Interoperable subway transponder antenna power monitoring circuit

Abstract

The application discloses an interconnection and intercommunication subway transponder antenna power supply monitoring circuit which comprises a self-excitation oscillation circuit, a multi-stage amplification circuit and a rectification limiting circuit, wherein the multi-stage amplification circuit comprises a plurality of differential amplification circuits and a Wollman amplification circuit, all the circuit modules are realized by using analog discrete devices, the device price is low, a power supply self-checking signal is generated through the self-excitation oscillation circuit, the structure is simple, the number of the differential amplification circuits is configured according to the number of the power supply channels to be monitored, the applicability and portability of the circuit are improved, and coupling capacitors are connected in series between adjacent circuit modules, so that the self-checking reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of railway communication signals, and in particular to a power supply monitoring circuit for interoperable metro transponder antennas. Background Technology

[0002] In the field of railway communication and signaling, the circuit boards inside universally interconnected metro transponder antenna systems have high safety design requirements, necessitating the design of monitoring circuits for each signal processing module. Circuits built with voltage monitor chips featuring I2C ports and ADC (analog-to-digital converter) types are typically used for voltage monitoring across various channels of the board-level circuitry. However, these voltage monitor chips face the following challenges in actual circuit design, safety principle design, and circuit board mass production: 1. Voltage Monitor chips are expensive, and when circuit boards are mass-produced, these chips often face tight supply issues. 2. Circuits built based on Voltage Monitor chips have a fixed number of monitoring channels and are not easily expandable; 3. The method of inputting power signals to the chip through resistor voltage division lacks self-test signals, resulting in low safety redundancy in the open-loop system; 4. When a power supply fault occurs on the circuit board, it is difficult to quickly determine whether the problem lies with the power channel or the power monitoring module.

[0003] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention

[0004] The purpose of this invention is to provide an interconnected subway transponder antenna power monitoring circuit that is low in cost, simple in structure, easy to expand, and has high reliability and accuracy.

[0005] To achieve the above objectives, the present invention provides an interconnected subway transponder antenna power supply monitoring circuit, comprising: The self-excited oscillation circuit has its input terminal connected to the first power supply path, and its output terminal generates a primary self-test signal. A multi-stage amplifier circuit includes N differential amplifier circuits and one Wolman amplifier circuit. The input of the first-stage differential amplifier circuit is connected to the second power supply path and the primary self-test signal. The output of the first-stage differential amplifier circuit generates an amplified second-stage self-test signal. The input of the second-stage differential amplifier circuit is connected to the third power supply path and the second-stage self-test signal. The output of the second-stage differential amplifier circuit generates an amplified third-stage self-test signal, and so on. The input of the Nth-stage differential amplifier circuit is connected to the (N+1)th power supply path and the (N-1)th-stage self-test signal. The output of the Nth-stage differential amplifier circuit generates an amplified (N+1)th-stage self-test signal. The input of the Wolman amplifier circuit is connected to the (N+2)th power supply path and the (N+1)th-stage self-test signal. The output of the Wolman amplifier circuit generates an amplified (N+2)th-stage self-test signal. The rectifier limiting circuit has its input terminal connected to the N+2th stage self-test signal generated by the output terminal of the Worman amplifier circuit, and its output terminal outputs a DC signal.

[0006] The number of differential amplifier circuits is N = M - 2, where N and M are both natural numbers, and M is the total number of power paths that the interconnected subway transponder antenna power monitoring circuit needs to monitor.

[0007] A coupling capacitor is connected in series between the output terminal of the self-excited oscillation circuit and the input terminal of the first-stage differential amplifier circuit; a coupling capacitor is connected in series between the output terminal of the previous-stage differential amplifier circuit and the input terminal of the next-stage differential amplifier circuit; a coupling capacitor is connected in series between the output terminal of the last-stage differential amplifier circuit and the input terminal of the Worman amplifier circuit; a coupling capacitor is connected in series between the output terminal of the Worman amplifier circuit and the input terminal of the rectifier limiting circuit.

[0008] The self-excited oscillation circuit is an RC self-excited oscillation circuit composed of inverters. One power supply path is input to the power terminals of the first inverter, the second inverter, and the third inverter respectively. The output terminal of the first inverter is connected to the input terminal of the second inverter, and the output terminal of the second inverter is connected to the input terminal of the third inverter. The output terminal of the third inverter outputs a primary self-test signal. The two ends of the first resistor are connected to the output terminal of the first inverter and the first capacitor respectively. One end of the first capacitor is connected to the first resistor, and the other end of the first capacitor is connected to the input terminal of the third inverter.

