A remote monitoring system based on cable voltage

Abstract

The application provides a remote monitoring system based on cable voltage, and belongs to the technical field of cable monitoring. The system comprises a first end device and a second end device which are interconnected by a cable. The first end device comprises a voltage operation circuit and a first end grading power supply, and the second end device comprises a back-check comparison circuit and a second end communication device. The voltage operation circuit is used for measuring voltage loss of the cable, obtaining measurement data, determining voltage information of the second end device according to the measurement data, and monitoring the working state of the second end communication device. The first end grading power supply is used for providing grading voltage for the second end communication device. The back-check comparison circuit is used for back-check comparison and outputs an IO control signal to control the working state of the second end communication device. According to the application, the back-check comparison circuit of the second end does not need additional control lines and control signals, and the working mode of the remote second end device can be stably and reliably controlled by adjusting the output voltage of the first end grading power supply.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable monitoring, in particular to a remote monitoring system based on cable voltage. BACKGROUND

[0002] With the progress of science and technology, more and more small unattended devices are used, and field unattended environmental monitoring devices and unmanned communication devices are applied more and more widely. In the fields of natural environment monitoring and covert communication, such as field monitoring, underwater monitoring, and tunnel environment, the front-end communication device and the back-end device are often set separately, and the front-end device is in an unattended state.

[0003] The distance between the front-end communication device and the back-end device often differs by hundreds of meters to thousands of meters, and it is difficult to monitor and control the front-end device from the back-end. Usually, the front-end power supply is provided from the back-end through a cable. Therefore, how to monitor and control the front-end device by using the power supply cable and improve the state monitoring and control capabilities of the front-end device have become important problems to be solved. SUMMARY

[0004] The present application provides a remote monitoring system based on cable voltage to solve the defects of the prior art and realize a portable Beidou-based positioning instrument that can work in an unattended area without relying on a signal base station.

[0005] In a first aspect, the present application provides a remote monitoring system based on cable voltage, comprising a first end device and a second end device interconnected by a cable; the first end device comprises a voltage operation circuit and a first end graded power supply; the second end device comprises a back-check comparison circuit and a second end communication device;

[0006] The voltage operation circuit is configured to measure the voltage loss of the cable, obtain measurement data, determine the voltage information of the second end device according to the measurement data, and monitor the working state of the second end communication device.

[0007] The first end graded power supply is configured to provide a graded voltage for the second end communication device.

[0008] The back-check comparison circuit is configured to perform back-check comparison according to the graded voltage, output an IO control signal, and control the working state of the second end communication device.

[0009] According to the remote monitoring system based on cable voltage, the graded voltage comprises a first-grade voltage and a second-grade voltage, the back-check comparison is performed according to the graded voltage, the IO control signal is output, and the working state of the second end communication device is controlled, which comprises:

[0010] Comparing the graded voltage with a reference back-check conversion point;

[0011] When the grading voltage is greater than the hysteresis high line switching point voltage of the reference hysteresis switching point, a high level is output to control the second-end communication device to be in the transmitting state;

[0012] When the hysteresis switching voltage is lower than the hysteresis low-line switching voltage of the reference hysteresis switching point, a low level is output to control the second-end communication device to be in the receiving state.

[0013] When the step voltage is less than the hysteresis low-line transition point but greater than the hysteresis low-line transition point voltage, the output level remains unchanged.

[0014] According to the aforementioned remote monitoring system based on cable voltage, the voltage calculation circuit includes:

[0015] The system includes an inverting amplifier and a non-inverting subtractor. One end of the inverting amplifier is connected to the shielding layer of the cable, and the other end is connected to one end of the non-inverting subtractor. The other end of the non-inverting subtractor is connected to the core layer of the cable. The inverting amplifier is used to measure the voltage loss of the cable and obtain measurement data. The non-inverting subtractor is used to determine the voltage data of the second-end device based on the measurement data, so as to monitor the working status of the second-end communication device.

[0016] According to the aforementioned remote monitoring system based on cable voltage, the voltage loss of the cable is measured to obtain measurement data. The voltage information of the second-end device is determined based on the measurement data, including:

[0017] Obtain the current information of the cable's shield layer, and determine the measurement data of the cable's voltage loss based on the cable core resistance and the cable shield layer resistance;

[0018] Based on the measured data of the output voltage of the first-end graded power supply and the voltage loss of the cable, the voltage information of the second-end communication device is determined.

