Non-contact track frequency-shift signal monitoring method and system based on online calibration

Abstract

The application discloses an online calibration-based non-contact track frequency-shift signal monitoring method and system, and applies to the technical field of intelligent monitoring.The method comprises the following steps: sensing a measured voltage of a sensing signal line; receiving an output voltage output by a conditioning circuit; calculating the measured voltage; when calibration is performed, injecting a starting signal to record a starting voltage; injecting a calibration signal to an injection point; and calibrating a zero voltage of the conditioning circuit according to a calibration voltage output by the conditioning circuit in response to the calibration signal and the starting voltage.The online calibration-based non-contact track frequency-shift signal monitoring method and system adopts a calibration signal with the same frequency and amplitude as a reference voltage, records reference frequency band voltages before and after the calibration signal is injected, directly obtains the zero voltage by subtracting the two, and does not need to solve complex simultaneous equations, so that the calculation is simple and efficient.

Description

Technical Field

[0001] This invention relates to the field of intelligent monitoring technology, specifically to a non-contact track frequency shift signal monitoring method and system based on online calibration. Background Technology

[0002] Online monitoring of track frequency shift (RF) transmission and reception signals is a crucial component of centralized railway signal monitoring systems, directly impacting train operation safety. Existing contact-based RF signal monitoring requires connection to the signal loop. Although monitoring modules all require high-impedance, high-isolation input signals, the risk of short circuits in the monitoring module affecting the signal loop remains. With the development of non-contact voltage measurement technology, non-contact online monitoring of track RF signals has become the main trend, and railway bureaus have explicitly mandated that all newly built stations must adopt non-contact monitoring.

[0003] In the prior art, the inventor's earlier application, Chinese Patent Application No. CN202511301102.1, discloses a non-contact online monitoring method and system for track frequency shift signals, applied in the field of intelligent monitoring technology. The method includes: receiving a first measured voltage and a second measured voltage; inputting the first measured voltage and the second measured voltage into a first conditioning circuit through a first transmission line to receive a first output voltage output by the first conditioning circuit; inputting the first measured voltage and the second measured voltage into a parallel transmission line formed by connecting the second and third transmission lines in parallel to receive a second output voltage output by the second conditioning circuit; and calculating the first measured voltage based on the first output voltage and the second output voltage. However, in actual use, the inventor found that as the capacitance values ​​to ground of the first, second, and third transmission lines may change, after long-term use of this patented technology, the capacitance values ​​to ground of the second and third transmission lines will no longer remain twice that of the first transmission line, thus causing a deviation in the final output result. Summary of the Invention

[0004] In order to at least overcome the above-mentioned shortcomings in the prior art, the purpose of this application is to provide a non-contact track frequency shift signal monitoring method and system based on online calibration.

[0005] In a first aspect, embodiments of this application provide a non-contact track frequency shift signal monitoring method based on online calibration, including:

[0006] The sensing layer copper tube is fitted onto the signal line and senses the voltage being measured on the signal line;

[0007] The voltage to be measured is input to the conditioning circuit through a transmission line, and the output voltage output by the conditioning circuit is received.

[0008] The measured voltage is calculated based on the output voltage and the zero-point voltage of the conditioning circuit;

[0009] When calibrating the zero-point voltage of the conditioning circuit, a start signal is injected into the injection point; the injection point is the connection point between the sensing layer copper tube and the transmission line.

[0010] When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage;

[0011] After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit.

[0012] The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

[0013] In one possible implementation, calculating the measured voltage includes:

[0014] The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage;

[0015] The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

[0016] In one possible implementation, the output voltage is expressed by the following formula:

[0017] ;

[0018] ;

[0019] ;

[0020] In the formula, V OUT Where ω is the output voltage, K is the total gain of the conditioning circuit, and ω is the output voltage. in V is the frequency of the voltage being measured. in+ The measured voltage is C1, which is the coupling capacitance between the induction layer copper tube of the signal line and the signal line. ω R V is the frequency of the reference voltage for the conditioning circuit. R C is the reference voltage for the conditioning circuit. in V is the equivalent distributed capacitance of the transmission line and the copper tube of the sensing layer to ground. zero The zero-point voltage, V Oin V is the voltage of the measured frequency band of the output voltage. OR This is the reference frequency band voltage for the output voltage.

