A multi-sensitivity composite vibration sensor and its separation method

Abstract

The present invention discloses a multi-sensitivity composite vibration sensor and a separation method thereof. The composite vibration sensor includes a preamplifier and a signal separation unit. The preamplifier includes an access identification circuit, an analog switch, a microcontroller (MCU), an anti-reverse and interface protection module, and a signal acquisition unit. The signal acquisition unit is connected to the access identification circuit, then to the analog switch, then to the microcontroller (MCU), and finally to the anti-reverse and interface protection module. The signal separation unit includes a low-pass filter, a high-pass filter, a low-pass signal processor, a high-pass signal processor, an ADC (ADC) anti-aliasing, and an analog-to-digital converter (ADC). The low-pass or high-pass filter is connected to the anti-reverse and interface protection module. After the low-pass filter is connected to the low-pass signal processor, and after the high-pass filter is connected to the high-pass signal processor, both are connected to the ADC anti-aliasing. The ADC anti-aliasing is connected to the analog-to-digital converter (ADC). The sensor can obtain multiple sensitivities, so that the required signal has an appropriate sensitivity and a suitable signal-to-noise ratio is achieved during transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a multi-sensitivity composite vibration sensor and a separation method thereof. Background Art

[0002] In sensor network systems, sensors are particularly important. When multiple installation points are required but more installation locations are unavailable, the system challenges the need for sensors to meet multi-sensitivity monitoring requirements for vibration monitoring. The current common practice is to use a single sensitivity within the passband and amplify the signals in each frequency band within the signal separation unit. In practice, this approach has the following shortcomings: The system's sensitivity requirements for each frequency band vary, particularly in the low-frequency region, resulting in insufficient signal-to-noise ratio. In rail transit systems, electromagnetic interference can interfere with signal acquisition units and transmission lines, making some signals susceptible to interference. Furthermore, the sensitivity requirements for vibration monitoring of various components in rail transit systems vary slightly. For example, in polygonal and derailment monitoring, improved sensitivity in the low-frequency band is desirable. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a multi-sensitivity composite vibration sensor and a separation method thereof.

[0004] The object of the present invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention discloses a multi-sensitivity composite vibration sensor, comprising a preamplifier and a signal separation unit, wherein the signal separation unit is connected to at least one preamplifier;

[0006] The preamplifier includes an access identification circuit, an analog switch, a microcontroller MCU, an anti-reverse and interface protection module and at least one signal acquisition unit; the output end of the signal acquisition unit is connected to the access identification circuit, the output end of the access identification circuit is connected to the analog switch, the analog switch is connected to the microcontroller MCU, and the output end of the analog switch is connected to the anti-reverse and interface protection module;

[0007] The signal separation unit includes a third low-pass filter, a third high-pass filter, a low-pass signal processor, a high-pass signal processor, an ADC anti-mixing filter and an analog-to-digital converter ADC. The input end of the third low-pass filter or the third high-pass filter is connected to the anti-reverse and interface protection module, the output end of the third low-pass filter is connected to the low-pass signal processor, the output end of the low-pass signal processor is connected to the ADC anti-mixing filter, the output end of the third high-pass filter is connected to the high-pass signal processor, the output end of the high-pass signal processor is connected to the ADC anti-mixing filter, and the output end of the ADC anti-mixing filter is connected to the analog-to-digital converter ADC.

[0008] Based on the first aspect, the preamplifier further includes a V / I conversion module, the input end of the V / I conversion module is connected to the output end of the analog switch, and the output end of the V / I conversion module is connected to the anti-reverse and interface protection module.

[0009] Based on the first aspect, the signal separation unit further includes an I / V conversion module, the input end of the I / V conversion module is connected to the anti-reverse and interface protection module, and the output end of the I / V conversion module is respectively connected to the high pass and low pass.

[0010] Based on the first aspect, the signal acquisition unit includes a low-pass amplification module, a high-pass amplification module, an addition circuit and an interface protection module. The low-pass amplification module is used to filter out the high-frequency signal of the original vibration signal and amplify the sensitivity of the low-frequency signal to the target value; the high-pass amplification module is used to filter out the low-frequency signal of the original vibration signal and adjust the sensitivity of the high-frequency signal to the target value; the signals output by the low-pass amplification module and the high-pass amplification module are added by the addition circuit to synthesize the signal again. At this time, the sensitivities of the low-frequency part and the high-frequency part of the signal are different; the interface protection module is used to protect the installation environment of the signal acquisition unit, and the interface protection module includes a TVS device or an ESD device.

[0011] Based on the first aspect, the low-pass amplification module includes a first low-pass filter and a second low-pass filter, which are connected in series to form a first sixth-order filter; the high-pass amplification module includes a first high-pass filter and a second high-pass filter, which are connected in series to form a second sixth-order filter; the adding circuit includes a fifth operational amplifier; the first sixth-order filter and the second sixth-order filter are connected in parallel and then connected in series to the fifth operational amplifier.

[0012] Based on the first aspect, the signal acquisition unit further includes a first signal source VG1 of an analog signal, the first low-pass filter includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13 and a first operational amplifier OP1, one end of the eleventh resistor R11 is connected to the first signal source VG1, the other end of the eleventh resistor R11 is connected in series with the twelfth resistor R12 and the thirteenth resistor R13 and then connected to the positive input terminal of the first operational amplifier OP1, and one end of the eleventh capacitor C11 is connected between the eleventh resistor R11 and the twelfth resistor R12. The other end of the eleventh capacitor C11 is connected to the first reference voltage point, one end of the twelfth capacitor C12 is connected between the twelfth resistor R12 and the thirteenth resistor R13, the other end of the twelfth capacitor C12 is connected to the output terminal of the first operational amplifier OP1, one end of the thirteenth capacitor C13 is connected between the thirteenth resistor R13 and the positive input terminal of the first operational amplifier OP1, the other end of the thirteenth capacitor C13 is connected to the other end of the eleventh capacitor C11 and then to one end of the fourteenth resistor R14, the other end of the fourteenth resistor R14 is connected to the negative input terminal of the first operational amplifier OP1, and the fifteenth resistor R15 is connected in parallel between the negative input terminal and the output terminal of the first operational amplifier OP1;

