Baseband transmission coding method and device based on digital seismograph

Abstract

The invention provides a baseband transmission coding method and device based on a digital seismograph, and belongs to the seismic exploration and development technology, and the method comprises the steps: obtaining unipolar non-return-to-zero code data in the digital seismograph; the unipolar non-return-to-zero code data are converted into alternating inversion code data; under the condition that 2N continuous zeros appear in the alternative inversion code data for the ith time, replacing a first zero in the 2N zeros with a first code; replacing the last zero in the 2N zeros with V; determining the value of the first code and the polarity of the second code by adopting a preset rule to obtain coded alternate inversion code data; and transmitting the coded alternate inversion code data. According to the method, the data transmission speed is greatly improved, the transmitted data has no direct-current component, and clutter information is effectively suppressed. The transmission lines of different stations are connected with each other without polarity discrimination, and can be butted at will, thereby facilitating field construction.

Description

Technical Field

[0001] This application belongs to the technical field of seismic exploration and development, and specifically relates to a baseband transmission coding method and device based on a digital seismograph. Background Art

[0002] In the data transmission process of a digital seismograph, a baseband transmission coding technology is usually required. Using this technology, serial baseband transmission can be completed and clutter signals can be effectively suppressed.

[0003] Existing common coding methods for medium-rate data transmission include Alternate Mark Inversion (AMI), High-Density Bipolar of Order 3 (HDB3), Manchester code, Differential Manchester code, and so on.

[0004] However, on the premise of achieving the same technical effect, it is very difficult to further improve the data transmission rate. Summary of the Invention

[0005] Based on the above technical problems, this application proposes a baseband transmission coding method and device based on a digital seismograph.

[0006] In a first aspect, this application proposes a baseband transmission coding method based on a digital seismograph, including:

[0007] Obtain unipolar non-return-to-zero code data in the digital seismograph;

[0008] Convert the unipolar non-return-to-zero code data into alternate reverse code data;

[0009] When the first i consecutive 2N zeros appear in the alternate reverse code data, use a first code to replace the first zero among the 2N zeros; use a second code to replace the last zero among the 2N zeros, where N≥2 and i≥1;

[0010] Determine the value of the first code and the polarity of the second code according to a preset rule to obtain the encoded alternate reverse code data;

[0011] Transmit using the encoded alternate reverse code data.

[0012] The baseband transmission coding method based on a digital seismograph further includes: when there are no consecutive 2N zeros in the alternate reverse code data, directly transmit using the alternate reverse code data.

[0013] The step of using the second code to replace the last zero among the 2N zeros includes:

[0014] Determine the value of the second code;

[0015] Replace the last zero among the 2N zeros with the second code after determining its value.

[0016] Determining the value of the second code includes: the value of the second code is the same as the value of the non-zero code before the 2N zeros.

[0017] Determining the value of the first code using a preset rule includes:

[0018] When i = 1, the value of the first code is zero;

[0019] When i > 1, count the total number of occurrences of the second code when there are 2N consecutive zeros for the (i - 1)-th time and the i-th time;

[0020] If the total number of occurrences of the second code is odd, the value of the first code is zero;

[0021] If the total number of occurrences of the second code is even, the value of the first code is the value of the non-zero code before the 2N zeros, and the polarity of the first code is opposite to the polarity of the non-zero code before the 2N zeros.

[0022] The polarity of the second code is opposite to the polarity of the first code after determining its value.

[0023] In a second aspect, the present application proposes a baseband transmission coding device based on a digital seismograph, including:

[0024] A data acquisition module for acquiring unipolar non-return-to-zero code data in the digital seismograph;

[0025] A data conversion module for converting the unipolar non-return-to-zero code data into alternate mark inversion code data;

[0026] A first data coding module for, when there are 2N consecutive zeros for the i-th time in the alternate mark inversion code data, replacing the first zero among the 2N zeros with the first code; replacing the last zero among the 2N zeros with the second code, where N ≥ 2 and i ≥ 1;

[0027] A second data coding module for determining the value of the first code and the polarity of the second code using a preset rule to obtain the coded alternate mark inversion code data;

[0028] A first data transmission module for transmitting using the coded alternate mark inversion code data.

