A DAS data conversion method, device and equipment for earthquake early warning and a medium

Abstract

The present application relates to the technical field of earthquake monitoring, in particular to a DAS data conversion method, device and equipment for earthquake warning and a medium. The present application firstly performs segmented processing on original strain data generated by measuring points on an entire optical fiber, so that strain data of optical fiber measuring points located on the same straight section are divided into the same segmented strain data, that is, the segmented strain data does not contain strain data generated by measuring points located on the other side of the bending point, so that the wave number direction of the segmented strain data is consistent, and strain data with consistent wave number direction can correctly distinguish the propagation direction of the wave in subsequent Fourier transform, and the propagation direction of the wave is related to kinematic data, so that the present application can improve the accuracy of kinematic data analyzed based on strain data.

Description

Technical Field

[0001] This invention relates to the field of earthquake monitoring technology, specifically to a DAS data conversion method, device, equipment, and medium for earthquake early warning. Background Technology

[0002] Laying optical fibers underground allows information about crustal movement to be transmitted to the fibers, causing them to deform. This deformation generates strain data, which DAS (Distributed Acoustic Sensing) can detect. DAS, a novel seismic observation technology, utilizes the backscattering Rayleigh principle to transform conventional communication optical fibers into a continuous, ultra-dense seismic array system. This enables large-scale, high-density, and long-term stable seismic observation at a relatively low cost. DAS technology has broad application prospects, especially in environments where traditional seismographs are difficult to deploy, such as marine areas, remote mountainous regions, and urban underground spaces.

[0003] The DAS system naturally outputs a strain rate signal along the fiber optic axis. Integrating the strain rate signal yields strain data. Converting this strain data into kinematic data such as velocity, acceleration, and position along the fiber optic axis has become a key technical bottleneck for DAS observation systems to connect with traditional seismic networks and achieve rapid earthquake early warning and damage assessment.

[0004] Existing technology directly processes the strain data of the entire optical fiber to obtain the kinematic data of each measurement point on the fiber. However, the entire optical fiber is not a straight line; there are local bending points along the fiber. Existing technology does not consider that the strain data of a local bending point differs from that of other points, resulting in lower accuracy of the final calculated kinematic data.

[0005] Therefore, existing technologies still need to be improved and enhanced. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a DAS data conversion method, apparatus, equipment, and medium for earthquake early warning, which solves the problem of low accuracy of kinematic data calculated from fiber optic measurement points using existing technologies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a DAS data conversion method for earthquake early warning, comprising: The raw strain data of the entire optical fiber was acquired by DAS, and the geometry of the entire optical fiber was obtained underground. Based on the layout geometry, the original strain data is segmented to obtain segmented strain data. Each segmented strain data includes strain data generated by optical fibers located on the same straight line segment. A sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window; The strain data within the window are subjected to Fourier transforms in both the time and spatial domains to obtain the strain spectrum data of the strain data within the window. The strain spectrum data within multiple windows are converted into kinematic data of measurement points on the optical fiber located within the window along the fiber axis. This kinematic data is used for earthquake early warning.

[0008] In one implementation, based on the layout geometry, the original strain data is segmented to obtain segmented strain data, including: Based on the aforementioned layout geometry, determine the turnaround point and / or bending point of the entire optical fiber segment; The entire optical fiber is segmented using the reversal point and / or the bending point to obtain segmented optical fiber; The original strain data is mapped onto the segmented optical fiber to achieve segmented processing of the original strain data, so as to obtain the segmented strain data corresponding to each segmented optical fiber.

[0009] In one implementation, a sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window, including: The segmented strain data is preprocessed, and the preprocessing includes at least one of the following: mean removal, trend removal, filtering, channel extraction, and downsampling. Determine the Tukey sliding window within the sliding window; A Tukey sliding window with a set overlap rate is applied to the preprocessed segmented strain data to obtain multiple sets of strain data within the window.

