Filtering circuit, geophysical electromagnetic signal collector, method and storage medium

Abstract

This application discloses a filtering circuit, a geophysical electromagnetic signal acquisition device, a method, and a storage medium. By obtaining signal frequency group transmission time data (including multiple signal frequency groups and their corresponding transmission times), the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter based on the highest frequency. The switching time for each filter is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter is switched for filtering. Compared to traditional filtering techniques, this method can automatically switch the corresponding filter for different signal frequency groups, effectively suppressing electromagnetic noise, providing good filtering results, and improving the detection accuracy of exploration equipment.

Description

Technical Field

[0001] This application relates to the field of filtering technology, and in particular to a filtering circuit, a geophysical electromagnetic signal acquisition device, a method, and a storage medium. Background Technology

[0002] With the rapid development of geophysical exploration equipment and technology, mineral exploration is moving towards more refined detection in both deep and shallow areas. Rare strategic mineral resources generally have relatively small ore bodies and relatively low grade content, resulting in relatively small differences in electrical properties on the ground. Detection of these materials requires exploration equipment with high detection resolution, high signal receiving sensitivity, and strong resistance to electromagnetic interference.

[0003] However, in order to obtain information over a wide range from shallow to deep, traditional geophysical exploration equipment uses instruments with a wide signal bandwidth. Consequently, the bandwidth of the electromagnetic signal analog filter circuit in the equipment is also designed to be wide, and the bandwidth of the analog filter circuit cannot be automatically adjusted, making it difficult to suppress electromagnetic noise. As a result, a large amount of external electromagnetic noise signals are collected and superimposed on the useful signal, seriously interfering with the reliable and stable acquisition of the useful signal. It is difficult to distinguish relatively small electrical difference signals, affecting the detection accuracy of the exploration equipment, making it impossible to achieve refined detection of target minerals, and making it difficult to obtain the corresponding mineral resources. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a filter circuit, a geophysical electromagnetic signal acquisition device, a method, and a storage medium, which can solve the problem that the filtering effect of traditional filter circuits is poor, affecting the detection accuracy of exploration equipment.

[0005] The filtering circuit according to the first aspect of this application is used to receive multiple signal frequency groups with different highest frequencies sequentially emitted by a geophysical electromagnetic signal transmitter, including:

[0006] The signal input terminal is used to input the response signal generated during the propagation of the signal frequency group.

[0007] A first multiplex analog switch, wherein the signal input terminal is connected to the input terminal of the first multiplex analog switch;

[0008] A filter that corresponds one-to-one with the signal frequency group, wherein the cutoff frequency of the filter is equal to twice the highest frequency of the signal frequency group corresponding to the filter, and the output terminal of the first multiplex analog switch is connected to the input terminal of the filter for switching the filter;

[0009] The output terminal of the filter is connected to the signal output terminal.

[0010] The control module, the output of which is connected to the control terminal of the first multi-channel analog switch;

[0011] A synchronization clock module, connected to the control module, is used to keep the time synchronized with the time of the geophysical electromagnetic signal transmitter;

[0012] The control module is used to execute a filtering method, which includes:

[0013] Obtain signal frequency group transmission time data, wherein the signal frequency group transmission time data includes multiple signal frequency groups and the transmission time corresponding to the signal frequency group;

[0014] Obtain the highest frequency of each of the aforementioned signal frequency groups;

[0015] Based on the cutoff frequencies of multiple filters and the highest frequency, a filter signal frequency group correspondence is established, which is used to select the corresponding filter according to the highest frequency;

[0016] Based on the correspondence between the signal frequency group transmission time data and the filter signal frequency group, the switching time of each filter is determined, and the switching time is synchronized with the transmission time;

[0017] Based on the switching time, the corresponding filter is switched for filtering.