[0029] The baseband transmission coding device based on the digital seismograph further includes: a second data transmission module for directly transmitting the alternate mark inversion code data when there are no 2N consecutive zeros in the alternate mark inversion code data.

[0030] In a third aspect, the present application provides an electronic device, including: one or more processors, and a memory storing instructions, which when executed by the one or more processors, cause the one or more processors to execute the baseband transmission encoding method based on a digital seismograph.

[0031] In a fourth aspect, the present application provides a computer-readable storage medium storing executable instructions, which when executed cause a processor to execute the baseband transmission encoding method based on a digital seismograph.

[0032] Advantageous effects:

[0033] The present application provides a baseband transmission encoding method and apparatus based on a digital seismograph. The present application can perform serial baseband transmission and effectively suppress clutter information, while effectively improving the data transmission speed. When the transmission lines at different sites of the apparatus of the present application are interconnected, there is no need to distinguish polarities and they can be connected arbitrarily, which is convenient for field construction. Description of the Drawings

[0034] Figure 1 It is a flowchart of a baseband transmission encoding method based on a digital seismograph according to an embodiment of the present application;

[0035] Figure 2 It is an exemplary flowchart of the baseband transmission encoding method based on a digital seismograph according to an embodiment of the present application;

[0036] Figure 3 It is a schematic block diagram of a baseband transmission encoding apparatus based on a digital seismograph according to an embodiment of the present application. Detailed Embodiments

[0037] The following further describes the present disclosure with reference to the embodiments shown in the drawings.

[0038] Similar to Ethernet, baseband transmission technology is also adopted in digital seismographs. Inside the computer, unipolar NRZ code (NRZ, Non-Return to Zero) is used. NRZ code is a binary code. When the bit unit in the data is equal to 1, it is at a high level, and when the bit unit is equal to 0, it is at a low level. Since the number of occurrences of 1s and 0s in the data stream is neither equal nor symmetric, the serial signal of NRZ code contains a DC component. Using it to drive a transformer will magnetize the magnetic core of the transformer, resulting in signal transmission failure. In addition, NRZ code does not contain clock information, so NRZ code is not suitable for baseband transmission and must be appropriately transformed, that is, the so-called encoding. After the NRZ code undergoes a line code transformation and is directly sent to the channel for transmission without modulation, it is called baseband transmission. Baseband transmission all adopts serial transmission mode, that is, one symbol follows another in chronological order on the channel. The number of binary symbols sent per second is called the symbol rate. Note that the symbol rate is not directly equal to the data transmission rate. The serial transmission mode only requires one channel, so the equipment is simple and the investment is small, which is especially suitable for low-cost short-distance data transmission. The encoding method for baseband transmission of seismographs requires the following characteristics:

[0039] The encoded signal does not contain a DC component, the bandwidth is as narrow as possible, and the highest point of the signal spectrum is in the center of the bandwidth;

[0040] The encoded data contains clock information, and the receiving end can extract the synchronous clock from the data;

[0041] The encoded data has an inherent error detection ability;

[0042] When the transmission lines of different stations are interconnected, there is no need to distinguish the polarity and they can be connected arbitrarily, which is convenient for field construction.

[0043] If the signal does not contain a DC component, digital signals can be sent and received using a transformer. Since the encoded data stream contains clock information, the receiving end can extract the synchronous clock from the data stream to recover the data. There is no need to use another cable to transmit the clock, which simplifies the transceiver equipment.

[0044] The inherent error detection function means that there is a certain restrictive relationship between adjacent symbols. If the received data stream violates this restrictive relationship, errors in the data transmission process can be detected. This feature can also be used to generate code sequences with special functions, such as the frame header of a data frame.

[0045] Baseband transmission generally uses 2 differential lines (twisted pairs) to transmit signals. The encoding method required by the seismograph should have no positive or negative polarity requirements for the connection of the transmission lines. In this way, when connecting the survey lines during field construction, they can be connected arbitrarily without having to identify the positive and negative polarities of each line.

