Multifunctional data acquisition and processing method for mine electrical method

Abstract

The present invention discloses a multifunctional mine electrical data acquisition and processing method, comprising the following steps: Step 1: Obtaining an IP address assigned to a microcontroller by a host computer centralized control station; Step 2: The host computer centralized control station selects a signal acquisition mode as either an electrical profile mode or an electrical perspective mode; Step 3: Configuring a primary filtering and amplifying module, a secondary amplifying module, and an AD acquisition module; Step 4: Connecting the receiving electrodes selected by the switch matrix module to the primary filtering and amplifying module according to different signal acquisition modes; Step 5: Acquiring electrical profile data based on a DC square wave signal; Step 6: Calculating a final observed voltage; Step 7: Obtaining a full waveform file of a pseudo-random multi-frequency signal; and Step 8: Calculating a final observed voltage value. The present method can effectively improve the signal-to-noise ratio of the acquired signal.

Description

Technical Field

[0001] The present invention relates to a mine electrical data acquisition and processing method, belongs to the field of mine geophysical exploration, and specifically relates to a mine electrical multifunctional data acquisition and processing method, which is suitable for underground strong electromagnetic interference environment. Background Art

[0002] Because mine electrical monitoring is sensitive to changes in coal and rock resistivity, it has been widely used in monitoring coal seam mining damage and water hazards, as well as in monitoring grouting effects. Underground coal mines are a special and dangerous working environment filled with explosive gases. All instruments and equipment must meet the requirements of industrial explosion-proof electrical equipment and obtain relevant inspection permits. Therefore, when conducting electrical monitoring in coal mines, the power of the electrical field source is strictly limited. Generally, the emission voltage is limited to no more than 100V, and the emission current is limited to no more than 60mA. The field source response signal is extremely weak. According to experimental tests, for conventional coal mining working faces with an inclination of more than 200 meters, when performing the lane transmission and reception monitoring mode, the effective field source response signal generally does not exceed 500uV. This places high demands on the weak signal acquisition capability of the monitoring equipment.

[0003] Furthermore, when conducting electrical data acquisition, monitoring electrodes are driven into the coal seam floor or roof, establishing a direct connection between the monitoring equipment's signal acquisition input and the "ground" without any signal isolation measures. Consequently, the grounding of large electromechanical equipment underground in coal mines, such as shearers, substations, and belt conveyors, causes significant electromagnetic interference to the monitoring electrodes. This interference is primarily 50Hz power frequency interference, and with the development of frequency conversion technology, the types and frequency distribution of electromagnetic interference have become increasingly complex and variable, potentially contaminating the target frequency point of the field source. Furthermore, electrical monitoring differs from electrical prospecting, which can proactively select special time periods for data acquisition, such as shutdowns for maintenance. However, electrical monitoring collects data throughout the entire mining process, inevitably facing direct electromagnetic interference. This places more stringent demands on the front-end signal processing circuits, anti-interference measures, and data processing methods of the monitoring instrument's data acquisition.

[0004] In summary, the challenges faced by electrical monitoring data collection, both in terms of instrumentation and data processing, are even more severe than those encountered with manual electrical exploration. Currently, there are two main approaches to electrical monitoring: a single monitoring host, with autonomous potential acquisition, for electrical profiling data collection; and a dual monitoring host, with mutual potential acquisition, for electro-perspective data collection. In a potential acquisition scheme with a single monitoring host, DC signal transmission is used. Power can be supplied to any electrode, while potential measurements are performed simultaneously at all other electrodes. This results in faster acquisition speeds, but the potential difference data required for inversion is a reconstruction of the potential data. Because the potential data is acquired between a single-point electrode and an infinitely distant electrode, the stronger signal also introduces stronger interference signals. The true, weak potential difference data is drowned out by the stronger potential data, making it difficult to obtain reliable and accurate data by subtracting the two. Furthermore, for electrical profile observations, the spatial localization capability of the detection results is poor. In a potential difference acquisition scheme with two monitoring hosts, AC signals of a specific frequency are used. While transmission occurs in one tunnel, the other monitoring host in the opposite tunnel receives the potential difference signal that penetrates the working face. FFT analysis of the effective signal from the field source with known frequency characteristics enhances the resolution of weak signals. However, reliable and accurate data is also difficult to obtain when affected by broadband interference generated by high-power electromechanical equipment. Furthermore, for electrical perspective observations, the resolution of the detection results along the working face dip (perpendicular to the survey line) and depth is poor. In order to suppress broadband interference, monitoring technology and equipment based on pseudo-random field source signals have been gradually promoted and applied. Pseudo-random signal transmission modules and full-waveform data acquisition modules are used in hardware, and relevant identification methods are used in signal processing to extract effective signals, which improves the system's anti-interference ability to a certain extent. However, the system is difficult to overcome the problem of weakening effective signals after energy is redistributed among different frequencies during multi-frequency wave transmission. In actual use, single-frequency wave transmission mode is generally still used, which fails to give full play to the advantages of multi-frequency pseudo-random signals in anti-interference ability, and the collected signals still face the problem of low signal-to-noise ratio.