[0018] The filter circuit according to the first aspect of the present application has at least the following beneficial effects:

[0019] By obtaining signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times, the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter based on the highest frequency. The switching time for each filter is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence, and the switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter is switched for filtering. The filtering circuit of the first aspect embodiment of this application, compared to traditional filtering techniques, can automatically switch the corresponding filter for filtering different signal frequency groups. Since the cutoff frequency of the filter is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0020] According to some embodiments of this application, the filter includes a first second-order active low-pass filter and a second second-order active low-pass filter. The output terminal of the first multiplexer is connected to the input terminal of the first second-order active low-pass filter, the output terminal of the first second-order active low-pass filter is connected to the input terminal of the second second-order active low-pass filter, and the output terminal of the second second-order active low-pass filter is connected to the signal output terminal.

[0021] According to some embodiments of this application, the first second-order active low-pass filter includes a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a first operational amplifier. The output terminal of the first multiplexer is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to the inverting input terminal of the first operational amplifier, the non-inverting input terminal of the first operational amplifier is grounded, the output terminal of the first operational amplifier is connected to the inverting input terminal of the first operational amplifier through the first capacitor, the output terminal of the first operational amplifier is connected to one end of the second resistor through the third resistor, and one end of the second resistor is grounded through the second capacitor.

[0022] According to some embodiments of this application, the second second-order active low-pass filter includes a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, and a second operational amplifier. The output terminal of the first operational amplifier is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the inverting input terminal of the second operational amplifier, the non-inverting input terminal of the second operational amplifier is grounded, the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through the third capacitor, the output terminal of the second operational amplifier is connected to one end of the fifth resistor through the sixth resistor, one end of the fifth resistor is grounded through the fourth capacitor, and the output terminal of the second operational amplifier is connected to the signal output terminal.

[0023] According to some embodiments of this application, a second multiplexer is also included, wherein the output terminal of the filter is connected to the input terminal of the second multiplexer, the output terminal of the second multiplexer is connected to the signal output terminal, and the output terminal of the control module is connected to the control terminal of the second multiplexer.

[0024] The geophysical electromagnetic signal acquisition device according to the second aspect of this application includes the filtering circuit described above.

[0025] The geophysical electromagnetic signal acquisition device according to the second aspect of this application has at least the following beneficial effects:

[0026] By obtaining signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times, the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter based on the highest frequency. The switching time for each filter is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter is switched for filtering. The geophysical electromagnetic signal acquisition device of the second aspect of this application, compared to traditional filtering techniques, can automatically switch the corresponding filter for filtering based on different signal frequency groups. Since the cutoff frequency of the filter is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0027] The filtering method according to a third aspect of this application includes:

[0028] Obtain signal frequency group transmission time data, wherein the signal frequency group transmission time data includes multiple signal frequency groups and the transmission time corresponding to the signal frequency groups;

[0029] Obtain the highest frequency of each of the aforementioned signal frequency groups;

[0030] Based on the cutoff frequencies of multiple filters and the highest frequency, a frequency group correspondence relationship of filter signals is established. This frequency group correspondence relationship is used to select the corresponding filter according to the highest frequency.

[0031] Based on the correspondence between the signal frequency group transmission time data and the filter signal frequency group, the switching time of each filter is determined, and the switching time is synchronized with the transmission time;

[0032] Based on the switching time, the corresponding filter is switched for filtering.

[0033] The filtering method according to the third aspect of this application has at least the following beneficial effects:

[0034] By obtaining signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times, the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter based on the highest frequency. The switching time for each filter is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter is switched for filtering. The filtering method of the third aspect of this application, compared to traditional filtering techniques, can automatically switch the corresponding filter for filtering different signal frequency groups. Since the cutoff frequency of the filter is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0035] A computer-readable storage medium according to a fourth aspect of this application stores a processor-executable program, which, when executed by a processor, is used to implement the filtering method as described above.