[0021] In one possible implementation, calibrating the zero-point voltage includes:

[0022] The calibrated voltage is filtered to the frequency band of the reference voltage of the conditioning circuit to form the filtered voltage;

[0023] The difference between the filtered voltage and the starting voltage is calculated as the difference voltage;

[0024] The difference between the starting voltage and the differential voltage is calculated as the zero-point voltage.

[0025] In one possible implementation, the calculation of the measured voltage includes:

[0026] The measured voltage is calculated using the following formula:

[0027]

[0028] In the formula, K2 is the gain coefficient.

[0029] In one possible implementation, the conditioning circuit detects the start signal by including:

[0030] When a signal corresponding to the frequency band of the start signal is detected in the output voltage of the conditioning circuit, it is determined that the conditioning circuit has detected the start signal.

[0031] In one possible implementation, the generation of the output voltage includes:

[0032] The measured voltage is processed by two cascaded operational amplifiers to generate an operational voltage. The non-inverting input of the first operational amplifier is connected to a reference voltage, and the inverting input of the second operational amplifier is connected to the measured voltage. The inverting input is connected to the output of the first operational amplifier through a voltage divider resistor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the second operational amplifier is connected to the voltage-divided reference voltage. The inverting input is connected to the output of the second operational amplifier through a voltage divider resistor.

[0033] The first operational voltage is connected to the non-inverting input of the terminal operational amplifier, and the second operational voltage is connected to the inverting input of the terminal operational amplifier; the inverting input of the terminal operational amplifier is connected to the output of the terminal operational amplifier through a resistor.

[0034] The voltage output from the output terminal of the terminal operational amplifier is taken as the output voltage.

[0035] In one possible implementation, the frequencies of the reference voltage, the start signal, and the measured voltage are all different.

[0036] Secondly, this application also provides a non-contact track frequency shift signal monitoring system based on online calibration, including:

[0037] The sensing unit is configured to have a sensing layer copper tube fitted onto a signal line and to sense the measured voltage of the signal line;

[0038] The conditioning unit is configured to input the measured voltage into the conditioning circuit via a transmission line and receive the output voltage output by the conditioning circuit;

[0039] The calculation unit is configured to calculate the measured voltage based on the output voltage and the zero-point voltage of the conditioning circuit;

[0040] The calibration unit is configured to inject a start signal into the injection point when calibrating the zero-point voltage of the conditioning circuit; the injection point is the connection point between the sensing layer copper tube and the transmission line.

[0041] When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage;

[0042] After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit.

[0043] The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

[0044] In one possible implementation, the computing unit is further configured as follows:

[0045] The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage;

[0046] The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] 1. The present invention is a non-contact track frequency shift signal monitoring method and system based on online calibration. It uses a calibration signal with the same frequency and amplitude as the reference voltage. The reference frequency band voltage is recorded before and after the calibration signal is injected. The zero-point voltage is obtained directly by subtracting the two, without the need for complex simultaneous equations. The calculation is simple and efficient.

[0049] 2. The present invention is based on a non-contact track frequency shift signal monitoring method and system with online calibration. It only requires a single transmission line and a conditioning circuit, without the need for complex differential structures or multi-line symmetrical designs. The injection circuit only needs to add a high-impedance coupling injection unit at the copper tube node. The hardware modification is small, the cost is low, and it is easy to upgrade existing equipment. Attached Figure Description

[0050] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0051] Figure 1 This is a schematic diagram of the method steps in an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of the conditioning circuit in an embodiment of this application. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0054] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0055] Please refer to the following: Figure 1 The above is a flowchart illustrating the non-contact track frequency shift signal monitoring method based on online calibration provided in this embodiment of the invention. Further, the non-contact track frequency shift signal monitoring method based on online calibration may specifically include the contents described in steps S1-S7.

[0056] S1: The sensing layer copper tube is fitted onto the signal line, and the measured voltage of the signal line is sensed;

[0057] S2: Input the voltage to be measured into the conditioning circuit through the transmission line, and receive the output voltage output by the conditioning circuit;

[0058] S3: Calculate the measured voltage based on the output voltage and the zero-point voltage of the conditioning circuit;

[0059] S4: When calibrating the zero-point voltage of the conditioning circuit, a start signal is injected into the injection point; the injection point is the connection point between the sensing layer copper tube and the transmission line.

