Microseismic sensor front-end signal conditioning circuit based on lag correction frequency expansion

Abstract

The invention relates to the technical field of signal processing, in particular to a microseismic sensor front-end signal conditioning circuit based on lag correction frequency expansion. The microseismic sensor front-end signal conditioning circuit based on lag correction frequency broadening comprises a differential amplification circuit used for converting a differential signal input by a microseismic sensor into a single-ended vibration signal and carrying out pre-amplification processing on the vibration signal according to a preset gain to obtain an amplified vibration signal; and the filtering and lag correction circuit is used for widening the frequency range of the amplified vibration signal in a filtering and lag correction mode to obtain a conditioned vibration signal. According to the invention, frequency expansion can be carried out on the magnetoelectric sensor through a low-frequency compensation technology, and the response capability of the magnetoelectric sensor to a low-frequency signal is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of signal processing technology, and in particular to a front-end signal conditioning circuit of a microseismic sensor based on hysteresis correction and frequency spreading. Background Art

[0002] As coal mining depth increases, the frequency and hazard of mine tremors are becoming increasingly severe. Mine tremors are microseismic phenomena caused by the rapid and substantial release of elastic energy accumulated in coal and rock masses due to mining disturbances. They are not only a mine hazard in themselves but can also be a source of other coal and rock dynamic hazards. To effectively prevent mine tremor disasters, microseismic monitoring systems are widely used both domestically and internationally to acquire vibration signals from coal and rock mass fractures, thereby locating the earthquake source and studying the distribution patterns of mine tremors. They can even infer information such as the geological structure, coal and rock fractures, and stress distribution near the earthquake source. The lower the frequency of the vibration signal, the slower it decays in the coal and rock formations. Therefore, low-frequency vibration signals have a longer propagation distance and a larger impact range. Mine tremor waves are characterized by high energy and low-frequency concentration, which requires microseismic monitoring systems to respond well to low-frequency vibration signals. The vibration sensor is the first to receive the vibration wave signal in a microseismic monitoring system. The sensor's ability to pick up signals of different frequencies directly determines the overall frequency response range of the microseismic monitoring system, which should cover a frequency range of 0.1-600Hz. Due to the harsh working environment underground in coal mines, the vibration sensors currently used in microseismic monitoring systems are generally magnetoelectric sensors, which offer advantages such as adaptability to complex environments, mature technology, high economic benefits, and suitability for large-scale installation. However, magnetoelectric vibration sensors attenuate signals below their natural frequency. Furthermore, due to the limitations of their mechanical structure, traditional magnetoelectric microseismic sensors cannot simultaneously meet the requirements of good low-frequency response, suitable size and mass, and long-term stable operation, making it difficult to effectively pick up low-frequency vibration signals below 1Hz. To address these issues, low-frequency compensation technology is needed to expand the frequency range of magnetoelectric sensors and improve their response to low-frequency signals. Summary of the Invention

[0003] The present disclosure provides a front-end signal conditioning circuit for a microseismic sensor based on hysteresis correction frequency spreading, the main purpose of which is to perform frequency spreading on a magnetoelectric sensor through low-frequency compensation technology to improve its response capability to low-frequency signals.

[0004] According to one aspect of the present disclosure, a microseismic sensor front-end signal conditioning circuit based on hysteresis correction and frequency spreading is provided, comprising: A differential amplifier circuit, configured to convert the differential signal inputted by the microseismic sensor into a single-ended vibration signal, and pre-amplify the vibration signal according to a preset gain to obtain an amplified vibration signal; The filtering and hysteresis correction circuit is used to widen the frequency range of the amplified vibration signal by filtering and hysteresis correction to obtain a conditioned vibration signal.

[0005] Optionally, in one embodiment of the present disclosure, the circuit further includes: The damping ratio correction circuit is used to receive the initial differential signal input by the microseismic sensor, perform damping ratio correction on the initial differential signal to obtain a corrected differential signal, and input the corrected differential signal to the differential amplifier circuit.

[0006] Optionally, in one embodiment of the present disclosure, the damping ratio correction circuit includes a first resistor; wherein, The positive output end of the microseismic sensor is respectively connected to the first end of the first resistor and the positive input end of the differential amplifier circuit, and the negative output end of the microseismic sensor is respectively connected to the second end of the first resistor and the negative input end of the differential amplifier circuit.

[0007] Optionally, in one embodiment of the present disclosure, the differential amplifier circuit includes a first operational amplifier; wherein, The positive input terminal of the first operational amplifier is connected to the positive output terminal of the microseismic sensor, the negative input terminal of the first operational amplifier is connected to the negative output terminal of the microseismic sensor, and the output terminal of the first operational amplifier is connected to the input terminal of the filtering and lag correction circuit.