[0009] The self-excited oscillation circuit includes a compensation resistor, the two ends of which are respectively connected to the input terminal of the first inverter and the first capacitor.

[0010] The differential amplifier circuit includes a first transistor and a second transistor arranged symmetrically. One power supply path is input to the base of the first transistor, the base of the second transistor, and the collectors of the first transistor and the second transistor respectively. The base of the first transistor is connected to the primary self-test signal output by the output terminal of the self-excited oscillation circuit. The collector of the second transistor outputs the amplified self-test signal. The emitters of the first transistor and the second transistor are grounded.

[0011] The base of the first transistor is connected to the power supply path through a resistor, the base of the second transistor is connected to the power supply path through a resistor, the collector of the first transistor is connected to the power supply path through a resistor, and the collector of the second transistor is connected to the power supply path through a resistor; the base of the first transistor is grounded through a resistor, and the base of the second transistor is grounded through a resistor; the emitters of the first transistor and the emitters of the second transistor are grounded through the same resistor.

[0012] The Worman amplifier circuit includes a third transistor and a fourth transistor. One power supply path is input to the base and collector of the third transistor and the base of the fourth transistor. The bases of both the third and fourth transistors are connected to the self-test signal output from the output terminal of the last stage differential amplifier circuit. The bases of both the third and fourth transistors are grounded. The emitter of the third transistor is connected to the emitter of the fourth transistor. The emitters of the third and fourth transistors output a self-test signal. The collector of the fourth transistor is grounded.

[0013] The bases of the third transistor and the fourth transistor are connected to the power supply path through a resistor, and the bases of the third transistor and the fourth transistor are grounded through a resistor.

[0014] The rectifier limiting circuit includes a rectifier diode and a Zener diode. The rectifier diode converts the AC self-test signal output by the Worman amplifier circuit into a DC signal, and the Zener diode limits the amplitude of the DC signal output by the rectifier diode to within 5V. The anode of the rectifier diode is connected to the self-test signal output by the Worman amplifier circuit, the cathode of the rectifier diode outputs the DC signal, the cathode of the Zener diode is connected to the cathode of the rectifier diode, and the anode of the Zener diode is grounded.

[0015] The rectifier limiting circuit includes a voltage divider resistor connected in series with the cathode of the rectifier diode to finely adjust the amplitude of the output voltage.

[0016] The amplification factor of each stage of the differential amplifier circuit and the Worman amplifier circuit is adjustable.

[0017] The present invention has the following beneficial effects: 1. Configure the number of differential amplifier circuits in the interconnected metro transponder antenna power monitoring circuit according to the number of power channels to be monitored. Adjust the number of monitorable power channels by increasing or decreasing the number of differential amplifier circuits, thereby improving the applicability and portability of the circuit.

[0018] 2. All circuit modules are implemented using analog discrete components, which are inexpensive and readily available from domestic and international manufacturers. There are no issues with tight supply chains, making it ideal for low-cost circuit solutions and saving on R&D and manufacturing costs.

[0019] 3. A power self-test signal is generated through a self-excited oscillation circuit. The structure is simple and the oscillation period is adjustable. Due to the existence of the power self-test signal, when a power-related fault occurs on the monitored circuit board, it is possible to quickly locate whether the problem is with the power channel or the power monitoring module.

[0020] 4. Adjacent circuit modules are connected in series with coupling capacitors to isolate DC current in the circuit, thus improving the reliability of self-test. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of an interconnected subway transponder antenna power monitoring circuit provided by the present invention.

[0022] Figure 2 This is a specific circuit diagram of an interconnected subway transponder antenna power monitoring circuit provided by the present invention. Detailed Implementation

[0023] The following is based on Figures 1-2 The preferred embodiments of the present invention will be described in detail below.

