Three-component geological motion signal sampling circuit and fault self-checking method

Abstract

The invention discloses a three-component geological motion signal sampling circuit and a fault self-checking method. The three-component geological motion signal sampling circuit comprises an RC filtering unit, a resistance voltage dividing unit and a CLC filtering unit which are connected in sequence. The RC filtering unit is used for filtering high-frequency interference signals higher than fmax in the collected X / Y / Z direction geological motion signals; the resistance voltage division unit limits the X / Y / Z direction geological motion signals filtered by the RC filtering unit in a sampling voltage range-VCC-+ VCC through resistance voltage division; and the CLC filtering unit is used for filtering common-mode interference signals in the X / Y / Z direction geological motion signals after resistor voltage division and realizing conversion from differential signals to single-ended signals. According to the invention, the total noise, a large amount of transient interference, radiation noise, PCB wiring introduced noise and the like of the whole signal chain can be reduced to the greatest extent, and the sampling precision is high. In addition, fault self-checking of the sampling circuit can be carried out in real time, normal and stable work of the sampling circuit is guaranteed, and therefore accuracy and reliability of sampling data are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of geological testing, and in particular to a three-component geological motion signal sampling circuit and a fault self-testing method. Background Technology

[0002] In geological testing, there is a type of geological testing equipment, such as... Figure 2 As shown, geological movements in the three orthogonal directions (X, Y, and Z) are converted into voltage signals using motion sensors. High-precision sampling and data processing of these three voltage signals yields geological movement data, which is then stored in a database. The application layer uses relevant algorithms to deduce geological information such as earthquakes, landslides, and subsidence. The sampling accuracy, interference resistance, data correction, and erroneous data removal capabilities of the sampling circuit are crucial to the detection equipment.

[0003] The aforementioned geological testing equipment is usually installed in the field. In order to ensure the accuracy of the data, the sampling device usually needs to be calibrated periodically. If the acquisition equipment malfunctions, the sampling data error cannot be detected in time. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a three-component geological motion signal sampling circuit and a fault self-diagnosis method. This three-component geological motion signal sampling circuit and fault self-diagnosis method can minimize the overall noise, a large amount of transient interference, radiated noise and PCB trace-introduced noise of the entire signal chain, and has high sampling accuracy. At the same time, it can automatically detect and diagnose sampling circuit faults to ensure the accuracy of the data.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A three-component geological motion signal sampling circuit includes an RC filter unit, a resistor voltage divider unit, and a CLC filter unit connected in sequence.

[0007] The operating frequency of the RC filter unit is f max Then f0 < f max ≤1.2 f0; where f0 is the seismic wave frequency; the RC filter unit is used to filter the acquired X / Y / Z geomotion signals higher than f0. max High-frequency interference signals are filtered out.

[0008] The resistor voltage divider unit limits the X / Y / Z geological motion signals filtered out by the RC filter unit to the sampling voltage range of -VCC to +VCC.

[0009] The CLC filter unit is used to filter out common-mode interference signals in the X / Y / Z direction geological motion signals after resistor voltage division, and to convert differential signals to single-ended signals.

[0010] It also includes a TVS unit connected to the input of the RC filter unit; the TVS unit has a bipolar TVS diode D1, and the clamping voltage V of the bipolar TVS diode D1 is selected. D1 It can collect instantaneous vibrations in geological movement signals and provide lightning and electrostatic protection for the sampling circuit.

[0011] It also includes an operational amplifier circuit unit connected to the output of the CLC filter unit.

[0012] The operational amplifier circuit unit is used to reduce the single-ended signal output by the CLC filter unit by half and provide a DC bias voltage Va = VCC / 2 to the reduced signal, thereby outputting a compressed signal of 0~VCC.

[0013] The TVS unit, RC filter unit, resistor voltage divider unit, and CLC filter unit are all arranged with equal lengths of positive and negative electrodes and symmetrical layout.

[0014] A fault self-testing method for a three-component geological motion signal sampling circuit includes the following steps.

[0015] Step 1: Through wavelet analysis, extract the DC component, low-frequency component, and high-frequency component from the X / Y / Z direction signals output by the three-component geological motion signal sampling circuit.