[0013] The second low-pass filter includes a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-first capacitor C21, a twenty-second capacitor C22, a twenty-third capacitor C23, and a second operational amplifier OP2, one end of the twenty-first resistor R21 is connected to the output end of the first operational amplifier OP1, the other end of the twenty-first resistor R21 is connected in series with the twenty-second resistor R22 and the twenty-third resistor R23, and then connected to the positive input end of the second operational amplifier OP2, one end of the twenty-first capacitor C21 is connected between the twenty-first resistor R21 and the twenty-second resistor R22, and the twenty-first capacitor C21 is connected to the positive input end of the second operational amplifier OP2. the other end of the twenty-second capacitor C22 is connected to the second reference voltage point, one end of the twenty-second capacitor C22 is connected between the twenty-second resistor R22 and the twenty-third resistor R23, the other end of the twenty-second capacitor C22 is connected to the output terminal of the second operational amplifier OP2, one end of the twenty-third capacitor C23 is connected between the twenty-third resistor R23 and the positive input terminal of the second operational amplifier OP2, the other end of the twenty-third capacitor C23 is connected to the other end of the twenty-first capacitor C21 and then to one end of the twenty-fourth resistor R24, the other end of the twenty-fourth resistor R24 ​​is connected to the negative input terminal of the second operational amplifier OP2, and a twenty-fifth resistor R25 is connected in parallel between the negative input terminal and the output terminal of the second operational amplifier OP2;

[0014] The first high-pass filter includes a thirty-first capacitor C31, a thirty-second capacitor C32, a thirty-third capacitor C33, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35 and a third operational amplifier OP3, one end of the thirty-first capacitor C31 is connected to the first signal source VG1, the other end of the thirty-first capacitor C31 is connected in series with the thirty-second capacitor C32 and the thirty-third capacitor C33, and then connected to the positive input terminal of the third operational amplifier OP3, one end of the thirty-first resistor R31 is connected between the thirty-first capacitor C31 and the thirty-second capacitor C32, and the other end of the thirty-first resistor R31 is connected to the positive input terminal of the third operational amplifier OP3. connected to the third reference voltage point, one end of the thirty-second resistor R32 is connected between the thirty-second capacitor C32 and the thirty-third capacitor C33, the other end of the thirty-second resistor R32 is connected to the output terminal of the third operational amplifier OP1, one end of the thirty-third resistor R33 is connected between the thirty-third capacitor C33 and the positive input terminal of the third operational amplifier OP3, the other end of the thirty-third resistor R33 is connected to the other end of the thirty-first resistor R31 and then to one end of the thirty-fourth resistor R34, the other end of the thirty-fourth resistor R34 is connected to the negative input terminal of the third operational amplifier OP3, and a thirty-fifth resistor R35 is connected in parallel between the negative input terminal and the output terminal of the third operational amplifier OP3;

[0015] The second high-pass filter includes a forty-first capacitor C41, a forty-second capacitor C42, a forty-third capacitor C43, a forty-first resistor R41, a forty-second resistor R42, a forty-third resistor R43, a forty-fourth resistor R44, a forty-fifth resistor R45 and a fourth operational amplifier OP4, one end of the forty-first capacitor C41 is connected to the output end of the third operational amplifier OP3, the other end of the forty-first capacitor C41 is connected in series with the forty-second capacitor C42 and the forty-third capacitor C43, and then connected to the positive input end of the fourth operational amplifier OP4, one end of the forty-first resistor R41 is connected between the forty-first capacitor C41 and the forty-second capacitor C42, and the forty-first resistor R41 is connected to the positive input end of the fourth operational amplifier OP4. the other end of the forty-second resistor R42 is connected to the fourth reference voltage point, one end of the forty-second resistor R42 is connected between the forty-second capacitor C42 and the forty-third capacitor C43, the other end of the forty-second resistor R42 is connected to the output terminal of the fourth operational amplifier OP4, one end of the forty-third resistor R43 is connected between the forty-third capacitor C43 and the positive input terminal of the fourth operational amplifier OP4, the other end of the forty-third resistor R43 is connected to the other end of the forty-first resistor R41 and then to one end of the forty-fourth resistor R44, the other end of the forty-fourth resistor R44 is connected to the negative input terminal of the fourth operational amplifier OP4, and a forty-fifth resistor R45 is connected in parallel between the negative input terminal and the output terminal of the fourth operational amplifier OP4;

[0016] The adding circuit includes a first resistor R01, a second resistor R02, a third resistor R03, a fourth resistor R04 and a fifth operational amplifier OP5, one end of the first resistor R01 is connected to the output end of the second operational amplifier, the other end of the first resistor R01 is connected to the positive input end of the fifth operational amplifier OP5, one end of the second resistor R02 is connected to the positive input end of the fifth operational amplifier OP5, the other end of the second resistor R02 is connected to the fifth reference voltage point, one end of the third resistor R03 is connected to the output end of the fourth operational amplifier OP4, the other end of the third resistor R03 is connected to the negative input end of the fifth operational amplifier OP5, and the fourth resistor R04 is connected in parallel between the negative input end and the output end of the fifth operational amplifier OP5.

