodulation of the measurement signal with each group of reference signals, to obtain the wavelength shift data of each sensing optical fiber.The fast demodulation device can improve the timeliness of optical frequency domain reflection multi-path signal demodulation.

Description

Technical Field

[0001] This invention relates to optical frequency domain reflection technology, and more particularly to a fast demodulation method, apparatus and system for optical frequency domain reflection multi-channel sensing. Background Technology

[0002] With the rapid development of fiber optic communication technology, fiber optic sensing technology has quickly become an important component of sensing technology. Compared with traditional sensing technologies, fiber optic sensing technology has many advantages, including high sensitivity, electrical insulation, suitability for high and low temperature environments, corrosion resistance, and resistance to electromagnetic interference, which has attracted widespread attention from researchers.

[0003] Optical Frequency Domain Reflectometry (OFDR) is a fiber optic sensing and measurement technology. It works by utilizing the Rayleigh scattering phenomenon of light propagating through an optical fiber. By analyzing the frequency changes of the light signal emitted from the light source as it travels back and forth through the fiber, it detects changes in physical parameters along the fiber, such as temperature and strain. OFDR plays a significant role in national and civilian perimeter security monitoring, oil and gas pipeline monitoring, wind turbine health monitoring, and deep-sea and submarine earthquake monitoring.

[0004] To achieve signal acquisition from multiple sensing optical fibers, Chinese patent application CN202210554559.3 discloses a method in which signals from different sensing optical fibers can be distinguished based on the unique Rayleigh scattering light between them in an optical frequency domain reflectometer. This method uses a coupler instead of an optical switch to achieve parallel acquisition of multiple data streams. Then, a cross-correlation algorithm is used to demodulate the wavelength drift spectrum of each sensing optical fiber, thereby realizing multi-channel sensing.

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

[0006] To address the shortcomings of the prior art, this 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] This invention provides a fast demodulation method and system based on the above-mentioned fast demodulation device.

[0008] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0009] A fast demodulation device for optical frequency domain reflection multi-channel sensing is used to perform cross-correlation demodulation on a multi-channel fiber optic sensing module, wherein the multi-channel fiber optic sensing module includes multiple sensing fibers arranged in parallel; the fast demodulation device includes:

[0010] Connected CPU and GPU chips;

[0011] The CPU chip includes a cache module and a parsing module. The cache module is used to store measurement signals and multiple sets of reference signals. Each set of reference signals corresponds to one sensing fiber, and the measurement signals correspond to all sensing fibers. The parsing module is used to parse the wavelength drift data of each sensing fiber to obtain the wavelength drift spectrum of each sensing fiber.

[0012] The GPU chip includes multiple cross-correlation demodulation modules, each corresponding to a sensing fiber. Each cross-correlation demodulation module is used to cross-correlate and demodulate the measurement signal with each set of reference signals to obtain the wavelength drift data of each sensing fiber.

[0013] Furthermore, the caching module includes a first caching unit and a plurality of second caching units, each second caching unit corresponding to a set of reference signals, the first caching unit being used to store the measurement signals, and each second caching unit being used to store each set of reference signals.

[0014] Furthermore, the GPU chip also includes an FFT operation module, which performs a Fast Fourier Transform on the measurement signal and each set of reference signals to convert the reference signals and each set of measurement signals from the time domain to the distance domain; each cross-correlation demodulation module includes:

[0015] The sliding window value unit is used to slide and select values ​​for each measurement signal and reference signal according to a preset window length to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber.

[0016] Multiple IFFT operation units, each IFFT operation unit corresponds to a set of window data. Each IFFT operation unit is used to perform inverse fast Fourier transform on the measurement signal and reference signal in each set of window data, so as to transform the measurement signal and reference signal in each set of window data from the range domain to the frequency domain.

[0017] Multiple cross-correlation operation units are provided, with each cross-correlation operation unit corresponding to a set of window data. Each cross-correlation operation unit is used to perform cross-correlation operations on the measurement signal and reference signal in each set of window data to obtain the wavelength drift data of each spatial position on the sensing fiber.

[0018] Furthermore, the cross-correlation function used by the cross-correlation operation unit is as follows:

[0019]

[0020] Where F(x) is the result of performing an FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate of the measurement signal after performing an FFT operation.

