A method and apparatus for half-wave decoupling of induced polarization detection based on multi-level emission.

Abstract

To address the limitations of existing chopping decoupling methods, such as waveform distortion and residual interference, which cause weak induced polarization (IP) signals at deep depths to be submerged by noise and fail to meet the requirements for deep ore body identification, this invention provides a half-wave decoupling method and apparatus for IPD detection based on multi-level transmission. By employing single-field-source multi-level transmission technology at the transmitting end, a multi-level signal waveform is synthesized to provide a waveform signal for decoupling at the receiving end. Furthermore, at the receiving end, a translation-convolution decoupling method is proposed. Through waveform translation, frequency-division convolution, and signal amplitude compensation, the electromagnetic coupling signal and the effective IPD signal are accurately separated, avoiding the loss of effective signal in traditional chopping decoupling methods.

Description

Technical Field

[0001] This invention relates to the field of mineral geophysical exploration technology, specifically to an induced polarization detection half-wave decoupling method and apparatus based on multi-level emission. Background Technology

[0002] Based on the induced polarization (IP) effect of underground rocks and minerals, alternating current (frequency domain) or direct current (time domain) is supplied to the ground to measure parameters such as the secondary potential difference, dispersion rate, or apparent phase of the rocks and minerals, thereby identifying ore body anomalies or geological structures. Frequency domain induced polarization (such as dual-frequency induced polarization) is widely used in resource exploration for metal mines, groundwater, and other areas due to its lightweight equipment and strong anti-interference capabilities.

[0003] The detection depth of the induced polarization (IP) method is determined by both the signal-to-noise ratio (SNR) and signal attenuation characteristics. The core contradiction lies in the fact that the IPA signal (such as the secondary potential difference) of deep targets decreases exponentially with increasing depth, while electromagnetic induction coupling nonlinearly increases with increasing electrode distance (the distance between the first emitting electrode A and the second emitting electrode B) (in the intermediate gradient method, a larger electrode distance allows for deeper detection). As the electrode distance increases, electromagnetic induction coupling gradually masks the deep IPA signal, leading to a bottleneck in detection depth.

[0004] Electromagnetic induction coupling is essentially a process where a changing current (often a square wave or pseudo-random signal in IP circuits) generates a changing primary magnetic field within a closed loop formed by the power supply conductor and the ground. This magnetic field induces a secondary electromotive force in the loop itself and adjacent measurement loops. This effect is proportional to frequency; the higher the signal frequency, the stronger the electromagnetic induction coupling. Existing chopping decoupling methods suppress interference by removing waveform spikes, but this results in the loss of effective signals (such as the initial stage of the induced polarization response), leading to errors in dispersion rate calculations. Residual noise can still mask weak anomalies at deeper levels.

[0005] Induced polarization (IP) detection needs further improvement in its anti-interference capabilities and signal fidelity to support the demands of deep, high-precision exploration. Existing methods such as chopping decoupling have limitations such as waveform distortion and residual interference, which cause weak deep IPI signals to be submerged by noise, failing to meet the requirements for deep ore body identification. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a method and apparatus for decoupling half-wave induced polarization detection based on multi-level emission.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, a half-wave decoupling method for induced polarization detection based on multi-level transmission is provided, including:

[0009] A multi-level signal is output to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first half-cycle waveform sequence and the second half-cycle waveform sequence satisfy the following conditions: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal.

[0010] It receives signals that contain electromagnetic induction coupling components after being coupled to the earth, and performs electromagnetic induction coupling elimination processing on the received signals.

[0011] On the other hand, an induced polarization detection half-wave decoupling device based on multi-level transmission is provided to implement the above-mentioned induced polarization detection half-wave decoupling method based on multi-level transmission, including a transmitter and a receiver;

[0012] The transmitter is used to output a multi-level signal to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first half-cycle waveform sequence and the second half-cycle waveform sequence satisfy the following: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal.

[0013] The receiver is used to receive the received signal containing electromagnetic induction coupling components after being coupled to the ground, and to perform electromagnetic induction coupling elimination processing on the received signal.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention transmits multi-level synthesized waveforms from a single field source, providing a multi-level signal for the receiver to eliminate electromagnetic induction coupling. This improves the signal-to-noise ratio of deep induced polarization signals, extending the detection depth from the traditional hundreds of meters to the kilometer level. This significantly increases the detection depth, breaks through the bottleneck of deep resource induced polarization exploration, and meets the needs of deep mineral exploration.