[0024] like Figure 1 As shown, the present invention provides an interconnected subway transponder antenna power monitoring circuit, comprising: The self-excited oscillation circuit 1 has its input terminal connected to the first power supply path, and its output terminal generates an initial self-test signal. A multi-stage amplifier circuit 2 includes N differential amplifier circuits 21 and one Worman amplifier circuit 22. The input of the first-stage differential amplifier circuit is connected to another power supply path, and the input of the first-stage differential amplifier circuit is also connected to the initial self-test signal. The output of the first-stage differential amplifier circuit generates an amplified second-stage self-test signal. The input of the second-stage differential amplifier circuit is connected to a third power supply path, and the input of the second-stage differential amplifier circuit is also connected to the second-stage self-test signal. The output of the second-stage differential amplifier circuit generates an amplified third-stage self-test signal, and so on. The input terminal of the Nth stage differential amplifier circuit is connected to the (N+1)th power supply path. The input terminal of the Nth stage differential amplifier circuit is also connected to the (N-1)th stage self-test signal output by the (N-1)th stage differential amplifier circuit. The output terminal of the Nth stage differential amplifier circuit generates an amplified (N+1)th stage self-test signal. The input terminal of the Wolman amplifier circuit 22 is connected to the (N+2)th power supply path. The input terminal of the Wolman amplifier circuit 22 is also connected to the (N+1)th stage self-test signal output by the last stage differential amplifier circuit. The output terminal of the Wolman amplifier circuit 22 generates an amplified (N+2)th stage self-test signal. N is a natural number. Assuming that the number of power paths that the interconnected metro transponder antenna power monitoring circuit needs to monitor is M, then N = M - 2. The rectifier limiting circuit 3 has its input terminal connected to the N+2th stage self-test signal generated by the output terminal of the Worman amplifier circuit 22, and its output terminal outputs a DC signal.

[0025] In this embodiment, taking the monitoring of four power supply paths as an example, the multi-stage amplifier circuit 2 includes two differential amplifier circuits, namely, a first-stage differential amplifier circuit and a second-stage differential amplifier circuit. The interconnected subway transponder antenna power supply monitoring circuit is applicable to monitoring voltage ranges of 2V~30V (such as standard power supplies of 3.3V, 5V, 12V, and 24V, all of which are applicable). The voltage in the four monitored power supply paths provides power to each corresponding input circuit (self-excited oscillation circuit, differential amplifier circuit, and Worman amplifier circuit). If there is a problem with the first power supply path (no power signal), the self-oscillating circuit 1 will not generate an initial self-test signal; if the first power supply path is normal, but the second power supply path has a problem (no power signal), the self-test signal will be cut off at the first-stage differential amplifier circuit; if the first and second power supply paths are normal, but the third power supply path has a problem (no power signal), the self-test signal will be cut off at the second-stage differential amplifier circuit; if the first, second, and third power supply paths are all normal, but the fourth power supply path has a problem (no power signal), the self-test signal will be cut off at the Worman amplifier circuit 22; if all four power supply paths are normal, the self-test signal will output a DC signal DCSignalOut after passing through the rectification and limiting circuit 4.

[0026] The self-excited oscillation circuit 1 is used to generate a power self-test signal to cooperate with the interconnected metro transponder antenna power monitoring circuit to monitor multiple power channels of the interconnected metro transponder antenna circuit board. It can also perform a self-test on the integrity and connectivity of the interconnected metro transponder antenna power monitoring circuit itself. If a self-test signal can be detected at the output of the interconnected metro transponder antenna power monitoring circuit, it can be concluded that the integrity and connectivity of the interconnected metro transponder antenna power monitoring circuit are not problematic.

[0027] Multiple differential amplifier circuits are set in the multi-stage amplifier circuit 2. The number of differential amplifier circuits in the power monitoring circuit of the interconnected metro transponder antenna can be configured according to the number of power channels that need to be monitored on the circuit board of the interconnected metro transponder antenna. That is, the number of differential amplifier circuits N = M - 2, where N and M are natural numbers, and M is the number of power paths that the interconnected metro transponder antenna power monitoring circuit needs to monitor. If the number of power paths that need to be monitored increases, the number (stages) of the differential amplifier circuits can be increased accordingly, which greatly improves the applicability and portability of the circuit.

[0028] The last stage of the multi-stage amplifier circuit 2 uses a Worman amplifier circuit 22, which has good frequency characteristics and high input impedance, and can increase the driving capability of the next stage circuit (rectifier and limiter circuit 3).

[0029] Each differential amplifier circuit and Worman amplifier circuit 22 in the multi-stage amplifier circuit 2 has a fixed amplification factor. The operation of the amplifier circuit itself can be detected by detecting the output amplitude of the amplifier circuit, thereby quickly distinguishing whether the fault is in the internal circuit of the interconnected subway transponder antenna power supply monitoring circuit or in the monitored power supply channel.