[0046] Based on the above technical requirements, the present application proposes a baseband transmission coding method and device based on a digital seismograph, so that the encoded signal does not contain a DC component, can transmit and receive digital signals through a transformer, and the method of the present application can also effectively suppress clutter information. At the same time, compared with the prior art, the data transmission speed is effectively improved. Finally, the coding method of the present application has no positive and negative requirements for the two differential lines of the baseband transmission, and can be arbitrarily docked when connecting the survey line during field construction, without identifying the positive and negative polarities of each line.

[0047] Embodiment 1

[0048] This embodiment proposes a baseband transmission coding method based on a digital seismograph, as Figure 1 shown, including:

[0049] Step S1: Obtain unipolar non-return-to-zero code data in the digital seismograph;

[0050] Step S2: Convert the unipolar non-return-to-zero code data into alternative mark inversion code data;

[0051] Step S3: When the first i consecutive 2N zeros appear in the alternative mark inversion code data, use the first code to replace the first zero among the 2N zeros; use the second code to replace the last zero among the 2N zeros, where N≥2 and i≥1;

[0052] Step S4: Determine the value of the first code and the polarity of the second code according to a preset rule to obtain the encoded alternative mark inversion code data;

[0053] Step S5: Transmit using the encoded alternative mark inversion code data.

[0054] Under the existing technical conditions, it is very difficult to further improve the transmission speed of the coding method. In this embodiment, first, after obtaining the unipolar non-return-to-zero code data (Non-Return to Zero, NRZ) in the digital seismograph, convert the unipolar non-return-to-zero code data into alternative mark inversion code data (Alternative Mark Inversion, AMI), and then start to judge whether there are consecutive 2N zeros. In the specific implementation, N≥2, and the value of N needs to be specified in advance.

[0055] When the first i consecutive 2N zeros appear in the alternative mark inversion code data, use the first code B to replace the first zero among the 2N zeros; use V to replace the last zero among the 2N zeros, and do not change the several zeros in the middle; at this time, determine the value of B and the polarity of the second code V according to a preset rule to obtain the encoded alternative mark inversion code data without a DC component; finally, transmit using the encoded alternative mark inversion code data.

[0056] When there are no consecutive 2N zeros in the alternating reverse code data, the alternating reverse code data is directly used for transmission without encoding again.

[0057] The above encoding method greatly improves the data transmission speed. The transmitted data has no DC component and effectively suppresses clutter information. There is no requirement for the positive and negative poles of the two differential lines for baseband transmission. When connecting the survey line during field construction, they can be docked arbitrarily without identifying the positive and negative polarities of each line.

[0058] In order not to generate a DC component, in this embodiment, B is used to replace the first zero among the 2N zeros; the second encoding V is used to replace the last zero among the 2N zeros. It is necessary to determine the value and polarity of B, and the value and polarity of V. First, determine the value of V; use the determined V to replace the last zero among the 2N zeros. The determination of the value of V includes: the value of V is the same as the value of the non-zero code before the 2N zeros.

[0059] Secondly, when determining the value of B, it includes: when i = 1, the value of B is zero, that is, when encountering consecutive 2N zeros for the first time, B is directly set to zero; when i > 1, count the total number of occurrences of V when encountering consecutive 2N zeros for the (i - 1)-th time and the i-th time; if the total number of occurrences of V is odd, the value of B is zero; if the total number of occurrences of V is even, the value of B is the value of the non-zero code before the 2N zeros, and the polarity of B is opposite to the polarity of the non-zero code before the 2N zeros. The polarity of V is opposite to the polarity of B after the value is determined.

[0060] For example, when i = 2, that is, when encountering consecutive 2N zeros for the second time, it is necessary to count the number of occurrences of V when encountering consecutive 2N zeros for the first time and the number of occurrences of V when encountering consecutive 2N zeros for the second time, and add the two counted Vs to get the final total number of V. When the total number of V is odd, the value of B is zero; when the total number of V is even, the value of B is the value of the non-zero code before the 2N zeros, and the polarity of B is opposite to the polarity of the non-zero code before the 2N zeros. At this time, it should be noted that after the value and polarity of B are determined, the polarity of V needs to be adjusted again, that is, the polarity of V is opposite to the polarity of B after the value is determined. If the value of B is zero, there is no need to adjust the polarity of B. If B is the value of the non-zero code before the 2N zeros, the polarity of the second encoding V needs to be adjusted.