[0016] The transmitter adopts a single-field source design, eliminating the need for additional reference stations or complex synchronization equipment. Synchronization is achieved via GPS timing or an internal clock, simplifying operation. The duty cycle of the transmitted signal waveform is adjustable to adapt to different site conditions, improving launch convenience, reducing the complexity of field operations, and making it more suitable for field operations in complex terrain.

[0017] Furthermore, at the receiving end, through waveform shifting, convolution, and signal amplitude compensation, the electromagnetic induction coupling signal and the induced polarization signal are effectively separated, and the residual interference is reduced to less than 1%, ensuring accurate identification of deep induced polarization weak anomalies.

[0018] In summary, this invention provides a half-wave decoupling method for induced polarization (IP) detection based on multi-level transmission. By employing single-source multi-level transmission technology at the transmitting end, a multi-level signal waveform is synthesized to provide a waveform signal for decoupling at the receiving end. Furthermore, at the receiving end, a translation-convolution decoupling method is proposed. Through waveform translation, frequency division convolution, and signal amplitude compensation, precise separation of the electromagnetic coupling signal and the effective IPD signal is achieved, avoiding the loss of the effective signal caused by traditional chopping decoupling methods. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of an induced polarization detection half-wave decoupling device based on multi-level transmission provided in one embodiment;

[0021] Figure 2 This is a schematic diagram of the transmitter structure in one embodiment;

[0022] Figure 3 This is a schematic diagram of a multi-level signal in one embodiment;

[0023] Figure 4 This is a schematic diagram of a received signal containing electromagnetic inductive coupling received by a receiver in one embodiment;

[0024] Figure 5 This is a time-domain waveform diagram of eight high-frequency cycles contained in the first half of a low-frequency cycle of a received signal in one embodiment.

[0025] Figure 6 This is a time-domain waveform diagram of eight high-frequency cycles contained in the second half of a low-frequency cycle of a received signal in one embodiment. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] In one embodiment, an induced polarization detection half-wave decoupling method based on multi-level transmission is proposed, comprising:

[0028] A multi-level signal is transmitted to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first and second half-cycle waveform sequences satisfy the following conditions: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal.

[0029] It receives signals that contain electromagnetic induction coupling components after being coupled to the earth, and performs electromagnetic induction coupling elimination processing on the received signals.

[0030] In one embodiment, the multi-level signal includes: positive 2 level, positive 1 level, 0 level, negative 1 level, and negative 2 level.

[0031] In one embodiment, such as Figure 3 The diagram illustrates a multi-level signal. A multi-level signal consists of a first half-cycle and a second half-cycle within a low-frequency period. Within this low-frequency period, the first half-cycle contains eight high-frequency cycles. The first seven high-frequency cycles in the first half-cycle correspond to a first-level value sequence composed of positive 2, positive 1, 0, and positive 1. The last high-frequency cycle in the first half-cycle corresponds to a level sequence composed of positive 2, positive 1, negative 1, and 0. The second half-cycle also contains eight high-frequency cycles. The first seven high-frequency cycles in the second half-cycle correspond to a second-level value sequence composed of 0, negative 1, negative 2, and negative 1. The last high-frequency cycle in the second half-cycle corresponds to a level sequence composed of 0, negative 1, negative 1, and 0. Specifically, Figure 3The signal sequence for the first half of the cycle is: positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, 0 level, positive 1 level, positive 2 level, positive 1 level, negative 1 level, 0 level. The signal sequence for the second half of the cycle is: 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -2 level, -1 level, 0 level, -1 level, -1 level, 0 level, -1 level, -1 level, 0 level.

[0032] In summary, the waveform characteristics of the multi-level signal in the above embodiments are as follows: within a low-frequency cycle, the first half of the cycle first repeatedly outputs a first level value sequence consisting of positive 2 level, positive 1 level, 0 level, and positive 1 level in sequence, and the first half of the cycle ends with positive 2 level, positive 1 level, negative 1 level, and 0 level; the second half of the cycle first repeatedly outputs a second level value sequence consisting of 0 level, negative 1 level, negative 2 level, and negative 1 level in sequence, and the second half of the cycle ends with 0 level, negative 1 level, negative 1 level, and 0 level.