[0005] Effective solutions are urgently needed to address these issues. First, the design of data acquisition channels for electrical monitoring equipment needs to be improved, with appropriate signal processing and filtering schemes designed to amplify effective signals and suppress electromagnetic interference in hardware. Second, data processing methods such as signal superposition, data correlation, and frequency domain analysis need to be employed to suppress broadband interference and improve the signal-to-noise ratio of the received signal. Third, data acquisition devices compatible with both electrical profiling and electro-perspective data acquisition should be designed, allowing for time-sharing data acquisition using different methods to obtain richer observation data within a limited observation space. This allows for the application of appropriate prior information to constrain the resistivity inversion process and improve the imaging resolution of the inversion results regarding the spatial location and distribution of the anomaly. Summary of the Invention

[0006] The purpose of this patent is to provide a multifunctional mine electrical data acquisition and processing method to solve the technical problem of low signal-to-noise ratio of the collected signals in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A mine electrical multifunctional data acquisition and processing method is provided. The method is based on a mine electrical multifunctional data acquisition device having the following structure:

[0009] It includes a switch matrix module, a primary filtering and amplifying module, a power frequency filtering module, a secondary amplifying module, a mining multi-channel isolation low-noise explosion-proof and intrinsically safe power supply module, a microcontroller, an optocoupler isolation module, a network communication module, an AD acquisition module, an embedded central control module and a communication module; wherein the mining multi-channel isolation low-noise explosion-proof and intrinsically safe power supply module serves as a power source, and the microcontroller is respectively connected to the amplification control pins of the primary filtering and amplifying module and the secondary amplifying module through the optocoupler isolation module; the microcontroller is connected to the AD acquisition module, and in addition, is also connected to the external host computer centralized control station of the present invention through the network communication module; the switch matrix module is respectively connected to the embedded central control module and the monitoring electrode group; the signal input end of the primary filtering and amplifying module is used to connect one or two receiving electrodes selected by the switch matrix module in the monitoring motor group, and its output end is connected to the signal input end of the power frequency filtering module; the signal output end of the power frequency filtering module is connected to the signal input end of the secondary amplifying module; the signal output end of the secondary amplifying module is connected to the signal input end of the AD acquisition module;

[0010] The method specifically comprises the following steps:

[0011] Step 1: The microcontroller obtains the IP address assigned to it by the host computer centralized control station through the network communication module;

[0012] Step 2: The host computer centralized control station selects the signal acquisition mode as electrical profile mode or electro-fluoroscopy mode; when the electrical profile working mode is selected, set the number of superpositions and magnification; when the electro-fluoroscopy working mode is selected, set the sampling frequency, sampling time, and magnification;

[0013] Step 3: The microcontroller receives the control command from the host computer centralized control station and configures the first-stage filter amplifier module, the second-stage amplifier module and the AD acquisition module in accordance with the parameters set in step 2;

[0014] Step 4: According to different signal acquisition modes, the embedded central control module generates different control logic signals and connects the receiving electrode selected by the switch matrix module to the input end of the first-stage filter amplifier module;

[0015] Step 5: When performing electrical profile data acquisition, the microcontroller captures the field source emission signal, i.e., the DC square wave signal, and generates a trigger signal synchronized with the rising and falling edges of the DC square wave signal, which is sent to the AD sampling module. After receiving the trigger signal, the AD sampling module begins data acquisition, collecting 20 values ​​of the positive emission half cycle at the rising edge and 20 values ​​of the negative emission half cycle at the falling edge. In this way, electrical profile data is obtained based on the DC square wave signal, and step 6 is executed to process the collected electrical profile data.

[0016] Step 6: Superimpose and average the collected data to obtain the measured value, and use the square wave signal source to calibrate the collected signal to calculate the experimental value. According to the experimental value, the observed voltage coefficient is obtained, and the final observed voltage is calculated according to the measured value and the observed voltage coefficient.

[0017] Step 7: The AD sampling module collects electro-perspective data according to the set sampling frequency and sampling time to obtain a pseudo-random multi-frequency signal full waveform file, and then executes step 8;

[0018] Step 8: Use a sine wave signal source to calibrate the collected pseudo-random multi-frequency signal full waveform file. If the field source emission signal is a single-frequency wave, calculate the calibration coefficient of the target frequency point, and then calculate the observed voltage value of the target frequency point; if it is a multi-frequency wave signal, obtain the calibration coefficient of the multi-frequency point, calculate the voltage value of each main frequency point in the pseudo-random multi-frequency signal according to the calibration coefficient, eliminate the data with the largest deviation in the voltage value, calculate the arithmetic mean of the remaining voltage values, and obtain the final observed voltage value U.