[0019] According to the remote monitoring system based on cable voltage, the voltage information of the second-end device is the difference between the output voltage of the first-end graded power supply and the measured voltage loss of the cable.

[0020] According to the remote monitoring system based on cable voltage, the second-end device also includes a second-end regulated power supply for providing a stable power supply to the second-end communication device to overcome voltage fluctuations of the second-end communication device and to offset changes in the output voltage of the first-end graded power supply.

[0021] According to the remote monitoring system based on cable voltage, the first-end graded regulated power supply includes: an AC input transformer, a rectifier circuit, and a voltage regulator circuit connected in sequence, wherein the voltage regulator circuit is an LM317 integrated voltage regulator chip.

[0022] According to the remote monitoring system based on cable voltage, the first end device further comprises:

[0023] a voltage display and a current display, the voltage display being connected in parallel across the first end step-down power supply for displaying output voltage of the first end step-down power supply;

[0024] the current display accessing a shielding layer of the cable for displaying output current of the first end step-down power supply.

[0025] The remote monitoring system based on cable voltage provided by the application has the following beneficial effects compared with the prior art:

[0026] The application provides a remote monitoring system based on cable voltage, which comprises a first end device and a second end device interconnected by a cable. The first end device comprises a voltage operation circuit and a first end step-down power supply, and the second end device comprises a back-check comparison circuit and a second end communication device. The voltage operation circuit is used for measuring voltage loss of the cable, obtaining measurement data, determining voltage information of the second end device according to the measurement data, and monitoring the working state of the second end communication device. The first end step-down power supply is used for providing a step-down voltage for the second end communication device. The back-check comparison circuit is used for performing back-check comparison according to the step-down voltage, outputting an IO control signal, and controlling the working state of the second end communication device. The application is suitable for occasions where power supply is provided through a cable with a length of hundreds of meters or even thousands of meters. By adding the voltage operation circuit, the power supply voltage of the second end device at the remote end can be stably and reliably monitored, and the working state of the remote device can be mastered. In the back-check comparison circuit of the second end device, an additional control line and control signal are not needed, and the working mode of the remote device can be stably and reliably controlled by adjusting the output voltage of the near-end output voltage stabilizing circuit. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0028] Figure 1 is one of the structural schematic diagrams of the remote monitoring system based on cable voltage provided by the application;

[0029] Figure 2 is a structural schematic diagram of a remote voltage operation circuit provided by the application;

[0030] Figure 3 is another structural schematic diagram of the remote monitoring system based on cable voltage provided by the application;

[0031] Figure 4 is a structural schematic diagram of a return difference comparison circuit provided by the present application.

[0032] Figure 5 is a principle schematic diagram of a return difference comparison circuit provided by the present application. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0034] It should be noted that, in the description of the embodiments of the present application, the terms “comprise”, “contain” or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement “comprising a…” does not exclude the presence of other identical elements in the process, method, article or device comprising the element. Unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting” should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] The terms “first”, “second” and the like in the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by “first”, “second” and the like are generally a category, and do not limit the number of objects, for example, the first object can be one or more.

[0036] The embodiments of the present application will be described below. Figures 1-5 A cable voltage-based remote monitoring system is provided by the embodiments of the present application.

[0037] Figure 1 is a structural schematic diagram of a cable voltage-based remote monitoring system provided by the present application, as Figure 1The system comprises:

[0038] The first end device and the second end device are interconnected by a cable; the first end device comprises a voltage operation circuit and a first end grading power supply; the second end device comprises a back-check comparison circuit and a second end communication device;

[0039] The voltage operation circuit is configured to measure voltage loss of the cable, acquire measurement data, determine voltage information of the second end device according to the measurement data, and monitor the working state of the second end communication device;

[0040] The first end grading power supply is configured to provide grading voltage for the second end communication device;

[0041] The back-check comparison circuit is configured to perform back-check comparison according to the grading voltage, and output an IO control signal to control the working state of the second end communication device.

[0042] The remote monitoring system mainly comprises the first end device, the power supply cable and the second end device, and the first end device and the second end device are connected by the cable. The first end device mainly comprises the voltage operation circuit and the first end grading power supply, and the second end device mainly comprises the back-check comparison circuit and the second end communication device.