[0033] In one embodiment, the received signal contains multiple high-frequency cycles within a low-frequency cycle, and the electromagnetic induction coupling cancellation processing of the received signal includes:

[0034] For the first half of a low-frequency cycle of the received signal, the multiple high-frequency cycle signals contained in the first half of the cycle are shifted down by one unit, and then convolution operations are performed on them respectively. The absolute values ​​of the convolution results of each cycle are summed and amplitude compensation is performed to obtain the first response of the corresponding high-frequency component.

[0035] For the second half of a low-frequency cycle of the received signal, the multiple high-frequency cycle signals contained in the second half of the cycle are shifted upward by one unit, and then convolution operations are performed on them respectively. The absolute values ​​of the convolution results of each cycle are accumulated and amplitude compensation is performed to obtain the second response of the corresponding high-frequency component.

[0036] The absolute values ​​of the first response and the second response of the high-frequency component are summed to obtain the high-frequency response after eliminating electromagnetic induction coupling.

[0037] Reference Figure 5 The image shows the time-domain waveform of the eight high-frequency cycles contained in the first half of a low-frequency cycle of the received signal. Figure 5 The eight high-frequency cycles contained in the first half of the cycle are labeled T1-T8. First, each of the T1-T8 cycles in the first half of the cycle is shifted downward by one unit. Then, each cycle is convolved separately. Finally, the absolute values ​​of the convolution results of the T1-T8 cycles are summed. The summed result is then subjected to amplitude compensation and denoted as the first response V of the corresponding high-frequency component in the first half of the cycle. f H1 ).

[0038] Reference Figure 6 The image shows the time-domain waveform of the eight high-frequency cycles contained in the second half of a low-frequency cycle of the received signal. Figure 6 The eight high-frequency cycles contained in the second half of the cycle are sequentially labeled T1-T8. First, each of the T1-T8 cycles in the second half of the cycle is shifted downward by one unit. Then, each cycle is convolved separately. Finally, the absolute values ​​of the convolution results of the T1-T8 cycles are summed. The summed result is then subjected to amplitude compensation and denoted as the second response V of the corresponding high-frequency component in the second half of the cycle. f H2 ).

[0039] V ( f H1 ) and V ( f H2 By summing the absolute values, the high-frequency response V( after eliminating electromagnetic induction coupling) can be obtained. f H ).

[0040] Furthermore, the present invention performs electromagnetic induction coupling cancellation processing on the received signal, and also includes the step of electromagnetic induction coupling cancellation processing on low-frequency components:

[0041] For a low-frequency cycle of the received signal, the time-domain signal of the first half-cycle is convolved to obtain the first response of the corresponding low-frequency component; the time-domain signal of the second half-cycle is convolved to obtain the second response of the corresponding low-frequency component; the absolute values ​​of the first response and the second response of the low-frequency component are summed to obtain the low-frequency response after eliminating electromagnetic induction coupling.

[0042] This invention acquires both high-frequency and low-frequency responses, enabling the obtaining of shallow and deep geoelectric information in a single measurement. High-frequency signals reflect shallow geological structures, while low-frequency signals penetrate deeper to reflect deeper information, thus improving vertical resolution.

[0043] This invention transmits a multi-level signal with a specific symmetrical structure (the first half-cycle sequence minus 1 equals the second half-cycle sequence plus 1), so that the electromagnetic induction coupling components cancel each other out during signal processing due to symmetry, while the ground-induced electrostatic effect signal is preserved and enhanced.

[0044] This invention performs electromagnetic induction coupling elimination processing on the received signal, which is achieved entirely through signal processing at the receiving end (translation, convolution, accumulation), without the need to add additional hardware circuits (such as compensation coils, decoupling filters, etc.) at the transmitting or receiving end, thus reducing system complexity and cost.

[0045] This invention is applicable not only to decoupling of high-frequency signals (such as 4Hz) but also to decoupling of low-frequency signals (such as 1 / 4Hz), achieving synchronous decoupling of all frequency components in a composite waveform.