[0021] Furthermore, the GPU chip includes multiple stream processors, each stream processor includes multiple thread blocks, and each thread block includes multiple threads.

[0022] A fast demodulation method for optical frequency domain reflection multiplexing is provided for cross-correlation demodulation of a multi-channel fiber optic sensing module, wherein the multi-channel fiber optic sensing module comprises multiple sensing fibers arranged in parallel; the fast demodulation method includes the following steps:

[0023] Step 100: Based on the data volume of each sensing fiber, construct multiple cross-correlation demodulation modules in the GPU chip, with one cross-correlation demodulation module corresponding to one sensing fiber;

[0024] Step 200: The CPU chip acquires multiple sets of reference signals in sequence, saves each set of reference signals and transmits them to the GPU chip. Each set of reference signals corresponds to a sensing fiber.

[0025] Step 300: The GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module;

[0026] Step 400: The CPU chip simultaneously acquires the measurement signals of all sensing fibers, saves the measurement signals, and transmits them to the GPU chip;

[0027] Step 500: The GPU chip simultaneously saves the measurement signal to each cross-correlation demodulation module;

[0028] Step 600: Each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber.

[0029] Step 700: The GPU chip transmits the wavelength drift data of each sensing fiber to the CPU chip;

[0030] Step 800: The CPU chip analyzes the wavelength drift data of each sensing fiber to obtain the wavelength drift spectrum of each sensing fiber.

[0031] Furthermore, in step 100, a first cache unit and multiple second cache units are constructed in the CPU chip according to the data volume of each sensing fiber. One second cache unit corresponds to a set of reference signals, and the first cache unit corresponds to the measurement signal. In step 200, the CPU chip saves each set of reference signals to the corresponding second cache unit. In step 400, the CPU chip saves the measurement signal to the first cache unit.

[0032] Furthermore, in step 300, before the GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module, it first uses the FFT operation module to perform a fast Fourier transform on each set of reference signals to convert each set of reference signals from the time domain to the range domain; and in step 500, before the GPU chip saves the measurement signal to each cross-correlation demodulation module simultaneously, it first uses the FFT operation module to perform a fast Fourier transform on the measurement signal to convert the measurement signal from the time domain to the range domain.

[0033] In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber. The steps are as follows:

[0034] Step 610: According to the preset window length, slide the values ​​of the stored mixed measurement signal and reference signal to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber.

[0035] Step 620: Based on the amount of data in each group of window data, construct multiple IFFT operation units and multiple cross-correlation operation units. One IFFT operation unit and one cross-correlation operation unit correspond to one group of window data.

[0036] Step 630: Each IFFT operation unit performs inverse Fourier operation on the reference signal and measurement signal in each group of window data to convert the measurement signal and reference signal in each group of window data from the range domain to the frequency domain.

[0037] Step 640: Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and reference signal in each group of window data to obtain wavelength drift data at each spatial position on the sensing fiber.

[0038] Furthermore, the cross-correlation function used by the cross-correlation operation unit is as follows:

[0039]

[0040] Where F(x) is the result of performing an FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate of the measurement signal after performing an FFT operation.

[0041] An optical frequency domain reflectometry multi-channel sensing system includes a data acquisition device, an optical frequency domain reflectometer, an optical fiber coupler, a multi-channel optical fiber sensing module, and the aforementioned fast demodulation device. The multi-channel optical fiber sensing module includes multiple sensing optical fibers arranged in parallel. The optical frequency domain reflectometer is connected to each sensing optical fiber through the optical fiber coupler, and the fast demodulation device is connected to the optical frequency domain reflectometer.

[0042] The present invention has the following beneficial effects: The fast demodulation device of the present invention is based on the collaboration of CPU chip and GPU chip. The CPU chip is responsible for front-end data preprocessing and data caching, as well as back-end data parsing. The GPU chip is responsible for intermediate data demodulation operations. At the same time, by utilizing the parallel processing capability of the GPU chip, multiple cross-correlation demodulation modules are constructed in the GPU chip. Each cross-correlation demodulation module is specifically responsible for the cross-correlation demodulation of one sensing fiber, so that the cross-correlation demodulation of each sensing fiber can be performed simultaneously, which greatly improves the timeliness of demodulation of multi-optical-path signals in the optical frequency domain reflection. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the optical frequency domain reflection multi-channel sensing system provided by the present invention.