[0008] Optionally, in one embodiment of the present disclosure, the filtering and hysteresis correction circuit includes: a high-pass filter circuit, configured to perform high-pass filtering on the amplified vibration signal to obtain a high-pass filtered vibration signal; A first-stage hysteresis correction circuit is used to perform hysteresis correction processing on the vibration signal after high-pass filtering to obtain a hysteresis-corrected vibration signal; a second-stage hysteresis correction circuit, configured to perform a secondary hysteresis correction process on the hysteresis-corrected vibration signal to obtain a secondary hysteresis-corrected vibration signal; The low-pass filter circuit is used to perform low-pass filtering on the vibration signal after the secondary lag correction to obtain the conditioned vibration signal.

[0009] Optionally, in one embodiment of the present disclosure, the high-pass filter circuit includes a first capacitor; wherein, The first end of the first capacitor is connected to the output end of the differential amplifier circuit, and the second end of the first capacitor is connected to the input end of the first-stage lag correction circuit.

[0010] Optionally, in one embodiment of the present disclosure, the first-stage lag correction circuit includes a second capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a second operational amplifier; wherein, The first end of the second resistor is connected to the output end of the high-pass filter circuit, the second capacitor and the third resistor are connected in series to form a first series branch, the second end of the second resistor is respectively connected to the negative input end of the second operational amplifier, the first end of the first series branch and the first end of the fourth resistor, the second end of the fourth resistor is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, the connection point between the second end of the first series branch, the second end of the fifth resistor and the output end of the second operational amplifier is connected to the input end of the second-stage lag correction circuit; the positive input end of the second operational amplifier and the second end of the sixth resistor are grounded.

[0011] Optionally, in one embodiment of the present disclosure, the second-stage lag correction circuit includes a third capacitor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, and a third operational amplifier; wherein, The first end of the seventh resistor is connected to the output end of the first-stage lag correction circuit, the third capacitor and the eighth resistor are connected in series to form a second series branch, the second end of the seventh resistor is respectively connected to the negative input end of the third operational amplifier, the first end of the second series branch, the first end of the ninth resistor and the first end of the low-pass filter circuit, the second end of the ninth resistor is respectively connected to the first end of the tenth resistor and the first end of the eleventh resistor, the connection point between the second end of the second series branch, the second end of the tenth resistor, the output end of the third operational amplifier and the second end of the low-pass filter circuit is the output end of the filtering and lag correction circuit; the positive input end of the third operational amplifier and the second end of the eleventh resistor are grounded.

[0012] Optionally, in one embodiment of the present disclosure, the low-pass filter circuit includes a fourth capacitor; wherein, The first end of the fourth capacitor is respectively connected to the second end of the seventh resistor, the negative input end of the third operational amplifier, the first end of the second series branch and the first end of the ninth resistor, and the connection point between the second end of the second series branch, the second end of the tenth resistor, the output end of the third operational amplifier and the second end of the fourth capacitor is the output end of the filtering and lag correction circuit.

[0013] Optionally, in one embodiment of the present disclosure, the circuit further includes: A control circuit, configured to adjust the preset gain in the differential amplifier circuit; The control circuit is also used to adjust the filtering parameters and lag correction parameters in the filtering and lag correction circuit so that the filtering and lag correction circuit widens the frequency range of the amplified vibration signal to the preset frequency range corresponding to the filtering parameters and the lag correction parameters, thereby obtaining a conditioned vibration signal.

[0014] In summary, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction spectrum spreading provided by the embodiment of the present disclosure can effectively filter out such noise interference while better receiving effective signals by connecting a differential amplifier circuit in series at the output end of the sensor. In addition, by combining the filtering circuit and the hysteresis correction compensation circuit to obtain the filtering and hysteresis correction circuit, the number of operational amplifiers can be reduced, the overall structure of the circuit can be simplified, and the impact caused by noise can be reduced. Secondly, by adopting the hysteresis correction compensation and filtering principle technology to spread the spectrum, the lower limit of the frequency range of the vibration signal monitored by the sensor can be widened, while the upper limit of the frequency range of the vibration signal monitored by the sensor can be retained to the greatest extent. The low-frequency compensation technology can be used to spread the spectrum of the magnetoelectric sensor to improve its response capability to low-frequency signals.