[0016] Step 2: Perform a lateral comparison of the DC components, low-frequency components, and high-frequency components in the X / Y / Z directions and determine whether there is a DC component, low-frequency component, or high-frequency component in one direction that is significantly different from the corresponding components in the other two directions. If so, determine that the circuit in that direction is faulty and jump to step 5; otherwise, proceed to step 3.

[0017] Step 3: Determine the DC component, low-frequency component, and high-frequency component in the X / Y / Z directions to see if there is a sudden change in the intensity of a component in a certain direction that cannot be automatically recovered after the change. If so, determine that the circuit in that direction is faulty and jump to step 5; otherwise, proceed to step 4.

[0018] Step 4: Remove the DC and high-frequency components in each direction and retain the low-frequency components to achieve automatic correction of the data in the corresponding direction, and then transmit the corrected data to the application layer.

[0019] Step 5: Determine the DC component, low-frequency component, and high-frequency component in the direction of the fault by comparing them with the DC component amplitude threshold, low-frequency component amplitude threshold, or high-frequency component amplitude threshold, thereby locating the fault location and transmitting the fault data to the application layer.

[0020] In step 2, the specific method for determining that the DC component or high-frequency component in a certain direction is significantly different from the corresponding components in the other two directions is as follows: set a channel error threshold. When the error of the DC component or high-frequency component in a certain direction is greater than the error threshold of the corresponding components in the other two directions, it is determined that the circuit in that direction has failed.

[0021] Step 5, regarding the DC component in the direction of the fault, the method for locating the fault location includes the following steps:

[0022] Step 5A-1: Determine the normal value of the DC component Dd0, then Dd0 = VCC / 2 + V0; where V0 is the fixed deviation of the sampling circuit.

[0023] Step 5A-2: Set the DC component fault thresholds, including TVS unit ground fault threshold a, op amp circuit unit negative terminal fault threshold b, and resistor divider unit ground fault threshold c, where a < b < c = VCC / 2.

[0024] Step 5A-3: Compare and judge the DC component Ddx of each direction and each time with Dd0 to locate the fault location. Specifically:

[0025] when If this occurs, then the TVS unit is grounded.

[0026] when If this occurs, then the negative terminal of the operational amplifier circuit unit is faulty.

[0027] when If this occurs, the resistor voltage divider unit will have a grounding fault.

[0028] In step 5, the method for locating the fault location for the low-frequency component in the direction of the fault is as follows:

[0029] If a low-frequency component with an amplitude greater than VCC / 2 is present, the resistor divider unit is faulty.

[0030] If the amplitude of a low-frequency component in one direction is significantly smaller than that in the other two directions and is less than 10mV, then the circuit is open.

[0031] For the low-frequency component in the direction of the fault, the method for locating the fault location is as follows:

[0032] If the amplitude of all frequencies in the high-frequency component increases by w, then the RC filter circuit is considered faulty; where w ≥ 20%.

[0033] If a high-frequency component with an amplitude greater than VCC / 2 is present, it is determined to be a fault in the resistor divider unit.

[0034] The present invention has the following beneficial effects:

[0035] 1. The sampling circuit of the present invention uses an RC filter unit, a resistor voltage divider unit and a CLC filter unit connected in sequence, which can minimize the overall noise of the entire signal chain, a large amount of transient interference, radiated noise and noise introduced by PCB traces, etc., and achieve high sampling accuracy.

[0036] 2. The fault self-testing method of the present invention can perform fault self-testing of the sampling circuit in real time, ensuring the normal and stable operation of the sampling circuit, thereby ensuring the accuracy and reliability of the sampling data. Attached Figure Description

[0037] Figure 1 The diagram shows a schematic of the structure of a three-component geological motion signal sampling circuit according to the present invention.

[0038] Figure 2 The diagram shows the application principle of the sampling circuit in the prior art.

[0039] Figure 3 The flowchart of a self-testing method for a three-component geological motion signal sampling circuit according to the present invention is shown. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0041] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0042] like Figure 1 As shown, a three-component geological motion signal sampling circuit includes a TVS unit, an RC filter unit, a resistor divider unit, a CLC filter unit, and an operational amplifier circuit unit connected in sequence.

[0043] The aforementioned TVS unit has a bipolar TVS transistor D1, and the clamping voltage V of the bipolar TVS transistor D1 is selected. D1 It can collect instantaneous vibrations in geological movement signals.