[0017] In a second aspect, the present invention discloses a separation method for the multi-sensitivity composite vibration sensor described above, comprising the following steps:

[0018] S1. Identify signals from the first to Nth signal acquisition units through an identification circuit;

[0019] S2. Controlling the analog switch through the microcontroller MCU to start the analog signal routing function, selecting one or more routes of the signals from the first to Nth signal acquisition units to be routed to the V / I conversion module;

[0020] S3, the V / I conversion module converts the signal after the analog signal selection into voltage and current. If the signal transmission is voltage transmission, only voltage regulation and following are required; anti-reverse and interface protection modules are set on the output interface to protect the interface;

[0021] S4. Convert the current signal back into a voltage signal through the I / V conversion module, separate the low-frequency signal from the signal of the signal acquisition unit through a third low-pass filter, where the low-frequency frequency of the third low-pass filter cannot be higher than that of the low-pass amplification module of the signal acquisition unit; and separate the high-frequency signal from the signal of the signal acquisition unit through a third high-pass filter, where the high-frequency frequency of the third high-pass filter cannot be lower than that of the high-pass amplification module of the signal acquisition unit;

[0022] S5. Extract the low-frequency signal and obtain the velocity through integration, obtain the displacement through double integration, and extract the DC signal to determine whether the static operating point of the signal acquisition unit is normal; process the high-frequency signal through bandpass filtering or modulation and demodulation;

[0023] S6. After the signal processing is completed, an ADC anti-aliasing filter is used to perform anti-aliasing processing, and then an analog-to-digital converter ADC is used to perform analog-to-digital conversion.

[0024] Based on the second aspect, in step S2, the microcontroller MCU generates one or more signals, and when selecting multiple signals, different prime frequency signals are output, which are output to the signal separation unit through the analog switch. The signal separation unit judges whether the circuit is wrongly connected and whether the short circuit is normal through the frequency, DC component, and AC component, and analyzes whether the corresponding circuit has an open circuit or a short circuit.

[0025] Based on the second aspect, the signal separation unit further determines whether the transmission coefficient ratio is correct by using the AC amplitude to analyze whether the corresponding line is open or short-circuited.

[0026] Based on the second aspect, the signal separation unit further determines whether there is leakage in the line by DC amplitude and analyzes whether the corresponding line is open or short-circuited.

[0027] The beneficial effects of the present invention are:

[0028] 1) The multi-sensitivity composite sensor of the present invention enables the sensor to obtain multiple sensitivities, so that the required signal has its own appropriate sensitivity and has an appropriate signal-to-noise ratio during the subsequent transmission process.

[0029] 2) The present invention adjusts the gain of high and low frequency signals respectively in the signal acquisition unit, and superimposes the adjusted signals again in the signal acquisition unit to form signals with different frequency sensitivities in each segment.

[0030] 3) In the present invention, since signals with different frequency sensitivities are still transmitted on one signal line, the number of cores in the signal acquisition unit is not increased.

[0031] 4) The present invention separates high and low frequencies at the user end (usually a signal separation unit), restores each frequency component again, and obtains the corresponding sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a multi-sensitivity composite vibration sensor according to an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the structure of a signal acquisition unit according to an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of signal transmission according to an embodiment of the present invention;

[0035] Figure 4 Schematic diagram of signal separation according to an embodiment of the present invention;

[0036] Figure 5 A schematic flow chart of the steps of a separation method according to an embodiment of the present invention;

[0037] Figure 6 A circuit diagram of signal separation and superposition of a signal acquisition unit according to an embodiment of the present invention;

[0038] Figure 7 This is a simulation result diagram of a low-frequency design filter after eliminating high frequencies according to an embodiment of the present invention;

[0039] Figure 8 This is a simulation result diagram of a high-frequency design filter after eliminating low frequencies according to an embodiment of the present invention;

[0040] Figure 9 This is a low-frequency signal equivalent output circuit diagram of an embodiment of the present invention;

[0041] Figure 10 This is a circuit diagram for equivalently outputting high-frequency signals according to an embodiment of the present invention;

[0042] Figure 11 is a simulation diagram of an adding circuit according to an embodiment of the present invention;

[0043] Figure 12 A circuit diagram of a signal input line switch of a preamplifier signal acquisition unit in an embodiment of the present invention being disconnected;

[0044] Figure 13 A circuit diagram of a closed switch of a signal input line of a preamplifier signal acquisition unit according to an embodiment of the present invention;

[0045] Figure 14The schematic diagram of the structure of adding an identification preamplifier to the signal separation unit of the preamplifier according to the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0047] The present invention discloses a multi-sensitivity composite vibration sensor, the structural diagram of which is shown in FIG. Figure 1 As shown, it includes a preamplifier and a signal separation unit, and the signal separation unit is connected to at least one preamplifier; the preamplifier includes an access identification circuit, an analog switch, a microcontroller MCU, a communication module (RS485 or network module), an anti-reverse and interface protection module and at least one signal acquisition unit; the output end of the signal acquisition unit is connected to the access identification circuit, the output end of the access identification circuit is connected to the analog switch, the analog switch is connected to the microcontroller MCU, the microcontroller MCU is connected to the communication module (RS485 or network module), and the output end of the analog switch is connected to the anti-reverse and interface protection module; The signal separation unit includes a third low-pass filter, a third high-pass filter, a low-pass signal processor, a high-pass signal processor, an ADC anti-mixing filter and an analog-to-digital converter ADC. The input end of the third low-pass filter or the third high-pass filter is connected to the anti-reverse and interface protection module, the output end of the third low-pass filter is connected to the low-pass signal processor, the output end of the low-pass signal processor is connected to the ADC anti-mixing filter, the output end of the third high-pass filter is connected to the high-pass signal processor, the output end of the high-pass signal processor is connected to the ADC anti-mixing filter, and the output end of the ADC anti-mixing filter is connected to the analog-to-digital converter ADC.

[0048] Specifically, due to the limitations of the system and physical conditions, the signal acquisition unit adopts a uniform sensitivity, which will result in insufficient low-frequency signal-to-noise ratio. The signal acquisition unit is used to separate the vibration signal and adjust the sensitivity, and then output it to the preamplifier after merging; the preamplifier needs to add an identification circuit that is not inserted into the signal acquisition unit; the preamplifier is connected to at least one signal acquisition unit, and is used to route the signal of the signal acquisition unit out one or more paths to the signal separation unit; the signal separation unit is connected to at least one preamplifier, and the signal separation is integrated inside the signal separation unit to separate and process signals of different sensitivities at each frequency; it is also used to determine whether the signal output by the preamplifier is short-circuited and identify a circuit breaker.