[0061] A baseband transmission coding based on a digital seismograph proposed in this embodiment. First, obtain the unipolar non-return-to-zero code data in the digital seismograph; secondly, convert the unipolar non-return-to-zero code data into alternate mark inversion code data; when there are 2N consecutive zeros for the i-th time in the alternate mark inversion code data, use B to replace the first zero among the 2N zeros; use V to replace the last zero among the 2N zeros; determine the value of B and the polarity of V according to a preset rule to obtain the encoded alternate mark inversion code data; finally, use the encoded alternate mark inversion code data for transmission. The above coding method greatly improves the data transmission speed, the transmitted data has no DC component, and effectively suppresses clutter information. When the transmission lines at different stations are connected to each other, there is no need to distinguish the polarity, and they can be connected arbitrarily, which is convenient for field construction.

[0062] Embodiment 2

[0063] Based on Embodiment 1, this embodiment proposes an example of a baseband transmission coding method based on a digital seismograph, and details the specific implementation process of the baseband transmission coding method based on a digital seismograph, such as Figure 2 As shown, in this embodiment, N is taken as 4, including:

[0064] Step S101: Convert the unipolar non-return-to-zero code data in the digital seismograph into alternate mark inversion code data;

[0065] Step S102: Determine whether there are 4 consecutive zeros in the alternate mark inversion code data;

[0066] Step S103: If there are 4 consecutive zeros in the alternate mark inversion code data, use B00V to replace the 4 consecutive zeros;

[0067] In this example, the coding is an improved coding method based on the AMI code (alternate mark inversion code), and its feature is that the encoded output does not allow more than 2 consecutive zeros. When there are 3 consecutive zeros in the input data stream, a specific coding sequence B00V is used to replace these 4 zeros. B can be 0, +v or -v (3 possibilities), and V can be +v and -v (2 possibilities). If there are 4 consecutive zeros in the alternate mark inversion code data (AMI code), the code sequence B00V should be used to replace them. Specifically: first, change the 4th zero among the 4 consecutive zeros into the replacement code V, and the value of V is the same as the last non-zero code (+v or -v) before the 4 consecutive zeros, while the replacement code B for the 1st zero temporarily remains 0. So +v0000 becomes +v000+v, and -v0000 becomes -v000-v.

[0068] Step S104: Determine the value of B;

[0069] In this example, first, check whether the code V has appeared before. If it has not (i.e., this is the first time to take the code V in the data stream), then the value of B remains 0. If the code V has appeared before, then it is necessary to count whether the total number of +v and -v between this code V and the previous code V is even or odd. If it is odd, the value of B is 0, so the conversion code is still 000V. If it is even, the value of B is the opposite polarity of the non-zero code before the four consecutive 0s. So +v000+v becomes +v-v00+v, and -v000-v becomes -v+v00-v.

[0070] Step S105: Determine the polarity of V using the determined value of B to obtain the encoded data, and go to step S107;

[0071] It should be noted that after the value of B for four consecutive 0s in non-first occurrences is determined, the V in the substitution code should be converted to the opposite polarity of B. So +v-v00+v finally becomes +v-v00-v, and -v+v00-v becomes -v+v00+v.

[0072] Step S106: If four consecutive 0s do not appear in the alternate inversion code data, directly use the alternate inversion code data as the encoded data;

[0073] Step S107: Transmit the encoded data and return to step S102 to continue judging other alternate inversion code data.

[0074] In this example, when four consecutive 0s first appear in the alternate inversion code data (AMI code), since the code V has not occurred before, execute the conversion of 0000 to 000+v, and B is equal to 0 without transformation. Then four consecutive 0s appear again in the alternate inversion code data (AMI code). First, still execute the conversion to 000+v (note that at this time, the number of +v and -v in the code stream is already unbalanced, and a positive DC component appears in the data stream). Then execute step S104. Since the number of non-0s between this counted V and the previous counted V is even (2), the value of B cannot be 0. Since the non-zero code before B is +v, the value of B must be -v, and the substitution code becomes -v00+v. Then execute step S105. In step S103, the replaced V should be consistent with B, so the substitution code for four consecutive 0s becomes -v00-v. Finally, the number of +v and -v in the code stream reaches balance again. The subsequent code stream still changes the polarity according to the normal rule.