[0036] The computer-readable storage medium according to the fourth aspect of the present application has at least the following advantages:

[0037] By obtaining signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times, the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter based on the highest frequency. The switching time for each filter is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence, and the switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter is switched for filtering. The computer-readable storage medium of the fourth aspect embodiment of this application, compared to traditional filtering techniques, can automatically switch the corresponding filter for filtering based on different signal frequency groups. Since the cutoff frequency of the filter is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0038] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0039] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0040] Figure 1 This is a functional block diagram of a filter circuit in one embodiment of this application;

[0041] Figure 2 This is a circuit diagram of a filter circuit in one embodiment of this application;

[0042] Figure 3 This is a flowchart of a filtering method in one embodiment of this application.

[0043] Figure label:

[0044] First multi-channel analog switch 100

[0045] Filter 200

[0046] Control module 300

[0047] Synchronous clock module 400

[0048] Second multi-channel analog switch 500. Detailed Implementation

[0049] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0050] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0051] In the description of this application, "multiple" refers to two or more. The use of "first" and "second" is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or the order in which the technical features are indicated.

[0052] In the description of this application, unless otherwise expressly defined, terms such as "setting," "installation," and "electrical connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0053] like Figure 1As shown, a filtering circuit according to an embodiment of this application is used to receive multiple signal frequency groups with different highest frequencies sequentially transmitted by a geophysical electromagnetic signal transmitter. The circuit includes: a signal input terminal, a first multiplexer analog switch 100, filters 200 corresponding to each signal frequency group, a signal output terminal, a synchronization clock module 400, and a control module 300. The signal input terminal is used to input the response signal generated during the propagation of the signal frequency group. The signal input terminal is connected to the input terminal of the first multiplexer analog switch 100. The cutoff frequency of the filter 200 is equal to twice the highest frequency of the signal frequency group corresponding to the filter 200. The output terminal of the first multiplexer analog switch 100 is connected to the input terminal of the filter 200 for switching the filter 200. The output terminal of the filter 200 is connected to the signal output terminal. The output terminal of the control module 300 is connected to the control terminal of the first multiplexer analog switch 100. The synchronization clock module 400 is connected to the control module 300 and is used to maintain synchronization with the time of the geophysical electromagnetic signal transmitter. The synchronization clock module 400 is a GPS synchronization clock module.

[0054] Control module 300 is used to execute filtering methods, such as Figure 3 As shown, the filtering methods include:

[0055] Filtering methods include:

[0056] Step S100: Obtain signal frequency group transmission time data, which includes multiple signal frequency groups and the transmission time corresponding to each signal frequency group;

[0057] Step S200: Obtain the highest frequency of each signal frequency group;

[0058] Step S300: Based on the cutoff frequency and highest frequency of multiple filters 200, establish the frequency group correspondence of filter signals. The frequency group correspondence of filter signals is used to select the corresponding filter 200 according to the highest frequency.

[0059] Step S400: Based on the signal frequency group transmission time data and the correspondence between the filter signal frequency groups, determine the switching time of each filter 200, and synchronize the switching time with the transmission time;

[0060] Step S500: Based on the switching time, switch the corresponding filter 200 for filtering.

[0061] According to the filtering circuit of this application embodiment, by obtaining signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times, the highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters 200, a filter-signal frequency group correspondence relationship is established. This relationship is used to select the corresponding filter 200 based on the highest frequency. The switching time of each filter 200 is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence relationship. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter 200 is switched for filtering. Compared to traditional filtering techniques, the filtering circuit of this application embodiment can automatically switch the corresponding filter 200 for filtering based on different signal frequency groups. Since the cutoff frequency of the filter 200 is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0062] According to one embodiment of this application, such as Figure 2 As shown, filter 200 includes a first second-order active low-pass filter and a second second-order active low-pass filter. The output terminal of the first multiplexer 100 is connected to the input terminal of the first second-order active low-pass filter, the output terminal of the first second-order active low-pass filter is connected to the input terminal of the second second-order active low-pass filter, and the output terminal of the second second-order active low-pass filter is connected to the signal output terminal. By cascading the first and second second-order active low-pass filters, a fourth-order active low-pass filter is formed, which can effectively attenuate electromagnetic noise signals above the dielectric frequency and improve the signal-to-noise ratio of the useful signal.