[0049] Exemplarily, the preamplifier further includes a V / I conversion module, the input end of which is connected to the output end of the analog switch, and the output end of which is connected to the anti-reverse and interface protection module. The signal separation unit further includes an I / V conversion module, the input end of which is connected to the anti-reverse and interface protection module, and the output end of which is connected to the high-pass and low-pass switches, respectively.

[0050] Specifically, the signal acquisition unit includes a low-pass amplification module, a high-pass amplification module, an addition circuit and an interface protection module, and its structural diagram is shown in FIG. Figure 2 As shown, the high-frequency signal of the original vibration signal is filtered out by the low-pass amplification module, and the sensitivity of the low-frequency signal is amplified to the target value (the actual sensitivity needs to be matched with the adding circuit again). At the same time, because the high frequency is filtered out, the high frequency has little effect on the low frequency and can be ignored. The low-frequency signal of the original vibration signal is filtered out by the high-pass amplification module, and the sensitivity of the high-frequency signal is adjusted to the target value (the actual sensitivity needs to be matched with the adding circuit again). At the same time, because the low frequency is filtered out, the low frequency has little effect on the high frequency and can be ignored. The signals output by the low-pass amplification module and the high-pass amplification module are added by the adding circuit to synthesize the signal again. At this time, the sensitivity of the low-frequency part and the high-frequency part of the signal are different. The preferred adding circuit matches the sensitivity again to amplify (or reduce) the signal gain after the (low-pass and amplification) module and the (high-pass and amplification) module to finally determine the actual required sensitivity. The installation environment of the signal acquisition unit is harsh, so the interface requires certain protection. The installation environment of the signal acquisition unit is protected by the interface protection module, and the interface protection module includes a TVS device or an ESD device.

[0051] Specifically, it is assumed that the first signal source VG1 of the signal acquisition unit has a DC component ( Figure 6The acceleration sensitivity of AC10mV / g is 5V, and the frequency range is 5Hz~25kHz. Assuming that the required high-frequency sensitivity is still 10mV / g, the selected frequency is 4kHz~25kHz; the required low-frequency sensitivity is 40mV / g, and the selected frequency is 1Hz~1kHz. Assuming that the fluctuation of the above required sensitivity due to circuit adjustment is about 0.5dB, the high-frequency effect on the low-frequency is required to meet -40dB, and the low-frequency effect on the high-frequency is required to meet -40dB. The low-pass amplification module includes a first low-pass filter and a second low-pass filter. The first low-pass filter and the second low-pass filter are connected in series to form a first sixth-order filter. The filter type is Chebyshev type, and the frequency multiplication attenuation can reach 36dB (theoretical value). The high-pass amplification module includes a first high-pass filter and a second high-pass filter. The first high-pass filter and the second high-pass filter are connected in series to form a second sixth-order filter. The frequency multiplication attenuation of the high-frequency part can also reach 36dB. Therefore, the interval between the high frequency and the low frequency only needs to be slightly greater than 1 times; the adding circuit includes a fifth operational amplifier; the first sixth-order filter and the second sixth-order filter are connected in parallel and then connected in series with the fifth operational amplifier.

[0052] Specifically, the circuit diagram of internal signal separation and superposition is as follows: Figure 6 As shown, the signal acquisition unit also includes a first signal source VG1 of an analog signal, which can be a voltage signal output by a MEMS or after piezoelectric conversion. The first low-pass filter includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13 and a first operational amplifier OP1. One end of the eleventh resistor R11 is connected to the first signal source VG1, the other end of the eleventh resistor R11 is connected in series with the twelfth resistor R12 and the thirteenth resistor R13, and then connected to the positive input terminal of the first operational amplifier OP1. One end of the eleventh capacitor C11 is connected to the positive input terminal of the first operational amplifier OP1. the twelfth resistor R12, the other end of the eleventh capacitor C11 is connected to the first reference voltage point, one end of the twelfth capacitor C12 is connected between the twelfth resistor R12 and the thirteenth resistor R13, the other end of the twelfth capacitor C12 is connected to the output terminal of the first operational amplifier OP1, one end of the thirteenth capacitor C13 is connected between the thirteenth resistor R13 and the positive input terminal of the first operational amplifier OP1, the other end of the thirteenth capacitor C13 is connected to the other end of the eleventh capacitor C11 and then to one end of a fourteenth resistor R14, the other end of the fourteenth resistor R14 is connected to the negative input terminal of the first operational amplifier OP1, and a fifteenth resistor R15 is connected in parallel between the negative input terminal and the output terminal of the first operational amplifier OP1;

[0053] The second low-pass filter includes a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-first capacitor C21, a twenty-second capacitor C22, a twenty-third capacitor C23, and a second operational amplifier OP2, one end of the twenty-first resistor R21 is connected to the output end of the first operational amplifier OP1, the other end of the twenty-first resistor R21 is connected in series with the twenty-second resistor R22 and the twenty-third resistor R23, and then connected to the positive input end of the second operational amplifier OP2, one end of the twenty-first capacitor C21 is connected between the twenty-first resistor R21 and the twenty-second resistor R22, and the twenty-first capacitor C21 is connected to the positive input end of the second operational amplifier OP2. the other end of the twenty-second capacitor C22 is connected to the second reference voltage point, one end of the twenty-second capacitor C22 is connected between the twenty-second resistor R22 and the twenty-third resistor R23, the other end of the twenty-second capacitor C22 is connected to the output terminal of the second operational amplifier OP2, one end of the twenty-third capacitor C23 is connected between the twenty-third resistor R23 and the positive input terminal of the second operational amplifier OP2, the other end of the twenty-third capacitor C23 is connected to the other end of the twenty-first capacitor C21 and then to one end of the twenty-fourth resistor R24, the other end of the twenty-fourth resistor R24 ​​is connected to the negative input terminal of the second operational amplifier OP2, and a twenty-fifth resistor R25 is connected in parallel between the negative input terminal and the output terminal of the second operational amplifier OP2;