[0030] The rectifier limiting circuit 3 is used to convert the large-amplitude AC self-test signal, which has been amplified stage by stage 2, into a DC level signal with constant amplitude to protect subsequent circuits. The output DC Signal Out signal is input to the comparator circuit. A threshold voltage is preset at one input terminal of the comparator. The DC Signal Out signal is input to the other input terminal of the comparator. The threshold voltage is compared with the DC Signal Out signal and then output. Finally, the comparator output signal is sent to the FPGA / MCU for further processing.

[0031] like Figure 2 As shown, in this embodiment, the self-excited oscillation circuit 1 is an RC self-excited oscillation circuit composed of inverters. The self-excited oscillation circuit 1 includes two resistors, one capacitor, and three inverters. The first power supply path VCC_MONITOR1 is input to the power supply terminals (VCC terminals) of the first inverter U17A, the second inverter U17B, and the third inverter U17CA, respectively. The output terminal of the first inverter U17A is connected to the input terminal of the second inverter U17B, and the output terminal of the second inverter U17B is connected to the third inverter U17CA. The input terminal of 7CA and the output terminal of the third inverter U17CA output the initial self-test signal Test1. The two ends of the compensation resistor R108 are connected to the input terminal of the first inverter U17A and the first capacitor C69, respectively. The two ends of the first resistor R103 are connected to the output terminal of the first inverter U17A and the first capacitor C69, respectively. One end of the first capacitor C69 is connected to the compensation resistor R108 and the first resistor R103, and the other end of the first capacitor C69 is connected to the input terminal of the third inverter U17CA. At the moment VCC_MONITOR1 from the first power path is powered on, the self-excited oscillation circuit 1 will generate a CLK oscillation waveform, which is output as the self-test signal Test1. The self-excited oscillation circuit 1 can stably output a square wave CLK signal with adjustable frequency when it is powered on normally. The frequency of the output signal is obtained by adjusting the time constant T of the first resistor R103 and the first capacitor C69. The amplitude of the output signal is determined by the three inverters (U17A, U17B, U17CA). The compensation resistor R108 is used to reduce the influence of the inverters on the frequency of the output signal.

[0032] The circuit structure and working principle of the first-stage differential amplifier circuit and the second-stage differential amplifier circuit are the same. Here, the first-stage differential amplifier circuit is used as an example for explanation. The differential amplifier circuit 21 includes two symmetrically arranged transistors. The base of the first transistor V1 is connected to the output terminal of the self-excited oscillation circuit 1. That is, the primary self-test signal Test1 output by the self-excited oscillation circuit 1 is input to the base of the first transistor V1. The base of the first transistor V1 is connected to the second power supply path VCC_MONITOR2 through resistor R106. The base of the first transistor V1 is grounded through resistor R109. The collector of the first transistor V1 is connected to the second power supply path VCC_MONITOR2 through resistor R104. ITOR2, the emitter of the first transistor V1 is grounded through resistor R111, the base of the second transistor V2 is connected to the second power path VCC_MONITOR2 through resistor R107, the base of the second transistor V2 is grounded through resistor R110, the collector of the second transistor V2 is connected to the second power path VCC_MONITOR2 through resistor R105, the collector of the second transistor V2 outputs the amplified second-stage self-test signal Test2, and the emitter of the second transistor V2 is grounded through resistor R111.

[0033] The Worman amplifier circuit 22 includes two transistors. The bases of the third transistor V3 and the fourth transistor V7 are both connected to the output of the previous stage differential amplifier circuit. That is, the self-test signal Test3 output by the previous stage differential amplifier circuit is input to the bases of the third transistor V3 and the fourth transistor V7. The bases of the third transistor V3 and the fourth transistor V7 are connected to the fourth power supply path VCC_MONITOR4 through resistor R112. The bases of the third transistor V3 and the fourth transistor V7 are grounded through resistor R119. The collector of the third transistor V3 is connected to the fourth power supply path VCC_MONITOR4, and the collector of the fourth transistor V7 is grounded. The emitter of the third transistor V3 is connected to the emitter of the fourth transistor V7. The emitters of the third transistor V3 and the fourth transistor V7 output the self-test signal Test4.