[0019] Furthermore, in the mine electrical method multifunctional data acquisition device, the switch matrix module selects a 32x4 medium-density matrix switch module; the microcontroller selects an STM32F407 embedded microcontroller; and in the mine electrical method multifunctional data acquisition device, the embedded central control module selects an EMB8610I embedded industrial control module.

[0020] Furthermore, in step 2, the number of superpositions is selected from 1, 5 or 10 times; the sampling frequency is selected from 1200 Hz, 2400 Hz, 4800 Hz, 7200 Hz or 14400 Hz, and the sampling time is 1s to 12s.

[0021] Furthermore, step 6 includes the following process:

[0022] (1) Obtain the measured value by superposition and averaging: Collect 20 values ​​of the positive emission half cycle at the first rising edge, delete the first two values ​​and the last two values ​​to eliminate the influence of the rising and falling edge slopes on the data; then delete the maximum and minimum values ​​of the remaining 16 values ​​to eliminate the influence of random interference on the data; then take the average of the remaining 14 values, which is recorded as U p; Collect 20 values ​​of the negative emission half cycle on the falling edge and process them in the same way, denoted as U n ; In this way, the voltage value of the positive and negative half cycle in a low-frequency square wave cycle is obtained; take U=|(U p -U n )| / 2, as the measured value S of a square wave period 测量 If the number of superpositions is greater than 1, the measured values ​​of multiple square wave cycles are averaged to obtain the measured value S 测量 ;

[0023] (2) Calibration of the observed data coefficients using the electrical profile method: The electrical profile data collected in step 5 are calibrated using a square wave signal source; the absolute value of the amplitude of the square wave signal source is recorded as S0, and the average value of the absolute value of the amplitude of the collected square wave signal is recorded as S 实验 , the calculation formula of the observed voltage coefficient is: δ=S0 / S 实验 ; Use square wave signal sources with different amplitudes to perform multiple calibrations, calculate the observed voltage coefficients under different amplitudes, and calculate the average value of the observed voltage coefficients obtained from multiple calibrations as the final observed voltage coefficient δ;

[0024] (3) Calculate the observed voltage using the formula: U = δ × S 测量 .

[0025] Furthermore, the step 8 specifically includes the following process:

[0026] (1) Single-frequency received signal calibration and calculation of observed voltage value:

[0027] If the signal emitted by the field source is a single-frequency wave, its frequency is recorded as f 1 , then the target frequency point corresponding to the received signal is also f 1 ; Use a sine wave signal source to give an amplitude of Z0 and a frequency of f 1 The sine wave is input to the signal input terminal of the first-stage amplification and filtering module (2); the controller (6) sets the initial acquisition parameters, namely, the sampling frequency k = 1200 Hz, the sampling time τ = 1 s, and the amplification factor ν = 1, and performs data acquisition; the frequency response Z1 of the transmitted signal and the received signal is obtained by correlation detection, and the target frequency point f 1 Calibration coefficient δf 1 =Z0 / Z1; when the transmitting frequency is f 1 When selecting different sampling frequencies k, sampling durations τ, and magnification factors ν for data acquisition, the target frequency amplitude of the received signal is recorded as Zf 1 , the target frequency voltage value calculation formula is as follows:

[0028]

[0029] (2) Pseudo-random multi-frequency signal calibration and calculation of observed voltage values:

[0030] A. If the signal emitted by the field source is a multi-frequency wave, its frequency is recorded as f 1 、f 2 、……、f n , then the target frequency point corresponding to the received signal is also f 1 、f 2 、……、f n ; Using the above single-frequency received signal calibration method, the frequency point f is obtained respectively 1 、f 2 、……、f n Calibration coefficient

[0031] B. According to the energy proportion of different frequency points in the multi-frequency wave signal, set the weight of each frequency point to c. 1 、c 2 、……、c n The frequency responses of the ground at different frequencies obtained by detecting the pseudo-random multi-frequency signal are recorded as Z1, Z2, ..., Z n The voltage value calculation formula of each main frequency point of the pseudo-random multi-frequency wave is as follows:

[0032]

[0033] C. Eliminate the data with the largest deviation in the voltage values, calculate the arithmetic mean of the remaining voltage values, and obtain the final observed voltage value U.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The method of the present invention is compatible with data acquisition devices used for both electrical profiling and electrofluorescence data acquisition. It performs data acquisition for different methods in a time-sharing manner. It can be used to acquire observation data for electrical profiling using self-generated and self-received DC square wave signals, as well as for acquiring observation data for electrofluorescence using mutually generated and received pseudo-random multi-frequency signals. This method acquires richer observation data within a limited observation space, allows for the application of appropriate prior information to constrain the resistivity inversion process, and improves the imaging resolution of the inversion results regarding the spatial location and distribution of anomalies.

[0036] 2. It adopts two-stage amplification circuit for signal processing and AD acquisition module for synchronous signal acquisition, and has excellent weak signal resolution capability.