[0044] Figure 2 This is a schematic diagram of the optical frequency domain reflectometer provided by the present invention.

[0045] Figure 3 This is a schematic diagram of the structure of the fast demodulation device provided by the present invention.

[0046] Figure 4 This is a schematic diagram of the cross-correlation demodulation module in the fast demodulation device provided by the present invention.

[0047] Figure 5 A flowchart illustrating the steps of the fast demodulation method provided by this invention.

[0048] Figure 6 This is a flowchart illustrating the steps of the cross-correlation demodulation algorithm in the fast demodulation device provided by the present invention. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0050] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this invention, "multiple" means two or more, unless otherwise explicitly specified.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] Example 1

[0054] like Figure 1 As shown, an optical frequency domain reflectometer multi-channel sensing system includes a data acquisition device 2, an optical frequency domain reflectometer 3, a first fiber optic coupler 4, a multi-channel fiber optic sensing module 5, and a fast demodulation device 1. The multi-channel fiber optic sensing module 5 includes multiple sensing fibers 51 arranged in parallel. The optical frequency domain reflectometer 3 is connected to each sensing fiber 51 through the first fiber optic coupler 4. The data acquisition device 2 is connected to the optical frequency domain reflectometer 3 and the fast demodulation device 1.

[0055] During operation, the measurement optical signal emitted by the optical frequency domain reflectometer 3 is split into multiple paths by the first fiber coupler 4. Each measurement optical signal enters one of the sensing optical fibers 51. The Rayleigh scattered light generated by each sensing optical fiber 51 is collected by the first fiber coupler 4 and input to 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 acquires 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.

[0056] In this embodiment, the first fiber coupler 4 is a 1*N coupler, which can be connected to up to N sensing fibers 51 at the same time, where N≥2.

[0057] like Figure 2 As 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. 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.

[0058] The auxiliary interferometer arm includes a first fiber circulator 33, a third fiber coupler 34, a time-delay fiber 35, a first Faraday rotator mirror 36, and a second Faraday rotator mirror 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 balance detector 314. The second port of the third fiber coupler 34 is connected to the first photoelectric balance detector 314, the third port of the third fiber coupler 34 is connected to the first Faraday rotator mirror 36 via the time-delay fiber 35, and the fourth port of the third fiber coupler 34 is connected to the second Faraday rotator mirror 37.

[0059] 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 39, 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 balance detector 315 and the third photoelectric balance detector 316 via the first polarization beam splitter 312, and the fourth port of the fifth fiber coupler 311 is connected to the second photoelectric balance detector 315 and the third photoelectric balance detector 316 via the second polarization beam splitter 313.

[0060] In use, the swept light emitted by the tunable laser 31 is split at a ratio of 1:99 after passing through the second fiber coupler 32, with 1% of the swept light entering the auxiliary interferometer arm and the remaining 99% entering the main interferometer arm. The swept light in the auxiliary interferometer arm is split into two beams after passing through the first fiber circulator 33 and the third fiber coupler 34. One beam travels through the delay fiber 35 to the first Faraday rotator mirror 36, while the other beam directly reaches the second Faraday rotator mirror 37. After being reflected by the first and second Faraday rotator mirrors 36 and 37 respectively, the two beams return to the third fiber coupler 34 to generate the first beat frequency interference light. This first beat frequency interference light is ultimately input to the first photoelectric balance detector 314 for photoelectric signal conversion to form the first beat frequency interference. Frequency signal; the swept light in the main interferometer arm, after being split by the fourth fiber coupler 38, one swept light enters the fifth fiber coupler 311 through the polarization controller 39, and the other swept light enters the first fiber coupler 4 after passing through the second fiber circulator 310. After forming Rayleigh scattered light in each sensing fiber 51, it enters the fifth fiber coupler 311 through the second fiber circulator 310. The Rayleigh scattered light and the swept light generate a second beat frequency interference light in the fifth fiber coupler 311. After being split by the fifth fiber coupler 311, the second beat frequency interference light is further polarized and split by the first polarization beam splitter 312 and the second polarization beam splitter 313, and finally input to the second photoelectric balance detector 315 and the third photoelectric balance detector 316 for photoelectric signal conversion to form a second beat frequency signal.