[0054] The first high-pass filter includes a thirty-first capacitor C31, a thirty-second capacitor C32, a thirty-third capacitor C33, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35 and a third operational amplifier OP3, one end of the thirty-first capacitor C31 is connected to the first signal source VG1, the other end of the thirty-first capacitor C31 is connected in series with the thirty-second capacitor C32 and the thirty-third capacitor C33, and then connected to the positive input terminal of the third operational amplifier OP3, one end of the thirty-first resistor R31 is connected between the thirty-first capacitor C31 and the thirty-second capacitor C32, and the other end of the thirty-first resistor R31 is connected to the positive input terminal of the third operational amplifier OP3. connected to the third reference voltage point, one end of the thirty-second resistor R32 is connected between the thirty-second capacitor C32 and the thirty-third capacitor C33, the other end of the thirty-second resistor R32 is connected to the output terminal of the third operational amplifier OP1, one end of the thirty-third resistor R33 is connected between the thirty-third capacitor C33 and the positive input terminal of the third operational amplifier OP3, the other end of the thirty-third resistor R33 is connected to the other end of the thirty-first resistor R31 and then to one end of the thirty-fourth resistor R34, the other end of the thirty-fourth resistor R34 is connected to the negative input terminal of the third operational amplifier OP3, and a thirty-fifth resistor R35 is connected in parallel between the negative input terminal and the output terminal of the third operational amplifier OP3;

[0055] The second high-pass filter includes a forty-first capacitor C41, a forty-second capacitor C42, a forty-third capacitor C43, a forty-first resistor R41, a forty-second resistor R42, a forty-third resistor R43, a forty-fourth resistor R44, a forty-fifth resistor R45 and a fourth operational amplifier OP4, one end of the forty-first capacitor C41 is connected to the output end of the third operational amplifier OP3, the other end of the forty-first capacitor C41 is connected in series with the forty-second capacitor C42 and the forty-third capacitor C43, and then connected to the positive input end of the fourth operational amplifier OP4, one end of the forty-first resistor R41 is connected between the forty-first capacitor C41 and the forty-second capacitor C42, and the forty-first resistor R41 is connected to the positive input end of the fourth operational amplifier OP4. the other end of the forty-second resistor R42 is connected to the fourth reference voltage point, one end of the forty-second resistor R42 is connected between the forty-second capacitor C42 and the forty-third capacitor C43, the other end of the forty-second resistor R42 is connected to the output terminal of the fourth operational amplifier OP4, one end of the forty-third resistor R43 is connected between the forty-third capacitor C43 and the positive input terminal of the fourth operational amplifier OP4, the other end of the forty-third resistor R43 is connected to the other end of the forty-first resistor R41 and then to one end of the forty-fourth resistor R44, the other end of the forty-fourth resistor R44 is connected to the negative input terminal of the fourth operational amplifier OP4, and a forty-fifth resistor R45 is connected in parallel between the negative input terminal and the output terminal of the fourth operational amplifier OP4;

[0056] The adding circuit includes a first resistor R01, a second resistor R02, a third resistor R03, a fourth resistor R04 and a fifth operational amplifier OP5, one end of the first resistor R01 is connected to the output end of the second operational amplifier, the other end of the first resistor R01 is connected to the positive input end of the fifth operational amplifier OP5, one end of the second resistor R02 is connected to the positive input end of the fifth operational amplifier OP5, the other end of the second resistor R02 is connected to the fifth reference voltage point, one end of the third resistor R03 is connected to the output end of the fourth operational amplifier OP4, the other end of the third resistor R03 is connected to the negative input end of the fifth operational amplifier OP5, and the fourth resistor R04 is connected in parallel between the negative input end and the output end of the fifth operational amplifier OP5.

[0057] Specifically, the high frequency 4kHz and the low frequency 1kHz meet the above requirements, so the filter is designed: the low-pass filter is designed to be 1kHz, and the attenuation is 22.8dB when simulating 2kHz, plus the gain 12dB, the total attenuation is 34.8dB, which is close to the theory. The attenuation of high frequencies above 4kHz can reach 60dB, which basically eliminates the influence of high frequencies on low frequencies. The simulation results of the low-frequency design filter after eliminating high frequencies are shown in the figure below. Figure 7As shown in the figure, if the in-band fluctuation is allowed to be slightly larger (0.5dB), the filtering effect will be better. The high-pass filter is designed to be 4kHz, and the attenuation is 19.5dB when simulating 2k, plus the gain of 12dB, it is about 31.5dB. For signals below 1kHz, the attenuation can reach 57dB, which basically eliminates the influence of low frequency on high frequency. The simulation result of the high-frequency design filter after eliminating low frequency is shown in the figure. Figure 8 As shown; similarly, if the in-band fluctuation is allowed to be slightly larger (0.5dB), the filtering effect will be better.

[0058] Specifically, the addition and gain adjustment circuits are designed to form a differential circuit, where the low-frequency signal is input from the positive terminal and the high-frequency signal is input from the negative terminal. The positive and negative inputs can be adjusted to achieve various gain adjustments; since the high frequency has been filtered out, it can be equivalent to a reference voltage. The output circuit diagram of the low-frequency signal is as follows Figure 9 As shown, it includes a first resistor R01, a second resistor R02, a third resistor R03, a fourth resistor R04, an operational amplifier and a second signal source VG2; one end of the second signal source VG2 is connected to the sixth reference voltage point, the other end of the second signal source VG2 is connected in series with the first resistor R01 and then connected to the positive input terminal of the operational amplifier, one end of the second resistor R02 is connected between the first resistor and the positive input terminal of the operational amplifier, the power supply terminal of the operational amplifier is connected to a 12V voltage, and the ground terminal is grounded; the other end of the second resistor R02 is also connected to the seventh reference voltage point; one end of the third resistor R03 is connected to the eighth reference voltage point, the other end of the third resistor R03 is connected to the negative input terminal of the operational amplifier and one end of the fourth resistor R04, and the other end of the fourth resistor R04 is connected to the output terminal of the operational amplifier; through the formula Compute the output of the low-frequency signal.