[0060] S5: When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage;

[0061] S6: After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit.

[0062] S7: The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

[0063] In implementing this application embodiment, the measured induction needs to be acquired first, which is achieved through the copper induction layer. The specific induction process has been described in previous applications, and this application embodiment will not be limited further. It should be understood that the signal lines include L signal lines and N signal lines, so the corresponding measured voltages are also the measured voltages corresponding to the L signal lines and the measured voltages corresponding to the N signal lines; for the structure of the conditioning circuit, please refer to [link to relevant documentation]. Figure 2 Where Vin+ is the input terminal of the measured voltage of the L signal line, Vin- is the input terminal of the measured voltage of the N signal line, C1 is the coupling capacitance between the sensing layer copper tube of the L signal line and the L signal line, C2 is the coupling capacitance between the sensing layer copper tube of the N signal line and the L signal line, and C... in1 C is the equivalent distributed capacitance to ground of the copper tube in the sensing layer of the transmission line and the L signal line. in2 The table shows the equivalent distributed capacitance to ground of the induction layer copper tubes of the transmission line and N signal line. Generally, Vin- is approximately zero, so its corresponding parameters will not be characterized in the following content; VRG1 and VRG2 are reference voltages, VCC is the positive supply voltage, VEE is the negative supply voltage, GND is ground, and R1~R14 are resistors.

[0064] In this embodiment, the measured voltage can be calculated from the zero-point voltage and output voltage of the conditioning circuit. The calculation process has been described in detail in previous applications, and this embodiment will not be limited further. The zero-point voltage is the capacitance C corresponding to the transmission line and the copper tube in the sensing layer. in The influence of capacitance value is eliminated in previous applications by using three transmission lines. However, over time, even within the same cable, these three transmission lines may exhibit different capacitance values, thus affecting monitoring accuracy. Therefore, in this embodiment, an injection calibration method is used for zero-point voltage calibration. Unlike existing calibration methods, this application employs an automatic on-line calibration method. During calibration, a start signal is injected first, indicating that calibration must begin immediately. The reference frequency band voltage component of the output voltage from the conditioning circuit must be recorded immediately. This component represents the inherent characteristics from the signal line to the conditioning circuit and is unaffected by the measured voltage itself, thus remaining constant within a limited timeframe. After a preset duration of the start signal injection, such as 500ms, the formal calibration signal injection begins. Unlike existing calibration methods, the calibration signal in this embodiment uses the same frequency and voltage amplitude as the reference voltage of the conditioning circuit. This is because, for the conditioning circuit, its... The output voltage comprises two components: the voltage of the measured frequency band and the voltage of the reference frequency band. The voltage of the measured frequency band is generated by filtering the output voltage to the frequency band of the measured voltage and directly represents the measured voltage. The voltage of the reference frequency band is generated by filtering the output voltage to the frequency band of the reference frequency band and represents the state of the entire line and the conditioning circuit. When the start-up voltage has been recorded, after the conditioning circuit responds to the calibration signal and outputs the calibration voltage, the calibration voltage also contains two components: the voltage of the measured frequency band and the voltage of the reference frequency band. The voltage of the reference frequency band is the start-up voltage. Therefore, by filtering the calibration voltage to the frequency band of the reference voltage and then subtracting the start-up voltage, the voltage of the measured frequency band corresponding to the calibration voltage can be obtained. The zero-point voltage is the difference between the start-up voltage and the voltage of the measured frequency band. The embodiments of this application achieve the calibration of the zero-point voltage in a simple and effective way.

[0065] In one possible implementation, calculating the measured voltage includes:

[0066] The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage;

[0067] The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

[0068] In one possible implementation, the output voltage is expressed by the following formula:

[0069] ;

[0070] ;

[0071] ;

[0072] In the formula, V OUT Where ω is the output voltage, K is the total gain of the conditioning circuit, and ω is the output voltage. in V is the frequency of the voltage being measured. in+ The measured voltage is C1, which is the coupling capacitance between the induction layer copper tube of the signal line and the signal line. ω R V is the frequency of the reference voltage for the conditioning circuit. R C is the reference voltage for the conditioning circuit. in V is the equivalent distributed capacitance of the transmission line and the copper tube of the sensing layer to ground. zero The zero-point voltage, V Oin V is the voltage of the measured frequency band of the output voltage. OR This is the reference frequency band voltage for the output voltage.