[0075] From this example, it can be seen that the insertion of the V code disrupts the normal coding rule, resulting in a DC component in the code sequence. The insertion of B is to restore the rebalancing of the DC component, so that the average value of the DC component in the output signal returns to 0 again. The above coding method greatly improves the data transmission speed. The transmitted data has no DC component, effectively suppressing clutter information. When the transmission lines at different stations are interconnected, there is no need to distinguish the polarity and they can be connected arbitrarily, which is convenient for field construction.

[0076] Embodiment Three

[0077] This embodiment proposes a baseband transmission coding device based on a digital seismograph, as Figure 3 shown, including: a data acquisition module, a data conversion module, a first data coding module, a second data coding module, and a first data transmission module;

[0078] The data acquisition module is connected to the data conversion module, the data conversion module is connected to the first data coding module, and the second data coding module is connected to the first data transmission module;

[0079] The data acquisition module is used to acquire unipolar non-return-to-zero code data in the digital seismograph;

[0080] The data conversion module is used to convert the unipolar non-return-to-zero code data into alternate mark inversion code data;

[0081] The first data coding module is used to, when there are continuously 2N zeros for the i-th time in the alternate mark inversion code data, use B to replace the first zero among the 2N zeros; use V to replace the last zero among the 2N zeros, where N≥2 and i≥1;

[0082] The second data coding module is used to determine the value of B and the polarity of V according to a preset rule to obtain the coded alternate mark inversion code data;

[0083] The first data transmission module is used to transmit using the coded alternate mark inversion code data.

[0084] The baseband transmission coding device based on the digital seismograph further includes: a second data transmission module, connected to the data conversion module, and used to directly transmit the alternate mark inversion code data when there are no continuously 2N zeros in the alternate mark inversion code data.

[0085] A baseband transmission coding device based on a digital seismograph proposed in this embodiment acquires unipolar non-return-to-zero code data in the digital seismograph by using a data acquisition module; converts the unipolar non-return-to-zero code data into alternate mark inversion code data by using a data conversion module; then, when the first data coding module encounters 2N consecutive zeros for the i-th time in the alternate mark inversion code data, replaces the first zero among the 2N zeros with B; replaces the last zero among the 2N zeros with V; then uses a second data coding module to determine the value of B and the polarity of V; finally, transmits the coded alternate mark inversion code data by using a first data transmission module. This device greatly improves the data transmission speed, the transmitted data has no DC component, and effectively suppresses clutter information. When the transmission lines at different sites are interconnected, there is no need to distinguish the polarity, and they can be connected arbitrarily, which is convenient for field construction. This example can serve the exploration and development of minerals, conventional oil and gas, shale oil and gas, and coalbed methane.

[0086] Embodiment 4

[0087] This embodiment proposes an electronic device, including: one or more processors, and a memory, where the memory stores instructions, and when the instructions are executed by the one or more processors, the one or more processors are caused to execute the baseband transmission coding method based on a digital seismograph as described above.

[0088] The electronic device can be a mobile phone, a computer, a tablet computer, etc., including a memory and a processor. A computer program is stored on the memory, and when the computer program is executed by the processor, it implements the baseband transmission coding method as described in the embodiment. It can be understood that the electronic device can further include an input / output (I / O) interface and a communication component.

[0089] Among them, the processor is used to execute all or part of the steps in the baseband transmission coding method based on a digital seismograph as described in the above embodiment. The memory is used to store various types of data, which may include, for example, instructions of any application program or method in the electronic device, and data related to the application program.

[0090] The processor may be implemented by an application specific integrated circuit (ASIC), a digital signal processor (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor, or other electronic components, and is used to execute the baseband transmission coding method based on a digital seismograph described in the foregoing embodiments.

[0091] Embodiment 5

[0092] This embodiment provides a computer-readable storage medium storing executable instructions that, when executed, cause a processor to execute the baseband transmission coding method based on a digital seismograph.