[0044] Due to the periodic nature of seismic motion, the TVS diode D1 employs a bipolar design; by selecting different TVS diode parameters, the acquisition range for different seismic magnitudes can be set. Furthermore, since acquisition equipment is often installed in the field, this circuit, as the first stage of the sampling circuit, can effectively provide lightning and electrostatic discharge protection. If the motion sensor parameters are 100V / m / s, then the clamping voltage V should be selected. D1 It is a 100V bidirectional TVS diode that can collect instantaneous vibrations at a speed of 1m / s and effectively protect the sampling circuit from lightning and electrostatic discharge.

[0045] In this embodiment, the TVS unit has positive and negative electrodes of equal length and is arranged symmetrically.

[0046] Assume the amplitude of the sampled signal VIN is VIN max If the signal frequency is f, then:

[0047]

[0048] The aforementioned RC filter unit also has equal and symmetrically arranged positive and negative terminals, including resistors R1 and R2, and capacitors C1 and C2. The circuit connection is as follows: R1 and R2 are symmetrically arranged at the two output terminals of TVS diode D1, preferably R1=R2=10Ω. The output terminal of R1 is divided into two paths: one path serves as the input of the resistor voltage divider unit, and the other path is connected to capacitor C1 and grounded; the output terminal of R2 is also divided into two paths: one path serves as the input of the resistor voltage divider unit, and the other path is connected to capacitor C2 and grounded. Preferably, C1=C2=0.1uf.

[0049] The aforementioned RC filter unit first performs the first-stage filtering of the input signal, and its operating frequency (i.e., cutoff frequency) is f. max Then f0 < f max ≤1.2 f0, that is, slightly higher than f0, and:

[0050]

[0051]

[0052] Where f0 is the seismic wave frequency; the RC filter unit is used to filter out the seismic wave frequency from the acquired X / Y / Z geomotion signals that are higher than f0. max High-frequency interference signals are filtered out.

[0053] In this embodiment, f is preferred. max =160Hz, which can effectively isolate high-frequency interference above 160Hz.

[0054] The aforementioned resistor voltage divider unit limits the X / Y / Z-axis geological motion signals, after being filtered out by the RC filter unit, to the sampling voltage range of -VCC to +VCC. When the vibration sensor's voltage signal is 100V, VCC=5V is selected, and the signal is converted to 5V through voltage division.

[0055] Furthermore, the aforementioned resistor voltage divider unit is also arranged symmetrically with equal positive and negative terminals, including resistors R3, R4, R5, and R6. The input terminal of R3 is connected to R1, and R3 has two outputs: one serves as the input terminal of the CLC filter unit, and the other is connected to R5 and then grounded. The input terminal of R4 is connected to R2, and R4 has two outputs: one serves as the input terminal of the CLC filter unit, and the other is connected to R6 and then grounded.

[0056] Furthermore, R3=R5=19Ω and R4=R6=19Ω.

[0057] After RC filtering and resistor voltage division, the output signal amplitude VOUT can be obtained. max Then VOUT max With VIN max The relationship can be represented as:

[0058]

[0059] and:

[0060]

[0061] In this invention, an RC filter unit is combined with a resistor voltage divider unit. In common sampling circuit designs, voltage division is performed first, followed by filtering. This design is considered to reduce design costs and has lower requirements for computational accuracy and wiring. However, in the application scenario involved in this invention, filtering before voltage division is more important, mainly considering the following two aspects:

[0062] First, the design objective is to perform ultra-high precision sampling. The original sampled signal has no inherent pattern. The goal is to remove useless noise from a set of "noise" signals based on geological characteristics, leaving only the useful noise. Filtering is used to minimize the overall noise of the entire signal chain, including thermal noise.

[0063] Secondly, these types of data acquisition devices are installed directly in the field to measure geological movements, or at construction sites such as tunnels and subways where large machinery impacts the geology, resulting in significant transient interference and radiated noise. Pre-filtering can act as the first line of defense, protecting the sensitive circuitry used in subsequent sampling stages.

[0064] However, the main drawback of the circuit design that filters before voltage division is that noise introduced after filtering but before voltage division (such as noise introduced by PCB traces) in subsequent circuits may not be filtered out and will directly enter the ADC. Therefore, this invention specifically adds a CLC filter unit to supplement filtering. Since the circuit design uses a bipolar circuit, all possible noise interference is theoretically equal for both the positive and negative terminals. The common-mode filter inductor in the CLC circuit specifically solves this problem, and the noise signals present at both the positive and negative terminals will cancel each other out in this filtering stage. In the circuit routing design, the positive and negative terminals need to be of equal length and symmetrically designed. The addition of a CLC filter stage and special routing design requirements, although slightly increasing the cost, significantly improve the circuit performance.