[0015] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 A schematic structural diagram of a front-end signal conditioning circuit of a microseismic sensor based on hysteresis correction and frequency spreading provided by an embodiment of the present disclosure; Figure 2 A schematic structural diagram of a front-end signal conditioning circuit of a microseismic sensor based on hysteresis correction and frequency spreading provided by another embodiment of the present disclosure; Figure 3 A schematic structural diagram of a damping ratio correction circuit and a differential amplifier circuit provided in an embodiment of the present disclosure; Figure 4 A schematic structural diagram of a filtering and hysteresis correction circuit provided by an embodiment of the present disclosure; Figure 5 A schematic diagram of the amplitude-frequency characteristic curve of the second-order lag correction system provided by an embodiment of the present disclosure; Figure 6 A schematic diagram of the amplitude-frequency characteristic curve of the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading provided by an embodiment of the present disclosure; Figure 7 This is a graph showing the amplitude-frequency characteristic of a vibration sensor before and after frequency scaling provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure. On the contrary, the embodiments of the present disclosure include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0018] It should be noted that the relatively mature low-frequency compensation technologies for magnetoelectric sensors currently include passive servo compensation, series compensation, feedback compensation, negative resistance compensation, system identification compensation, etc. Considering the application scenarios of microseismic monitoring, although the sensor's ability to pick up low-frequency signals has been improved after compensation, it still has deficiencies in other aspects. For example: (1) Different low-frequency compensation methods have problems such as reducing sensor sensitivity, complicating the structure or sacrificing the upper limit of the monitoring frequency band; (2) Coal mines are full of complex noise interference. Active low-frequency compensation circuits can improve the anti-interference ability of sensors by adding differential amplifier circuits, but circuit design requires pre-setting parameters. Inappropriate preset parameters may cause weak signals to be lost or strong signals to be over-amplified; (3) Low-frequency compensation methods with better frequency extension effects are usually cascade structures of operational amplifiers, but they will amplify the background noise of the circuit and affect the judgment of effective signals; (4) The lower the lower limit of the expected widened frequency band, the larger the resistance value in the circuit. The mismatch between large resistors and small capacitors will not only cause signal distortion, but also introduce higher electronic noise; (5) The low-frequency compensation technology of pure analog circuits has very high requirements for model and parameter accuracy, and cannot be adjusted during application. Sensors with fixed parameters also require analog circuits with fixed parameters to correspond to them. Although the low-frequency compensation technology of pure digital circuits can dynamically adjust circuit parameters, it has problems with high quantization error and delay, and cannot fully meet the real-time requirements of coal mine microseismic monitoring.

[0019] Specifically, different types of magnetoelectric vibration sensor frequency extension technologies have their own problems: (1) Passive servo compensation will reduce the sensor sensitivity, increase the damping ratio, and the frequency spreading effect is not ideal.

[0020] (2) Electronic feedback compensation reduces the damping ratio of the sensor and limits the frequency range; the force balance feedback compensation technical indicators are high and the process cost is expensive.

[0021] (3) Negative resistance compensation requires the introduction of negative inductance, and the circuit structure is extremely complex and difficult to implement.

[0022] (4) System identification and compensation requires high computing power, and there are problems of quantization error and poor real-time performance.

[0023] (5) The zero-pole configuration method requires a precise mathematical model and will sacrifice the response capability of medium and high frequency signals.

[0024] The present disclosure is described in detail below with reference to specific embodiments.

[0025] Figure 1 This is a schematic structural diagram of a front-end signal conditioning circuit of a microseismic sensor based on hysteresis correction and spreading frequency according to an embodiment of the present disclosure.

[0026] like Figure 1 As shown, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading includes: A differential amplifier circuit is used to convert the differential signal input by the microseismic sensor into a single-ended vibration signal, and pre-amplify the vibration signal according to a preset gain to obtain an amplified vibration signal; The filtering and hysteresis correction circuit is used to widen the frequency range of the amplified vibration signal by filtering and hysteresis correction to obtain a conditioned vibration signal.

[0027] It should be noted that when the magnetoelectric vibration sensor works underground in a coal mine, it will receive environmental noise that interferes with the judgment of effective signals. By connecting a differential amplifier circuit in series at the output end of the sensor, this type of noise interference can be effectively filtered out while better receiving effective signals.

[0028] In addition, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction spectrum expansion, which is designed using the hysteresis correction compensation and filtering principle technology, can widen the lower limit of the frequency range of the vibration signal monitored by the sensor, while retaining the upper limit of the frequency range of the vibration signal monitored by the sensor to the greatest extent; by combining the filtering circuit and the hysteresis correction compensation circuit, the number of operational amplifiers can be reduced, the overall structure of the circuit can be simplified, and the impact of noise can be reduced.

[0029] Optionally, in one embodiment of the present disclosure, Figure 2 This is a structural diagram of a microseismic sensor front-end signal conditioning circuit based on hysteresis correction and frequency spreading provided by another embodiment of the present disclosure. Figure 2 As shown, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading also includes: The damping ratio correction circuit is used to receive the initial differential signal input by the microseismic sensor, perform damping ratio correction on the initial differential signal, obtain a corrected differential signal, and input the corrected differential signal to the differential amplifier circuit.