[0046] Reference Figure 1 This is a schematic diagram of an induced polarization (IP) half-wave decoupling device based on multi-level transmission in one embodiment, using a dipole-dipole configuration as an example. In the diagram, A and B are the two transmitting electrodes of the transmitter, and M and N are the two receiving electrodes of the receiver. The multi-level transmission-based IIP half-wave decoupling device includes a transmitter and a receiver.

[0047] The transmitter is used to output a multi-level signal to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first half-cycle waveform sequence and the second half-cycle waveform sequence satisfy the following: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal.

[0048] The receiver is used to receive the received signal containing electromagnetic induction coupling components after being coupled to the ground, and to perform electromagnetic induction coupling elimination processing on the received signal.

[0049] Reference Figure 2 The diagram shows the structure of the transmitter, which includes a first DC power supply BT1, a second DC power supply BT2, a single-pole double-throw switch S, a filter capacitor C, an H-bridge inverter circuit, and a ground load resistor RL.

[0050] The single-pole double-throw switch S is used to select either to connect to the first DC power supply for independent power supply or to connect to the first DC power supply BT1 and the second DC power supply BT2 in series to supply power between the DC positive bus and the DC negative bus.

[0051] The filter capacitor is connected between the DC positive bus and the DC negative bus, that is, in parallel with the DC input terminal of the H-bridge inverter circuit, and is used to filter and regulate the power supply.

[0052] The H-bridge inverter circuit is used to control the direction of the output current and realize the transmission and output of multi-level signals.

[0053] The transmitter provided in the above embodiments requires only two DC power supplies, a single-pole double-throw switch, a filter capacitor, and an H-bridge inverter circuit. It does not require complex high-voltage switching or multi-power supply arrays, has a compact structure, and a low failure rate.

[0054] Reference Figure 2 The H-bridge inverter circuit consists of four switching transistors: Q1, Q2, Q3, and Q4. Q1 and Q2 are connected in series to form the first bridge arm, and Q3 and Q4 are connected in series to form the second bridge arm. The first and second bridge arms are connected in parallel and their two ends are connected to the positive DC bus and the negative DC bus, respectively.

[0055] The first emitting electrode A is connected to the midpoint between the first switch Q1 and the second switch Q2, the second emitting electrode B is connected to the midpoint between the third switch Q3 and the fourth switch Q4, and the ground load resistor RL is connected between the first emitting electrode A and the second emitting electrode B.

[0056] The transmitter selects the power supply mode by controlling a single-pole double-throw switch and selects the current direction by controlling the conduction combination of the H-bridge inverter circuit, thereby realizing the output of positive 2 level, positive 1 level, 0 level, negative 1 level and negative 2 level in multi-level signals, specifically including:

[0057] The method to achieve positive 2-level output is as follows: the single-pole double-throw switch S selects to connect the first DC power supply BT1 and the second DC power supply BT2 in series to supply power between the DC positive bus and the DC negative bus. The first DC power supply BT1 and the second DC power supply BT2 in series supply power to the H-bridge inverter circuit through the filter capacitor C. The first switch Q1 and the fourth switch Q4 are turned on, the second switch Q2 and the third switch Q3 are turned off, and the current flows from the first emitter A to the second emitter B.

[0058] The method to achieve a positive 1 level output is as follows: the single-pole double-throw switch S selects to connect to the first DC power supply to supply power between the DC positive bus and the DC negative bus. The first DC power supply BT1 supplies power to the H bridge inverter circuit through the filter capacitor C. The first switch Q1 and the fourth switch Q4 are turned on, the second switch Q2 and the third switch Q3 are turned off, and the current flows from the first emitting electrode A to the second emitting electrode B.

[0059] The method to achieve 0-level output is as follows: in the H-bridge inverter circuit, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all turned off, and there is no signal output from the first emitter A and the second emitter B;

[0060] The method to achieve a negative 1 level output is as follows: the single-pole double-throw switch S selects to connect to the first DC power supply to supply power between the DC positive bus and the DC negative bus. The first DC power supply BT1 supplies power to the H bridge inverter circuit through the filter capacitor C. The second switch Q2 and the third switch Q3 are turned on, and the first switch Q1 and the fourth switch Q4 are turned off. The current flows from the second emitting electrode B to the first emitting electrode A.