[0010] In one implementation, the strain data within the window undergoes Fourier transforms in both the time and spatial domains to obtain strain spectrum data of the strain data within the window, including: The strain data within the window is subjected to a two-dimensional fast Fourier transform in both the time and spatial domains to transform the strain data within the window into the frequency-wavenumber domain, thereby obtaining the strain spectrum data of the strain data within the window.

[0011] In one implementation, the strain spectrum data within multiple windows is converted into kinematic data of measurement points along the fiber optic axis located within the windows. This kinematic data is used for earthquake early warning and includes: Determine the transfer function of the DAS, which characterizes the rate at which strain is transferred from the optical fiber to the DAS; Set the water level constant, and based on the water level constant, the strain spectrum data in multiple windows, and the transfer function, obtain the final velocity spectrum data of the measurement point; Based on the final velocity spectrum data, kinematic data of the measurement point is obtained, including velocity, displacement, and acceleration in the time domain.

[0012] In one implementation, the window is a Tukey sliding window, which overlaps the measurement points; based on the water level constant, the strain spectrum data within multiple windows, and the transfer function, the final velocity spectrum data of the measurement points is obtained, including: Based on the water level constant, the strain spectrum data within multiple windows, and the transfer function, the velocity spectrum data of the measurement point within each overlapping Tukey sliding window is obtained. The positions of the measurement points within the overlapping Tukey sliding windows are obtained, and the weights of each velocity spectrum data are determined based on these positions. Based on each weight and the velocity spectrum data corresponding to each weight, the final velocity spectrum data of the measurement point is obtained.

[0013] In one implementation, the strain data within the window is data filtered through a fan-shaped filter window.

[0014] Secondly, embodiments of the present invention also provide a DAS data conversion device for earthquake early warning, wherein the device includes the following components: The acquisition module is used to acquire the raw strain data of the entire optical fiber acquired by DAS, and to acquire the geometric shape of the entire optical fiber under the ground. The segmentation module is used to segment the original strain data based on the layout geometry to obtain segmented strain data. The same segmented strain data includes strain data generated by optical fibers located on the same straight line segment. A sliding window module is used to apply a sliding window to the segmented strain data to obtain multiple sets of strain data within the window. The Fourier transform module is used to perform Fourier transforms on the strain data within the window in the time and spatial domains to obtain the strain spectrum data of the strain data within the window. The data conversion module is used to convert the strain spectrum data in multiple windows into kinematic data of the measurement points on the optical fiber located in the window along the optical fiber axis. The kinematic data is used for earthquake early warning.

[0015] Thirdly, embodiments of the present invention also provide a terminal device, wherein the terminal device includes a memory, a processor, and a DAS data conversion program for earthquake early warning stored in the memory and executable on the processor, wherein when the processor executes the DAS data conversion program for earthquake early warning, it implements the steps of the DAS data conversion method for earthquake early warning described above.

[0016] Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing a DAS data conversion program for earthquake early warning, wherein when the DAS data conversion program for earthquake early warning is executed by a processor, the steps of the DAS data conversion method for earthquake early warning described above are implemented.

[0017] Beneficial effects: This invention first segments the raw strain data generated by the measurement points along the entire optical fiber, so that the strain data of the optical fiber measurement points located on the same straight segment are divided into the same segmented strain data. That is, the segmented strain data does not include the strain data generated by the measurement points located on the other side of the bending point, thereby making the wave number direction of the segmented strain data consistent. Strain data with consistent wave number direction can correctly distinguish the wave propagation direction in the subsequent Fourier transform. Since the wave propagation direction is related to the kinematic data, this invention can improve the accuracy of the kinematic data analyzed based on strain data. Attached Figure Description

[0018] Figure 1 This is the overall flowchart of the present invention.