[0037] 3. The multi-frequency superposition method is used to process pseudo-random multi-frequency signals, which can effectively suppress broadband electromagnetic noise in coal mines and improve the signal-to-noise ratio of the received signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic flow diagram of the method of the present invention.

[0039] Figure 2 This is a schematic diagram of the composition of a multifunctional mining electrical monitoring data acquisition device;

[0040] In the figure, 1- switch matrix module, 2- primary filter amplifier module, 3- power frequency filter module, 4- secondary amplifier module, 5- mining multi-channel isolation low-noise explosion-proof and intrinsically safe power supply module, 6- microcontroller, 7- optocoupler isolation module, 8- network communication module, 9- AD acquisition module, 10- embedded central control module, 11- communication module, 12- host computer centralized control station.

[0041] Figure 3 This is a schematic diagram of the switch matrix module. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and specific implementation methods.

[0043] The following will describe the implementation methods of the present application in detail with reference to the accompanying drawings and examples, so that the implementation process of how the present application applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0044] Please refer to Figure 1 The present invention provides a mine electrical multifunctional data acquisition and processing method. The method is based on a mine electrical multifunctional data acquisition device, whose structure includes a switch matrix module 1, a first-level filtering and amplifying module 2, a power frequency filtering module 3, a second-level amplifying module 4, a mine-use multi-channel isolated low-noise flameproof and intrinsically safe power supply module 5, a microcontroller 6, an optocoupler isolation module 7, a network communication module 8, an AD acquisition module 9, an embedded central control module 10 and a communication module 11. Among them, the mining multi-channel isolation low-noise explosion-proof and intrinsically safe power supply module 5 is used as the power supply, and the microcontroller 6 is connected to the amplification control pins of the first-level filter amplifier module 2 and the second-level amplifier module 4 respectively through the optical coupler isolation module 7; the microcontroller 6 is connected to the AD acquisition module 9, and in addition, it is also connected to the host computer centralized control station 12 outside the present invention through the network communication module 8; the switch matrix module 1 is respectively connected to the embedded central control module 10 and the monitoring electrode group; the signal input end of the first-level filter amplifier module 2 is used to connect one or two receiving electrodes selected by the switch matrix module 1 in the monitoring motor group (one is selected in the monopole receiving mode, and two are selected in the dipole receiving mode), and its output end is connected to the signal input end of the power frequency filter module 3; the signal output end of the power frequency filter module 3 is connected to the signal input end of the second-level amplifier module 4; the signal output end of the second-level amplifier module 4 is connected to the signal input end of the AD acquisition module 9.

[0045] In the above technical solution, the selection and function of each component are as follows:

[0046] Switch matrix module 1, using Pickering's 32x4 medium density matrix switch module, can realize any 32 to 4 logic switch, such as Figure 2 It is used to receive the control logic signal generated by the embedded central control module 10, and select one or two monitoring electrodes in the monitoring electrode group to be connected to the signal input end of the corresponding first-stage filter amplification module 2 according to the control logic signal, and use the selected electrodes as receiving electrodes to form a receiving channel. The selected receiving electrodes serve as signal receiving points at a certain moment to collect the actual potential difference signal between the two receiving electrodes.

[0047] The microcontroller 6 uses an STM32F407 embedded microcontroller, which is used to receive control instructions from the host computer centralized control station 12 through the network communication module 8, and collaboratively control each module to act according to the requirements of the instructions of the host computer centralized control station 12 according to the control instructions; specifically: generate a control signal for the embedded central control module 10, generate amplification control logic for the first-level filtering and amplifying module 2 and the second-level amplifying module 4, and realize control of the AD sampling module 9 (including register configuration, acquisition timing, acquisition configuration, data protocol, etc.).

[0048] The first-stage filter-amplifier module 2 performs primary filtering and amplification of the electrical monitoring signal. It consists of an AD8251 programmable instrumentation amplifier and its peripheral circuits. A low-pass filter with a cutoff frequency of 10 kHz is placed before its signal input, filtering out frequency components above 10 kHz and amplifying the signal according to a set amplification factor. The amplifier has selectable amplification factors of 1, 2, 4, or 8. The power frequency filter module 3, the post-stage circuit of the first-stage filter-amplifier module 2, suppresses 50 Hz power frequency interference signals with a suppression capability of at least -40 dB. It comprises a universal active filter (UAF42) and its peripheral circuits, equipped with a second-order Butterworth notch filter to achieve high-Q filtering at the target frequency. The second-stage amplifier module 4, consisting of a programmable instrumentation amplifier (PGA205) and its peripheral circuits, further amplifies the monitoring signal after passing through the first-stage filter-amplifier module 2 and the power frequency filter module 3 according to set parameters. The amplification factor can be selected from 1, 2, 4, or 8. It is worth noting that after the signal is amplified in two stages, the peak-to-peak value of the signal shall not be higher than 5V; then it enters the AD sampling module for analog-to-digital conversion.