[0061] The method to achieve negative 2 level output is as follows: the single-pole double-throw switch S selects to connect the first DC power supply BT1 and the second DC power supply BT2 in series to supply power between the DC positive bus and the DC negative bus. The first DC power supply BT1 and the second DC power supply BT2 in series supply power to the H bridge inverter circuit through the filter capacitor C. The second switch Q2 and the third switch Q3 of the inverter bridge are turned on, and the first switch Q1 and the fourth switch Q4 are turned off. The current flows from the second emitter B to the first emitter A.

[0062] The method and apparatus provided by this invention are applicable to all types of induced polarization (IP) exploration devices (such as dipole-dipole, Wenner, tripolar, etc.), and have good versatility and promotional value.

[0063] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A half-wave decoupling method for induced polarization detection based on multi-level transmission, characterized in that, include: A multi-level signal is transmitted to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first and second half-cycle waveform sequences satisfy the following conditions: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal. It receives signals that contain electromagnetic induction coupling components after being coupled to the earth, and performs electromagnetic induction coupling elimination processing on the received signals.

2. The induced polarization detection half-wave decoupling method based on multi-level transmission according to claim 1, characterized in that, The multi-level signals include: positive 2 level, positive 1 level, 0 level, negative 1 level, and negative 2 level.

3. The induced polarization detection half-wave decoupling method based on multi-level transmission according to claim 2, characterized in that, The waveform characteristics of the multi-level signal are as follows: within a low-frequency cycle, the first half of the cycle first repeats the output of the first level value sequence consisting of positive 2 level, positive 1 level, 0 level, and positive 1 level in sequence multiple times, and the first half of the cycle ends with positive 2 level, positive 1 level, negative 1 level, and 0 level; the second half of the cycle first repeats the output of the second level value sequence consisting of 0 level, negative 1 level, negative 2 level, and negative 1 level in sequence multiple times, and the second half of the cycle ends with 0 level, negative 1 level, negative 1 level, and 0 level.

4. The induced polarization detection half-wave decoupling method based on multi-level transmission according to claim 1, 2, or 3, characterized in that, The received signal contains multiple high-frequency cycles within a low-frequency cycle. Electromagnetic induction coupling cancellation processing is performed on the received signal, including: For the first half of a low-frequency cycle of the received signal, the multiple high-frequency cycle signals contained in the first half of the cycle are shifted down by one unit, and then convolution operations are performed on them respectively. The absolute values ​​of the convolution results of each cycle are summed and amplitude compensation is performed to obtain the first response of the corresponding high-frequency component. For the second half of a low-frequency cycle of the received signal, the multiple high-frequency cycle signals contained in the second half of the cycle are shifted upward by one unit, and then convolution operations are performed on them respectively. The absolute values ​​of the convolution results of each cycle are accumulated and amplitude compensation is performed to obtain the second response of the corresponding high-frequency component. The absolute values ​​of the first response and the second response of the high-frequency component are summed to obtain the high-frequency response after eliminating electromagnetic induction coupling.

5. The induced polarization detection half-wave decoupling method based on multi-level transmission according to claim 4, characterized in that, The electromagnetic induction coupling cancellation process for the received signal also includes steps for canceling electromagnetic induction coupling of low-frequency components. For a low-frequency cycle of the received signal, the time-domain signal of the first half-cycle is convolved to obtain the first response of the corresponding low-frequency component; the time-domain signal of the second half-cycle is convolved to obtain the second response of the corresponding low-frequency component. The absolute values ​​of the first response and the second response of the low-frequency component are summed to obtain the low-frequency response after eliminating electromagnetic induction coupling.

6. A induced polarization (IP) probe half-wave decoupling device based on multi-level transmission, used to implement the induced polarization probe half-wave decoupling method based on multi-level transmission as described in claim 1, 2, 3, or 5, characterized in that, Includes transmitter and receiver; The transmitter is used to output a multi-level signal to the ground. The multi-level signal includes a first half-cycle waveform sequence and a second half-cycle waveform sequence within a low-frequency cycle. The first half-cycle waveform sequence contains multiple repeating first level value sequences, and the second half-cycle waveform sequence contains multiple repeating second level value sequences. The first half-cycle waveform sequence and the second half-cycle waveform sequence satisfy the following: the sequence obtained by subtracting 1 from each level value in the first half-cycle waveform sequence is exactly the same as the sequence obtained by adding 1 to each level value in the second half-cycle waveform sequence; through the repetition of the first level value sequence in the first half-cycle waveform sequence and the repetition of the second level value sequence in the second half-cycle waveform sequence, multiple high-frequency cycles are contained within a low-frequency cycle, thereby simultaneously including low-frequency and high-frequency components in the transmitted signal. The receiver is used to receive the received signal containing electromagnetic induction coupling components after being coupled to the ground, and to perform electromagnetic induction coupling elimination processing on the received signal.