[0030] According to some embodiments, Figure 3 This is a schematic diagram of the structure of a damping ratio correction circuit and a differential amplifier circuit provided by an embodiment of the present disclosure. Figure 3As shown, the damping ratio correction circuit includes a first resistor R 1; among them, Positive output terminal of the microseismic sensor V in+ Respectively with the first resistor R The first end of 1 is connected to the positive input end of the differential amplifier circuit, and the negative output end of the microseismic sensor is connected to the positive input end of the differential amplifier circuit. V in- Respectively with the first resistor R The second end of 1 is connected to the negative input end of the differential amplifier circuit.

[0031] In some embodiments, the damping ratio of the corrected differential signal is The following formula can be satisfied:

[0032] in, Indicates the sensitivity of the microseismic sensor, represents the inertial mass of the microseismic sensor, represents the natural angular frequency of the microseismic sensor, Indicates the internal resistance of the microseismic sensor coil.

[0033] Optionally, in one embodiment of the present disclosure, Figure 3 As shown, the differential amplifier circuit includes a first operational amplifier U 1; among them, First operational amplifier U 1 is connected to the positive input terminal of the microseismic sensor, and the first operational amplifier U 1 is connected to the negative output terminal of the microseismic sensor, and the first operational amplifier U The output end of 1 is connected to the input end of the filtering and lag correction circuit.

[0034] Among them, such as Figure 3 As shown, the positive output terminal of the microseismic sensor V in+ Respectively with the first resistor R 1 and the first operational amplifier U 1 is connected to the positive input terminal and the negative output terminal of the microseismic sensor V in- Respectively with the first resistor R 1 and the second terminal of the first operational amplifier U 1 is connected to the negative input terminal.

[0035] According to some embodiments, the first operational amplifier UFor example, a programmable gain amplifier (PGA) can be used, specifically a programmable instrumentation operational amplifier. Because traditional differential amplifier circuit designs require pre-determined operating parameters, inappropriate preset parameters may result in weak signal loss or over-amplification of strong signals. This embodiment utilizes a programmable gain operational amplifier in the differential amplifier circuit, enabling dynamic adjustment of the differential amplifier circuit's gain through interaction with a control circuit.

[0036] It should be noted that the differential amplifier circuit is composed of an operational amplifier, which can convert the picked-up differential signal input into a single-ended output to suppress common-mode noise, and can select the gain as needed to pre-amplify the weak vibration signal, which can improve the differential amplification effect of the differential amplifier circuit.

[0037] Optionally, in one embodiment of the present disclosure, Figure 2 As shown, the filtering and hysteresis correction circuit includes: A high-pass filter circuit is used to perform high-pass filtering on the amplified vibration signal to obtain a high-pass filtered vibration signal; The first stage hysteresis correction circuit is used to perform hysteresis correction processing on the vibration signal after high-pass filtering to obtain a hysteresis-corrected vibration signal; The second-stage hysteresis correction circuit is used to perform a secondary hysteresis correction process on the hysteresis-corrected vibration signal to obtain a secondary hysteresis-corrected vibration signal; The low-pass filter circuit is used to perform low-pass filtering on the vibration signal after the secondary lag correction to obtain a conditioned vibration signal.

[0038] It should be noted that since the transfer function of the original magnetoelectric sensor is expressed as a second-order high-pass filter circuit, in order to achieve order matching and obtain better frequency spreading effect, a second-order correction system is formed by connecting a second-stage lag correction circuit in series at the output end of the first-stage lag correction circuit. The structure and parameters of the second-stage lag correction circuit can be consistent with those of the first-stage lag correction circuit.

[0039] In addition, a high-pass filter circuit and a low-pass filter circuit are provided in the filtering and lag correction circuit. The function of the high-pass filter circuit is to remove the influence of DC bias and temperature drift, and the function of the low-pass filter circuit is to eliminate the pseudo peaks and signal aliasing caused by high-frequency interference.

[0040] Among them, the traditional method of using cascade connection will result in the use of multiple operational amplifiers and additional capacitor and resistor elements in the circuit, thereby increasing the interference effect of electronic noise. This embodiment proposes a solution that combines a high-pass filter circuit, a low-pass filter circuit and a lag correction circuit respectively. The filter circuit is cascaded with the lag correction circuit in the entire signal conditioning link. That is, a high-pass filter circuit is connected in series at the input end of the first-stage lag correction compensation circuit and a low-pass filter circuit is connected in parallel at the feedback link of the second-stage lag correction compensation circuit to achieve high-pass and low-pass filtering. The circuit has both lag correction and high / low-pass filtering characteristics. While ensuring the frequency spreading performance, it simplifies the circuit structure and reduces the noise impact generated by electronic components, such as a large number of operational amplifiers.

[0041] According to some embodiments, Figure 4 This is a structural diagram of a filtering and hysteresis correction circuit provided by an embodiment of the present disclosure. Figure 4 As shown, the high-pass filter circuit includes a first capacitor C 1; among them, First capacitor C The first end of 1 is connected to the output end of the differential amplifier circuit, and the first capacitor C The second end of 1 is connected to the input end of the first-stage lag correction circuit.