[0049] The optocoupler isolation module 7 is composed of a TLP521-4 optocoupler isolator and its peripheral circuits, and is used for signal isolation communication between devices of different levels. The power supply level of the amplifier amplification factor selection pins of the first-stage filtering and amplifying module 2 and the second-stage amplifying module 4 is ±7V, while the power supply level of the control IO pin of the microcontroller 6 is 3.3V. Signal communication between the microcontroller 6 and the first-stage filtering and amplifying module 2 and the second-stage amplifying module 4 is achieved through the optocoupler isolation module 7.

[0050] The AD acquisition module 9, comprised of an AD1262IPW and its peripheral circuitry, has a signal input connected to the output of the secondary amplification module 4. This module is used to perform analog-to-digital conversion and data acquisition for the electrical monitoring signal from the receiving electrode, which is then processed sequentially by the primary filtering and amplification module 2, the power frequency filtering module 3, and the secondary amplification module 4. During electrical profiling data acquisition, two rising edges within one cycle of the transmitted square wave signal serve as trigger signals for the AD chip to initiate acquisition, synchronously acquiring the response signal from the receiving electrode. The AD data sampling frequency is set to 50 Hz. At this data rate, the AD chip's internal digital filter can be configured to further filter 50 Hz interference signals, achieving a suppression ratio of -100 dB and nearly completely eliminating power frequency interference. During electrofluorescence data acquisition, there is no synchronous trigger signal for signal acquisition; instead, the microcontroller 6 generates the acquisition start signal. The AD data sampling frequency can be configured to be 1200 Hz, 2400 Hz, 4800 Hz, 7200 Hz, or 14400 Hz, depending on the frequency of the transmitting field signal and data quality.

[0051] The multi-channel low-noise isolated power supply module 5 uses a KDY127-12(A) mine-grade flameproof and intrinsically safe DC power supply manufactured by China Coal Technology and Engineering Corporation (Group) Xi'an Research Institute Co., Ltd., with explosion-proof certificate number CCCMT22,0958. This power supply is connected to the underground industrial power grid to power the entire device, providing independent power inputs with low ripple noise, thereby ensuring the weak signal acquisition performance of the multifunctional mine electrical data acquisition device of the present invention. Specifically, the power supply design for each module is as follows: the first-stage filter amplifier module 2, the power frequency filter module 3, and the second-stage amplifier module 4 are analog signal processing components, providing ±9V power; the switch matrix module 1, the microcontroller 6, the optocoupler isolation module 7, the network communication module 8, the embedded central control module 10, and the communication module 11 are digital signal control components, providing +5V power; the AD acquisition module is a hybrid analog and digital module, providing ±9V as drive power and +5V as reference power. The ±9V power supply and the +5V power supply are isolated and can withstand a power frequency withstand voltage of 500V for 1 minute, with a leakage current of no more than 5mA.

[0052] The network communication module 8 is composed of a 10 / 100M PHY Ethernet transceiver DP83848KSQ and its peripheral circuits, and is used to implement the TCP / IP network communication function between the microcontroller 6 and the host centralized control station 12.

[0053] The embedded central control module 10 is an EMB8610I embedded industrial control module produced by Beijing Zhongjian Lingyun Company, which is used to generate control logic signals for the switch matrix module 11 according to the control of the microcontroller 6.

[0054] The communication module 11 can be an RSM3485PHT isolated RS485 transceiver produced by Zhou Ligong, which is used to realize isolated communication between the embedded central control module 10 and the microcontroller 6;

[0055] The upper computer centralized control station 12 is a ground server host, which is used to install the electrical acquisition device control software to control the data acquisition process and data processing.

[0056] Please refer to Figure 2 The mine electrical multifunctional data acquisition and processing method provided by the present invention is based on the above-mentioned device of the present invention, and specifically includes the following steps:

[0057] Step 1: The microcontroller 6 obtains the IP address assigned to the microcontroller 6 by the host computer centralized control station 12 through the network communication module 8;

[0058] Step 2: The host computer centralized control station 12 selects the signal acquisition mode as the electrical profile mode or the electro-fluoroscopy mode; when the electrical profile working mode is selected, the number of stacking times (the number of stacking times can be selected as 1, 5, or 10 times) and the magnification (the magnification is a combination of the first and second magnifications) are set; when the electro-fluoroscopy working mode is selected, the sampling frequency (the optional ranges are 1200 Hz, 2400 Hz, 4800 Hz, 7200 Hz, and 14400 Hz), the sampling time (1 s to 12 s), and the magnification (the magnification is a combination of the first and second magnifications) are set.