[0065] The aforementioned CLC filtering unit is used to filter out common-mode interference signals in the X / Y / Z direction geological motion signals after resistor voltage division, and to convert differential signals to single-ended signals.

[0066] Furthermore, the aforementioned CLC filter unit also has equal and symmetrically arranged positive and negative terminals, including capacitor C3, common-mode choke inductor L1, and capacitor C4.

[0067] The two input terminals of the common-mode choke inductor L1 are connected to resistors R3 and R4 respectively. One output terminal of the common-mode choke inductor L1 is connected to the operational amplifier circuit unit, and the other output terminal outputs voltage -VCC.

[0068] Preferably, capacitor C3 = 1nF is connected in parallel with the two input terminals of common-mode choke inductor L1, and is connected to resistors R3 and R4 respectively; capacitor C4 = 1nF is connected in parallel with the two output terminals of common-mode choke inductor L1.

[0069] The above-mentioned operational amplifier circuit unit is connected to the output terminal of the CLC filter unit. It is used to reduce the single-ended signal output by the CLC filter unit by half and provide a DC bias voltage Va = VCC / 2 (i.e. 2.5V) to the reduced signal, thereby outputting a compressed signal of 0~VCC (i.e. 0~5V).

[0070] The aforementioned operational amplifier circuit unit includes a voltage follower circuit composed of operational amplifier U1 and a proportional and adder circuit composed of operational amplifier U2. The signal is halved and a DC bias voltage of 2.5V is provided, ultimately compressing the signal to 0V~5V before it is sent to a high-precision sampling and data processing chip.

[0071] like Figure 3 As shown, a fault self-testing method for a three-component geological motion signal sampling circuit includes the following steps.

[0072] Step 1: Through wavelet analysis, extract the DC component, low-frequency component, and high-frequency component from the X / Y / Z direction signals output by the three-component geological motion signal sampling circuit.

[0073] The low-frequency signals from the three directions are the geological movement information that the system is interested in.

[0074] The amplitude values ​​of each component can be used for fault self-checking and direct intensity comparison.

[0075] Assume that the data Dx in the x-direction consists of a DC component Ddx, a low-frequency component group Dlx, and a high-frequency component group Dhx.

[0076]

[0077] Where Ddx is a numerical value, and Dlx and Dhx can be decomposed into a set of low-frequency signals and a set of high-frequency signals.

[0078]

[0079] Where Al1, Al2, Al3... represent the amplitudes of each component in the low-frequency signal.

[0080] fl1, fl2, fl3... represent the frequencies of the low-frequency components, and their values ​​are all less than fmax.

[0081] Phase indication

[0082] Similarly,

[0083]

[0084] Where Ah1, Ah2, Ah3... represent the amplitudes of each component in the high-frequency signal.

[0085] fh1, fh2, fh3... represent the frequencies of the high-frequency components, and their values ​​are all greater than fmax.

[0086] Indicates phase

[0087] Fault analysis can be performed by using the relationship between the numerical changes of Dd, Al1, Al2, Al3..., Ah1, Ah2, Ah3... and time to determine and locate the problem.

[0088] Ddx, Ddy, and Ddz represent the inherent voltage level of the circuit design and the inherent bias voltage level caused by thermal noise. These values ​​should always remain stable at their initial factory values, and all three values ​​should always be consistent.

[0089] Step 2: Perform a lateral comparison of the DC components, low-frequency components, and high-frequency components in the X / Y / Z directions and determine whether there is a DC component, low-frequency component, or high-frequency component in one direction that is significantly different from the corresponding components in the other two directions. If so, determine that the circuit in that direction is faulty and jump to step 5; otherwise, proceed to step 3.

[0090] Furthermore, the specific method for determining that the DC component or high-frequency component in a certain direction is significantly different from the corresponding components in the other two directions is as follows: set a channel error threshold, such as 5%. When the error of the DC component or high-frequency component in a certain direction is greater than the error threshold of the corresponding components in the other two directions, it is determined that the circuit in that direction has failed.