[0042] Among them, the first capacitor C 1 and the first operational amplifier U 1 output terminal connection.

[0043] According to some embodiments, Figure 4 As shown, the first stage hysteresis correction circuit includes a second capacitor C 2. Second resistor R 2. The third resistor R 3. The fourth resistor R 4. Fifth resistor R 5. Sixth resistor R 6. Second operational amplifier U 2; among them, Second resistor R The first end of 2 is connected to the output end of the high-pass filter circuit, and the second capacitor C 2 and the third resistor R 3 are connected in series to form the first series branch, the second resistor R The second terminals of 2 are connected to the second operational amplifier U 2, the first end of the first series branch, and the fourth resistor R 4 is connected to the first end of the fourth resistor R The second end of 4 is connected to the fifth resistor R 5 the first end and the sixth resistor R6, the second end of the first series branch, the fifth resistor R The second terminal of 5 and the second operational amplifier U The connection point between the output terminals of 2 is connected to the input terminal of the second stage lag correction circuit; the second operational amplifier U 2 and the positive input terminal of the sixth resistor R The second end of 6 is grounded.

[0044] Among them, the second resistor R The first terminal of 2 and the first capacitor C 1, the second end of the second resistor R The second terminals of 2 are connected to the second operational amplifier U 2's negative input terminal, the second capacitor C 2 and the first terminal of the fourth resistor R 4 is connected to the first end, the second capacitor C The second end of 2 and the third resistor R 3, the first end is connected to the third resistor R The second end of 3, the fifth resistor R The second terminal of 5 and the second operational amplifier U The connection point between the output terminals of 2 is connected to the input terminal of the second-stage lag correction circuit.

[0045] According to some embodiments, Figure 4 As shown, the second stage hysteresis correction circuit includes a third capacitor C 3. Seventh resistor R 7. Eighth resistor R 8. Ninth resistor R 9. Tenth resistor R 10 , the eleventh resistor R 11 , the third operational amplifier U 3; among them, Seventh resistor R The first end of 7 is connected to the output end of the first stage hysteresis correction circuit, and the third capacitor C 3 and the eighth resistor R 8 are connected in series to form a second series branch, the seventh resistor R The second end of 7 is connected to the third operational amplifier U 3, the negative input terminal, the first terminal of the second series branch, the ninth resistor R 9 and the first end of the low-pass filter circuit are connected, and the ninth resistor R The second end of 9 is connected to the tenth resistor R 10 The first end and the eleventh resistor R 11The first end of the second series branch is connected to the second end of the tenth resistor R 10 The second end of the third operational amplifier U The connection point between the output terminal of 3 and the second terminal of the low-pass filter circuit is the output terminal of the filter and lag correction circuit; the third operational amplifier U 3's positive input and the eleventh resistor R 11 The second end is grounded.

[0046] Among them, the third resistor R The second end of 3, the fifth resistor R The second terminal of 5 and the second operational amplifier U The connection point between the output terminal 2 and the seventh resistor R 7 is connected to the first end of the seventh resistor R The second end of 7 is connected to the third operational amplifier U 3's negative input terminal, the third capacitor C The first end of 3, the ninth resistor R 9 and the first end of the low-pass filter circuit are connected, and the third capacitor C The second end of 3 and the eighth resistor R 8 is connected to the first end of the eighth resistor R The second end of 8, the tenth resistor R 10 The second end of the third operational amplifier U The connection point between the output end of 3 and the second end of the low-pass filter circuit is the output end of the filtering and lag correction circuit.

[0047] According to some embodiments, the low-pass filter circuit includes a fourth capacitor C 4; among them, Fourth capacitor C 4 and the first end of the seventh resistor R The second end of 7, the third operational amplifier U 3, the first end of the second series branch, and the ninth resistor R 9, the first end of the second series branch, the second end of the tenth resistor R 10 The second end of the third operational amplifier U 3 output terminal and the fourth capacitor C The connection point between the second ends of 4 is the output end of the filtering and lag correction circuit.

[0048] Among them, the seventh resistor R The second end of 7 is connected to the third operational amplifier U 3's negative input terminal, the third capacitor C The first end of 3, the ninth resistorR The first terminal of 9 and the fourth capacitor C 4 is connected to the first end of the third capacitor C The second end of 3 and the eighth resistor R 8 is connected to the first end of the eighth resistor R The second end of 8, the tenth resistor R 10 The second end of the third operational amplifier U 3 output terminal and the fourth capacitor C The connection point between the second ends of 4 is the output end of the filtering and lag correction circuit.