[0043] In the embodiment, the first end device is placed at the near end, and the second end device is placed at the far end. The voltage operation circuit in the first end device deployed at the near end is configured to monitor voltage and current information of the second end device at the far end, so as to master the working state of the second end device at the far end. The first end grading power supply in the first end device deployed at the near end is configured to provide grading voltage for the second end communication device. The second end device at the far end is configured to detect power supply voltage change through the back-check comparison circuit in the second end device, and output an IO control signal to control the second end communication device, so as to control the working state of the second end communication device deployed at the far end.

[0044] Optionally, the first end grading power supply comprises an alternating current input transformer, a rectifier circuit and a voltage stabilizing circuit connected in sequence, and the voltage stabilizing circuit is an LM317 integrated voltage stabilizing chip.

[0045] The alternating current input transformer has an input of 220V alternating current and an output of 32V alternating current. The rectifier circuit rectifies the alternating current to direct current of 38V. The voltage stabilizing circuit is an LM317 integrated voltage stabilizing chip. The output direct current voltage can be changed by changing the setting resistance of the LM317 integrated voltage stabilizing chip. The output working voltage can reach 30V, and the maximum working current can reach 1A.

[0046] In an embodiment, the first end grading power supply provides the second end communication device with grading voltage including first-grade voltage and second-grade voltage. The back-check comparison circuit performs back-check comparison according to the grading voltage, and outputs an IO control signal to control the working state of the second end communication device.

[0047] Specifically, the return difference comparison circuit compares the grading voltage with the reference return difference conversion point, outputs a high level to control the second-end communication device to be in a transmitting state when the grading voltage is greater than the return difference high line conversion point voltage of the reference return difference conversion point, outputs a low level to control the second-end communication device to be in a receiving state when the grading voltage is less than the return difference low line conversion point voltage of the reference return difference conversion point, and maintains the output level unchanged when the grading voltage is less than the return difference low line conversion point and greater than the return difference low line conversion point voltage.

[0048] In an embodiment, the first-end grading power supply outputs 28V DC high voltage and 20V DC low voltage respectively, and outputs the 20V DC low voltage to supply the second-end device to receive information in normal working state, and outputs the 28V DC high voltage when the second-end communication device in the second-end device needs to transmit information.

[0049] Since the remote power supply is usually a single power supply, the return difference comparison circuit can use a single power supply operational amplifier to stably and reliably determine whether the output of the first-end grading power supply deployed in the near-end is 28V DC high voltage or 20V DC low voltage, and further control the working state of the remote communication device. When the return difference comparison circuit determines that the input voltage is 28V DC high voltage, the return difference comparison circuit outputs a high level to control the second-end communication device to be in a transmitting state; when it is determined that the input voltage is 20V DC low voltage, the return difference comparison circuit outputs a low level to control the second-end communication device to be in a receiving state.

[0050] Compared with the ordinary comparator, the return difference comparator has a large state conversion maintenance voltage space, and will not repeatedly convert near the reference comparison voltage, thereby avoiding the problem of repeatedly switching the working mode of the remote device.

[0051] In an embodiment, the voltage loss of the cable is measured to obtain measurement data, and the voltage information of the second-end device is determined according to the measurement data, including:

[0052] The current information of the shielding layer of the cable is obtained, and the measurement data of the voltage loss of the cable is determined according to the cable core resistance and the cable shielding layer resistance;

[0053] The voltage information of the second-end communication device is determined according to the output voltage of the first-end grading power supply and the measurement data of the voltage loss of the cable.

[0054] Figure 2 is a structural schematic diagram of a remote voltage operational circuit provided by the present application, as Figure 2As shown, the remote voltage operation circuit can measure the current on the sampling resistor Ra, calculate the voltage loss on the long cable according to the long cable core wire resistance and long cable shield layer resistance, and then calculate the voltage loss on the long cable by using the operational amplifier, and then subtract the voltage loss from the output voltage of the near-end grading voltage source to obtain the remote voltage.

[0055] In an embodiment, the first end device further comprises: a voltage display and a current display, the voltage display is connected in parallel across the first end grading voltage source for displaying the output voltage of the first end grading voltage source; and the current display is connected to the shield layer of the cable for displaying the output current of the first end grading voltage source.