[0059] Specifically, since the low frequency has been filtered out, it can be equivalent to the reference voltage. The output circuit diagram of the high frequency signal is as follows: Figure 10 As shown, the high-frequency signal equivalent output circuit includes a first resistor R01, a second resistor R02, a third resistor R03, a fourth resistor R04, an operational amplifier and a third signal source VG3; one end of the third signal source VG3 is connected to the ninth reference voltage point, and the other end is connected in series with one end of the fourth resistor R04, the other end of the fourth resistor R04 is connected to the negative input terminal of the operational amplifier and one end of the third resistor R03, and the other end of the third resistor R03 is connected to the output terminal of the operational amplifier; one end of the first resistor R01 is connected to the tenth reference voltage point, the other end of the first resistor R01 is connected to one end of the second resistor R02 and the positive input terminal of the operational amplifier, the other end of the second resistor R02 is connected to the eleventh reference voltage point, the power supply terminal of the operational amplifier is connected to the 12V voltage, and the ground terminal is grounded; through the formula Calculates the output of a high-frequency signal.

[0060] The simulation diagram of the adding circuit is as follows Figure 11 As shown, at this time, the signal below 1kHz has a 12dB gain (amplified to 4 times), while the signal above 4k has 0dB, which meets the above design requirements. The circuit diagram of the signal input line switch of the signal acquisition unit of the preamplifier is as follows Figure 12 As shown, it includes a pull-up resistor R1 and a pull-down resistor R2. When SW1 is disconnected and the analog signal acquisition unit is not connected: Assuming VCC is 12V, R1=100k, R2=20k, then the voltage of VF1 can be obtained by voltage division: VCC*R2 / (R1+R2)=12*20 / 120=2V. The circuit diagram of the signal input line switch of the preamplifier signal acquisition unit is as follows Figure 13 As shown, when SW1 is closed, the analog signal acquisition unit is connected: at this time, the VF1 voltage is driven by CGQ1, and its voltage is equal to the output voltage of CGQ1.

[0061] The present invention discloses a separation method for the above-mentioned multi-sensitivity composite vibration sensor, the steps of which are shown in the following flow chart: Figure 5 As shown, the signal transmission diagram is as follows Figure 3 As shown; the signal separation diagram is as follows Figure 4 As shown; including the following steps:

[0062] S1. Identify the signals of the first to Nth signal acquisition units through an identification circuit. If the access identification circuit is not added, the system may not be able to identify whether a signal acquisition unit is connected. After adding the access identification circuit, the system can identify the signal acquisition unit when it is not connected.

[0063] S2. The analog switch is controlled by the microcontroller MCU to start the analog signal routing function, and the signals of the first to Nth signal acquisition units are selected to be routed to the V / I conversion module through one or more routes. The analog switch has the analog signal routing function, and is controlled by the microcontroller MCU to select one or more routes of the signals of the first to Nth signal acquisition units to be routed to the V / I conversion module. The microcontroller MCU communicates with the host computer through the communication module (RS485 or network), and cooperates with the host computer to transmit the signals of the first to Nth signal acquisition units. The V / I conversion module This module is optional for converting the selected analog signal into voltage and current. It is required when the signal transmission is current transmission. When voltage transmission is voltage transmission, only voltage regulation and following are required. It also includes anti-reverse and interface protection modules. Since there may be multiple output signals connected in parallel (multiple preamplifiers connected in parallel), the system with parallel connection needs to have anti-reverse function and the interface needs to be protected. In general, signal transmission is the microcontroller MCU assisting the host computer to select the signal of the signal acquisition unit in the preamplifier (the bus identification signal output by the microcontroller needs to be added) and transmit it through the specified voltage or current.

[0064] S3, the V / I conversion module converts the signal after the analog signal selection into voltage and current. The V / I conversion module is optional. If the signal transmission is voltage transmission, only voltage regulation and following are required. Because there may be multiple output signals connected in parallel (multiple preamplifiers connected in parallel), the system with parallel connection needs to have an anti-reverse function and the interface needs to be protected. Therefore, an anti-reverse and interface protection module is set on the output interface. In general, signal transmission is the microcontroller MCU assisting the host computer to select the signal of the signal acquisition unit in the preamplifier (adding the bus identification signal output by the microcontroller) and transmit it through the specified voltage or current.

[0065] S4. Convert the current signal back to a voltage signal through an I / V conversion module, separate the low-frequency signal in the signal of the signal acquisition unit through a third low-pass filter, the low-frequency frequency of the third low-pass filter cannot be higher than the low-pass amplification module of the signal acquisition unit; separate the high-frequency signal in the signal of the signal acquisition unit through a third high-pass filter, the high-frequency frequency of the third high-pass filter cannot be lower than the high-pass amplification module of the signal acquisition unit; the preamplifier signal is the signal output in step S3; current transmission is usually adopted; if the system adopts current transmission, an I / V conversion module needs to be added here to convert the current signal back to a voltage signal; the signal at this time contains all the sensor signals of the signal acquisition unit;

[0066] S5. Extract the low-frequency signal and obtain the velocity through integration, obtain the displacement through double integration, and extract the DC signal to determine whether the static operating point of the signal acquisition unit is normal; process the high-frequency signal through bandpass filtering or modulation and demodulation;

[0067] S6. After the signal processing is completed, analog-to-digital conversion is required. Before the analog-to-digital conversion, the signal needs to be anti-aliased. Usually, an ADC anti-aliasing filter is used for filtering. Some ADC chips have built-in anti-aliasing filters. For example, a Σ-Δ type ADC is selected to meet the sampling theorem; then the analog-to-digital conversion is performed through the analog-to-digital converter ADC.

[0068] Specifically, the structural diagram of the preamplifier adding the recognition preamplifier is as follows Figure 14 As shown, in step S2, the microcontroller MCU generates one or more signals (which can be consistent with the number of analog switch outputs). When selecting multiple signals, different prime frequency signals are output (such as 3, 5, 7, 11, 13, 17, etc.). The signals are output to the signal separation unit through the analog switch (the analog switch is implemented by the host computer controlling the microcontroller MCU). The signal separation unit determines whether the circuit is connected incorrectly and whether the short circuit is normal based on the frequency, DC component, and AC component, and analyzes whether the corresponding circuit has an open circuit or a short circuit. The signal separation unit also determines whether the transmission coefficient ratio is correct based on the AC signal amplitude and analyzes whether the corresponding line is open or short-circuited. The signal separation unit also determines whether there is leakage in the line based on the DC signal amplitude and analyzes whether the corresponding line is open or short-circuited.