[0061] The data acquisition device 2 uses the first beat frequency signal as a sampling clock signal to acquire the second beat frequency signal, thereby obtaining the time-domain data of the reference signal and the measurement signal. When the measurement parameters in the target environment, such as temperature and strain, do not change, the time-domain data acquired by the data acquisition device 2 is the reference signal; when the measurement parameters in the target environment, such as temperature and strain, change, the time-domain data acquired by the data acquisition device 2 is the measurement signal.

[0062] Example 2

[0063] like Figure 3 As shown, a fast demodulation device 1 for optical frequency domain reflection multiplexing is used in the optical frequency domain reflection multiplexing system described in Embodiment 1 to perform cross-correlation demodulation on the multiple fiber optic sensing module 5; the fast demodulation device 1 includes a CPU chip and a GPU chip connected to each other.

[0064] 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.

[0065] The CPU chip includes a cache module and a parsing module. The cache module is used to store the measurement signal and multiple sets of reference signals. Each set of reference signals corresponds to one sensing fiber 51, and the measurement signal corresponds to all sensing fibers 51. The parsing module is used to parse the wavelength drift data of each sensing fiber 51 to obtain the wavelength drift spectrum of each sensing fiber 51.

[0066] The GPU chip includes multiple cross-correlation demodulation modules, each corresponding to a sensing fiber 51. Each cross-correlation demodulation module is used to cross-correlate and demodulate the measurement signal with each set of reference signals to obtain the wavelength drift data of each sensing fiber 51.

[0067] The fast demodulation device 1 of the present invention is based on the collaboration of a CPU chip and a GPU chip. The CPU chip is responsible for front-end data preprocessing and data caching, as well as back-end data parsing. 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. Each cross-correlation demodulation module is specifically responsible for the cross-correlation demodulation of one sensing fiber 51, so that the cross-correlation demodulation of each sensing fiber 51 can be performed simultaneously, which greatly improves the timeliness of demodulation of multi-optical-path signals in the optical frequency domain.

[0068] It should be noted that when the optical frequency domain reflectometer 3 collects the second beat frequency signal of each sensing fiber 51, it connects each sensing fiber 51 to the first fiber coupler 4 in sequence so that the first fiber coupler 4 can receive the Rayleigh scattered light of each sensing fiber 51 in sequence. Therefore, the data acquisition device 2 collects multiple sets of reference signals, and each set of reference signals contains only the reference signal of one sensing fiber 51. However, when the optical frequency domain reflectometer 3 collects the measurement signal of each sensing fiber 51, it connects all sensing fibers 51 to the first fiber coupler 4 simultaneously so that the first fiber coupler 4 can receive the Rayleigh scattered light of all sensing fibers 51 simultaneously. Therefore, the data acquisition device 2 collects only one set of measurement signals, and this set of measurement signals contains the measurement signals of all sensing fibers 51.

[0069] Preferably, the caching module includes a first caching unit and a plurality of second caching units, each second caching unit corresponding to a set of reference signals, the first caching unit being used to store the measurement signals, and each second caching unit being used to store each set of reference signals.

[0070] The fast demodulation device 1 of the present invention incorporates a first cache unit and multiple second cache units in the CPU chip. Each second cache unit is dedicated to storing a reference signal of a sensing fiber 51, while the first cache unit simultaneously stores the measurement signals of all sensing fibers 51. Each cache unit uses a dedicated transmission channel to transmit data with the GPU chip, thereby improving the efficiency of data transmission between the CPU chip and the GPU chip.

[0071] When constructing the first cache unit and multiple second cache units, firstly, based on the number of sensing optical fibers 51, construct the same number of second cache units in the cache of the CPU chip. Then, based on the data volume of each sensing optical fiber 51, configure a corresponding size of cache space for each second cache unit. Finally, use the remaining cache space in the cache to construct the first cache unit.

[0072] To improve the spatial resolution of wavelength drift demodulation, this embodiment uses a sliding window cross-correlation algorithm to perform cross-correlation demodulation of the measured signal with each set of reference signals.