[0063] It should be noted that the number of cascaded second-order active low-pass filters is not limited. Depending on the requirement to suppress electromagnetic noise signals above the highest frequency signal of the signal group, multiple second-order active low-pass filters can be cascaded to achieve different attenuation ratios of electromagnetic noise signals above the cutoff frequency, suppress the amplitude of electromagnetic noise to a greater extent, and further improve the signal-to-noise ratio of the useful signal.

[0064] According to some embodiments of this application, such as Figure 2As shown, the first second-order active low-pass filter includes a first resistor R1-1, a second resistor R3-1, a third resistor R2-1, a first capacitor C2-1, a second capacitor C1-1, and a first operational amplifier OPA1. The output terminal of the first multiplexer 100 is connected to one end of the first resistor R1-1, the other end of the first resistor R1-1 is connected to one end of the second resistor R3-1, the other end of the second resistor R3-1 is connected to the inverting input terminal of the first operational amplifier OPA1, the non-inverting input terminal of the first operational amplifier OPA1 is grounded, the output terminal of the first operational amplifier OPA1 is connected to the inverting input terminal of the first operational amplifier OPA1 through the first capacitor C2-1, the output terminal of the first operational amplifier OPA1 is connected to one end of the second resistor R3-1 through the third resistor R2-1, and one end of the second resistor R3-1 is grounded through the second capacitor C1-1. The first and second order active low-pass filters are Butterworth low-pass filters. The frequency response curve of the Butterworth low-pass filter is as flat as possible in the passband without fluctuations. It has the advantage of balanced characteristics in terms of linear phase, attenuation slope and loading characteristics.

[0065] The formulas for calculating the cutoff frequency of first and second-order active low-pass filters are as follows:

[0066] fc = 1 / (2πCf*Rf),

[0067] Where fc is the cutoff frequency, Cf is the capacitance value of the second-order active low-pass filter, and Rf is the resistance value of the second-order active low-pass filter.

[0068] Rf = R1 = R2 = R3,

[0069] Wherein, R1, R2, and R3 are the resistance values ​​of the first resistor R1-1, the second resistor R3-1, and the third resistor R2-1, respectively;

[0070]

[0071] Wherein, C1 and C2 are the capacitance values ​​of the first capacitor C2-1 and the second capacitor C1-1, respectively;

[0072] C1 = 3QCf, C2 = Cf / 3Q

[0073] Where Q is the quality factor.

[0074] According to some embodiments of this application, such as Figure 2As shown, the second second-order active low-pass filter includes a fourth resistor R1-2, a fifth resistor R3-2, a sixth resistor R2-2, a third capacitor C2-2, a fourth capacitor C1-2, and a second operational amplifier OPA2. The output terminal of the first operational amplifier OPA1 is connected to one end of the fourth resistor R1-2, the other end of the fourth resistor R1-2 is connected to one end of the fifth resistor R3-2, the other end of the fifth resistor R3-2 is connected to the inverting input terminal of the second operational amplifier OPA2, the non-inverting input terminal of the second operational amplifier OPA2 is grounded, the output terminal of the second operational amplifier OPA2 is connected to the inverting input terminal of the second operational amplifier OPA2 through the third capacitor C2-2, the output terminal of the second operational amplifier OPA2 is connected to one end of the fifth resistor R3-2 through the sixth resistor R2-2, one end of the fifth resistor R3-2 is grounded through the fourth capacitor C1-2, and the output terminal of the second operational amplifier OPA2 is connected to the signal output terminal. The second-order active low-pass filter is the Butterworth low-pass filter. The frequency response curve of the Butterworth low-pass filter is as flat as possible in the passband without fluctuations. It has the advantage of balanced characteristics in terms of linear phase, attenuation slope and loading characteristics.

[0075] According to some embodiments of this application, such as Figure 2 As shown, it also includes a second multiplexer 500. The output of the filter 200 is connected to the input of the second multiplexer 500, and the output of the second multiplexer 500 is connected to the signal output. The output of the control module 300 is connected to the control terminal of the second multiplexer 500. The control module 300 switches between different filters 200 by controlling the second multiplexer 500 and the first multiplexer 100.