[0091] Step 3: Determine the DC component, low-frequency component, and high-frequency component in the X / Y / Z directions to see if there is a sudden change in the intensity of a component in a certain direction that cannot be automatically recovered after the change. If so, determine that the circuit in that direction is faulty and jump to step 5; otherwise, proceed to step 4.

[0092] Step 4: Remove the DC and high-frequency components in each direction and retain the low-frequency components to achieve automatic correction of the data in the corresponding direction, and then transmit the corrected data to the application layer.

[0093] Step 5: Determine the DC component, low-frequency component, and high-frequency component in the direction of the fault by comparing them with the DC component amplitude threshold, low-frequency component amplitude threshold, or high-frequency component amplitude threshold, thereby locating the fault location and transmitting the fault data to the subsequent application layer.

[0094] A. For the DC component in the direction of the fault, the method for locating the fault location includes the following steps.

[0095] Step 5A-1: Determine the normal value of the DC component Dd0, then Dd0 = VCC / 2 + V0; where V0 is the fixed deviation of the sampling circuit, which is preferably 0.05V in this embodiment.

[0096] Step 5A-2: Set the DC component fault thresholds, including TVS unit ground fault threshold a, op amp circuit unit negative terminal fault threshold b, and resistor divider unit ground fault threshold c, where a < b < c = VCC / 2.

[0097] The ground fault threshold 'a' of the TVS unit and the negative fault threshold 'b' of the operational amplifier circuit unit are obtained through data simulation; in this embodiment, it is preferred that a = 0.3V and b = 2V.

[0098] Step 5A-3: Compare and judge the DC component Ddx of each direction and each time with Dd0 to locate the fault location. Specifically:

[0099] when If this occurs, then the TVS unit is grounded.

[0100] when If this occurs, then the negative terminal of the operational amplifier circuit unit is faulty.

[0101] when If this occurs, the resistor voltage divider unit will have a grounding fault.

[0102] B. For the low-frequency component in the direction of the fault, the method for locating the fault location is as follows:

[0103] If a low-frequency component with an amplitude greater than VCC / 2 is present, the resistor divider unit is faulty.

[0104] If the amplitude of the low-frequency component in one direction is significantly smaller than that in the other two directions and is less than 10mV, then there is an open circuit.

[0105] C. For the low-frequency component in the direction of the fault, the method for locating the fault location is as follows:

[0106] If the amplitude of all frequencies in the high-frequency component increases by w, it is determined that the RC filter circuit is faulty; where w ≥ 20%, in this embodiment, w = 50% is obtained through simulation.

[0107] If a high-frequency component with an amplitude greater than VCC / 2 is present, it is determined to be a fault in the resistor divider unit.

[0108] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A three-component geological motion signal sampling circuit, characterized in that: It includes an RC filter unit, a resistor voltage divider unit, and a CLC filter unit connected in sequence; The operating frequency of the RC filter unit is f max Then f0 < f max ≤1.2 f0; where f0 is the seismic wave frequency; the RC filter unit is used to filter the acquired X / Y / Z geomotion signals higher than f0. max High-frequency interference signals are filtered out; The resistor voltage divider unit limits the X / Y / Z geological motion signals filtered out by the RC filter unit to the sampling voltage range of -VCC to +VCC. The CLC filter unit is used to filter out common-mode interference signals in the X / Y / Z direction geological motion signals after resistor voltage division, and to convert differential signals to single-ended signals.

2. The three-component geological motion signal sampling circuit according to claim 1, characterized in that: It also includes a TVS unit connected to the input of the RC filter unit; the TVS unit has a bipolar TVS diode D1, and the clamping voltage V of the bipolar TVS diode D1 is selected. D1 It can collect instantaneous vibrations in geological movement signals and provide lightning and electrostatic protection for the sampling circuit.

3. The three-component geological motion signal sampling circuit according to claim 1 or 2, characterized in that: It also includes an operational amplifier circuit unit connected to the output of the CLC filter unit; The operational amplifier circuit unit is used to reduce the single-ended signal output by the CLC filter unit by half and provide a DC bias voltage Va = VCC / 2 to the reduced signal, thereby outputting a compressed signal of 0~VCC.

4. The three-component geological motion signal sampling circuit according to claim 2, characterized in that: The TVS unit, RC filter unit, resistor voltage divider unit, and CLC filter unit are all arranged with equal lengths of positive and negative electrodes and symmetrical layout.