[0059] Step 3: The microcontroller 6 receives the control command from the host computer centralized control station 12 and configures the first-stage filter amplification module 2, the second-stage amplification module 4 and the AD acquisition module 9 in accordance with the parameters set in step 2;

[0060] Step 4: According to different signal acquisition modes, the embedded central control module 10 generates different control logic signals to connect the receiving electrode selected by the switch matrix module 1 to the input end of the first-stage filter amplifier module 2;

[0061] Step 5: When performing electrical profiling data acquisition, the microcontroller 6 captures the field source emission signal, i.e., the DC square wave signal, and generates a trigger signal synchronized with the rising and falling edges of the DC square wave signal, which is sent to the AD sampling module 9. After receiving the trigger signal, the AD sampling module 9 begins data acquisition, collecting 20 values ​​of the positive emission half cycle at the rising edge and 20 values ​​of the negative emission half cycle at the falling edge. In this way, electrical profiling data is acquired based on the DC square wave signal, and step 6 is executed to process the acquired electrical profiling data.

[0062] Step 6: Superimpose and average the collected data to obtain the measured value, and use the square wave signal source to calibrate the collected signal to calculate the experimental value. According to the experimental value, the observed voltage coefficient is obtained, and the final observed voltage is calculated based on the measured value and the observed voltage coefficient. It includes the following sub-steps:

[0063] (1) Obtain the measured value by superposition and averaging. Collect 20 values ​​of the positive emission half cycle at the first rising edge, delete the first 2 values ​​and the last 2 values ​​to eliminate the influence of the rising and falling edge slopes on the data; then delete the maximum and minimum values ​​of the remaining 16 values ​​to eliminate the influence of random interference on the data; then take the average of the remaining 14 values, which is recorded as U p ; Collect 20 values ​​of the negative emission half cycle on the falling edge and process them in the same way, denoted as U n ; In this way, the voltage value of the positive and negative half cycle in a low-frequency square wave cycle is obtained; take U=|(U p -U n )| / 2, as the measured value S of a square wave period 测量 If the number of superpositions is greater than 1, the measured values ​​of multiple square wave cycles are averaged to obtain the measured value S 测量 ;

[0064] (2) Calibration of the coefficients of the observation data of the electrical profile method. In the laboratory, the electrical profile data collected in step 5 are calibrated using a square wave signal source; the absolute value of the amplitude of the square wave signal source is recorded as S0, and the average value of the absolute value of the amplitude of the collected square wave signal is recorded as S 实验 , the calculation formula of the observed voltage coefficient is: δ=S0 / S 实验 ; Use square wave signal sources with different amplitudes to perform multiple calibrations, calculate the observed voltage coefficients under different amplitudes, and calculate the average value of the observed voltage coefficients obtained from multiple calibrations as the final observed voltage coefficient δ.

[0065] (3) Calculate the observed voltage. The calculation formula is: U = δ × S 测量 .

[0066] Step 7: When performing electro-perspective data acquisition, perform full waveform real-time acquisition. The AD sampling module 9 acquires electro-perspective data at the set sampling frequency and sampling time, obtains a pseudo-random multi-frequency signal full waveform file, and executes step 8 for data processing.

[0067] Step 8: Process the collected pseudo-random multi-frequency signal waveform file to suppress electromagnetic noise in the coal mine and improve the signal-to-noise ratio of the received signal. This includes the following sub-steps:

[0068] (1) Single-frequency received signal calibration and calculation of observed voltage value:

[0069] If the signal emitted by the field source is a single-frequency wave, its frequency is recorded as f 1 , then the target frequency point corresponding to the received signal is also f 1 ; Use a sine wave signal source to give an amplitude of Z0 and a frequency of f 1 The sine wave is input to the signal input terminal of the first-stage amplification and filtering module 2; the controller 6 sets the initial acquisition parameters, namely the sampling frequency k = 1200Hz, the sampling time τ = 1s, the amplification factor ν = 1, and performs data acquisition; the frequency response Z1 of the transmitted signal and the received signal is obtained by correlation detection, and the target frequency point f 1 Calibration coefficient δf 1 =Z0 / Z1; when the transmitting frequency is f 1 When selecting different sampling frequencies k, sampling durations τ, and magnification factors ν for data acquisition, the target frequency amplitude of the received signal is recorded as Zf 1 , the target frequency voltage value calculation formula is as follows:

[0070]

[0071] (2) Pseudo-random multi-frequency signal calibration and calculation of observed voltage values: including the following process:

[0072] A. If the signal emitted by the field source is a multi-frequency wave, its frequency is recorded as f 1 、f 2 、……、f n , then the target frequency point corresponding to the received signal is also f 1 、f 2 、……、f n ; Using the above single-frequency received signal calibration method, the frequency point f is obtained respectively 1 、f 2 、……、f n Calibration coefficient

[0073] B. Calculate the observed voltage. Since the pseudo-random multi-frequency signal is a combination of multiple frequencies multiplied by 2, the weight of each frequency point is set to c according to the energy proportion of different frequency points in the multi-frequency wave signal. 1 、c 2 、……、c n After the correlation detection of the pseudo-random multi-frequency signal, the frequency response of the earth at different frequency points is recorded as Z1, Z2, ..., Z n The voltage value calculation formula of each main frequency point of the pseudo-random multi-frequency wave is as follows:

[0074]

[0075] C. Superposition and averaging of voltage values ​​at different frequencies. If there are voltage values ​​at multiple frequencies at the current measurement point (current receiving electrode), remove the data with the largest deviation from the voltage values, calculate the arithmetic mean of the remaining voltage values, and obtain the final observed voltage value U. The calculation formula is:

[0076]

[0077] Among them, U f i is the voltage value of the ith frequency at a single measuring point, and n is the number of remaining voltage values ​​involved in the calculation.