[0056] The voltage display Utotal and the current display I are used to display the output voltage and output current of the near-end grading voltage source.

[0057] In an embodiment, the second end device further comprises a second end voltage source for providing stable power supply to the second end communication device to overcome the voltage fluctuation of the second end communication device and offset the change of the output voltage of the first end grading voltage source.

[0058] Specifically, Figure 3 Another structure schematic diagram of the remote monitoring system based on cable voltage provided by the embodiment of the present application is shown in FIG. 4. Figure 3 As shown, the remote voltage operation circuit can measure the current on the sampling resistor Ra, calculate the voltage loss on the long cable according to the long cable core wire resistance and long cable shield layer resistance, and then calculate the voltage loss on the long cable by using the operational amplifier, and then subtract the voltage loss from the output voltage of the near-end grading voltage source to obtain the remote voltage.

[0059] In an embodiment, the voltage operation circuit comprises: a reverse amplifier and a same-direction subtractor, one end of the reverse amplifier is connected to the shield layer of the cable, and the other end is connected to one end of the same-direction subtractor; the other end of the same-direction subtractor is connected to the core layer of the cable; the reverse amplifier is used to measure the voltage loss of the cable and obtain measurement data; and the same-direction subtractor is used to determine the voltage data of the second end device according to the measurement data to monitor the working state of the second end communication device.

[0060] Specifically, the remote voltage operation circuit mainly comprises an operational amplifier A1, an operational amplifier A2, a current sampling resistor Ra, resistors R1, R2, R3, R4, R5, R6, etc., and a block diagram is shown in FIG. 5. Figure 2

[0061] The operational amplifier A1, the current sampling resistor Ra, and the resistors R1 and R2 constitute a reverse amplifier for calculating the supply voltage Utotal and the voltage loss Uloss on the long cable. Assuming that the current on the long cable is I, the voltage loss caused by the long cable is:

[0062] U 损耗 ​= I * (RL1 + RL2 + Ra) = I * Ra * ((RL1 + RL2) / Ra + 1) (1)

[0063] The output of the operational amplifier A1 is UA1:

[0064] U A1 = I * Ra * R2 / R1 (2)

[0065] Comparing equation (1) with equation (2), when R2 / R1 = (RL1 + RL2) / Ra + 1, UA1 = Uloss, the operational amplifier A1 calculates the long cable loss Uloss.

[0066] Generally, the resistance of a 500-meter SYV50-5 coaxial cable is about 20 ohms, and the current sampling resistance Ra is 0.1 ohm. The calculation is as follows:

[0067] R2 / R1 = (RL1 + RL2) / Ra + 1 = 20 / 0.1 + 1 = 201

[0068] Therefore, when R2 / R1 = 201, generally R1 = 100 Ω and R2 = 20.1 kΩ, UA1 = Uloss, that is, the operational amplifier A1 outputs UA1 accurately calculates the long cable voltage loss Uloss.

[0069] The operational amplifier A2 and resistors R3, R4, R5, and R6 constitute a homodyne subtractor. When R3 = R4 = R5 = R6 = 10 kΩ,

[0070] V+ = R3 / (R3 + R4) * U 总 = 1 / 2 * U 总 ; (3)

[0071] V- = R6 / (R5 + R6) * (U A2 - U A1 ) + U A1 = 1 / 2 * (U A1 + U A2 ) (4)

[0072] According to the operational amplifier working principle V+ = V-, it is obtained that:

[0073] UA2 = Utotal - UA1 = Uremote

[0074] Therefore Figure 2 the remote voltage operational circuit A2 outputs UA2 to calculate the remote power supply voltage Uremote.

[0075] In the present embodiment, the main component design parameters are as follows, for example:

[0076] 1) Ra = 0.1 Ω;

[0077] 2) R1 = 100 Ω, R2 = 20.1 kΩ;

[0078] 3) R3 = R4 = R5 = R6 = 10 kΩ.

[0079] In one embodiment, since the far end is powered by a single power supply, the return difference comparator is powered by a single power supply, the return difference comparator is composed of A3 operational amplifier, output stable diode Dz, reference diode Dr and resistors Ro, R7, R8, R9, R10, Rr, etc. Figure 4 is a structural diagram of a return difference comparison circuit provided by the present application, as Figure 4 indicated. The return difference comparison circuit transmission curve is as Figure 5 indicated. When the input voltage Ui is greater than the flip high voltage UTH, the return difference comparator outputs high voltage Uz; when the input voltage Ui is less than the flip low voltage UTL, the return difference comparator outputs low voltage 0V; when the input voltage Ui is greater than the flip high voltage UTH, the return difference comparator outputs high voltage Uz; when the input voltage UTH > Ui > UTL, the return difference comparator maintains the original output voltage unchanged.

