Remote monitoring system based on cable voltage

Abstract

The invention provides a remote monitoring system based on cable voltage, and belongs to the technical field of cable monitoring, and the system comprises a first end device and a second end device which are connected through a cable. The first end device comprises a voltage operation circuit and a first end stepping power supply, and the second end device comprises a recheck comparison circuit and a second end communication device. And the voltage operation circuit is used for measuring the voltage loss of the cable, acquiring measurement data, and determining the voltage information of the second-end equipment according to the measurement data so as to monitor the working state of the second-end communication equipment. And the first end grading power supply is used for providing grading voltage for the second end communication equipment. And the return difference comparison circuit is used for carrying out return difference comparison and outputting an IO control signal so as to control the working state of the second-end communication equipment. Through the return difference comparison circuit at the second end, extra control lines and control signals are not needed, and the working mode of the second end equipment at the far end can be stably and reliably controlled by adjusting the output voltage of the stepping power supply at the first end.

Description

Technical Field

[0001] The invention relates to the technical field of cable monitoring, and in particular to a remote monitoring system based on cable voltage. Background Art

[0002] With the advancement of science and technology, there are more and more miniaturized unmanned equipment, and unmanned field environmental monitoring equipment and unmanned communication equipment are being used more and more widely. In the fields of natural environment monitoring, covert communications, such as field monitoring, underwater monitoring, tunnels and other special environments, it is often necessary to separate the front-end communication equipment from the back-end equipment, and the front-end equipment is in an unmanned state.

[0003] The distance between the front-end communication equipment and the back-end equipment is often hundreds of meters to thousands of meters, and it is difficult to monitor and control the working status of the front-end equipment from the back-end. Usually, the front-end power supply is provided from the back-end through cables. Therefore, how to use the power supply cable to monitor and control the front-end equipment and improve the status monitoring and control capabilities of the front-end equipment has become an important issue to be solved. Summary of the invention

[0004] The present invention provides a remote monitoring system based on cable voltage, which is used to solve the defects of the prior art and realize a portable Beidou-based positioning instrument that is independent of signal base stations and can work in unmanned areas.

[0005] In a first aspect, the present invention 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 step power supply; the second end device comprises a backcheck comparison circuit and a second end communication device;

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

[0007] The first-end graded power supply is used to provide graded voltage for the second-end communication device;

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

[0009] According to the remote monitoring system based on cable voltage, the step voltage includes a first step voltage and a second step voltage, and the hysteresis comparison is performed according to the step voltage to output an IO control signal to control the working state of the second end communication device, including:

[0010] Comparing the binned voltage with a reference hysteresis conversion point;

[0011] When the bin 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 a transmitting state;

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

[0013] When the bin voltage is less than the hysteresis low line switching point and greater than the hysteresis low line switching point voltage, the output level is maintained unchanged.

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

[0015] A reverse amplifier and a unidirectional subtractor, one end of the reverse amplifier is connected to the shielding layer of the cable, and the other end is connected to one end of the unidirectional subtractor; the other end of the unidirectional 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; the unidirectional subtractor is used to determine the voltage data of the second-end device according to the measurement data to monitor the working status of the second-end communication device.

[0016] According to the remote monitoring system based on cable voltage, measuring the voltage loss of the cable to obtain measurement data, and determining the voltage information of the second end device according to the measurement data includes:

[0017] Obtaining current information of the shielding layer of the cable, and determining measurement data of voltage loss of the cable according to the cable core resistance and the cable shielding layer resistance;

[0018] The voltage information of the communication device at the second end is determined according to the output voltage of the first end stepped power supply and the measurement data of the voltage loss of the cable.

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

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

[0021] According to the cable voltage-based remote monitoring system, the first-end step-by-step voltage-stabilized power supply comprises: an AC 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.

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

[0023] A voltage display and a current display, wherein the voltage display is connected in parallel to both ends of the first end stepped power supply and is used to display the output voltage of the first end stepped power supply;

[0024] 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.

[0025] The present invention provides a remote monitoring system based on cable voltage, which has the following beneficial effects compared with the prior art:

[0026] The present invention provides a remote monitoring system based on cable voltage, which includes a first-end device and a second-end device interconnected by a cable. The first-end device includes a voltage operation circuit and a first-end step power supply, and the second-end device includes a retrieval comparison circuit and a second-end communication device. The voltage operation circuit is used to measure the voltage loss of the cable, obtain measurement data, and determine the voltage information of the second-end device according to the measurement data to monitor the working state of the second-end communication device. The first-end step power supply is used to provide step voltages for the second-end communication device. The hysteresis comparison circuit is used to perform hysteresis comparison according to the step voltages and output an IO control signal to control the working state of the second-end communication device. The present invention is suitable for occasions where power is supplied through cables hundreds of meters to thousands of meters long. By adding a voltage operation circuit, the power supply voltage of the remote second-end device can be stably and reliably monitored to grasp the working state of the remote device; the hysteresis comparator of the second-end device can stably and reliably control the working mode of the remote device by adjusting the output voltage of the near-end output voltage stabilization circuit without the need for additional control lines and control signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0030] Figure 3 This is the second structural schematic diagram of the remote monitoring system for cable voltage provided by the present invention;

