A low-frequency natural potential seepage field channel multiplexing parallel data acquisition device and method

Abstract

The present invention discloses a low-frequency natural potential seepage field channel multiplexing parallel data acquisition device and method, which adopts an electromagnetic relay combination design to form a channel multiplexing natural potential acquisition method. Through the combination design of the electromagnetic relay and the specific switching process, only a few sampling modules are needed to collect the voltage signals of more measuring electrodes, thereby improving the utilization rate of the equipment and reducing the cost. While ensuring multi-channel data acquisition, the number of devices is reduced, and low hardware costs are taken into account. In addition, the acquired data is optimized by a specific data processing method, thereby ensuring the high quality and reliability of long-term low-frequency data acquisition. Therefore, the present invention successfully solves the problems of high hardware cost, large system complexity, low data acquisition efficiency, and long-term data instability in the existing hardware, and significantly improves the efficiency, accuracy and reliability of low-frequency natural potential seepage field data acquisition and processing, thereby meeting the application needs in diverse and complex environments.

Description

Technical Field

[0001] The invention relates to a low-frequency natural potential seepage field channel multiplexing parallel data acquisition device and method, belonging to the technical field of geological exploration data acquisition. Background Art

[0002] In the process of geological survey, the collection of natural potential data of seepage fields such as groundwater and soil is a crucial link. However, the existing low-frequency natural potential seepage field data collection technology mainly relies on multi-channel independent acquisition systems. These systems require a large number of hardware equipment and complex wiring, resulting in high overall cost and large system complexity, which limits its application in complex environments. In addition, during the low-frequency signal acquisition process, although the system is collecting data all the time, due to the slow change of the signal, many data collected at the same location in a short time are meaningless, which not only wastes time and resources, but also reduces the efficiency of the system. Although there is a technical solution for multi-channel signal acquisition using analog switches, in a long-term monitoring environment, the nonlinear characteristics and thermal drift of analog switches will have a negative impact on the long-term stability and accuracy of low-frequency signals.

[0003] In response to these problems, the present invention proposes a new data acquisition device and method, which significantly reduces the hardware cost and complexity of the system through the combined design of electromagnetic relays and signal optimization processing algorithms, and allows multiple signals to be multiplexed on the same hardware channel through the combined design of electromagnetic relays, reducing the required hardware quantity and wiring complexity. The optimized signal processing algorithm improves the efficiency and accuracy of data processing, ensuring the high quality and reliability of long-term low-frequency data acquisition, which is the research direction of the present invention. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a low-frequency natural potential seepage field channel multiplexing parallel data acquisition device and method, which can effectively solve the above-mentioned technical problems.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a low-frequency natural potential seepage field channel multiplexing parallel data acquisition device, including a control module, a sampling module, a switch switching module, a measuring electrode and a reference electrode;

[0006] There are M switch switching modules, each of which is provided with M-level relays, wherein the output end of the first-level relay is connected to the output end of the switch switching module, the input A end of the first-level relay is connected to a measuring electrode, and the input B end is connected to the output end of the second-level relay, the input A end of the second-level relay is connected to another measuring electrode, and the input B end is connected to the output end of the tertiary relay, and the input A ends of subsequent relays of each level are respectively connected to a measuring electrode, and the input B ends are connected to the output end of the next level relay, until the input A ends and the input B ends of the M-level relays are respectively connected to a measuring electrode;

[0007] The number of the sampling modules is the same as that of the switch switching modules, each sampling module corresponds to a switch switching module, one input end of each sampling module is connected to the output end of the corresponding switch switching module, and the other input end is connected to the reference electrode, and the output end of each sampling module is connected to the control module, which is used to compare the voltage signal output by each switch switching module with the voltage signal obtained by the reference electrode and then feed it back to the control module;

[0008] The control module is provided with M control signal output ports, each control signal output port is respectively connected to relays of each level of each switch switching module, and the relays of the same level in each switch switching module are connected to the same control signal output port. The control signal output port of the control module switches the on-off of the relay input A terminal or input B terminal connected to it and the relay output terminal by outputting high and low levels, thereby connecting different measuring electrodes to the output terminal of the switch switching module respectively, and the collected voltage signal is compared with the voltage signal obtained by the reference electrode and then fed back to the control module.