[0080] Wherein, the operational amplifier A3 and the resistors R7, R8 constitute a positive feedback circuit, since the output stable diode Dz works at 0 or the stable voltage Uz, the + input of the operational amplifier A3 changes between UTH and UTL as Figure 4 indicated, constituting a return difference comparator.

[0081] Wherein, the return difference high limit conversion point UTH:

[0082] UTH = (UrR7 + UZR8) / (R7 + R8) (5)

[0083] The return difference low limit conversion point UTL:

[0084] UTL = Ur × R7 / (R7 + R8) (6)

[0085] The return difference voltage ΔU:

[0086] ΔU = UTH - UTL = Uz × R8 / (R7 + R8) (7)

[0087] Design Uz = 6V, 2R8 = R7, UR = 3V, according to formula (5), formula (6), formula (7) calculation:

[0088] UTH = (URR7 + UZR8) / (R7 + R8) = (3 * R7 + 6 * 0.5R7) / 1.5R7 = 4V UTL = 3 × R1 / (R1 + 0.5R1) = 3 × 0.666 = 2V

[0089] ΔU = 6 × 0.3333 = 2V

[0090] In this embodiment, the resistance values of R9 and R10 are designed as 1:4 to form a 1:5 voltage attenuator, and the corresponding far-end voltage flip-over working points are UTH=20V and UTL=10V, respectively, and the return difference voltage is ΔU=10V.

[0091] The main component design parameters are, for example:

[0092] 1) The voltage stabilizing diode has a stabilizing value Uz=6V and Ro=3kΩ, and Ro provides working current for Uz;

[0093] 2) The reference diode has a stabilizing value Ur=3V and Rr=5kΩ, and Rr provides working current for Ur;

[0094] 3) R7=R8=5kΩ;

[0095] 4) R9=8kΩ and R10=2kΩ, and R9 and R10 form a 1:5 voltage attenuator.

[0096] In an embodiment, the second-end communication device configured in the second-end device has a working current of 0.2A when receiving and a working current of 0.7A when transmitting.

[0097] When the far-end communication device is receiving, the near-end stepped voltage stabilizing power supply outputs a high voltage Utotal=28V, and when the far-end communication device is transmitting, the cable loss voltage Uloss=20Ω*0.7A=14V, and the far-end voltage Ufar=Utotal-Uloss=28V-14V=14V.

[0098] When the far-end communication device is receiving, the near-end stepped voltage stabilizing power supply outputs a low voltage Utotal=20V, and when the far-end communication device is transmitting, the cable loss voltage Uloss=20Ω*0.2A=4V, and the far-end voltage Ufar=Utotal-Uloss=20V-4V=16V.

[0099] When the stepped voltage stabilizing power supply output is changed from the high voltage Utotal=28V to the low voltage Utotal=20V, the far-end communication device is first in the transmitting state, the far-end voltage Ufar=Utotal-Uloss=20V-14V=6V, which is lower than the return difference low limit conversion point UTL=10V, and thus the return difference circuit flips to the low level, setting the far-end communication device from the transmitting state to the receiving state.

[0100] When the stepped voltage stabilizing power supply output is changed from the low voltage Utotal=20V to the high voltage Utotal=28V, the far-end communication device is first in the receiving state, the far-end voltage Ufar=Utotal-Uloss=28V-4V=24V, which is higher than the return difference low limit conversion point UTH=20V, and thus the return difference circuit flips to the high level, setting the far-end communication device from the receiving state to the transmitting state.

[0101] The present application uses a single power operational amplifier in the return difference comparison circuit, and realizes stable and reliable discrimination of whether the output of the near-end grading voltage stabilizing power supply is 28V DC high voltage or 20V DC low voltage through return difference comparison, so as to control the working state of the remote communication equipment. When judging as 28V DC high voltage, the return difference comparator outputs high level, and controls the remote communication equipment to work in the transmitting state; when judging as 20V DC low voltage, the return difference comparator outputs low level, and controls the remote communication equipment to work in the receiving state.