5. A fault self-testing method for a three-component geological motion signal sampling circuit, characterized in that: Includes the following steps: Step 1: Through wavelet analysis, extract the DC component, low-frequency component, and high-frequency component from the X / Y / Z direction signals output by the three-component geological motion signal sampling circuit. Step 2: Perform a lateral comparison of the DC components, low-frequency components, and high-frequency components in the X / Y / Z directions and determine whether there is a DC component, low-frequency component, or high-frequency component in one direction that is significantly different from the corresponding components in the other two directions; if so, determine that the circuit in that direction is faulty and proceed to step 5. Otherwise, proceed to step 3; Step 3: Determine the DC component, low-frequency component, and high-frequency component in the X / Y / Z directions to see if there is a sudden change in the intensity of a component in a certain direction that cannot be automatically recovered after the change; if so, determine that the circuit in that direction is faulty and jump to step 5; otherwise, proceed to step 4. Step 4: Remove the DC component and high-frequency component in each direction, and retain the low-frequency component, thereby realizing the automatic correction of the data in the corresponding direction, and transmit the corrected data to the application layer. Step 5: Determine the DC component, low-frequency component, and high-frequency component in the direction of the fault by comparing them with the DC component amplitude threshold, low-frequency component amplitude threshold, or high-frequency component amplitude threshold, thereby locating the fault location and transmitting the fault data to the application layer.

6. The fault self-testing method for the three-component geological motion signal sampling circuit according to claim 5, characterized in that: In step 2, the specific method for determining that the DC component or high-frequency component in a certain direction is significantly different from the corresponding components in the other two directions is as follows: set a channel error threshold. When the error of the DC component or high-frequency component in a certain direction is greater than the error threshold of the corresponding components in the other two directions, it is determined that the circuit in that direction has failed.

7. The fault self-testing method for the three-component geological motion signal sampling circuit according to claim 5, characterized in that: Step 5 includes an RC filter unit, a resistor voltage divider unit, and a CLC filter unit connected in sequence; The operating frequency of the RC filter unit is f max Then f0 < f max ≤1.2 f0; where f0 is the seismic wave frequency; the RC filter unit is used to filter the acquired X / Y / Z geomotion signals higher than f0. max High-frequency interference signals are filtered out; The resistor voltage divider unit limits the X / Y / Z geological motion signals filtered out by the RC filter unit to the sampling voltage range of -VCC to +VCC. The CLC filter unit is used to filter out common-mode interference signals in the X / Y / Z direction geological motion signals after resistor voltage division, and to convert differential signals to single-ended signals.

8. The fault self-testing method for the three-component geological motion signal sampling circuit according to claim 5, characterized in that: Step 5, regarding the DC component in the direction of the fault, the method for locating the fault location includes the following steps: Step 5A-1: Determine the normal value of the DC component Dd0, then Dd0 = VCC / 2 + V0; Where V0 is the fixed deviation of the sampling circuit; Step 5A-2: Set the DC component fault thresholds, including TVS unit ground fault threshold a, op amp circuit unit negative terminal fault threshold b, and resistor divider unit ground fault threshold c, where a < b < c = VCC / 2. Step 5A-3: Compare and judge the DC component Ddx of each direction and each time with Dd0 to locate the fault location. Specifically: when If this occurs, then the TVS unit is grounded. when If this occurs, the negative terminal of the operational amplifier circuit unit is faulty; when If this occurs, the resistor voltage divider unit will have a grounding fault.

9. The fault self-testing method for the three-component geological motion signal sampling circuit according to claim 5, characterized in that: In step 5, the method for locating the fault location for the low-frequency component in the direction of the fault is as follows: If a low-frequency component with an amplitude greater than VCC / 2 is present, the resistor divider unit is faulty. If the amplitude of a low-frequency component in one direction is significantly smaller than that in the other two directions and is less than 10mV, then the circuit is open.

10. The fault self-testing method for the three-component geological motion signal sampling circuit according to claim 5, characterized in that: In step 5, the method for locating the fault location for the low-frequency component in the direction of the fault is as follows: If the amplitude of all frequencies in the high-frequency components increases by w, then the RC filter circuit is considered faulty; where w ≥ 20%. If a high-frequency component with an amplitude greater than VCC / 2 is present, it is determined to be a fault in the resistor divider unit.

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