[0034] The rectifier limiting circuit 3 includes a rectifier diode V4 and a Zener diode V8. The rectifier diode V4 converts the AC self-test signal into a DC signal, and the Zener diode V8 limits the amplitude of the DC signal output by the rectifier diode V4 to within 5V. The anode of the rectifier diode V4 is connected to the output terminal of the Worman amplifier circuit 22, meaning the self-test signal Test4 output by the Worman amplifier circuit 22 is input to the anode of the rectifier diode V4, and the cathode of the rectifier diode V4 outputs the DC signal DC SIGNAL OUT. The cathode of the Zener diode V8 is connected to the cathode of the rectifier diode V4, and the anode of the Zener diode V8 is grounded. A voltage divider resistor R120 is connected in series with the cathode of the rectifier diode V4 to fine-tune the amplitude of the output voltage. If the rectifier limiting circuit 3 ultimately outputs a DC voltage of 4.5V~5.0V, it indicates that the interconnected subway transponder antenna power supply monitoring circuit has completed its self-test, and the four-channel power supply of the circuit board is powered on normally.

[0035] Each stage of the multi-stage amplifier circuit 2, including the differential amplifier circuit 21 and the final Wolman amplifier circuit 22, amplifies the initial self-test signal output from the self-oscillating circuit 1 stage by stage. The amplification factor of each amplifier circuit can be adjusted by changing the resistance values ​​in each circuit. For example, in this embodiment, adjusting resistors R104, R105, and R111 in the first-stage differential amplifier circuit adjusts the amplification factor of the first-stage differential amplifier circuit, and adjusting resistors R112 and R119 in the Wolman amplifier circuit adjusts the amplification factor of the Wolman amplifier circuit. The significance of adjusting the amplification factor is as follows: because the signal amplitude output by the self-excited oscillation circuit is relatively low (several hundred mV), assuming the signal amplitude output by the self-excited oscillation circuit is 1V, and the amplification factor of each stage of the amplifier circuit is 1.5, then the amplitude output by the first stage differential amplifier circuit is 1.50V, the amplitude output by the second stage differential amplifier circuit is 2.25V, and the amplitude output by the third stage Worman amplifier circuit is 3.34V. The operation of the amplifier circuit itself can be detected by detecting the output amplitude of the amplifier circuit. For example, if the final output DC SignalOut signal reaches the predetermined amplitude, it is considered that the four power supply channels are normal, and the power supply detection circuit itself is also normal.

[0036] In this embodiment, because the self-test signal is an AC signal, coupling capacitors are connected in series between adjacent circuit modules to isolate the DC signal and improve the reliability of the self-test. Figure 2As shown, a coupling capacitor C70 is connected in series between the output terminal of the self-excited oscillation circuit 1 and the input terminal of the first-stage differential amplifier circuit; a coupling capacitor C72 is connected in series between the output terminal of the first-stage differential amplifier circuit and the input terminal of the second-stage differential amplifier circuit; a coupling capacitor C71 is connected in series between the output terminal of the second-stage differential amplifier circuit and the input terminal of the Worman amplifier circuit 22; and a coupling capacitor C121 is connected in series between the output terminal of the Worman amplifier circuit 22 and the input terminal of the rectifier limiting circuit 3.

[0037] The present invention has the following beneficial effects: 1. Configure the number of differential amplifier circuits in the interconnected metro transponder antenna power monitoring circuit according to the number of power channels to be monitored. Adjust the number of monitorable power channels by increasing or decreasing the number of differential amplifier circuits, thereby improving the applicability and portability of the circuit.

[0038] 2. All circuit modules are implemented using analog discrete components, which are inexpensive and readily available from domestic and international manufacturers. There are no issues with tight supply chains, making it ideal for low-cost circuit solutions and saving on R&D and manufacturing costs.

[0039] 3. A power self-test signal is generated through a self-excited oscillation circuit. The structure is simple and the oscillation period is adjustable. Due to the existence of the power self-test signal, when a power-related fault occurs on the monitored circuit board, it is possible to quickly locate whether the problem is with the power channel or the power monitoring module.

[0040] 4. Adjacent circuit modules are connected in series with coupling capacitors to isolate DC current in the circuit, thus improving the reliability of self-test.