[0102] Compared with the common comparator, the return difference comparison circuit of the present application has a larger state conversion maintaining voltage space, and will not repeatedly convert near the reference comparison voltage, so as to avoid the problem of repeatedly switching the working mode of the remote equipment.

[0103] The present application can accurately locate the position of personnel in various inconvenient communication situations, greatly guarantees the safety of personnel, and can also receive warning prompts from base station personnel through the indicator light for outdoor operating personnel. In addition, the present application uses various communication interfaces to meet the use requirements of more scenes, and has the advantages of strong anti-interference ability.

[0104] The apparatus embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0105] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of software products, and the computer software product can be stored in a computer readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, server, or network device, etc.) execute the method described in each embodiment or some parts of the embodiment.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A remote monitoring system based on cable voltage, characterized in that, The device includes a first-end device and a second-end device interconnected by a cable; the first-end device includes a voltage calculation circuit and a first-end graded power supply; the second-end device includes a hysteresis comparison circuit and a second-end communication device. The voltage calculation circuit is used to measure the voltage loss of the cable, acquire measurement data, and determine the voltage information of the second-end device based on the measurement data, so as to monitor the working status of the second-end communication device. The first-end graded power supply is used to provide graded voltage to the second-end communication device; the graded voltage includes a first-level voltage and a second-level voltage. The hysteresis comparison circuit is used to perform hysteresis comparison based on the graded voltage and output IO control signal to control the working state of the second-end communication device. The step of performing hysteresis comparison based on the graded voltages and outputting an IO control signal to control the operating state of the second-end communication device includes: Compare the voltage rating with the reference hysteresis switching point; When the grading voltage is greater than the hysteresis high line switching point voltage of the reference hysteresis switching point, a high level is output to control the second-end communication device to be in the transmitting state; When the hysteresis switching voltage is lower than the hysteresis low-line switching voltage of the reference hysteresis switching point, a low level is output to control the second-end communication device to be in the receiving state. When the voltage level is lower than the high hysteresis transition point but higher than the low hysteresis transition point, the output level remains unchanged.

2. The remote monitoring system based on cable voltage according to claim 1, characterized in that, The voltage calculation circuit includes: The system includes an inverting amplifier and a non-inverting subtractor. One end of the inverting amplifier is connected to the shielding layer of the cable, and the other end is connected to one end of the non-inverting subtractor. The other end of the non-inverting subtractor is connected to the core layer of the cable. The inverting amplifier is used to measure the voltage loss of the cable and obtain measurement data. The non-inverting subtractor is used to determine the voltage data of the second-end device based on the measurement data, so as to monitor the working status of the second-end communication device.

3. The remote monitoring system based on cable voltage according to claim 2, characterized in that, The voltage loss of the cable is measured to obtain measurement data. The voltage information of the second-end device is determined based on the measurement data, including: Obtain the current information of the cable's shield layer, and determine the measurement data of the cable's voltage loss based on the cable core resistance and the cable shield layer resistance; Based on the measured data of the output voltage of the first-end graded power supply and the voltage loss of the cable, the voltage information of the second-end communication device is determined.

4. The remote monitoring system based on cable voltage according to claim 3, characterized in that, The voltage information of the second-end device is the difference between the output voltage of the first-end graded power supply and the measured voltage loss of the cable.

5. The remote monitoring system based on cable voltage according to claim 1, characterized in that, The second-end device also includes a second-end regulated power supply, which provides a stable power supply to the second-end communication device to overcome voltage fluctuations of the second-end communication device and to offset changes in the output voltage of the first-end graded power supply.

6. The remote monitoring system based on cable voltage according to claim 1, characterized in that, The first-terminal graded regulated power supply includes: an AC input transformer, a rectifier circuit, and a voltage regulator circuit connected in sequence, wherein the voltage regulator circuit is an LM317 integrated voltage regulator chip.

7. The remote monitoring system based on cable voltage according to claim 1, characterized in that, The first terminal device also includes: A voltage display and a current display, wherein the voltage display is connected in parallel across the first-end graded power supply and is used to display the output voltage of the first-end graded power supply; The current display is connected to the shielding layer of the cable and is used to display the output current of the first-end graded power supply.

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