[0076] In addition, one embodiment of this application also discloses a geophysical electromagnetic signal acquisition device, including the above-described filtering circuit.

[0077] An embodiment of the geophysical electromagnetic signal acquisition device of this application obtains signal frequency group transmission time data, including multiple signal frequency groups and their corresponding transmission times. The highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters 200, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter 200 based on the highest frequency. The switching time of each filter 200 is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter 200 is switched for filtering. Compared to traditional filtering techniques, the geophysical electromagnetic signal acquisition device of this application can automatically switch the corresponding filter 200 for filtering based on different signal frequency groups. Since the cutoff frequency of the filter 200 is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0078] In addition, such as Figure 3 As shown, one embodiment of this application also discloses a filtering method, including:

[0079] Step S100: Obtain signal frequency group transmission time data, which includes multiple signal frequency groups and the transmission time corresponding to each signal frequency group;

[0080] Step S200: Obtain the highest frequency of each signal frequency group;

[0081] Step S300: Based on the cutoff frequency and highest frequency of multiple filters 200, establish the frequency group correspondence of filter signals. The frequency group correspondence of filter signals is used to select the corresponding filter 200 according to the highest frequency.

[0082] Step S400: Based on the signal frequency group transmission time data and the correspondence between the filter signal frequency groups, determine the switching time of each filter 200, and synchronize the switching time with the transmission time;

[0083] Step S500: Based on the switching time, switch the corresponding filter 200 for filtering.

[0084] One embodiment of the filtering method in this application obtains signal frequency group transmission time data, which includes multiple signal frequency groups and their corresponding transmission times. The highest frequency of each signal frequency group is obtained. Based on the cutoff frequencies and highest frequencies of multiple filters 200, a filter-signal frequency group correspondence is established. This correspondence is used to select the corresponding filter 200 based on the highest frequency. The switching time of each filter 200 is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter 200 is switched for filtering. Compared to traditional filtering techniques, this filtering method can automatically switch the corresponding filter 200 for filtering different signal frequency groups. Since the cutoff frequency of the filter 200 is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0085] In addition, one embodiment of this application discloses a computer-readable storage medium storing a processor-executable program, which, when executed by a processor, is used to implement the filtering method described above.

[0086] One embodiment of the computer-readable storage medium of this application obtains signal frequency group transmission time data, including multiple signal frequency groups and their corresponding transmission times, and obtains the highest frequency of each signal frequency group. Based on the cutoff frequencies and highest frequencies of multiple filters 200, a filter-signal frequency group correspondence relationship is established. This relationship is used to select the corresponding filter 200 based on the highest frequency. The switching time of each filter 200 is determined based on the signal frequency group transmission time data and the filter-signal frequency group correspondence relationship. The switching time is synchronized with the transmission time. Based on the switching time, the corresponding filter 200 is switched for filtering. Compared to traditional filtering techniques, this computer-readable storage medium can automatically switch the corresponding filter 200 for filtering based on different signal frequency groups. Since the cutoff frequency of the filter 200 is equal to twice the highest frequency of the signal frequency group, it can effectively suppress electromagnetic noise, resulting in good filtering performance and improved detection accuracy of exploration equipment.