[0019] Figure 2 This is a schematic diagram of fiber optic segmentation in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the strain data monitored by DAS in an embodiment of the present invention; Figure 4 This is a schematic diagram of the velocity monitored by the seismograph in an embodiment of the present invention; Figure 5 This is a schematic diagram of the velocity obtained by converting strain data monitored by DAS in an embodiment of the present invention; Figure 6 The fk spectrum of the horizontal eastward fiber array in this embodiment of the invention; Figure 7 This is a schematic diagram comparing the correlation coefficient obtained using the present invention with the correlation coefficient obtained using the prior art. Figure 8 A comparison of the velocity waveforms recorded by DAS and nodal seismographs at a distance of 8 km from the epicenter. Figure 9A comparison of the velocity waveforms recorded by DAS and nodal seismographs at a distance of 200 km from the epicenter. Figure 10 A structural diagram of the DAS data conversion device for earthquake early warning provided by the present invention; Figure 11 This is a block diagram illustrating the internal structure of a terminal device provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] Research has shown that when optical fibers are laid underground, information about the Earth's crustal movement is transmitted to the fibers, causing them to deform. This deformation generates strain data, which can be detected by Distributed Acoustic Sensing (DAS). DAS is a novel seismic observation technology that utilizes the backscattering Rayleigh principle to transform conventional communication optical fibers into a continuous, ultra-dense seismic array system. This allows for large-scale, high-density, and long-term stable seismic observation at a relatively low cost. DAS technology has broad application prospects, especially in environments where traditional seismographs are difficult to deploy, such as marine areas, remote mountainous regions, and urban underground spaces.

[0022] The DAS system naturally outputs a strain rate signal along the fiber optic axis. Integrating the strain rate signal yields strain data. Converting this strain data into kinematic data such as velocity, acceleration, and position along the fiber optic axis has become a key technical bottleneck for DAS observation systems to connect with traditional seismic networks and achieve rapid earthquake early warning and damage assessment.

[0023] Existing technology directly processes the strain data of the entire optical fiber to obtain the kinematic data of each measurement point on the fiber. However, the entire optical fiber is not a straight line; there are local bending points along the fiber. Existing technology does not consider that the strain data of a local bending point differs from that of other points, resulting in lower accuracy of the final calculated kinematic data.

[0024] To address the aforementioned technical problems, this invention provides a DAS data conversion method, apparatus, device, and medium for earthquake early warning, solving the problem of low accuracy in kinematic data of fiber optic measurement points calculated by existing technologies. Specifically, based on the layout geometry, the original strain data is first segmented to obtain segmented strain data, where each segmented strain data includes strain data generated by fibers located on the same straight segment. Then, a sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window. Next, the strain data within the window undergoes Fourier transforms in both the time and spatial domains to obtain strain spectrum data for multiple sets of strain data within the window. Finally, the strain spectrum data within the window is converted into kinematic data of the measurement points on the fiber optic cable located within the window along the fiber axis. This kinematic data is used for earthquake early warning.

[0025] For example, the raw strain data generated by all measurement points on the entire optical fiber is collected by DAS. In other words, the raw strain data is a combination of the strain data generated by each measurement point. The shape of the entire optical fiber is not a complete straight line, but is composed of several straight line segments. There are bending points between the straight line segments. The bending points are used as the dividing points to divide the entire optical fiber into several straight line segments.

[0026] The original strain data is divided into straight line segments to obtain segmented strain data corresponding to each straight line segment. For example, if there are three straight line segments, the original strain data is mapped to these three straight line segments to obtain segmented strain data composed of strain data generated by the measurement points on each straight line segment.

[0027] The strain data for each segment are processed as follows: A sliding window is applied to each segment of strain data to divide the data into sections. For example, if the strain data consists of strain data from ten measurement points, and the window width is the distance between five measurement points, then if the overlap between sliding windows is 80%, the first window covers the strain data from the first to the fifth measurement point, the second window covers the strain data from the second to the sixth measurement point, the third window covers the strain data from the third to the seventh measurement point, the fourth window covers the strain data from the fourth to the eighth measurement point, and the fifth window covers the strain data from the fifth measurement point. The strain data from the first measurement point to the ninth measurement point are displayed in the sixth window, the seventh window, the eighth window, the ninth window, and the tenth window.