[0049] It should be noted that the hysteresis correction compensation link in the hysteresis correction circuit is composed of multiple resistors and a capacitor, wherein the fourth resistor in the first-stage hysteresis correction circuit R 4. Fifth resistor R 5. Sixth resistor R 6. The ninth resistor in the second-stage hysteresis correction circuit R 9. Tenth resistor R 10 , the eleventh resistor R 11 They can all form a T-type resistor network to replace a large resistor. The T-type resistor network can eliminate the problem of signal distortion caused by the mismatch between large resistors and small capacitors. The asymmetric structure can make the total resistance of the equivalent resistor smaller than the original large resistor value. Without affecting the working performance of the overall circuit network and maintaining the original frequency spreading performance, it optimizes parameters such as noise and power consumption, and reduces the impact of problems such as high cost, high noise, high power consumption, and low-frequency signal distortion caused by temperature drift caused by large resistors and symmetrical networks.

[0050] Among them, taking the first-stage hysteresis correction circuit as an example, the equivalent relationship of its T-type resistor network satisfies:

[0051] At this time, the transfer function of the first-stage lag correction circuit is satisfy:

[0052] in, is the equivalent resistance of the T-type resistor network, is the input voltage of the first-stage hysteresis correction circuit, is the output voltage of the first-stage lag correction circuit. s is the Laplace operator.

[0053] At this time, there are two cutoff angular frequencies in the first-stage lag correction circuit, which are:

[0054]

[0055] in, is the first cutoff frequency, is the second cutoff frequency.

[0056] Optionally, in one embodiment of the present disclosure, Figure 2 As shown, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading also includes: A control circuit, configured to adjust a preset gain in the differential amplifier circuit; The control circuit is also used to adjust the filtering parameters and lag correction parameters in the filtering and lag correction circuit so that the filtering and lag correction circuit widens the frequency range of the amplified vibration signal to the preset frequency range corresponding to the filtering parameters and lag correction parameters, thereby obtaining a conditioned vibration signal.

[0057] According to some embodiments, the control circuit may be implemented as a microcontroller unit (MCU), for example.

[0058] In some embodiments, as Figure 2 As shown in the figure, in order to adapt to magnetoelectric sensors with different parameters such as damping ratio, natural frequency and sensitivity, the differential amplifier circuit, damping ratio correction circuit and filtering and lag correction circuit can be integrated into the same data acquisition board. The signal picked up by the sensor is directly processed by the data acquisition board and then output to the data acquisition system. It is equivalent to connecting the data acquisition board in series with the output end of the sensor and using the control circuit to achieve parameter adjustment.

[0059] Among them, the first operational amplifier in the differential amplifier circuit U 1. Select a PGA and connect it to an MCU. You can use the SPI protocol to programmatically control the PGA gain, making the overall signal gain dynamically adjustable. At the same time, to avoid weak signal loss and over-amplification of strong signals, the MCU can control the signal gain within a reasonable range by setting a threshold, enabling dynamic interaction and adjustment between the MCU and PGA. Among them, the capacitor in the filtering and lag correction circuit can be a liquid crystal capacitor (LCV). The control end of the LCV can be connected to the output end of the digital-to-analog converter (DAC). The input end of the DAC is connected to the MCU. The MCU sends a digital signal corresponding to the capacitance value to the DAC through the SPI protocol. The DAC converts it into an analog voltage and applies it to the LCV control end to adjust the capacitance value of the LCV.

[0060] Among them, the resistor in the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading can be a digital potentiometer (DP), which is directly connected to the MCU and uses the SPI protocol to control the change of the DP resistance value through programming.

[0061] Therefore, the advantages of analog circuits and digital circuits can be combined, and numerical control electronic components such as MCU, PGA, LCA and DP can be used to replace some analog components to achieve adjustable circuit components and working parameters. This solves the problem that pure analog circuits cannot adapt to magnetoelectric vibration sensors with different working parameters, and provides a high-precision front-end vibration signal data source for subsequent earthquake source positioning, energy calculation, stress inversion and other functions.

[0062] It should be noted that when the structure and parameters of the second-stage lag correction circuit are consistent with those of the first-stage lag correction circuit, the new natural angular frequency of the compensated sensor can be obtained by combining the transfer function of the sensor and the second-order lag correction system and defining the cutoff frequency. satisfy:

[0063] in, , and the damping ratio correction circuit of the previous stage makes , and finally we get:

[0064] Combined with the above filtering and hysteresis correction circuit related calculation formula, according to the frequency extension target and the original natural angular frequency of the sensor Determine circuit element parameters, including but not limited to filtering parameters, hysteresis correction parameters, etc.

[0065] Among them, for the lag correction parameter, you can choose , make the capacitance and resistance values ​​as appropriate as possible, select In addition, in order to reduce the large resistance The resistance value can meet the requirements of low noise and low power consumption. The T-type resistor network can be designed as an asymmetric structure. .