[0069] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A multi-sensitivity composite vibration sensor, characterized in that: It includes a preamplifier and a signal separation unit, wherein the signal separation unit is connected to at least one preamplifier; The preamplifier includes an access identification circuit, an analog switch, a microcontroller MCU, an anti-reverse and interface protection module and at least one signal acquisition unit; the output end of the signal acquisition unit is connected to the access identification circuit, the output end of the access identification circuit is connected to the analog switch, the analog switch is connected to the microcontroller MCU, and the output end of the analog switch is connected to the anti-reverse and interface protection module; The signal separation unit includes a third low-pass filter, a third high-pass filter, a low-pass signal processor, a high-pass signal processor, an ADC anti-mixing filter and an analog-to-digital converter ADC, the input end of the third low-pass filter or the third high-pass filter is connected to the anti-reverse and interface protection module, the output end of the third low-pass filter is connected to the low-pass signal processor, the output end of the low-pass signal processor is connected to the ADC anti-mixing filter, the output end of the third high-pass filter is connected to the high-pass signal processor, the output end of the high-pass signal processor is connected to the ADC anti-mixing filter, and the output end of the ADC anti-mixing filter is connected to the analog-to-digital converter ADC; The signal acquisition unit includes a low-pass amplification module, a high-pass amplification module, an addition circuit and an interface protection module. The low-pass amplification module is used to filter out the high-frequency signal of the original vibration signal and amplify the sensitivity of the low-frequency signal to the target value; the high-pass amplification module is used to filter out the low-frequency signal of the original vibration signal and adjust the sensitivity of the high-frequency signal to the target value; the signals output by the low-pass amplification module and the high-pass amplification module are added by the addition circuit to synthesize the signal again. At this time, the sensitivities of the low-frequency part and the high-frequency part of the signal are different; the interface protection module is used to protect the installation environment of the signal acquisition unit, and the interface protection module includes a TVS device or an ESD device.

2. The multi-sensitivity composite vibration sensor according to claim 1, characterized in that: The preamplifier further includes a V / I conversion module, the input end of the V / I conversion module is connected to the output end of the analog switch, and the output end of the V / I conversion module is connected to the anti-reverse and interface protection module.

3. The multi-sensitivity composite vibration sensor according to claim 2, characterized in that: The signal separation unit further includes an I / V conversion module, the input end of the I / V conversion module is connected to the anti-reverse and interface protection module, and the output end of the I / V conversion module is respectively connected to the third low-pass filter and the third high-pass filter.

4. The multi-sensitivity composite vibration sensor according to claim 1, characterized in that: The low-pass amplification module includes a first low-pass filter and a second low-pass filter, which are connected in series to form a first sixth-order filter; the high-pass amplification module includes a first high-pass filter and a second high-pass filter, which are connected in series to form a second sixth-order filter; the adding circuit includes a fifth operational amplifier; the first sixth-order filter and the second sixth-order filter are connected in parallel and then connected in series to the fifth operational amplifier.