[0028] The strain data (i.e., the strain data within each window) of the above ten windows are subjected to Fourier transforms in both the time and spatial domains to obtain ten sets of strain spectrum data. Velocity spectrum data is then obtained based on the strain spectrum data, and inversely transformed to the spatiotemporal domain to obtain the kinematic data of the measurement point within each window. Since the same measurement point lies within multiple windows, the kinematic data of a single measurement point are weighted and calculated within each window to obtain the final kinematic data for that measurement point.

[0029] Example 1: The DAS data conversion method for earthquake early warning in this example can be applied to terminal devices, which can be terminal products with video playback capabilities, such as televisions and computers. In this example, as... Figure 1 As shown, the DAS data conversion method for earthquake early warning specifically includes the following steps: S100: Obtain the raw strain data of the entire optical fiber acquired by DAS, and obtain the layout geometry of the entire optical fiber underground. S200, based on the layout geometry, the original strain data is segmented to obtain each segment strain data, and the same segment strain data includes strain data generated by optical fibers located on the same straight line segment; S300, apply a sliding window to the segmented strain data to obtain multiple sets of strain data within the window; S400, Perform Fourier transform on the strain data within the window in both the time and spatial domains to obtain the strain spectrum data of the strain data within the window; S500 converts the strain spectrum data in multiple windows into kinematic data of the measurement points on the optical fiber located in the window along the optical fiber axis, and the kinematic data is used for earthquake early warning.

[0030] In this embodiment, the layout geometry in step S100 refers to the shape formed by the optical fiber underground. This shape can be composed of straight line segments of varying lengths, with bends between the straight line segments.

[0031] Step S200, based on the layout geometry, involves segmenting the original strain data to obtain segmented strain data, including the following specific steps S201, S202, and S203: S201, based on the layout geometry, determine the turnaround point and / or bending point of the entire optical fiber segment.

[0032] S202, the entire optical fiber is segmented using the turnaround point and / or the bend point to obtain segmented optical fiber.

[0033] The geometry of fiber optic cable deployment, such as Figure 2 As shown, it consists of two straight line segments, with a bend point between the two segments.

[0034] like Figure 2 As shown, the optical fiber is divided into a horizontal optical fiber segment and a northeast optical fiber segment. The horizontal optical fiber segment and the northeast optical fiber segment are two segmented optical fibers.

[0035] Figure 2 Both nodal seismometers and DAS (Digital Optical Array) measure the velocity / strain response of earthquakes at sampling points on the fiber optic segment. The nodal seismometer serves as a standard reference for DAS, used to determine the accuracy of the strain data acquired by DAS.

[0036] S203, the original strain data is mapped onto the segmented optical fiber to realize the segmented processing of the original strain data, so as to obtain the segmented strain data corresponding to each segmented optical fiber.

[0037] Mapping the raw strain data to segmented fiber means segmenting the raw strain data according to the measurement points corresponding to the raw strain data, so that the measurement points corresponding to the segmented strain data are located on the same segmented fiber.

[0038] This embodiment divides the acquired raw strain data into multiple local straight line segments to ensure that the wavenumber direction within each segment is consistent with the spatial coordinate axis direction. For optical fibers containing foldback sections or bending regions, this embodiment further divides the data based on the foldback point location to avoid wavenumber sign aliasing, thereby improving the accuracy of subsequent frequency domain transformation.

[0039] use The location represented by the segmented strain data is Strain data at the measurement points:

[0040] In the formula, For DAS based on input The position on the output optical fiber is The strain data at the measurement points. The optical phase change measured by DAS The unit is radians (rad). The wavelength of light in a vacuum. The refractive index of the optical fiber. These are parameters related to the properties of optical fiber materials. equal . This is the gauge length (i.e., spatial resolution) of the DAS system. The unit is meters (m).