[0009] Furthermore, the measuring electrode and the reference electrode are both non-polarizable electrodes.

[0010] Furthermore, the relay is an electronic relay with dual inputs and a single output.

[0011] Furthermore, an operational amplifier and an ADC module are provided in the sampling module. The operational amplifier is used to calculate the voltage difference between the voltage signal output by the switch switching module and the voltage signal obtained by the reference electrode, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is sent to the control module.

[0012] Furthermore, the control module is provided with a clock circuit, a power module and a cache module. The clock circuit is used for timing; the cache module is used for storing data fed back by the sampling module; and the power module supplies power to each component.

[0013] The working method of the low-frequency natural potential seepage field channel multiplexing parallel data acquisition device comprises the following specific steps:

[0014] Step 1. Layout the observation system: Assume that the number of measurement electrodes connected to each switch switching module is N, and these N electrodes are regarded as a group. There are M such groups in total, so the total number of measurement electrodes is M * N. Randomly arrange all the measurement electrodes at any positions within the observation area, and record the coordinate positions of each measurement electrode. At the same time, arrange the reference electrode G at an arbitrary position where it is determined that there is no electromagnetic interference, and record the coordinate position of this reference electrode G. Then connect each measurement electrode to each switch switching module according to the grouping. Next, connect each switch switching module, each sampling module, and the control module in the low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device. In the initial state, the input A terminals of all relays are connected to their respective output terminals, and their respective input B terminals are disconnected from their respective output terminals, thus completing the layout process of the observation system;

[0015] Step 2. Initialize the observation system: The initialization signal has a collection period of T. Let the start time be t0. Let the duration of each collection segment be T / (M + 1). Let the collection frequency of the sampling module be f (i.e., 1 / f < T / (M + 1)). The M control signal output ports of the control module are numbered P1, P2, …, PM respectively. The control module starts the collection module to start data collection, and the clock circuit starts timing. The specific collection process is as follows:

[0016] ① From the start time t0 to the time T / (M + 1), it is the first collection segment. During this segment, the control signal output ports P1, P2, …, PM of the control module all output low levels and remain so. At this time, all relays are in the initial state. As a result, the input A terminals of the first-stage relays in each switch switching module are connected to the output terminals of their respective first-stage relays, and since the input B terminals are disconnected from the output terminals of their respective first-stage relays, each first-stage relay is disconnected from the next-stage relay. Consequently, the output terminals of each switch switching module are connected to the input A terminals of their respective first-stage relays during this segment. The measurement electrodes connected to the input A terminals of each first-stage relay respectively transmit the collected voltage signals into each sampling module. At the same time, each sampling module obtains the voltage signal of the reference electrode G. Each sampling module performs a difference calculation on the two received voltage signals through an operational amplifier to obtain the potential difference between each measurement electrode and the reference electrode G. After completing analog-to-digital conversion by the ADC module, the converted digital signal is fed back to the control module for storage;

[0017] ② From the moment T / (M+1) to the moment 2*T / (M+1) is the second acquisition segment. In this segment, the control signal output port P1 of the control module outputs a high level and maintains it, and the other output ports maintain the original level unchanged. At this time, the input A terminal of the primary relay in each switch switching module is disconnected from the output terminal of each primary relay, and because the input B terminal is connected to the output terminal of each primary relay, each primary relay is connected to the output terminal of the secondary relay, and then the output terminal of each switch switching module in this segment is connected to the input A terminal of each secondary relay; the measuring electrode connected to the input A terminal of each secondary relay transmits the collected voltage signal to each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G. Each sampling module performs difference calculation on the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage;

[0018] ③ Each subsequent acquisition segment repeats the process of step ②, and the voltage signals of the measuring electrodes connected to the input A terminals of each three-level relay to the M-1-level relay are sequentially obtained through the sampling module to obtain the potential difference and then stored in the control module; until reaching the M+1th acquisition segment, that is, from time M*T / (M+1) to time T, the control signal output port PM of the control module in this segment outputs a high level and maintains it, and the other output ports maintain the original level unchanged (due to the previous acquisition segment adjustment process, all output ports are at a high level at this time). At this time, the input A terminals of all relays in each switch switching module are disconnected from their respective output terminals, and their respective input B terminals are disconnected from their respective output terminals. The ends are connected to their respective output ends, and then the output ends of each switch switching module in the segment are connected to the input B ends of their respective M-level relays; the measuring electrodes connected to the input B ends of each M-level relay transmit the voltage signals collected by each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G, and each sampling module performs difference calculation on the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage, thereby completing the data collection work of the sampling cycle;