[0041] It should be noted that, in the embodiments of the present invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the embodiments. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A power supply monitoring circuit for an interconnected subway transponder antenna, characterized in that, Include: The self-excited oscillation circuit has its input terminal connected to the first power supply path, and its output terminal generates a primary self-test signal. The self-excited oscillation circuit is an RC self-excited oscillation circuit composed of inverters. One power supply path is respectively input to the power supply terminals of the first inverter, the second inverter, and the third inverter. The output terminal of the first inverter is connected to the input terminal of the second inverter, the output terminal of the second inverter is connected to the input terminal of the third inverter, and the output terminal of the third inverter outputs the primary self-test signal. The two ends of the first resistor are respectively connected to the output terminal of the first inverter and the first capacitor. One end of the first capacitor is connected to the first resistor, and the other end of the first capacitor is connected to the input terminal of the third inverter. A multi-stage amplifier circuit includes N differential amplifier circuits and one Wolman amplifier circuit. The input of the first-stage differential amplifier circuit is connected to the second power supply path and the primary self-test signal. The output of the first-stage differential amplifier circuit generates an amplified second-stage self-test signal. The input of the second-stage differential amplifier circuit is connected to the third power supply path and the second-stage self-test signal. The output of the second-stage differential amplifier circuit generates an amplified third-stage self-test signal, and so on. The input of the Nth-stage differential amplifier circuit is connected to the (N+1)th power supply path and the (N-1)th-stage self-test signal. The output of the Nth-stage differential amplifier circuit generates an amplified (N+1)th-stage self-test signal. The input of the Wolman amplifier circuit is connected to the (N+2)th power supply path and the (N+1)th-stage self-test signal. The output of the Wolman amplifier circuit generates an amplified (N+2)th-stage self-test signal. Each differential amplifier circuit includes symmetrically arranged first and second transistors, and one power supply path outputs... The circuit inputs to the base of the first transistor, the base of the second transistor, and the collectors of both transistors. The base of the first transistor is connected to the primary self-test signal output from the output terminal of the self-excited oscillation circuit. The collector of the second transistor outputs an amplified self-test signal. The emitters of both transistors are grounded. The Waldman amplifier circuit includes a third transistor and a fourth transistor. One power path is input to the base and collector of the third transistor and the base of the fourth transistor. The bases of both transistors are connected to the self-test signal output from the output terminal of the last stage differential amplifier circuit. The bases of both transistors are grounded. The emitter of the third transistor is connected to the emitter of the fourth transistor. The emitters of both transistors output a self-test signal. The collector of the fourth transistor is grounded. The rectifier limiting circuit has its input terminal connected to the N+2th stage self-test signal generated by the output terminal of the Worman amplifier circuit, and its output terminal outputs a DC signal.

2. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 1, characterized in that, The number of differential amplifier circuits is N = M - 2, where N and M are both natural numbers, and M is the total number of power paths that the interconnected subway transponder antenna power monitoring circuit needs to monitor.

3. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 2, characterized in that, A coupling capacitor is connected in series between the output terminal of the self-excited oscillation circuit and the input terminal of the first-stage differential amplifier circuit; a coupling capacitor is connected in series between the output terminal of the previous-stage differential amplifier circuit and the input terminal of the next-stage differential amplifier circuit; a coupling capacitor is connected in series between the output terminal of the last-stage differential amplifier circuit and the input terminal of the Worman amplifier circuit; a coupling capacitor is connected in series between the output terminal of the Worman amplifier circuit and the input terminal of the rectifier limiting circuit.

4. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 1, characterized in that, The self-excited oscillation circuit includes a compensation resistor, the two ends of which are respectively connected to the input terminal of the first inverter and the first capacitor.

5. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 1, characterized in that, The base of the first transistor is connected to the power supply path through a resistor, the base of the second transistor is connected to the power supply path through a resistor, the collector of the first transistor is connected to the power supply path through a resistor, and the collector of the second transistor is connected to the power supply path through a resistor; the base of the first transistor is grounded through a resistor, and the base of the second transistor is grounded through a resistor; the emitters of the first transistor and the emitters of the second transistor are grounded through the same resistor.

6. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 1, characterized in that, The bases of the third transistor and the fourth transistor are connected to the power supply path through a resistor, and the bases of the third transistor and the fourth transistor are grounded through a resistor.

7. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 3, characterized in that, The rectifier limiting circuit includes a rectifier diode and a Zener diode. The rectifier diode converts the AC self-test signal output by the Worman amplifier circuit into a DC signal, and the Zener diode limits the amplitude of the DC signal output by the rectifier diode to within 5V. The anode of the rectifier diode is connected to the self-test signal output by the Worman amplifier circuit, the cathode of the rectifier diode outputs the DC signal, the cathode of the Zener diode is connected to the cathode of the rectifier diode, and the anode of the Zener diode is grounded.

8. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 7, characterized in that, The rectifier limiting circuit includes a voltage divider resistor connected in series with the cathode of the rectifier diode to finely adjust the amplitude of the output voltage.

9. The interconnected subway transponder antenna power supply monitoring circuit as described in claim 1, characterized in that, The amplification factor of each stage of the differential amplifier circuit and the Worman amplifier circuit is adjustable.

Images