[0041] Step S300, which involves applying a sliding window to the segmented strain data to obtain multiple sets of strain data within the window, includes the following specific steps S301, S302, and S303: S301, preprocess the segmented strain data, the preprocessing including at least one of the following: mean removal, trend removal, filtering, channel extraction, and downsampling.

[0042] Preprocessing of the segmented strain data, including mean removal, trend removal, filtering, channel extraction, and downsampling, is performed to suppress low-frequency trend drift and high-frequency random noise in the segmented strain data.

[0043] Figure 3 The raw segmented strain data obtained from DAS measurements. Figure 5 The velocity along the fiber optic axis is the velocity of the measurement point (i.e., the channel number in the figure) obtained based on the preprocessed piecewise strain data. The velocity is one of the data points in the kinematic data. Figure 4 This refers to the velocity along the fiber optic axis at the measurement points monitored by the seismograph. By comparison... Figure 4 and Figure 5 It can be observed that the velocity obtained based on the preprocessed segmented strain data is very close to the velocity measured by the seismograph used as a standard reference, thus demonstrating that the preprocessing in this embodiment can improve the accuracy of the subsequently obtained velocity.

[0044] S302, Determine the Tukey sliding window in the sliding window.

[0045] S303, apply a Tukey sliding window with a set overlap rate to the preprocessed segmented strain data to obtain multiple sets of strain data within the window.

[0046] Tukey windows are applied synchronously to the segmented strain data in both the time and spatial channels. If the length of the strain data segmented into the Tukey window is less than the width of the Tukey window, zero-padding is performed to ensure that the data length meets the integer power of 2 requirement of the Fourier transform.

[0047] This operation can not only effectively reduce spectrum leakage and improve frequency domain resolution and computational efficiency, but also significantly shorten the FFT computation time when dealing with massive amounts of data at the fiber end, in conjunction with downsampling processing, to meet the needs of near real-time monitoring.

[0048] In this embodiment, the overlap rate between windows is 95%. Overlap means that the strain data of the same measurement point is covered by multiple windows.

[0049] Step S400, which involves performing Fourier transforms in the time and spatial domains on the strain data within the window to obtain strain spectrum data, includes: performing a two-dimensional fast Fourier transform in the time and spatial domains on the strain data within the window to transform the strain data within the window to the frequency-wavenumber domain, thereby obtaining strain spectrum data of the strain data within the window.

[0050] The strain data contained in the strain data within the window are based on the following formula. Perform a two-dimensional fast Fourier transform:

[0051] Represents strain spectrum data, Represents wave number, Represents angular frequency.

[0052] The two-dimensional Fast Fourier Transform in this embodiment is used to convert the time domain to the spatial domain. Convert to frequency-wavenumber domain .

[0053] Step S500, which converts the strain spectrum data within multiple windows into kinematic data of the measurement points on the optical fiber located within the window along the fiber axis, includes the following specific steps S501, S502, S503, S504, and S505: S501, Determine the transfer function of the DAS, the transfer function being used to characterize the rate at which strain is transferred from the optical fiber to the DAS.

[0054] use Representative transfer function:

[0055] because , ,therefore The calculation formula is as follows:

[0056] make ,but .

[0057] This represents the measured strain data of the optical fiber acquired by DAS. Represents the actual strain data generated by the optical fiber. Displacement data representing measurement points on the optical fiber.

[0058] S502, based on the water level constant, the strain spectrum data in multiple windows, and the transfer function, the velocity spectrum data of the measurement point in each overlapping Tukey sliding window is obtained.

[0059] Water level constant A constant set to prevent numerical instability when the wavenumber approaches zero.

[0060] use Representative velocity spectrum data:

[0061] In the formula, The choice of is determined by the direction of wave propagation.