[0019] ④ Repeat steps ① to ③ in each subsequent collection cycle until the collection is completed, and obtain the data collected in all sampling cycles;

[0020] Step 3, data processing: The control module sends the data collected in all sampling periods to the data processing module for analysis and processing. The specific process is: taking the reference electrode G as the common ground, M*N discontinuous voltage difference U-time t curves can be obtained in the same coordinate system, and the time axis is compressed. Each measuring electrode only takes one sample to obtain the voltage value in each sampling period T (since the sampling module in each acquisition segment will perform multiple acquisitions according to the sampling frequency, each measuring electrode will obtain multiple voltage data), so the continuous voltage difference U-time t curve of M*N measuring electrodes can be obtained.

[0021] Furthermore, in the data collected during all sampling periods, since the sampling module adopts a full-time sampling mode, each acquired data will not only collect valid geoelectric field data, but also contain some pulse signals caused by switching actions and some abnormal signals. In order to eliminate the influence of these invalid signals on subsequent data analysis and processing, the following method is used to pre-process the data before analyzing and processing the data in step three:

[0022] Ⅰ. Eliminate the influence of pulse signals caused by switching action:

[0023] The sampling frequency of the sampling module is f, the duration of the acquisition segment is T / (M+1), the number of points collected in each acquisition segment is m=T / (M+1) / f, the first and last k points in the m data are eliminated, and m>2k, and the remaining data points are the points not affected by the pulse signal caused by the switch action; since the seepage field is a low-frequency electric field, this method can not only eliminate the influence of the pulse signal caused by the switch action, but also use non-high-speed switching relays when conditions permit, so as to further reduce the relay cost;

[0024] Ⅱ. Eliminate the influence of abnormal signals:

[0025] In the signal that eliminates the influence of the pulse signal caused by the switching action, other interference signals may still be mixed, such as high-frequency signals such as 50Hz power frequency, abnormal signals caused by human factors, and signals caused by abnormal electrode coupling conditions. In this case, the following processing is performed:

[0026] a) Average processing:

[0027]

[0028] Where: UM is the signal output by the Mth acquisition module, UNj is the jth data point of the Nth group of electrodes of the Mth acquisition module;

[0029] b) Take the median value: Sort the m-2k data points from small to large and then calculate:

[0030]

[0031] III. Compressed coordinate axis:

[0032] Taking the voltage reference electrode G as the common ground, M*N discontinuous voltage difference median value UM-time t curves can be obtained in the same coordinate system. By compressing the time axis and taking only one sample to obtain the voltage value of each measuring electrode in each sampling period T, the continuous voltage difference U-time t curve of M*N measuring electrodes can be obtained.

[0033] Compared with the traditional natural potential acquisition method and the channel multiplexing technology using analog switches, the present invention adopts the electromagnetic relay combination design to form a channel multiplexing natural potential acquisition method. Through the combination design of electromagnetic relays and the specific switching process, only M sampling modules are needed to collect the voltage signals of M*N measuring electrodes, which improves the utilization rate of the equipment and reduces the cost. While ensuring multi-channel data acquisition, the number of devices is reduced, and the lower hardware cost is taken into account. In addition, the collected data is optimized using a specific data processing method to ensure the high quality and reliability of long-term low-frequency data acquisition. Therefore, the present invention successfully solves the problems of high hardware cost, large system complexity, low data acquisition efficiency, and long-term data instability in the prior art through innovative technologies and methods, and significantly improves the efficiency, accuracy and reliability of low-frequency natural potential seepage field data acquisition and processing, thereby meeting the application needs in diverse and complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the overall hardware principle block diagram of the parallel data acquisition device in the present invention;

[0035] Figure 2 This is a hardware principle block diagram of the switch switching module in the present invention;

[0036] Figure 3 It is a hardware principle block diagram of the sampling module in the present invention;

[0037] Figure 4 It is a schematic diagram of the process of data collection in the present invention;

[0038] Figure 5 The figure is a schematic diagram of the hardware structure of a 10-channel natural electric field monitoring system built using the method of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below.