[0073] In one possible implementation, calibrating the zero-point voltage includes:

[0074] The calibrated voltage is filtered to the frequency band of the reference voltage of the conditioning circuit to form the filtered voltage;

[0075] The difference between the filtered voltage and the starting voltage is calculated as the difference voltage;

[0076] The difference between the starting voltage and the differential voltage is calculated as the zero-point voltage.

[0077] When implementing the embodiments of this application, it can be seen from the above formula that the calibration voltage itself includes two measured frequency band voltages and a reference frequency band voltage. The reference frequency band voltage is the starting voltage recorded at startup. By calculating the difference between the filtered voltage after calibrating the voltage and the starting voltage, the measured frequency band voltage of the calibration voltage, i.e., the difference voltage, can be obtained. Since the starting voltage and the difference voltage have the same frequency amplitude, the difference between the two is the zero-point voltage.

[0078] In one possible implementation, the calculation of the measured voltage includes:

[0079] The measured voltage is calculated using the following formula:

[0080]

[0081] In the formula, K2 is the gain coefficient.

[0082] In one possible implementation, the conditioning circuit detects the start signal by including:

[0083] When a signal corresponding to the frequency band of the start signal is detected in the output voltage of the conditioning circuit, it is determined that the conditioning circuit has detected the start signal.

[0084] In the implementation of this application embodiment, the frequency of the reference voltage, the frequency of the start signal, and the frequency of the measured voltage are all different, so the start signal can be effectively identified through filtering.

[0085] In one possible implementation, the generation of the output voltage includes:

[0086] The measured voltage is processed by two cascaded operational amplifiers to generate an operational voltage. The non-inverting input of the first operational amplifier is connected to a reference voltage, and the inverting input of the second operational amplifier is connected to the measured voltage. The inverting input is connected to the output of the first operational amplifier through a voltage divider resistor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the second operational amplifier is connected to the voltage-divided reference voltage. The inverting input is connected to the output of the second operational amplifier through a voltage divider resistor.

[0087] The first operational voltage is connected to the non-inverting input of the terminal operational amplifier, and the second operational voltage is connected to the inverting input of the terminal operational amplifier; the inverting input of the terminal operational amplifier is connected to the output of the terminal operational amplifier through a resistor.

[0088] The voltage output from the output terminal of the terminal operational amplifier is taken as the output voltage.

[0089] In one possible implementation, the frequencies of the reference voltage, the start signal, and the measured voltage are all different.

[0090] Based on the same inventive concept, this application also provides a non-contact track frequency shift signal monitoring system based on online calibration, including:

[0091] The sensing unit is configured to have a sensing layer copper tube fitted onto a signal line and to sense the measured voltage of the signal line;

[0092] The conditioning unit is configured to input the measured voltage into the conditioning circuit via a transmission line and receive the output voltage output by the conditioning circuit;

[0093] The calculation unit is configured to calculate the measured voltage based on the output voltage and the zero-point voltage of the conditioning circuit;

[0094] The calibration unit is configured to inject a start signal into the injection point when calibrating the zero-point voltage of the conditioning circuit; the injection point is the connection point between the sensing layer copper tube and the transmission line.

[0095] When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage;

[0096] After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit.

[0097] The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

[0098] In one possible implementation, the computing unit is further configured as follows:

[0099] The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage;

[0100] The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

[0101] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices or units, or may be electrical, mechanical or other forms of connection.