[0078] Previous downhole DC electrical sounding instruments typically transmitted and received single-frequency signals. By avoiding strong interference sources in time or space, they could collect high-quality raw data. However, electromagnetic noise during monitoring is complex, extremely intense, and varies across time and space. This makes it impossible to avoid it in time and space, and it's also difficult to predict its characteristics and type. Once the transmission frequency falls within a strong interference band, valid signals are difficult to collect. Because multi-frequency signals have numerous and dispersed frequency components, when the interference band is unknown, data affected by strong electromagnetic interference can be eliminated to improve the signal-to-noise ratio of valid data. Furthermore, downhole DC electrical sounding is a geometric sounding method. Without considering the induced polarization effect, the ground response at different frequencies is essentially the same. Therefore, after eliminating data affected by strong electromagnetic interference, the ground response at each frequency can be replaced by the arithmetic mean of the ground response at each frequency. This calculation method achieves the same effect as using multiple point-by-point acquisitions with a single-frequency signal without consuming additional instrument memory or reducing work efficiency, further improving the signal-to-noise ratio of valid data.

Claims

1. A mine electrical multifunctional data acquisition and processing method, characterized in that: The method is based on a mine electrical multifunctional data acquisition device, which has the following structure: The invention comprises a switch matrix module (1), a primary filter amplifier module (2), an industrial frequency filter module (3), a secondary amplifier module (4), a mine-used multi-channel isolation low-noise flameproof and intrinsically safe power supply module (5), a microcontroller (6), an optical coupling isolation module (7), a network communication module (8), an AD acquisition module (9), an embedded central control module (10) and a communication module (11); wherein the mine-used multi-channel isolation low-noise flameproof and intrinsically safe power supply module (5) serves as a power source, the microcontroller (6) is respectively connected to the amplification control pins of the primary filter amplifier module (2) and the secondary amplifier module (4) through the optical coupling isolation module (7); the microcontroller (6) is connected to the A A D acquisition module (9) is also connected to an external upper computer centralized control station (12) of the present invention through a network communication module (8); the switch matrix module (1) is respectively connected to the embedded central control module (10) and the monitoring electrode group; the signal input end of the first-level filter amplifier module (2) is used to connect to one or two receiving electrodes selected by the switch matrix module (1) in the monitoring motor group, and its output end is connected to the signal input end of the power frequency filter module (3); the signal output end of the power frequency filter module (3) is connected to the signal input end of the second-level amplifier module (4); the signal output end of the second-level amplifier module (4) is connected to the signal input end of the AD acquisition module (9); The method specifically comprises the following steps: Step 1: The microcontroller (6) obtains the IP address assigned to the microcontroller (6) by the host computer centralized control station (12) through the network communication module (8); Step 2: The host computer centralized control station (12) selects the signal acquisition mode as the electrical profile mode or the electro-fluoroscopy mode; when the electrical profile working mode is selected, the number of superpositions and the magnification are set; when the electro-fluoroscopy working mode is selected, the sampling frequency, sampling time, and magnification are set; Step 3: The microcontroller (6) receives the control command from the host computer centralized control station (12) and configures the first-stage filtering and amplifying module (2), the second-stage amplifying module (4) and the AD acquisition module (9) that meet the parameters set in step 2; Step 4: According to different signal acquisition modes, the embedded central control module (10) generates different control logic signals to connect the receiving electrode selected by the switch matrix module (1) to the input end of the first-stage filter amplifier module (2); Step 5: When performing electrical profile data acquisition, the microcontroller (6) captures the field source emission signal, i.e., the DC square wave signal, and generates a trigger signal synchronized with the rising edge and the falling edge of the DC square wave signal and sends it to the AD sampling module (9). After receiving the trigger signal, the AD sampling module (9) starts data acquisition, and acquires 20 values ​​of the positive emission half cycle at the rising edge and acquires 20 values ​​of the negative emission half cycle at the falling edge. In this way, electrical profile data is acquired based on the DC square wave signal, and step 6 is executed to process the acquired electrical profile data. Step 6: The collected data are superimposed and averaged to obtain the measured value, and the collected signal is calibrated using a square wave signal source to calculate the experimental value. The observed voltage coefficient is obtained based on the experimental value, and the final observed voltage is calculated based on the measured value and the observed voltage coefficient; Step 7: The AD sampling module (9) collects electro-perspective data according to the set sampling frequency and sampling time to obtain a pseudo-random multi-frequency signal full waveform file, and then executes step 8; Step 8: Use a sine wave signal source to calibrate the collected pseudo-random multi-frequency signal full waveform file. If the field source emission signal is a single-frequency wave, calculate the calibration coefficient of the target frequency point, and then calculate the observed voltage value of the target frequency point; if it is a multi-frequency wave signal, obtain the calibration coefficient of the multi-frequency point, calculate the voltage value of each main frequency point in the pseudo-random multi-frequency signal according to the calibration coefficient, eliminate the data with the largest deviation in the voltage value, calculate the arithmetic mean of the remaining voltage values, and obtain the final observed voltage value U.