[0040] like Figure 1 As shown, a low-frequency natural potential seepage field channel multiplexing parallel data acquisition device includes a control module, a sampling module, a switch switching module, a measuring electrode and a reference electrode;

[0041] The number of switch modules is M. Figure 2 As shown, each switch switching module is provided with M-level relays, wherein the output end of the first-level relay is connected to the output end of the switch switching module, the input A end of the first-level relay is connected to a measuring electrode, and the input B end is connected to the output end of the second-level relay, the input A end of the second-level relay is connected to another measuring electrode, and the input B end is connected to the output end of the tertiary relay, and the input A ends of the subsequent relays of each level are respectively connected to a measuring electrode, and the input B ends are connected to the output end of the next relay, until the input A ends and the input B ends of the M-level relays are respectively connected to a measuring electrode;

[0042] The number of the sampling modules is the same as that of the switch switching modules, each sampling module corresponds to a switch switching module, one input end of each sampling module is connected to the output end of its corresponding switch switching module, and the other input end is connected to the reference electrode, and the output end of each sampling module is connected to the control module, which is used to compare the voltage signal output by each switch switching module with the voltage signal obtained by the reference electrode and then feed it back to the control module; Figure 3 As shown, the sampling module is provided with an operational amplifier and an ADC module. The operational amplifier is used to calculate the voltage difference between the voltage signal output by the switch switching module and the voltage signal obtained by the reference electrode, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is sent to the control module.

[0043] The control module is provided with M control signal output ports, each control signal output port is respectively connected to each level of relays of each switch switching module, and the same level relays in each switch switching module are connected to the same control signal output port. The control signal output port of the control module switches the on-off of the relay input A end or input B end connected to it and the relay output end by outputting high and low levels, so that different measuring electrodes are respectively connected to the output end of the switch switching module, and the collected voltage signal is compared with the voltage signal obtained by the reference electrode and then fed back to the control module; the control module is provided with a clock circuit, a power supply module and a cache module, the clock circuit is used for timing; the cache module is used to store the data fed back by the sampling module; the power supply module supplies power to each component.

[0044] As an improvement of the present invention, the measuring electrode and the reference electrode are both non-polarized electrodes; and the relay is an electronic relay with dual inputs and a single output.

[0045] There is a landfill site that needs to monitor the seepage electric field. The above-mentioned low-frequency natural potential seepage field channel multiplexing parallel data acquisition device is used for monitoring. The specific steps are as follows:

[0046] Step 1: Arrange the observation system: design a total of 10 points according to the size of the observation area, that is, the total number of measuring electrodes is 10, and design two switch switching modules, and each switch switching module is equipped with a four-level relay, that is, each switch switching module is connected to 5 measuring electrodes, and each group of measuring electrodes is numbered, the first group is (1)-1, (2)-1...(5)-1; the second group is (1)-2, (2)-2...(5)-2; all measuring electrodes are randomly arranged in the observation area at any position, and the coordinate position of each measuring electrode is recorded; at the same time, the reference electrode G is arranged at any position determined to be free of electromagnetic interference, and the coordinate position of the reference electrode G is recorded; then each measuring electrode is connected to each switch switching module according to the group, and then each switch switching module, each sampling module and control module in the low-frequency natural potential seepage field channel multiplexing parallel data acquisition device are connected as follows: Figure 5 As shown; in the initial state, the input A terminals of each relay are connected to their respective output terminals, and the input B terminals of each relay are disconnected from their respective output terminals, completing the observation system deployment process;

[0047] Step 2, initialize the observation system: the initialization signal acquisition cycle is T = 60s (seconds), the start time is t0, the duration of the acquisition segment is T / (4+1) = 12s, the acquisition frequency of the sampling module is f = 1Hz, and the four control signal output ports of the control module are numbered P1, P2, P3, and P4 respectively; the control module starts the acquisition module and starts data acquisition, and the clock circuit starts timing, such as Figure 4 As shown in the figure, the specific collection process is as follows:

[0048] ① From the start time t0 to the time 12s is the first acquisition segment, and the control signal output ports P1, P2, P3, and P4 of the control module in this segment all output low level and maintain it. At this time, all relays are in the initial state, and then the input A end of the first-level relay in each switch switching module is connected to the output end of each first-level relay, and because the input B end is disconnected from the output end of each first-level relay, each first-level relay is disconnected from the next-level relay, and then the output end of each switch switching module in this segment is connected to the input A end of each first-level relay; the measuring electrodes (2)-1 and (2)-2 connected to the input A end of each first-level relay transmit the collected voltage signals to each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G. Each sampling module performs difference calculation on the two voltage signals received by each sampling module through the operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage;

[0049] ② From 12s to 24s is the second acquisition segment. In this segment, the control signal output port P1 of the control module outputs a high level and maintains it, and the other output ports maintain the original level unchanged. At this time, the input A terminal of each primary relay in each switch switching module is disconnected from the output terminal of each primary relay, and because the input B terminal is connected to the output terminal of each primary relay, each primary relay is connected to the output terminal of the secondary relay, and then the output terminal of each switch switching module in this segment is connected to the input A terminal of each secondary relay; the measuring electrodes (2)-1 and (2)-2 connected to the input A terminal of each secondary relay transmit the collected voltage signals to each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G. Each sampling module performs difference calculation on the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage;

[0050] ③ The subsequent third and fourth acquisition segments repeat the process of step ②, and the voltage signals of the measuring electrodes connected to the input A terminals of each three-level relay and four-level relay are successively obtained by the sampling module and stored in the control module after the potential difference is obtained; until the fifth acquisition segment, i.e., from 48s to 60s, is reached, the control signal output port P4 of the control module in this segment outputs a high level and maintains it, and the other output ports maintain the original level unchanged (due to the previous acquisition segment adjustment process, all output ports are at a high level at this time), at this time, the input A terminals of all relays in each switch switching module are disconnected from their respective output terminals, and their respective input B terminals are connected to their respective output terminals. The output ends are connected, and then the output ends of each switch switching module in the segment are connected to the input B ends of each four-level relay; the measuring electrodes (4)-1 and (N)-2 connected to the input B ends of each four-level relay transmit the voltage signals collected by each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G, and each sampling module performs difference calculation on the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage, thereby completing the data collection work of the sampling cycle;

[0051] ④ Repeat steps ① to ③ in each subsequent collection cycle until the collection is completed, and obtain the data collected in all sampling cycles;

[0052] Step 3: Data processing: Since the sampling module adopts the full-time sampling mode, each acquired data will not only collect valid geoelectric field data, but also contain some pulse signals caused by switching actions and some abnormal signals. In order to eliminate the influence of these invalid signals on subsequent data analysis and processing, the following method is used to pre-process the data before analyzing and processing the data:

[0053] Ⅰ. Eliminate the influence of pulse signals caused by switching action:

[0054] The sampling frequency of the sampling module is f=1Hz, the duration of the acquisition segment is T / (4+1)=12s, the number of points collected in each acquisition segment is m=T / (4+1) / f=12, and one point before and one point after the 12 data are eliminated. The remaining 10 data points are the points that are not affected by the pulse signal caused by the switch action. Since the seepage field is a low-frequency electric field, this method can not only eliminate the influence of the pulse signal caused by the switch action, but also use non-high-speed switching relays when conditions permit, further reducing the relay cost.

[0055] Ⅱ. Eliminate the influence of abnormal signals:

[0056] In the signal that eliminates the influence of the pulse signal caused by the switching action, other interference signals may still be mixed, such as high-frequency signals such as 50Hz power frequency, abnormal signals caused by human factors, and signals caused by abnormal electrode coupling conditions. In this case, the following processing is performed:

[0057] a) Average processing:

[0058]

[0059] Where: UM is the signal output by the Mth acquisition module, UNj is the jth data point of the Nth group of electrodes of the Mth acquisition module;

[0060] In this way, the average value of the data obtained by the two sampling modules in the first acquisition segment is:

[0061]

[0062] The average value of the data obtained by the two sampling modules in the second acquisition segment is:

[0063]

[0064] The average value of the data obtained by the two sampling modules in the third acquisition segment is:

[0065]

[0066] The average value of the data obtained by the two sampling modules in the fourth acquisition segment is:

[0067]

[0068] The average value of the data obtained by the two sampling modules in the fifth acquisition segment is:

[0069]

[0070] b) Take the median value: Sort the 10 sample data points from small to large and then calculate:

[0071]