[0031] Figure 4 It is a structural schematic diagram of a hysteresis comparison circuit provided by the present invention;

[0032] Figure 5 It is a schematic diagram of the principle of the transmission curve of the hysteresis comparator provided by the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that in the description of the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. Unless otherwise clearly specified and defined, the terms "install", "connect" and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0035] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0036] Combine the following Figure 1-Figure 5 A remote monitoring system based on cable voltage provided by an embodiment of the present invention is described.

[0037] Figure 1 Schematic diagram of a remote monitoring system based on cable voltage provided by the present invention. Figure 1As shown, the system includes:

[0038] A first-end device and a second-end device interconnected by a cable; the first-end device includes a voltage operation circuit and a first-end step power supply; the second-end device includes a check comparison circuit and a second-end communication device;

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

[0040] The first end divided power supply is used to provide divided voltage for the second end communication equipment;

[0041] The hysteresis comparison circuit is used to perform hysteresis comparison according to the graded voltage and output an IO control signal to control the working state of the second-end communication device.

[0042] The remote monitoring system mainly consists of three parts: the first-end device, the power supply cable and the second-end device. The first-end device and the second-end device are connected by a cable. The first-end device mainly includes a voltage calculation circuit and a first-end grading power supply, and the second-end device mainly includes a check comparison circuit and a second-end communication device.

[0043] In this embodiment, the first-end device is placed at the near end, and the second-end device is placed at the far end. The voltage and current information of the far-end second-end device is monitored by the voltage operation circuit in the first-end device deployed at the near end, so as to grasp the working state of the far-end second-end device. The first-end graded power supply in the first-end device deployed at the near end provides graded voltage to the second-end communication device, and the far end detects the change of the power supply voltage through the hysteresis comparison circuit in the second-end device, and outputs the IO control signal for controlling the second-end communication device, so as to realize the control of the working state of the far-end second-end communication device.

[0044] Optionally, the first-end stepped power supply includes an AC 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 input of the AC input transformer is 220V AC and the output is 32V AC, which is rectified to 38V DC by the rectifier circuit. The voltage stabilizing circuit is the LM317 integrated voltage stabilizing chip. Changing the setting resistance of the LM317 integrated voltage stabilizing chip can change the output DC voltage. The output operating voltage can reach 30V and the maximum operating current can reach 1A.

[0046] In one embodiment, the graded voltage provided by the first-end graded power supply to the second-end communication device includes a first-end voltage and a second-end voltage. The hysteresis comparison circuit performs hysteresis comparison based on the graded voltage and outputs an IO control signal to control the working state of the second-end communication device.

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

[0048] In one embodiment, the first-end graded power supply outputs are 28V DC high voltage and 20V DC low voltage respectively. During normal operation, 20V DC low voltage can be output for the second-end device to receive information, and 28V DC high voltage can be output 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 hysteresis comparison circuit can use a single power supply operational amplifier to stably and reliably determine whether the output of the first-end gradation power supply deployed at the near end is a 28V DC high voltage or a 20V DC low voltage through the hysteresis comparison, thereby controlling the working state of the remote communication device. When the hysteresis comparison circuit determines that the input voltage is a 28V DC high voltage, the hysteresis comparison circuit outputs a high level and controls the second-end communication device to be in the transmitting state; when it is determined to be a 20V DC low voltage, the hysteresis comparator outputs a low level and controls the second-end communication device to work in the receiving state.

[0050] Compared with ordinary comparators, the hysteresis comparator has a larger state transition maintenance voltage space and will not repeatedly switch around the reference comparison voltage, thus avoiding the problem of repeated switching of working modes of remote devices.

[0051] In one embodiment, measuring the voltage loss of the cable to obtain measurement data, and determining the voltage information of the second end device according to the measurement data includes:

[0052] Obtaining current information of the shielding layer of the cable, and determining measurement data of voltage loss of the cable according to the cable core resistance and the cable shielding layer resistance;

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

[0054] Figure 2 Schematic diagram of a remote voltage operation circuit provided by the present invention. 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 with an operational amplifier according to the long cable core resistance and the long cable shield resistance, and then subtract the voltage loss from the output voltage of the near-end stepped voltage-stabilized power supply to obtain the remote voltage.