[0073] The GPU chip also includes an FFT operation module, which is used to perform a fast Fourier transform on the measurement signal and each set of reference signals to convert the reference signal and each set of measurement signals from the time domain to the distance domain.

[0074] Since each set of reference signals only needs to be acquired once when the sensing system is set up, while the measurement signals need to be acquired multiple times at preset time intervals while the sensing system is working, in order 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 build a dedicated FFT operation module for the reference signals in the GPU chip, but adopts a scheme in which the measurement signals and reference signals share a single FFT operation module, in order to save the computing power resources of the GPU chip.

[0075] The GPU chip includes multiple stream processors, each stream processor includes multiple thread blocks, and each thread block includes multiple threads. The threads are the basic computing units of the GPU chip.

[0076] When constructing the FFT operation module and multiple cross-correlation demodulation modules, firstly, based on the number of sensing optical fibers 51, the same number of cross-correlation demodulation modules are constructed in the GPU chip. Then, based on 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. Finally, the remaining stream processors in the GPU chip are used to construct the FFT operation module.

[0077] like Figure 4 As shown, each cross-correlation demodulation module includes:

[0078] The sliding window value unit is used to slide and select values ​​for each measurement signal and reference signal according to a preset window length to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber 51.

[0079] Multiple IFFT operation units, each IFFT operation unit corresponds to a set of window data. Each IFFT operation unit is used to perform inverse fast Fourier transform on the measurement signal and reference signal in each set of window data, so as to transform the measurement signal and reference signal in each set of window data from the range domain to the frequency domain.

[0080] Multiple cross-correlation operation units are provided, with each cross-correlation operation unit corresponding to a set of window data. Each cross-correlation operation unit is used to perform cross-correlation operations on the measurement signal and reference signal in each set of window data to obtain the wavelength drift data of each spatial position on the sensing fiber 51.

[0081] 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 set of window data, and one cross-correlation operation unit is specifically responsible for the cross-correlation operation of a set of window data. This allows the cross-correlation demodulation of each spatial location on the sensing fiber 51 to be performed simultaneously, greatly improving the timeliness of demodulation of multi-optical-path signals reflected in the optical frequency domain. Only one cross-correlation demodulation cycle is needed to complete the cross-correlation demodulation operation of all spatial locations on all sensing fibers 51.

[0082] When constructing multiple IFFT operation units and multiple cross-correlation operation units, firstly, based on the number of windows slid and captured by the sliding window value-taking unit, construct the same number of IFFT operation units and cross-correlation operation units in each cross-correlation demodulation module. Then, based on the amount of data in each window and the number of parameters of the IFFT function and cross-correlation function, configure a corresponding number of thread blocks 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 is configured with multiple thread blocks.

[0083] Preferably, the cross-correlation function used by the cross-correlation operation unit is as follows:

[0084]

[0085] Where F(x) is the result of performing an FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate of the measurement signal after performing an FFT operation.

[0086] 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.

[0087] Example 3

[0088] A fast demodulation method for optical frequency domain reflection multiplexing is provided, used in the optical frequency domain reflection multiplexing system described in Embodiment 1, to perform cross-correlation demodulation on the multiple fiber optic sensing module 5; such as Figure 5 As shown, the fast demodulation method includes the following steps:

[0089] Step 100: Based on the data volume of each sensing fiber 51, construct multiple cross-correlation demodulation modules in the GPU chip, with one cross-correlation demodulation module corresponding to one sensing fiber 51.

[0090] In step 100, a first cache unit and multiple second cache units are constructed in the CPU chip according to the data volume of each sensing fiber 51. One second cache unit corresponds to a set of reference signals, and the first cache unit corresponds to the measurement signal.

[0091] When constructing the first cache unit and multiple second cache units, firstly, based on the number of sensing optical fibers 51, construct the same number of second cache units in the cache of the CPU chip. Then, based on the data volume of each sensing optical fiber 51, configure a corresponding size of cache space for each second cache unit. Finally, use the remaining cache space in the cache to construct the first cache unit.

[0092] Step 200: The CPU chip acquires multiple sets of reference signals in sequence, saves each set of reference signals and transmits them to the GPU chip. Each set of reference signals corresponds to a sensing fiber 51.