[0072] III. Compressed coordinate axis:

[0073] Taking the voltage reference electrode G as the common ground, 10 discontinuous voltage difference median value UM-time t curves in the same coordinate system can be obtained. The time axis is compressed and each measuring electrode only takes one sample to obtain the voltage value in each sampling period T (since the sampling module in each acquisition segment will perform multiple acquisitions according to the sampling frequency, each measuring electrode will obtain multiple voltage data), so the continuous voltage difference U-time t curve of the 10 measuring electrodes can be obtained.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-frequency natural potential seepage field channel multiplexing parallel data acquisition device, characterized in that: It includes a control module, a sampling module, a switch module, a measuring electrode and a reference electrode; There are M switch switching modules, each of which is provided with M-level relays, wherein the output end of the primary relay is connected to the output end of the switch switching module, the input A end of the primary relay is connected to a measuring electrode, and the input B end is connected to the output end of the secondary relay, the input A end of the secondary relay is connected to another measuring electrode, and the input B end is connected to the output end of the tertiary relay, and the input A ends of subsequent relays of each level are respectively connected to a measuring electrode, and the input B ends are connected to the output end of the next level relay, until the input A ends and the input B ends of the M-level relays are respectively connected to a measuring electrode; The number of the sampling modules is the same as that of the switch switching modules, each sampling module corresponds to a switch switching module, one input end of each sampling module is connected to the output end of the corresponding switch switching module, and the other input end is connected to the reference electrode, and the output end of each sampling module is connected to the control module, which is used to compare the voltage signal output by each switch switching module with the voltage signal obtained by the reference electrode and then feed it back to the control module; The control module is provided with M control signal output ports, each control signal output port is respectively connected to relays of each level of each switch switching module, and the relays of the same level in each switch switching module are connected to the same control signal output port. The control signal output port of the control module switches the on-off of the relay input A terminal or input B terminal connected to it and the relay output terminal by outputting high and low levels, thereby connecting different measuring electrodes to the output terminal of the switch switching module respectively, and the collected voltage signal is compared with the voltage signal obtained by the reference electrode and then fed back to the control module.

2. The low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device according to claim 1, characterized in that: The measuring electrode and the reference electrode are both non-polarizable electrodes.

3. The low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device according to claim 1, characterized in that: The relay is an electronic relay with dual inputs and single output.

4. The low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device according to claim 1, characterized in that: The sampling module is provided with an operational amplifier and an ADC module. The operational amplifier is used to calculate the voltage difference between the voltage signal output by the switch switching module and the voltage signal obtained by the reference electrode, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is sent to the control module.

5. The low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device according to claim 1, characterized in that: The control module is provided with a clock circuit, a power module and a cache module. The clock circuit is used for timing; the cache module is used for storing data fed back by the sampling module; and the power module supplies power to each component.