[0062] This embodiment uses the inverse function of H(k) as a compensation function to effectively correct the amplitude loss caused by the gauge length effect. To avoid numerical anomalies near the wavenumber zero point, a water level constant is set. The amplitude is stabilized and restored.

[0063] S503, obtain the position of the measurement point within each overlapping Tukey sliding window, and determine the weight of each velocity spectrum data based on the position.

[0064] The weight of the central region of the Tukey sliding window is higher than that of the boundary regions; that is, the weight gradually decreases from the central region to the boundary regions. When the same measurement point is covered by multiple windows, there are multiple velocity spectrum data points for that measurement point. Since the position of the measurement point is different in each window, the weights of the multiple velocity spectrum data points for that measurement point are different. Therefore, the weights of each velocity spectrum data point for that measurement point can be determined based on its position in the window.

[0065] S504, based on each of the weights and the velocity spectrum data corresponding to each weight, the final velocity spectrum data of the measurement point is obtained.

[0066]

[0067] In the formula, The representative position is The measurement point at the th Velocity spectrum data within a window , In order to target the A window displays the velocity spectrum data of the measurement point. The assigned weights This represents the total number of windows that cover a measurement point.

[0068] The representative position is The weighted result of the velocity spectrum data of the measurement points.

[0069] right After normalization, the final velocity spectrum data is obtained. :

[0070] S505, based on the final velocity spectrum data, obtain the kinematic data of the measurement point, the kinematic data including velocity, displacement and acceleration in the time domain.

[0071] The final velocity spectrum data is subjected to a two-dimensional inverse fast Fourier transform to obtain the velocity in the time-space domain, which is the velocity along the fiber axis.

[0072] Integrating velocity yields displacement, and differentiating velocity yields acceleration. Velocity, position, and acceleration are all kinematic data.

[0073] Example 2: To ensure that the strain data at both ends of the segmented fiber achieves the same number of coverage times as the middle section, thereby significantly increasing the correlation coefficient (CC, commonly used to assess waveform similarity) in the end regions, this example replaces the direct windowing of the segmented strain data in Example 1 with the following scheme: Before entering the sliding window cycle, approximately WinCh / 2 (WinCh is the length of the spatial sliding window) of strain data is copied to both ends of the segmented fiber and spliced ​​to both ends of the segmented fiber to expand the segmented strain data. Then, the expanded segmented strain data is processed by sliding window to obtain the strain data within the window. The copied strain data is then removed from the strain data within the window.

[0074] In Example 3, the strain data within the window in Example 1 is the data after being filtered by a fan-shaped filter window. The fan-shaped filter window can remove interference signals with directions different from the effective signal (such as oblique noise and temperature drift noise), significantly improving the signal-to-noise ratio. Taking the horizontal eastward segment as an example, its fk spectrum is as follows: Figure 6 As shown, the apparent speed window is Based on this, a filter window is constructed to filter out the remaining interference signals.

[0075] To verify the effectiveness of this invention, the strain data of the entire optical fiber in this invention are compared with those in the prior art. The k-transform was used to obtain the kinematic data of the optical fiber for comparison. The comparison results are shown in Table 1. Table 1

[0076] As shown in Table 1, the end correlation coefficient and the average correlation coefficient of the whole array of the present invention are both higher than those of the prior art, thus proving the effectiveness of the present invention.

[0077] by Figure 7 Taking the channel marked with a black pentagram (epicentral distance approximately 8 km) as an example, the velocity obtained from DAS conversion is compared with the velocity waveform measured by a nodal seismograph. Figure 8 As shown, the waveforms and amplitudes of the two devices are highly consistent, thus demonstrating the effectiveness of the invention. Furthermore, from... Figure 3 , Figure 4 , Figure 5 As shown in the cross-section, the DAS velocity field obtained through the conversion of this invention and the velocity field measured by the nodal seismograph exhibit significant consistency in overall waveform structure and amplitude characteristics. Meanwhile, Figure 9 The displayed records (epicentral distance approximately 200 km) also exhibit good consistency. These examples demonstrate that the method proposed in this invention works stably in both local and near-field earthquake scenarios, and also yields stable results in tests targeting typical distant earthquakes (epicentral distance > 1000 km).