[0055] In one embodiment, the first end device also includes: a voltage display and a current display, the voltage display is connected in parallel at both ends of the first end step power supply, and is used to display the output voltage of the first end step 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 step power supply.

[0056] The voltage display U and the total current display I are used to display the output voltage and output current of the proximal graded regulated power supply.

[0057] In one embodiment, the second-end device further includes a second-end voltage-stabilizing 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 offset changes in the output voltage of the first-end stepped power supply.

[0058] Specifically, Figure 3 Another schematic diagram of the structure of a remote monitoring system based on cable voltage provided in an embodiment of the present application is as follows: Figure 3 As shown, the remote voltage-stabilized power supply is used to provide a stable power supply to the second-end communication device configured in the remote second-end device to overcome the voltage fluctuation caused by the remote power supply and control the output voltage change of the first-end graded power supply.

[0059] In one embodiment, the voltage operation circuit includes: a reverse amplifier and a unidirectional subtractor, one end of the reverse amplifier is connected to the shielding layer of the cable, and the other end is connected to one end of the unidirectional subtractor; the other end of the unidirectional 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; the unidirectional subtractor is used to determine the voltage data of the second-end device according to the measurement data to monitor the working status of the second-end communication device.

[0060] Specifically, the remote voltage operation circuit is mainly composed of an operational amplifier A1, an operational amplifier A2, a current sampling resistor Ra and resistors R1, R2, R3, R4, R5, R6, etc. The block diagram is as follows: Figure 2 shown.

[0061] Operational amplifier A1 and current sampling resistor Ra, resistors R1 and R2 form an inverting amplifier, which is used to calculate the power supply voltage Utotal and the voltage loss Uloss caused by 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] Operational amplifier A1 outputs UA1:

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

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

[0066] Usually the resistance of SYV50-5 coaxial cable 500 meters is about 20 ohms, and the current sampling resistance Ra is 0.1 ohms. Calculate:

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

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

[0069] Operational amplifier A2 and resistors R3, R4, R5, and R6 form a same-direction subtractor. When R3=R4=R5=R6=10kΩ,

[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 working principle of the operational amplifier V+=V-, we can conclude:

[0073] UA2=Utotal-UA1=Ufar

[0074] therefore Figure 2 The remote voltage operation circuit A2 shown outputs UA2 to calculate the remote power supply voltage Uremote.

[0075] In this embodiment, the main component design parameters are as follows:

[0076] 1) Ra = 0.1Ω;

[0077] 2) R1=100Ω, R2=20.1kΩ;

[0078] 3) R3=R4=R5=R6=10kΩ.

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

[0080] Among them, the operational amplifier A3 and the resistors R7 and R8 form a positive feedback circuit. Since the output voltage zener diode Dz works at 0 or the voltage stabilization value Uz, the + input of the operational amplifier A3 is Figure 4 The changes between UTH and UTL shown in the figure constitute a hysteresis comparator.

[0081] Among them, the hysteresis upper limit conversion point UTH is:

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

[0083] Hysteresis lower limit conversion point UTL:

[0084] UTL=Ur×R7 / (R7+R8) (6)

[0085] Hysteresis voltage △U:

[0086] △U=UTH-UTL=UZ×R8 / (R7+R8) (7)

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

[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] △U=6×0.3333=2V

[0090] In this embodiment, the resistance values ​​of R9 and R10 are designed to be 1:4 to form a 1:5 voltage attenuator, and the corresponding remote voltage reversal operating points are UTH=20V and UTL=10V, and the hysteresis voltage △U=10V.

[0091] Main component design parameters such as:

[0092] 1) The voltage value of the Zener diode is Uz=6V, Ro=3kΩ, Ro provides the working current for the Zener diode Uz;

[0093] 2) The reference diode voltage value Ur=3V, Rr=5kΩ, Rr provides the working current for the reference diode Ur;

[0094] 3) R7 = R8 = 5kΩ;

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

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

[0097] When the remote communication device is designed to receive, the near-end stepped voltage regulated power supply outputs a high voltage Utotal = 28V, the remote communication device is in the transmitting state, the cable loss voltage Uloss = 20Ω*0.7A = 14V, and the remote voltage Ufar = Utotal - Uloss = 28V-14V = 14V.

[0098] When the remote communication device is designed to receive, the near-end stepped voltage regulated power supply outputs a low voltage Utotal = 20V, the remote communication device is in the receiving state, the cable loss voltage Uloss = 20Ω*0.2A = 4V, and the remote voltage Ufar = Utotal - Uloss = 20V-4V = 16V.