6. A working method of the low-frequency spontaneous potential seepage field channel multiplexing parallel data acquisition device according to any one of claims 1 to 5, characterized in that: The specific steps are: Step 1, laying out the observation system: suppose that each switch switching module is connected to N measuring electrodes and they are taken as a group, a total of M groups, then there are M*N measuring electrodes in total; all measuring electrodes are randomly arranged in the observation area at arbitrary positions, and the coordinate position of each measuring electrode is recorded; at the same time, the reference electrode G is arranged at an arbitrary position determined to be free of electromagnetic interference, and the coordinate position of the reference electrode G is recorded; then each measuring electrode is connected to each switch switching module according to the grouping, and then each switch switching module, each sampling module and control module in the low-frequency natural potential seepage field channel multiplexing parallel data acquisition device are connected; in the initial state, the input A end of each relay is connected to the respective output end, and the respective input B end is disconnected from the respective output end, and the observation system layout process is completed; Step 2, initialize the observation system: a sampling period of the initialization signal is T, the start time is t0, the duration of the acquisition segment is T / (M+1), the acquisition frequency of the sampling module is f, and the M control signal output ports of the control module are numbered P1, P2, ..., PM respectively; the control module starts the acquisition module, starts data acquisition, and the clock circuit starts timing. The specific acquisition process is: ① From the start time t0 to the time T / (M+1) is the first acquisition segment, and the control signal output ports P1, P2, ..., PM of the control module in this segment all output low level and maintain it. At this time, all relays are in the initial state, and then the input A end of the first-level relay in each switch switching module is connected to the output end of each first-level relay, and because the input B end is disconnected from the output end of each first-level relay, each first-level relay is disconnected from the next-level relay, and then the output end of each switch switching module in this segment is connected to the input A end of each first-level relay; the measuring electrodes connected to the input A end of each first-level relay transmit the collected voltage signals to each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G, and each sampling module performs difference calculation on the two voltage signals received by each sampling module through the operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage; ② From the moment T / (M+1) to the moment 2*T / (M+1) is the second acquisition segment. In this segment, the control signal output port P1 of the control module outputs a high level and maintains it, and the other output ports maintain the original level unchanged. At this time, the input A terminal of the primary relay in each switch switching module is disconnected from the output terminal of each primary relay, and because the input B terminal is connected to the output terminal of each primary relay, each primary relay is connected to the output terminal of the secondary relay, and then the output terminal of each switch switching module in this segment is connected to the input A terminal of each secondary relay; the measuring electrode connected to the input A terminal of each secondary relay transmits the collected voltage signal to each sampling module respectively, and at the same time, each sampling module obtains the voltage signal of the reference electrode G. Each sampling module performs difference calculation on the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage; ③ Each subsequent acquisition segment repeats the process of step ②, and the voltage signals of the measuring electrodes connected to the input A terminals of each three-level relay to the M-1-level relay are sequentially passed through the sampling module to obtain the potential difference and then stored in the control module; until reaching the M+1th acquisition segment, that is, from time M*T / (M+1) to time T, the control signal output port PM of the control module in this segment outputs a high level and maintains it, and the other output ports maintain the original level unchanged. At this time, the input A terminals of all relays in each switch switching module are disconnected from their respective output terminals, and their respective input B terminals are connected to their respective output terminals, and the process is completed. And the output end of each switch switching module in this segment is connected to the input B end of each M-level relay; the measuring electrode connected to the input B end of each M-level relay transmits the voltage signal collected by each sampling module respectively, and at the same time each sampling module obtains the voltage signal of the reference electrode G, and each sampling module calculates the difference between the two voltage signals received by each sampling module through an operational amplifier to obtain the potential difference between each measuring electrode and the reference electrode G, and after the ADC module completes the analog-to-digital conversion, the converted digital signal is fed back to the control module for storage, completing the data collection work of this sampling cycle; ④ Repeat steps ① to ③ in each subsequent sampling period until the collection is completed, and obtain the data collected in all sampling periods; Step 3, data processing: The control module sends the data collected in all sampling periods to the data processing module for analysis and processing. The specific process is: taking the reference electrode G as the common ground, M*N discontinuous voltage difference U-time t curves can be obtained in the same coordinate system, and the time axis is compressed. Each measuring electrode only takes one sample to obtain the voltage value in each sampling period T, so that the continuous voltage difference U-time t curve of M*N measuring electrodes can be obtained.

7. The working method according to claim 6, characterized in that: In the acquisition of data collected in all sampling periods, since the sampling module adopts a full-time sampling mode, each acquired data will not only collect valid geoelectric field data, but also contain some pulse signals caused by switching actions and some abnormal signals. In order to eliminate the influence of these invalid signals on subsequent data analysis and processing, step three uses the following method to pre-process the data before analyzing and processing the data: Ⅰ. Eliminate the influence of pulse signals caused by switching action: The sampling frequency of the sampling module is f, the duration of the acquisition segment is T / (M+1), the number of points collected in each acquisition segment is m=T / (M+1) / f, the first and last k points in the m data are eliminated, and m>2k, and the remaining data points are the points not affected by the pulse signal caused by the switch action; since the seepage field is a low-frequency electric field, this method can not only eliminate the influence of the pulse signal caused by the switch action, but also use non-high-speed switching relays when conditions permit, further reducing the relay cost; Ⅱ. Eliminate the influence of abnormal signals: In the signal that eliminates the influence of the pulse signal caused by the switching action, other interference signals may still be mixed in, so the following processing is performed: a) Taking the average value: ； Where: UM is the signal output by the Mth acquisition module, UNj is the jth data point of the Nth group of electrodes of the Mth acquisition module; b) Take the median value: Sort the m-2k data points from small to large and then calculate: 。

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