[0093] If it is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0094] Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the baseband transmission coding method based on a digital seismograph described in various embodiments of this application.

[0095] The foregoing storage medium includes: flash memory, hard disk, multimedia card, card-type memory (such as SD (Secure Digital Memory Card) or DX (abbreviation for Memory Data Register, MDR), memory data register, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, server, APP (abbreviation for Application, application software) application store, and other various media that can store program check codes. A computer program is stored thereon, and when the computer program is executed by a processor, it can implement each step of the baseband transmission coding method described above.

[0096] The various embodiments in the present disclosure are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other, and the key points of each embodiment are the differences from other embodiments.

[0097] The protection scope of the present disclosure is not limited to the above embodiments. Obviously, those skilled in the art can make various changes and deformations to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and deformations fall within the scope of the claims of the present disclosure and their equivalent technologies, the intention of the present disclosure also includes these changes and deformations.

Claims

1. A baseband transmission coding method based on a digital seismograph, characterized in that, including: obtaining unipolar non-return-to-zero (NRZ) code data in a digital seismograph; converting the unipolar NRZ code data into alternate mark inversion (AMI) code data; when there are 2N consecutive zeros for the i-th time in the AMI code data, using a first code to replace the first zero among the 2N zeros; using a second code to replace the last zero among the 2N zeros, where N≥2 and i≥1; determining the value of the first code and the polarity of the second code according to a preset rule to obtain the encoded AMI code data; transmitting using the encoded AMI code data.

2. The baseband transmission coding method based on a digital seismograph according to claim 1, characterized in that, The baseband transmission encoding method based on a digital seismograph further includes: when there are no 2N consecutive zeros in the AMI code data, directly transmitting using the AMI code data.

3. The baseband transmission coding method based on a digital seismograph according to claim 1, characterized in that, The step of using a second code to replace the last zero among the 2N zeros includes: determining the value of the second code; using the second code with the determined value to replace the last zero among the 2N zeros.

4. The baseband transmission coding method based on a digital seismograph according to claim 3, characterized in that, The step of determining the value of the second code includes: the value of the second code is the same as the value of the non-zero code before the 2N zeros.

5. The baseband transmission coding method based on a digital seismograph according to claim 1, characterized in that, The step of determining the value of the first code according to a preset rule includes: when i = 1, the value of the first code is zero; when i>1, counting the total number of occurrences of the second code when there are 2N consecutive zeros for the (i - 1)-th time and when there are 2N consecutive zeros for the i-th time; if the total number of occurrences of the second code is odd, the value of the first code is zero; if the total number of occurrences of the second code is even, the value of the first code is the value of the non-zero code before the 2N zeros, and the polarity of the first code is opposite to the polarity of the non-zero code before the 2N zeros.

6. The baseband transmission coding method based on a digital seismograph according to claim 1, characterized in that, The polarity of the second code is opposite to the polarity of the first code with the determined value.

7. A baseband transmission coding device based on a digital seismograph, characterized in that, including: a data acquisition module for obtaining unipolar NRZ code data in a digital seismograph; a data conversion module for converting the unipolar NRZ code data into AMI code data; a first data encoding module for, when there are 2N consecutive zeros for the i-th time in the AMI code data, using a first code to replace the first zero among the 2N zeros; using a second code to replace the last zero among the 2N zeros, where N≥2 and i≥1; a second data encoding module for determining the value of the first code and the polarity of the second code according to a preset rule to obtain the encoded AMI code data; a first data transmission module for transmitting using the encoded AMI code data.

8. The baseband transmission coding device based on a digital seismograph according to claim 1, characterized in that, The baseband transmission encoding device based on a digital seismograph further includes: a second data transmission module for, when there are no 2N consecutive zeros in the AMI code data, directly transmitting using the AMI code data.

9. An electronic device, characterized in that, including: one or more processors and a memory, the memory storing instructions, when the instructions are executed by the one or more processors, causing the one or more processors to execute the baseband transmission encoding method based on a digital seismograph according to any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that,It stores executable instructions which, when executed, cause a processor to execute the baseband transmission encoding method based on a digital seismograph according to any one of claims 1 to 6.

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