7. The induced polarization detection half-wave decoupling device based on multi-level transmission according to claim 6, characterized in that, The transmitter includes a first DC power supply, a second DC power supply, a single-pole double-throw switch, a filter capacitor, an H-bridge inverter circuit, and a ground load resistor. The single-pole double-throw switch is used to select whether to connect to the first DC power supply for independent power supply or to connect to the first DC power supply and the second DC power supply in series to supply power between the DC positive bus and the DC negative bus. The filter capacitor is connected between the DC positive bus and the DC negative bus, that is, in parallel with the DC input terminal of the H-bridge inverter circuit, and is used to filter and regulate the power supply. The H-bridge inverter circuit is used to control the direction of the output current and realize the transmission and output of multi-level signals.

8. The induced polarization detection half-wave decoupling device based on multi-level transmission according to claim 7, characterized in that, The H-bridge inverter circuit consists of four switching transistors: Q1, Q2, Q3, and Q4. Q1 and Q2 are connected in series to form the first bridge arm, and Q3 and Q4 are connected in series to form the second bridge arm. The first and second bridge arms are connected in parallel, and their two ends are connected to the positive DC bus and the negative DC bus, respectively. The first emitting electrode A is connected to the midpoint between the first switch Q1 and the second switch Q2, the second emitting electrode B is connected to the midpoint between the third switch Q3 and the fourth switch Q4, and the ground load resistor is connected between the first emitting electrode A and the second emitting electrode B.

9. The induced polarization detection half-wave decoupling device based on multi-level transmission according to claim 8, characterized in that: The transmitter selects the power supply mode by controlling a single-pole double-throw switch and selects the current direction by controlling the conduction combination of the H-bridge inverter circuit, thereby realizing the output of positive 2 level, positive 1 level, 0 level, negative 1 level and negative 2 level in multi-level signals.

10. The induced polarization detection half-wave decoupling device based on multi-level transmission according to claim 9, characterized in that: The method for positive 2-level output is as follows: a single-pole double-throw switch selects the first DC power supply and the second DC power supply connected in series to supply power between the DC positive bus and the DC negative bus. The first DC power supply and the second DC power supply are connected in series and supply power to the H-bridge inverter circuit through the filter capacitor. The first switch Q1 and the fourth switch Q4 are turned on, the second switch Q2 and the third switch Q3 are turned off, and the current flows from the first emitting electrode A to the second emitting electrode B. The method for positive 1 level output is as follows: a single-pole double-throw switch selects the first DC power supply to supply power separately between the DC positive bus and the DC negative bus. The first DC power supply supplies power to the H-bridge inverter circuit through the filter capacitor. The first switch Q1 and the fourth switch Q4 are turned on, and the second switch Q2 and the third switch Q3 are turned off. The current flows from the first emitting electrode A to the second emitting electrode B. The method for 0-level output is as follows: in the H-bridge inverter circuit, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all turned off, and there is no signal output from the first emitter A and the second emitter B; The method for outputting a negative 1 level is as follows: a single-pole double-throw switch selects to connect to the first DC power supply to supply power separately between the DC positive bus and the DC negative bus. The first DC power supply supplies power to the H-bridge inverter circuit through a filter capacitor. The second switch Q2 and the third switch Q3 are turned on, while the first switch Q1 and the fourth switch Q4 are turned off. The current flows from the second emitting electrode B to the first emitting electrode A. The method for outputting a negative 2 level is as follows: a single-pole double-throw switch selects the first DC power supply and the second DC power supply connected in series to supply power between the DC positive bus and the DC negative bus. The first DC power supply and the second DC power supply are connected in series and supply power to the H-bridge inverter circuit through a filter capacitor. The second switch Q2 and the third switch Q3 of the inverter bridge are turned on, while the first switch Q1 and the fourth switch Q4 are turned off. The current flows from the second emitting electrode B to the first emitting electrode A.

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