[0087] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A filtering circuit for receiving multiple signal frequency groups with different highest frequencies sequentially emitted by a geophysical electromagnetic signal transmitter, characterized in that: include: The signal input terminal is used to input the response signal generated during the propagation of the signal frequency group. A first multiplex analog switch (100), wherein the signal input terminal is connected to the input terminal of the first multiplex analog switch (100); A filter (200) is provided that corresponds one-to-one with the signal frequency group. The cutoff frequency of the filter (200) is equal to twice the highest frequency of the signal frequency group corresponding to the filter (200). The output terminal of the first multiplex analog switch (100) is connected to the input terminal of the filter (200) to switch the filter (200). The output terminal of the filter (200) is connected to the signal output terminal; A control module (300) is provided, the output of which is connected to the control terminal of the first multiplex analog switch (100). A synchronization clock module (400) is connected to the control module (300) and is used to keep the time synchronized with the time of the geophysical electromagnetic signal transmitter. The control module (300) is used to execute a filtering method, the filtering method comprising: Obtain signal frequency group transmission time data, wherein the signal frequency group transmission time data includes multiple signal frequency groups and the transmission time corresponding to the signal frequency group; Obtain the highest frequency of each of the aforementioned signal frequency groups; Based on the cutoff frequencies of the multiple filters (200) and the highest frequency, a filter signal frequency group correspondence is established, which is used to select the corresponding filter (200) according to the highest frequency. Based on the signal frequency group transmission time data and the correspondence between the filter signal frequency groups, the switching time of each filter (200) is determined, and the switching time is synchronized with the transmission time; According to the switching time, the corresponding filter (200) is switched for filtering.

2. The filter circuit according to claim 1, characterized in that: The filter (200) includes a first second-order active low-pass filter and a second second-order active low-pass filter. The output terminal of the first multiplexer (100) is connected to the input terminal of the first second-order active low-pass filter, the output terminal of the first second-order active low-pass filter is connected to the input terminal of the second second-order active low-pass filter, and the output terminal of the second second-order active low-pass filter is connected to the signal output terminal.

3. The filter circuit according to claim 2, characterized in that: The first second-order active low-pass filter includes a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a first operational amplifier. The output terminal of the first multiplexer (100) is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to the inverting input terminal of the first operational amplifier, the non-inverting input terminal of the first operational amplifier is grounded, the output terminal of the first operational amplifier is connected to the inverting input terminal of the first operational amplifier through the first capacitor, the output terminal of the first operational amplifier is connected to one end of the second resistor through the third resistor, and one end of the second resistor is grounded through the second capacitor.

4. The filter circuit according to claim 3, characterized in that: The second second-order active low-pass filter includes a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, and a second operational amplifier. The output terminal of the first operational amplifier is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the inverting input terminal of the second operational amplifier, the non-inverting input terminal of the second operational amplifier is grounded, the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through the third capacitor, the output terminal of the second operational amplifier is connected to one end of the fifth resistor through the sixth resistor, one end of the fifth resistor is grounded through the fourth capacitor, and the output terminal of the second operational amplifier is connected to the signal output terminal.

5. The filter circuit according to claim 1, characterized in that: It also includes a second multiplexer (500), the output of the filter (200) is connected to the input of the second multiplexer (500), the output of the second multiplexer (500) is connected to the signal output, and the output of the control module (300) is connected to the control terminal of the second multiplexer (500).

6. A geophysical electromagnetic signal acquisition device, characterized in that, Includes the filter circuit described in any one of claims 1 to 5.

7. A filtering method, characterized in that, include: Obtain signal frequency group transmission time data, wherein the signal frequency group transmission time data includes multiple signal frequency groups and the transmission time corresponding to the signal frequency groups; The multiple signal frequency groups are transmitted sequentially by a geophysical electromagnetic signal transmitter, and the multiple signal frequency groups have different highest frequencies; Obtain the highest frequency of each of the aforementioned signal frequency groups; Based on the cutoff frequencies of multiple filters (200) and the highest frequency, a filter signal frequency group correspondence is established. The filter signal frequency group correspondence is used to select the corresponding filter (200) according to the highest frequency. Among them, multiple filters (200) correspond one-to-one with multiple signal frequency groups, and the cutoff frequency of the filter (200) is equal to twice the highest frequency of the signal frequency group corresponding to the filter (200). Based on the signal frequency group transmission time data and the correspondence between the filter signal frequency groups, the switching time of each filter (200) is determined, and the switching time is synchronized with the transmission time; According to the switching time, the corresponding filter (200) is switched for filtering.

8. A computer-readable storage medium, characterized in that, It stores a processor-executable program, which, when executed by the processor, is used to implement the filtering method as described in claim 7.

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