[0078] In summary, this invention effectively solves the problems of data edge distortion, severe shortwave signal attenuation, and uneven spatial correlation coefficient distribution ("high in the middle and low at both ends") between the converted velocity and the true velocity field in traditional methods. This method is particularly suitable for DAS data processing of long-distance, complex fiber optic arrays, significantly improving data processing accuracy, efficiency, and result reliability, and has good engineering application value.

[0079] This embodiment also provides a DAS data conversion device for earthquake early warning, such as... Figure 10 As shown, the device comprises the following components: The acquisition module 01 is used to acquire the raw strain data of the entire optical fiber acquired by DAS, and to acquire the geometric shape of the entire optical fiber under the ground. Segmentation module 02 is used to segment the original strain data based on the layout geometry to obtain segmented strain data. The same segmented strain data includes strain data generated by optical fibers located on the same straight line segment. The window sliding module 03 is used to apply a sliding window to the segmented strain data to obtain multiple sets of strain data within the window. Fourier transform module 04 is used to perform Fourier transform on the strain data within the window in the time domain and the spatial domain to obtain the strain spectrum data of the strain data within the window. The data conversion module 05 is used to convert the strain spectrum data in multiple windows into kinematic data of the measurement points on the optical fiber located in the window along the optical fiber axis. The kinematic data is used for earthquake early warning.

[0080] Based on the above embodiments, the present invention also provides a terminal device, the principle block diagram of which can be as follows: Figure 11 As shown, the terminal device includes a processor, memory, network interface, and display screen connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The network interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a DAS data conversion method for earthquake early warning. The display screen of the terminal device can be a liquid crystal display (LCD) or an e-ink display.

[0081] Those skilled in the art will understand that Figure 11 The schematic diagram shown is only a partial structural diagram related to the present invention and does not constitute a limitation on the terminal device to which the present invention is applied. The specific terminal device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0082] In one embodiment, a terminal device is provided, comprising a memory, a processor, and a DAS data conversion program for earthquake early warning stored in the memory and executable on the processor. When the processor executes the DAS data conversion program for earthquake early warning, it implements the following operation instructions: The raw strain data of the entire optical fiber was acquired by DAS, and the geometry of the entire optical fiber was obtained underground. Based on the layout geometry, the original strain data is segmented to obtain segmented strain data. Each segmented strain data includes strain data generated by optical fibers located on the same straight line segment. A sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window; The strain data within the window are subjected to Fourier transforms in both the time and spatial domains to obtain the strain spectrum data of the strain data within the window. The strain spectrum data within multiple windows are converted into kinematic data of measurement points on the optical fiber located within the window along the fiber axis. This kinematic data is used for earthquake early warning.

[0083] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DAS data conversion method for earthquake early warning, characterized in that, include: The raw strain data of the entire optical fiber was acquired by DAS, and the geometry of the entire optical fiber was obtained underground. Based on the layout geometry, the original strain data is segmented to obtain segmented strain data. Each segmented strain data includes strain data generated by optical fibers located on the same straight line segment. A sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window; The strain data within the window are subjected to Fourier transforms in both the time and spatial domains to obtain the strain spectrum data of the strain data within the window. The strain spectrum data within multiple windows are converted into kinematic data of measurement points on the optical fiber located within the window along the fiber axis. This kinematic data is used for earthquake early warning.

2. The DAS data conversion method for earthquake early warning as described in claim 1, characterized in that, Based on the aforementioned layout geometry, the original strain data is segmented to obtain segmented strain data, including: Based on the aforementioned layout geometry, determine the turnaround point and / or bending point of the entire optical fiber segment; The entire optical fiber is segmented using the reversal point and / or the bending point to obtain segmented optical fiber; The original strain data is mapped onto the segmented optical fiber to achieve segmented processing of the original strain data, so as to obtain the segmented strain data corresponding to each segmented optical fiber.