[0093] In step 200, when the measured parameters in the target environment, such as temperature and strain, remain unchanged, the first sensing fiber 51 is first connected to the first port of the first fiber coupler 4, and the connections of other sensing fibers 51 to the first fiber coupler 4 are disconnected. The optical frequency domain reflectometer 3 receives the Rayleigh scattered light from the first sensing fiber 51 through the first fiber coupler 4 and outputs a second beat frequency signal to the data acquisition device 2 so that the data acquisition device 2 can acquire the first set of reference signals. Then, the second sensing fiber 51 is connected to the second port of the first fiber coupler 4, and the connections of other sensing fibers 51 to the first fiber coupler 4 are disconnected. The optical frequency domain reflectometer 3 receives the Rayleigh scattered light from the second sensing fiber 51 through the first fiber coupler 4 and outputs a second beat frequency signal to the data acquisition device 2 so that the data acquisition device 2 can acquire the second set of reference signals... and so on, until the data acquisition device 2 acquires the reference signals of each sensing fiber 51 in sequence and transmits them to the CPU chip. After performing preprocessing such as filtering on each set of reference signals, the CPU chip saves each set of reference signals to the corresponding second cache unit, and then transmits each set of reference signals to the GPU chip.

[0094] Step 300: The GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module.

[0095] In step 300, each cross-correlation demodulation module is configured with multiple stream processors, and each stream processor has a certain amount of video memory space, which together constitute the common video memory of each cross-correlation demodulation module; each set of reference signals is saved to the common video memory of the corresponding cross-correlation demodulation module.

[0096] Step 400: The CPU chip simultaneously acquires the measurement signals of all sensing optical fibers 51, saves the measurement signals, and transmits them to the GPU chip.

[0097] In step 400, all sensing optical fibers 51 are first connected to the first optical fiber coupler 4. The connection ports of each sensing optical fiber 51 on the first optical fiber coupler 4 are the same as the connection ports when acquiring the reference signal in step 200. When the measurement parameters in the target environment, such as temperature and strain, change, the optical frequency domain reflectometer 3 simultaneously receives the Rayleigh scattered light from all sensing optical fibers 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 acquire the measurement signal and transmit it to the CPU chip. After performing preprocessing such as filtering on the measurement signal, the CPU chip saves the measurement signal to the first cache unit and then transmits the measurement signal to the GPU chip.

[0098] Step 500: The GPU chip simultaneously saves the measurement signal to each cross-correlation demodulation module.

[0099] In step 500, the measurement signal is saved to the common video memory of each cross-correlation demodulation module. Since the measurement signal contains the measurement signals of all sensing optical fibers 51, the measurement signals saved by the GPU chip to each cross-correlation demodulation module are all the same and complete.

[0100] Step 600: Each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber 51.

[0101] In step 600, although the measurement signal contains measurement signals from all sensing fibers 51, during cross-correlation demodulation, due to the uniqueness of Rayleigh scattering light, only the data from the same sensing fiber 51 as the reference signal will show correlation, while the data 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 demodulation.

[0102] Step 700: The GPU chip transmits the wavelength drift data of each sensing fiber 51 to the CPU chip.

[0103] Step 800: The CPU chip analyzes the wavelength drift data of each sensing fiber 51 to obtain the wavelength drift spectrum of each sensing fiber 51.

[0104] To improve the spatial resolution of wavelength drift demodulation, this embodiment uses a sliding window cross-correlation algorithm to perform cross-correlation demodulation of the measured signal with each set of reference signals.

[0105] Preferably, in step 100, while constructing multiple cross-correlation demodulation modules, an FFT operation module is also constructed in the CPU chip; for example... Figure 6 As shown, in step 300, before the GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module, it first uses the FFT operation module to perform a fast Fourier transform on each set of reference signals to convert each set of reference signals from the time domain to the distance domain; in step 500, before the GPU chip saves the measurement signal to each cross-correlation demodulation module at the same time, it first uses the FFT operation module to perform a fast Fourier transform on the measurement signal to convert the measurement signal from the time domain to the distance domain.

[0106] The FFT function used by the FFT operation module is a library function that comes with the GPU chip.