2. The mine electrical multifunctional data acquisition and processing method according to claim 1, characterized in that: In the mine electrical method multifunctional data acquisition device, the switch matrix module (1) selects a 32x4 medium-density matrix switch module; the microcontroller (6) selects an STM32F407 embedded microcontroller; and in the mine electrical method multifunctional data acquisition device, the embedded central control module (10) selects an EMB8610I embedded industrial control module.

3. The mine electrical multifunctional data acquisition and processing method according to claim 1 or 2, characterized in that: In step 2, the number of superpositions is selected from 1, 5 or 10 times; the sampling frequency is selected from 1200 Hz, 2400 Hz, 4800 Hz, 7200 Hz or 14400 Hz, and the sampling time is 1s to 12s.

4. The mine electrical multifunctional data acquisition and processing method according to claim 1 or 2, characterized in that: Step 6 includes the following process: (1) Obtain the measured value by superposition and averaging: Collect 20 values ​​of the positive emission half cycle at the first rising edge, delete the first two values ​​and the last two values ​​to eliminate the influence of the rising and falling edge slopes on the data; then delete the maximum and minimum values ​​of the remaining 16 values ​​to eliminate the influence of random interference on the data; then take the average of the remaining 14 values, which is recorded as U p ; Collect 20 values ​​of the negative emission half cycle on the falling edge and process them in the same way, denoted as U n ; In this way, the voltage value of the positive and negative half cycle in a low-frequency square wave cycle is obtained; take U=|(U p -U n )| / 2, as the measured value S of a square wave period 测量 If the number of superpositions is greater than 1, the measured values ​​of multiple square wave cycles are averaged to obtain the measured value S 测量 ; (2) Calibration of the observed data coefficients using the electrical profile method: The electrical profile data collected in step 5 are calibrated using a square wave signal source; the absolute value of the amplitude of the square wave signal source is recorded as S0, and the average value of the absolute value of the amplitude of the collected square wave signal is recorded as S 实验 , the calculation formula of the observed voltage coefficient is: δ=S0 / S 实验 ; Use square wave signal sources with different amplitudes to perform multiple calibrations, calculate the observed voltage coefficients under different amplitudes, and calculate the average value of the observed voltage coefficients obtained from multiple calibrations as the final observed voltage coefficient δ; (3) Calculate the observed voltage using the formula: U = δ × S 测量 .

5. The mine electrical multifunctional data acquisition and processing method according to claim 1 or 2, characterized in that: The step 8 specifically includes the following process: (1) Single-frequency received signal calibration and calculation of observed voltage value: If the signal emitted by the field source is a single-frequency wave, its frequency is recorded as f 1 , then the target frequency point corresponding to the received signal is also f 1 ; Use a sine wave signal source to give an amplitude of Z0 and a frequency of f 1 The sine wave is input to the signal input terminal of the first-stage amplification and filtering module (2); the controller (6) sets the initial acquisition parameters, namely, the sampling frequency k = 1200 Hz, the sampling time τ = 1 s, and the amplification factor ν = 1, and performs data acquisition; the frequency response Z1 of the transmitted signal and the received signal is obtained by correlation detection, and the target frequency point f 1 Calibration coefficient δf 1 =Z0 / Z1; when the transmitting frequency is f 1 When selecting different sampling frequencies k, sampling durations τ, and magnification factors ν for data acquisition, the target frequency amplitude of the received signal is recorded as Z f 1 , the target frequency voltage value calculation formula is as follows: (2) Pseudo-random multi-frequency signal calibration and calculation of observed voltage values: A. If the signal emitted by the field source is a multi-frequency wave, its frequency is recorded as f 1 、f 2 、……、f n , then the target frequency point corresponding to the received signal is also f 1 、f 2 、……、f n ; Using the above single-frequency received signal calibration method, the frequency point f is obtained respectively 1 、f 2 、……、f n Calibration coefficient B. According to the energy proportion of different frequency points in the multi-frequency wave signal, set the weight of each frequency point to c. 1 、c 2 、……、c n The frequency responses of the ground at different frequencies obtained by detecting the pseudo-random multi-frequency signal are recorded as Z1, Z2, ..., Z n The voltage value calculation formula of each main frequency point of the pseudo-random multi-frequency wave is as follows: C. Eliminate the data with the largest deviation in the voltage values, calculate the arithmetic mean of the remaining voltage values, and obtain the final observed voltage value U.

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