5. The multi-sensitivity composite vibration sensor according to claim 4, characterized in that: The signal acquisition unit also includes a first signal source VG1 of an analog signal, the first low-pass filter includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13 and a first operational amplifier OP1, one end of the eleventh resistor R11 is connected to the first signal source VG1, the other end of the eleventh resistor R11 is connected in series with the twelfth resistor R12 and the thirteenth resistor R13 and then connected to the positive input end of the first operational amplifier OP1, one end of the eleventh capacitor C11 is connected between the eleventh resistor R11 and the twelfth resistor R12, the eleventh capacitor C11 is connected to the positive input end of the first operational amplifier OP1, The other end of the capacitor C11 is connected to the first reference voltage point, one end of the twelfth capacitor C12 is connected between the twelfth resistor R12 and the thirteenth resistor R13, the other end of the twelfth capacitor C12 is connected to the output terminal of the first operational amplifier OP1, one end of the thirteenth capacitor C13 is connected between the thirteenth resistor R13 and the positive input terminal of the first operational amplifier OP1, the other end of the thirteenth capacitor C13 is connected to the other end of the eleventh capacitor C11 and then to one end of a fourteenth resistor R14, the other end of the fourteenth resistor R14 is connected to the negative input terminal of the first operational amplifier OP1, and a fifteenth resistor R15 is connected in parallel between the negative input terminal and the output terminal of the first operational amplifier OP1; The second low-pass filter includes a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-first capacitor C21, a twenty-second capacitor C22, a twenty-third capacitor C23, and a second operational amplifier OP2, one end of the twenty-first resistor R21 is connected to the output end of the first operational amplifier OP1, the other end of the twenty-first resistor R21 is connected in series with the twenty-second resistor R22 and the twenty-third resistor R23, and then connected to the positive input end of the second operational amplifier OP2, one end of the twenty-first capacitor C21 is connected between the twenty-first resistor R21 and the twenty-second resistor R22, and the twenty-first capacitor C21 is connected to the positive input end of the second operational amplifier OP2. the other end of the twenty-second capacitor C22 is connected to the second reference voltage point, one end of the twenty-second capacitor C22 is connected between the twenty-second resistor R22 and the twenty-third resistor R23, the other end of the twenty-second capacitor C22 is connected to the output terminal of the second operational amplifier OP2, one end of the twenty-third capacitor C23 is connected between the twenty-third resistor R23 and the positive input terminal of the second operational amplifier OP2, the other end of the twenty-third capacitor C23 is connected to the other end of the twenty-first capacitor C21 and then to one end of the twenty-fourth resistor R24, the other end of the twenty-fourth resistor R24 ​​is connected to the negative input terminal of the second operational amplifier OP2, and a twenty-fifth resistor R25 is connected in parallel between the negative input terminal and the output terminal of the second operational amplifier OP2; The first high-pass filter includes a thirty-first capacitor C31, a thirty-second capacitor C32, a thirty-third capacitor C33, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35 and a third operational amplifier OP3, one end of the thirty-first capacitor C31 is connected to the first signal source VG1, the other end of the thirty-first capacitor C31 is connected in series with the thirty-second capacitor C32 and the thirty-third capacitor C33, and then connected to the positive input terminal of the third operational amplifier OP3, one end of the thirty-first resistor R31 is connected between the thirty-first capacitor C31 and the thirty-second capacitor C32, and the other end of the thirty-first resistor R31 is connected to the positive input terminal of the third operational amplifier OP3. connected to the third reference voltage point, one end of the thirty-second resistor R32 is connected between the thirty-second capacitor C32 and the thirty-third capacitor C33, the other end of the thirty-second resistor R32 is connected to the output terminal of the third operational amplifier OP1, one end of the thirty-third resistor R33 is connected between the thirty-third capacitor C33 and the positive input terminal of the third operational amplifier OP3, the other end of the thirty-third resistor R33 is connected to the other end of the thirty-first resistor R31 and then to one end of the thirty-fourth resistor R34, the other end of the thirty-fourth resistor R34 is connected to the negative input terminal of the third operational amplifier OP3, and a thirty-fifth resistor R35 is connected in parallel between the negative input terminal and the output terminal of the third operational amplifier OP3; The second high-pass filter includes a forty-first capacitor C41, a forty-second capacitor C42, a forty-third capacitor C43, a forty-first resistor R41, a forty-second resistor R42, a forty-third resistor R43, a forty-fourth resistor R44, a forty-fifth resistor R45 and a fourth operational amplifier OP4, one end of the forty-first capacitor C41 is connected to the output end of the third operational amplifier OP3, the other end of the forty-first capacitor C41 is connected in series with the forty-second capacitor C42 and the forty-third capacitor C43, and then connected to the positive input end of the fourth operational amplifier OP4, one end of the forty-first resistor R41 is connected between the forty-first capacitor C41 and the forty-second capacitor C42, and the forty-first resistor R41 is connected to the positive input end of the fourth operational amplifier OP4. the other end of the forty-second resistor R42 is connected to the fourth reference voltage point, one end of the forty-second resistor R42 is connected between the forty-second capacitor C42 and the forty-third capacitor C43, the other end of the forty-second resistor R42 is connected to the output terminal of the fourth operational amplifier OP4, one end of the forty-third resistor R43 is connected between the forty-third capacitor C43 and the positive input terminal of the fourth operational amplifier OP4, the other end of the forty-third resistor R43 is connected to the other end of the forty-first resistor R41 and then to one end of the forty-fourth resistor R44, the other end of the forty-fourth resistor R44 is connected to the negative input terminal of the fourth operational amplifier OP4, and a forty-fifth resistor R45 is connected in parallel between the negative input terminal and the output terminal of the fourth operational amplifier OP4; The adding circuit includes a first resistor R01, a second resistor R02, a third resistor R03, a fourth resistor R04 and a fifth operational amplifier OP5, one end of the first resistor R01 is connected to the output end of the second operational amplifier, the other end of the first resistor R01 is connected to the positive input end of the fifth operational amplifier OP5, one end of the second resistor R02 is connected to the positive input end of the fifth operational amplifier OP5, the other end of the second resistor R02 is connected to the fifth reference voltage point, one end of the third resistor R03 is connected to the output end of the fourth operational amplifier OP4, the other end of the third resistor R03 is connected to the negative input end of the fifth operational amplifier OP5, and the fourth resistor R04 is connected in parallel between the negative input end and the output end of the fifth operational amplifier OP5.

6. A separation method for a multi-sensitivity composite vibration sensor according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Identify signals from the first to Nth signal acquisition units through an identification circuit; S2. Controlling the analog switch through the microcontroller MCU to start the analog signal routing function, selecting one or more routes of the signals from the first to Nth signal acquisition units to be routed to the V / I conversion module; S3, the V / I conversion module converts the signal after the analog signal selection into voltage and current. If the signal transmission is voltage transmission, only voltage regulation and following are required; anti-reverse and interface protection modules are set on the output interface to protect the interface; S4. Convert the current signal back into a voltage signal through the I / V conversion module, separate the low-frequency signal from the signal of the signal acquisition unit through a third low-pass filter, where the low-frequency frequency of the third low-pass filter cannot be higher than that of the low-pass amplification module of the signal acquisition unit; and separate the high-frequency signal from the signal of the signal acquisition unit through a third high-pass filter, where the high-frequency frequency of the third high-pass filter cannot be lower than that of the high-pass amplification module of the signal acquisition unit; S5. Extract the low-frequency signal and obtain the velocity through integration, obtain the displacement through double integration, and extract the DC signal to determine whether the static operating point of the signal acquisition unit is normal; process the high-frequency signal through bandpass filtering or modulation and demodulation; S6. After the signal processing is completed, an ADC anti-aliasing filter is used to perform anti-aliasing processing, and then an analog-to-digital converter ADC is used to perform analog-to-digital conversion.

7. A separation method according to claim 6, characterized in that: In step S2, the microcontroller MCU generates one or more signals, and when selecting multiple signals, different prime frequency signals are output, and the signals are output to the signal separation unit through the analog switch. The signal separation unit determines whether the circuit is connected incorrectly and whether the short circuit is normal based on the frequency, DC component, and AC component, and analyzes whether the corresponding circuit has an open circuit or a short circuit.

8. A separation method according to claim 6, characterized in that: The signal separation unit also determines whether the transmission coefficient ratio is correct by the AC amplitude and analyzes whether the corresponding line is open or short-circuited.

9. A separation method according to claim 6, characterized in that: The signal separation unit further determines whether there is leakage in the line by DC amplitude and analyzes whether the corresponding line is open or short-circuited.

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