[0103] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-contact track frequency shift signal monitoring method based on online calibration, characterized in that, include: The sensing layer copper tube is fitted onto the signal line and senses the voltage being measured on the signal line; The voltage to be measured is input to the conditioning circuit through a transmission line, and the output voltage output by the conditioning circuit is received. The measured voltage is calculated based on the output voltage and the zero-point voltage of the conditioning circuit; When calibrating the zero-point voltage of the conditioning circuit, a start signal is injected into the injection point; the injection point is the connection point between the sensing layer copper tube and the transmission line. When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage; After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit. The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

2. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 1, characterized in that, The calculation of the measured voltage includes: The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage; The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

3. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 2, characterized in that, The output voltage is expressed by the following formula: ； ； ； In the formula, V OUT Where ω is the output voltage, K is the total gain of the conditioning circuit, and ω is the output voltage. in V is the frequency of the voltage being measured. in+ The measured voltage is C1, which is the coupling capacitance between the induction layer copper tube of the signal line and the signal line. ω R V is the frequency of the reference voltage for the conditioning circuit. R C is the reference voltage for the conditioning circuit. in V is the equivalent distributed capacitance of the transmission line and the copper tube of the sensing layer to ground. zero The zero-point voltage, V Oin V is the voltage of the measured frequency band of the output voltage. OR This is the reference frequency band voltage for the output voltage.

4. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 2, characterized in that, The calibration of the zero-point voltage includes: The calibrated voltage is filtered to the frequency band of the reference voltage of the conditioning circuit to form the filtered voltage; The difference between the filtered voltage and the starting voltage is calculated as the difference voltage; The difference between the starting voltage and the differential voltage is calculated as the zero-point voltage.

5. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 2, characterized in that, The calculation of the measured voltage includes: The measured voltage is calculated using the following formula: In the formula, K2 is the gain coefficient.

6. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 1, characterized in that, The conditioning circuit detects the start signal, including: When a signal corresponding to the frequency band of the start signal is detected in the output voltage of the conditioning circuit, it is determined that the conditioning circuit has detected the start signal.

7. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 1, characterized in that, The generation of the output voltage includes: The measured voltage is processed by two cascaded operational amplifiers to generate an operational voltage. The non-inverting input of the first operational amplifier is connected to a reference voltage, and the inverting input of the second operational amplifier is connected to the measured voltage. The inverting input is connected to the output of the first operational amplifier through a voltage divider resistor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the second operational amplifier is connected to the voltage-divided reference voltage. The inverting input is connected to the output of the second operational amplifier through a voltage divider resistor. The first operational voltage is connected to the non-inverting input of the terminal operational amplifier, and the second operational voltage is connected to the inverting input of the terminal operational amplifier; the inverting input of the terminal operational amplifier is connected to the output of the terminal operational amplifier through a resistor. The voltage output from the output terminal of the terminal operational amplifier is taken as the output voltage.

8. The non-contact track frequency shift signal monitoring method based on online calibration according to claim 1, characterized in that, The frequencies of the reference voltage, the start signal, and the measured voltage are all different.

9. A non-contact track frequency shift signal monitoring system based on online calibration, characterized in that, include: The sensing unit is configured to have a sensing layer copper tube fitted onto a signal line and to sense the measured voltage of the signal line; The conditioning unit is configured to input the measured voltage into the conditioning circuit via a transmission line and receive the output voltage output by the conditioning circuit; The calculation unit is configured to calculate the measured voltage based on the output voltage and the zero-point voltage of the conditioning circuit; The calibration unit is configured to inject a start signal into the injection point when calibrating the zero-point voltage of the conditioning circuit; the injection point is the connection point between the sensing layer copper tube and the transmission line. When the conditioning circuit detects the start signal, it records the reference frequency band voltage of the output voltage at the current moment as the start voltage; After a preset duration of the injection start signal, a calibration signal is injected into the injection point; the frequency and voltage amplitude of the calibration signal are the same as the frequency and voltage amplitude of the reference voltage of the conditioning circuit. The zero-point voltage of the conditioning circuit is calibrated based on the calibration voltage output by the conditioning circuit in response to the calibration signal and the start-up voltage.

10. The non-contact track frequency shift signal monitoring system based on online calibration according to claim 9, characterized in that, The computing unit is further configured to: The output voltage is filtered to the frequency band of the measured voltage to form the measured frequency band voltage, and the output voltage is filtered to the frequency band of the reference voltage to form the reference frequency band voltage; The measured voltage is calculated based on the measured frequency band voltage, the reference frequency band voltage, and the zero-point voltage.

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