[0107] In constructing the FFT operation module and multiple cross-correlation demodulation modules, firstly, based on the number of sensing optical fibers 51, the same number of cross-correlation demodulation modules are constructed in the GPU chip. Then, based on 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. Finally, the remaining stream processors in the GPU chip are used to construct the FFT operation module.

[0108] In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber 51. The steps are as follows:

[0109] Step 610: According to the preset window length, slide the values ​​of the stored mixed measurement signal and reference signal to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber 51.

[0110] In step 610, since the measurement 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, the data lengths of the measurement and reference signals correspond to the spatial length of the sensing fiber 51, and the data positions of the measurement and reference signals also correspond to the spatial positions of the sensing fiber 51. It can be understood that one data point of the measurement and reference signals corresponds to one Rayleigh scattering point of the sensing fiber 51. Sliding the values ​​of the mixed measurement and reference signals is equivalent to dividing the sensing fiber 51 into multiple segments according to a preset unit length (i.e., window length). The measurement and reference signals of each segment on the sensing fiber 51 form a set of window data.

[0111] The shorter the window length, the higher the spatial resolution of the final wavelength drift demodulation.

[0112] Step 620: Based on the amount of data in each group of window data, construct multiple IFFT operation units and multiple cross-correlation operation units. One IFFT operation unit and one cross-correlation operation unit correspond to one group of window data.

[0113] In step 620, when constructing multiple IFFT operation units and multiple cross-correlation operation units, firstly, based on the number of windows slid and captured by the sliding window value unit, the same number of IFFT operation units and cross-correlation operation units are constructed in each cross-correlation demodulation module. Then, based on the amount of data in each window and the number of parameters 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 is configured with multiple thread blocks.

[0114] Step 630: Each IFFT operation unit performs inverse Fourier operation on the reference signal and measurement signal in each group of window data to convert the measurement signal and reference signal in each group of window data from the range domain to the frequency domain.

[0115] In step 630, the IFFT function used by the IFFT operation unit is a library function provided by the GPU chip.

[0116] Step 640: Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and reference signal in each group of window data to obtain wavelength drift data at each spatial position on the sensing fiber 51.

[0117] In step 640, the cross-correlation function used by the cross-correlation operation unit is as follows:

[0118]

[0119] Where F(x) is the result of performing an FFT operation on the reference signal, and G*(x) is the result of taking the complex conjugate of the measurement signal after performing an FFT operation.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the embodiments of the present invention, and these modifications or equivalent substitutions 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-channel sensing, characterized in that, For performing cross-correlation demodulation on a multi-channel fiber optic sensing module, the multi-channel fiber optic sensing module comprising multiple sensing fibers arranged in parallel; the fast demodulation device includes: Connected CPU and GPU chips; The CPU chip includes a cache module and a parsing module. The cache module is used to store measurement signals and multiple sets of reference signals. Each set of reference signals corresponds to one sensing fiber, and the measurement signals correspond to all sensing fibers. The parsing module is used to parse the wavelength drift data of each sensing fiber to obtain the wavelength drift spectrum of each sensing fiber. The GPU chip includes multiple cross-correlation demodulation modules, each corresponding to a sensing fiber. Each cross-correlation demodulation module is used to cross-correlate and demodulate the measurement signal with each set of reference signals to obtain the wavelength drift data of each sensing fiber. The GPU chip also includes an FFT operation module, which performs a Fast Fourier Transform on the measurement signal and each set of reference signals to convert the reference signals and each set of measurement signals from the time domain to the distance domain; each cross-correlation demodulation module includes: The sliding window value unit is used to slide and select values ​​for each measurement signal and reference signal according to a preset window length to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber. Multiple IFFT operation units, each IFFT operation unit corresponds to a set of window data. Each IFFT operation unit is used to perform inverse fast Fourier transform on the measurement signal and reference signal in each set of window data, so as to transform the measurement signal and reference signal in each set of window data from the range domain to the frequency domain. Multiple cross-correlation operation units are provided, with each cross-correlation operation unit corresponding to a set of window data. Each cross-correlation operation unit is used to perform cross-correlation operations on the measurement signal and reference signal in each set of window data to obtain the wavelength drift data of each spatial position on the sensing fiber.