3. The DAS data conversion method for earthquake early warning as described in claim 1, characterized in that, A sliding window is applied to the segmented strain data to obtain multiple sets of strain data within the window, including: The segmented strain data is preprocessed, and the preprocessing includes at least one of the following: mean removal, trend removal, filtering, channel extraction, and downsampling. Determine the Tukey sliding window within the sliding window; A Tukey sliding window with a set overlap rate is applied to the preprocessed segmented strain data to obtain multiple sets of strain data within the window.

4. The DAS data conversion method for earthquake early warning as described in claim 1, characterized in that, The strain data within the window are subjected to Fourier transforms in both the time and spatial domains to obtain the strain spectrum data within the window, including: The strain data within the window is subjected to a two-dimensional fast Fourier transform in both the time and spatial domains to transform the strain data within the window into the frequency-wavenumber domain, thereby obtaining the strain spectrum data of the strain data within the window.

5. The DAS data conversion method for earthquake early warning as described in claim 1, characterized in that, The strain spectrum data within multiple windows are converted into kinematic data of measurement points along the fiber optic axis located within the windows. This kinematic data is used for earthquake early warning and includes: Determine the transfer function of the DAS, which characterizes the rate at which strain is transferred from the optical fiber to the DAS; Set the water level constant, and based on the water level constant, the strain spectrum data in multiple windows, and the transfer function, obtain the final velocity spectrum data of the measurement point; Based on the final velocity spectrum data, kinematic data of the measurement point is obtained, including velocity, displacement, and acceleration in the time domain.

6. The DAS data conversion method for earthquake early warning as described in claim 5, characterized in that, The window is a Tukey sliding window, and the Tukey sliding window covers the measurement points in an overlapping manner; Based on the water level constant, the strain spectrum data within multiple windows, and the transfer function, the final velocity spectrum data of the measurement point is obtained, including: Based on the water level constant, the strain spectrum data within multiple windows, and the transfer function, the velocity spectrum data of the measurement point within each overlapping Tukey sliding window is obtained. The positions of the measurement points within the overlapping Tukey sliding windows are obtained, and the weights of each velocity spectrum data are determined based on these positions. Based on each weight and the velocity spectrum data corresponding to each weight, the final velocity spectrum data of the measurement point is obtained.

7. The DAS data conversion method for earthquake early warning as described in any one of claims 1-6, characterized in that, The strain data within the window is the data after being filtered by a fan-shaped filter window.

8. A DAS data conversion device for earthquake early warning, characterized in that, The device comprises the following components: The acquisition module is used to acquire the raw strain data of the entire optical fiber acquired by DAS, and to acquire the geometric shape of the entire optical fiber under the ground. The segmentation module is used to segment the original strain data based on the layout geometry to obtain segmented strain data. The same segmented strain data includes strain data generated by optical fibers located on the same straight line segment. A sliding window module is used to apply a sliding window to the segmented strain data to obtain multiple sets of strain data within the window. The Fourier transform module is used to perform Fourier transforms on the strain data within the window in the time and spatial domains to obtain the strain spectrum data of the strain data within the window. The data conversion module is used to convert the strain spectrum data in multiple windows into kinematic data of the measurement points on the optical fiber located in the window along the optical fiber axis. The kinematic data is used for earthquake early warning.

9. A terminal device, characterized in that, The terminal device includes a memory, a processor, and a DAS data conversion program for earthquake early warning stored in the memory and executable on the processor. When the processor executes the DAS data conversion program for earthquake early warning, it implements the steps of the DAS data conversion method for earthquake early warning as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a DAS data conversion program for earthquake early warning. When the DAS data conversion program for earthquake early warning is executed by a processor, it implements the steps of the DAS data conversion method for earthquake early warning as described in any one of claims 1-7.

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