[0066] In some embodiments, Figure 5 Schematic diagram of the amplitude-frequency characteristic curve of the second-order lag correction system provided by the embodiment of the present disclosure. Figure 5 As shown, Frequency band, the circuit gain of the filtering and hysteresis correction circuit is a certain value; Frequency band, filtering and hysteresis correction circuit gain is attenuated; , the circuit gain of the filtering and lag correction circuit is a constant value after attenuation.

[0067] Among them, regarding the filtering parameters, the filtering circuit should have the characteristics of not affecting the frequency spreading effect while eliminating negative effects. Therefore, the high-pass cutoff frequency and low-pass cutoff frequency used by the high-pass filtering circuit and the low-pass filtering circuit respectively meet the following requirements: , while maintaining a maximum gain of 1.

[0068] In some embodiments, Figure 6 Schematic diagram of the amplitude-frequency characteristic curve of the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction and frequency spreading provided by the embodiment of the present disclosure. Figure 6 As shown, When , the circuit still provides high gain, When the circuit begins to decay significantly.

[0069] It should be noted that traditional frequency spreading circuit designs rely entirely on either analog or digital circuits. Each approach has its own advantages and disadvantages, with each approach's strengths compensating for the other's shortcomings. Therefore, this embodiment employs a control circuit to combine analog and digital circuits. This control circuit allows for adjustable circuit component parameters, adapting to detection units with different natural frequencies and initial damping ratios. It also leverages the low-noise advantage of digital potentiometers to improve frequency spreading accuracy.

[0070] Taking a scenario as an example, a magnetoelectric vibration sensor with a natural frequency of 4.5 Hz, which is widely used and has a large monitoring frequency range, is selected for verification. The normalized amplitude-frequency characteristic curve of the vibration sensor is compared with the amplitude-frequency characteristic curve of the microseismic sensor front-end signal conditioning circuit based on hysteresis correction and frequency spreading provided by the embodiment of the present disclosure. Figure 7 As shown. The cutoff frequency (gain of -3dB) of the magnetoelectric vibration sensor after signal conditioning and spectrum spreading is 0.1Hz. Compared with the original vibration sensor, the amplitude-frequency characteristic curve of the vibration sensor after spectrum spreading is shifted to the left as a whole, indicating that the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction spectrum spreading provided by the embodiment of the present disclosure significantly improves the magnetoelectric vibration sensor's ability to pick up low-frequency signals. In addition, after spectrum spreading, the sensor still maintains a relatively stable gain in the medium and high frequency range (4.5-600Hz), indicating that the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction spectrum spreading provided by the embodiment of the present disclosure retains the good response of the magnetoelectric vibration sensor to medium and high frequency signals as much as possible, and the spectrum spreading is effective.

[0071] Optionally, in one embodiment of the present disclosure, a plurality of microseismic sensor front-end signal conditioning circuits based on hysteresis correction and spreading with different parameters can be designed in advance, and the output ends of the plurality of magnetoelectric vibration sensors with different parameters can be directly connected in series with their corresponding microseismic sensor front-end signal conditioning circuits based on hysteresis correction and spreading to form a new vibration sensor. Thereafter, an explosion-proof shell is added, and a gear-adjustable switch is set on the shell to realize parameter adjustment of the microseismic sensor front-end signal conditioning circuit based on hysteresis correction and spreading.

[0072] In summary, the front-end signal conditioning circuit of the microseismic sensor based on hysteresis correction spectrum expansion provided by the embodiment of the present invention addresses the problem that the magnetoelectric sensor used in the microseismic monitoring system has insufficient ability to pick up low-frequency vibration signals. It takes into account the advantages and disadvantages of relatively mature low-frequency compensation technologies, relies on the design principle of the hysteresis correction filter circuit, and under the premise of fixing the damping ratio, not reducing the sensitivity of the sensor, and minimizing the sacrifice of the high-frequency characteristics of the sensor, combined with the vibration signal frequency monitoring range requirements of the current vibration monitoring system used in coal mines, improves the sensor's ability to pick up low-frequency signals without sacrificing the medium and high-frequency responses as much as possible, and has the advantages of being easy to implement and having high economic benefits.

[0073] Secondly, the signal conditioning circuit elements controlled by the control circuit have the function of adjustable parameters, which can be adaptively adjusted according to the magnetoelectric vibration sensors with different parameters and monitoring requirements, thereby realizing the function of the same type of signal conditioning circuit adapting to different types of magnetoelectric vibration sensors and monitoring requirements of different types and frequency ranges.