2. The fast demodulation device according to claim 1, characterized in that, The caching module includes a first caching unit and multiple second caching units. Each second caching unit corresponds to a set of reference signals. The first caching unit is used to store the measurement signals, and each second caching unit is used to store each set of reference signals.

3. The fast demodulation device according to claim 1, characterized in that, The cross-correlation function used by the cross-correlation operation unit is as follows: in, The result of performing an FFT operation on the reference signal. The result of performing an FFT operation on the measured signal and then taking the complex conjugate.

4. 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.

5. A fast demodulation method for optical frequency domain reflection multi-channel sensing, characterized in that, This method is used to perform cross-correlation demodulation on a multi-channel fiber optic sensing module, wherein the multi-channel fiber optic sensing module comprises multiple sensing fibers arranged in parallel; the fast demodulation method includes the following steps: Step 100: Based on the data volume of each sensing fiber, construct multiple cross-correlation demodulation modules in the GPU chip, with one cross-correlation demodulation module corresponding to one sensing fiber. Step 200: The CPU chip acquires multiple sets of reference signals in sequence, saves each set of reference signals and transmits them to the GPU chip. Each set of reference signals corresponds to a sensing fiber. Step 300: The GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module; Step 400: The CPU chip simultaneously acquires the measurement signals of all sensing fibers, saves the measurement signals, and transmits them to the GPU chip; Step 500: The GPU chip simultaneously saves the measurement signal to each cross-correlation demodulation module; Step 600: Each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber. Step 700: The GPU chip transmits the wavelength drift data of each sensing fiber to the CPU chip; Step 800: The CPU chip analyzes the wavelength drift data of each sensing fiber to obtain the wavelength drift spectrum of each sensing fiber. In step 300, before the GPU chip saves each set of reference signals to the corresponding cross-correlation demodulation module, it first uses the FFT operation module to perform a fast Fourier transform on each set of reference signals to convert each set of reference signals from the time domain to the range domain; and in step 500, before the GPU chip saves the measurement signal to each cross-correlation demodulation module simultaneously, it first uses the FFT operation module to perform a fast Fourier transform on the measurement signal to convert the measurement signal from the time domain to the range domain. In step 600, each cross-correlation demodulation module performs cross-correlation demodulation on its stored measurement signal and reference signal to obtain the wavelength drift data of each sensing fiber. The steps are as follows: Step 610: According to the preset window length, slide the values ​​of the stored mixed measurement signal and reference signal to obtain multiple sets of window data. Each set of window data corresponds to a spatial position on the sensing fiber. Step 620: Based on the amount of data in each group of window data, construct multiple IFFT operation units and multiple cross-correlation operation units. One IFFT operation unit and one cross-correlation operation unit correspond to one group of window data. Step 630: Each IFFT operation unit performs inverse Fourier operation on the reference signal and measurement signal in each group of window data to convert the measurement signal and reference signal in each group of window data from the range domain to the frequency domain. Step 640: Each cross-correlation operation unit performs cross-correlation operation on the measurement signal and reference signal in each group of window data to obtain wavelength drift data at each spatial position on the sensing fiber.

6. The fast demodulation method according to claim 5, characterized in that, In step 100, based on the data volume of each sensing fiber, a first cache unit and multiple second cache units are constructed in the CPU chip. One second cache unit corresponds to a set of reference signals, and the first cache unit corresponds to the measurement signal. In step 200, the CPU chip saves each set of reference signals to the corresponding second cache unit. In step 400, the CPU chip saves the measurement signal to the first cache unit.

7. The fast demodulation method according to claim 5, characterized in that, The cross-correlation function used by the cross-correlation operation unit is as follows: in, The result of performing an FFT operation on the reference signal. The result of performing an FFT operation on the measured signal and then taking the complex conjugate.

8. A multi-channel optical frequency domain reflectometer, further characterized in that it includes a data acquisition device, an optical frequency domain reflectometer, an optical fiber coupler, a multi-channel optical fiber sensing module, and the fast demodulation device as described in claim 1, wherein the multi-channel optical fiber sensing module includes multiple sensing optical fibers arranged in parallel, the optical frequency domain reflectometer is connected to each sensing optical fiber through the optical fiber coupler, and the fast demodulation device is connected to the optical frequency domain reflectometer.

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