[0074] In addition, this embodiment reduces the number of operational amplifiers and the use of large resistors in the circuit, solves the high noise problem introduced by the cascade structure and the large number of operational amplifiers and large resistors, and at the same time reduces the circuit cost and power consumption.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic expressions of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0076] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0077] Although the embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A microseismic sensor front-end signal conditioning circuit based on hysteresis correction and frequency spreading, characterized in that: include: A differential amplifier circuit, configured to convert the differential signal inputted by the microseismic sensor into a single-ended vibration signal, and pre-amplify the vibration signal according to a preset gain to obtain an amplified vibration signal; The filtering and hysteresis correction circuit is used to widen the frequency range of the amplified vibration signal by filtering and hysteresis correction to obtain a conditioned vibration signal.

2. The circuit according to claim 1, wherein: The circuit further comprises: The damping ratio correction circuit is used to receive the initial differential signal input by the microseismic sensor, perform damping ratio correction on the initial differential signal to obtain a corrected differential signal, and input the corrected differential signal to the differential amplifier circuit.

3. The circuit according to claim 2, characterized in that The damping ratio correction circuit includes a first resistor; wherein, The positive output end of the microseismic sensor is respectively connected to the first end of the first resistor and the positive input end of the differential amplifier circuit, and the negative output end of the microseismic sensor is respectively connected to the second end of the first resistor and the negative input end of the differential amplifier circuit.

4. The circuit according to claim 1, wherein: The differential amplifier circuit includes a first operational amplifier; wherein, The positive input terminal of the first operational amplifier is connected to the positive output terminal of the microseismic sensor, the negative input terminal of the first operational amplifier is connected to the negative output terminal of the microseismic sensor, and the output terminal of the first operational amplifier is connected to the input terminal of the filtering and lag correction circuit.

5. The circuit according to claim 1, wherein: The filtering and hysteresis correction circuit includes: a high-pass filter circuit, configured to perform high-pass filtering on the amplified vibration signal to obtain a high-pass filtered vibration signal; A first-stage hysteresis correction circuit is used to perform hysteresis correction processing on the vibration signal after high-pass filtering to obtain a hysteresis-corrected vibration signal; a second-stage hysteresis correction circuit, configured to perform a secondary hysteresis correction process on the hysteresis-corrected vibration signal to obtain a secondary hysteresis-corrected vibration signal; The low-pass filter circuit is used to perform low-pass filtering on the vibration signal after the secondary lag correction to obtain the conditioned vibration signal.

6. The circuit according to claim 5, characterized in that The high-pass filter circuit includes a first capacitor; wherein, The first end of the first capacitor is connected to the output end of the differential amplifier circuit, and the second end of the first capacitor is connected to the input end of the first-stage lag correction circuit.

7. The circuit according to claim 5, characterized in that The first-stage lag correction circuit includes a second capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a second operational amplifier; wherein, The first end of the second resistor is connected to the output end of the high-pass filter circuit, the second capacitor and the third resistor are connected in series to form a first series branch, the second end of the second resistor is respectively connected to the negative input end of the second operational amplifier, the first end of the first series branch and the first end of the fourth resistor, the second end of the fourth resistor is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, the connection point between the second end of the first series branch, the second end of the fifth resistor and the output end of the second operational amplifier is connected to the input end of the second-stage lag correction circuit; the positive input end of the second operational amplifier and the second end of the sixth resistor are grounded.

8. The circuit according to claim 5, characterized in that The second-stage hysteresis correction circuit includes a third capacitor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, and a third operational amplifier; wherein, The first end of the seventh resistor is connected to the output end of the first-stage lag correction circuit, the third capacitor and the eighth resistor are connected in series to form a second series branch, the second end of the seventh resistor is respectively connected to the negative input end of the third operational amplifier, the first end of the second series branch, the first end of the ninth resistor and the first end of the low-pass filter circuit, the second end of the ninth resistor is respectively connected to the first end of the tenth resistor and the first end of the eleventh resistor, the connection point between the second end of the second series branch, the second end of the tenth resistor, the output end of the third operational amplifier and the second end of the low-pass filter circuit is the output end of the filtering and lag correction circuit; the positive input end of the third operational amplifier and the second end of the eleventh resistor are grounded.

9. The circuit according to claim 8, characterized in that The low-pass filter circuit includes a fourth capacitor; wherein, The first end of the fourth capacitor is respectively connected to the second end of the seventh resistor, the negative input end of the third operational amplifier, the first end of the second series branch and the first end of the ninth resistor, and the connection point between the second end of the second series branch, the second end of the tenth resistor, the output end of the third operational amplifier and the second end of the fourth capacitor is the output end of the filtering and lag correction circuit.

10. The circuit according to claim 1, wherein: The circuit further comprises: A control circuit, configured to adjust the preset gain in the differential amplifier circuit; The control circuit is also used to adjust the filtering parameters and lag correction parameters in the filtering and lag correction circuit so that the filtering and lag correction circuit widens the frequency range of the amplified vibration signal to the preset frequency range corresponding to the filtering parameters and the lag correction parameters, thereby obtaining a conditioned vibration signal.

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