[0099] When the output of the stepped regulated power supply is changed from high voltage Utotal = 28V to low voltage Utotal = 20V, the remote communication device is first in the transmitting state, and the remote voltage Ufar = Utotal - Uloss = 20V - 14V = 6V, which is lower than the hysteresis lower limit conversion point UTL = 10V. Therefore, the hysteresis circuit flips to a low level, and the remote communication device is set from the transmitting state to the receiving state.

[0100] When the output of the stepped regulated power supply is changed from a low voltage Utotal = 20V to a high voltage Utotal = 28V, the remote communication device is first in a receiving state, and the remote voltage Ufar = Utotal - Uloss = 28V - 4V = 24V, which is higher than the hysteresis lower limit conversion point UTH = 20V. Therefore, the hysteresis circuit flips to a high level, setting the remote communication device from the receiving state to the transmitting state.

[0101] The hysteresis comparison circuit of the present invention uses a single power supply operational amplifier, and realizes stable and reliable judgment of whether the output of the near-end graded voltage-stabilized power supply is a 28V DC high voltage or a 20V DC low voltage through hysteresis comparison, so as to control the working state of the remote communication device. When it is judged to be a 28V DC high voltage, the hysteresis comparator outputs a high level to control the remote communication device to work in the transmitting state; when it is judged to be a 20V DC low voltage, the hysteresis comparator outputs a low level to control the remote communication device to work in the receiving state.

[0102] Compared with common comparators, the hysteresis comparison circuit of the present invention has a larger state conversion maintaining voltage space and will not repeatedly convert near the reference comparison voltage, thereby avoiding the problem of repeatedly switching working modes of remote equipment.

[0103] The present invention can accurately locate personnel positions in various communication inconvenient situations, greatly ensuring personnel safety. Outdoor workers can also receive warning prompts from base station personnel through indicator lights, and the product is highly reliable and easy to carry. In addition, the present invention uses multiple communication interfaces to meet the needs of more scenarios and has the advantage of strong anti-interference ability.

[0104] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0105] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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: It includes a first end device and a second end device interconnected by a cable; the first end device includes a voltage operation circuit and a first end step power supply; the second end device includes a backcheck comparison circuit and a second end communication device; The voltage operation circuit is used to measure the voltage loss of the cable, obtain measurement data, and determine the voltage information of the second-end device according to the measurement data to monitor the working state of the second-end communication device; The first-end graded power supply is used to provide graded voltage for the second-end communication device; The hysteresis comparison circuit is used to perform hysteresis comparison according to the graded voltage and output an IO control signal to control the working state of the second-end communication device.

2. The cable voltage-based remote monitoring system according to claim 1, characterized in that: The step voltage includes a first step voltage and a second step voltage, and the hysteresis comparison circuit is used to perform hysteresis comparison according to the step voltage and output an IO control signal to control the working state of the second end communication device. Comparing the binned voltage with a reference hysteresis conversion point; When the bin 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 a transmitting state; When the graded voltage is less than the hysteresis low line switching point voltage of the reference hysteresis switching point, a low level is output to control the second end communication device to be in a receiving state; When the bin voltage is less than the hysteresis low line switching point and greater than the hysteresis low line switching point voltage, the output level is maintained unchanged.

3. The cable voltage-based remote monitoring system according to claim 1, characterized in that: The voltage operation circuit comprises: A reverse amplifier and a unidirectional subtractor, one end of the reverse amplifier is connected to the shielding layer of the cable, and the other end is connected to one end of the unidirectional subtractor; the other end of the unidirectional 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; the unidirectional subtractor is used to determine the voltage data of the second-end device according to the measurement data to monitor the working status of the second-end communication device.

4. The cable voltage-based remote monitoring system according to claim 3, characterized in that: Measuring the voltage loss of the cable to obtain measurement data, and determining the voltage information of the second end device according to the measurement data includes: Obtaining current information of the shielding layer of the cable, and determining measurement data of voltage loss of the cable according to the cable core resistance and the cable shielding layer resistance; The voltage information of the communication device at the second end is determined according to the output voltage of the first end stepped power supply and the measurement data of the voltage loss of the cable.

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

6. The cable voltage-based remote monitoring system according to claim 1, characterized in that: The second-end device also includes a second-end voltage-stabilized power supply for providing a stable power supply for the second-end communication device to overcome voltage fluctuations of the second-end communication device and offset changes in the output voltage of the first-end stepped power supply.

7. The cable voltage-based remote monitoring system according to claim 1, characterized in that: The first-end step-by-step voltage-stabilizing power supply comprises: an AC 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.

8. The cable voltage-based remote monitoring system according to claim 1, characterized in that: The first end device also includes: A voltage display and a current display, wherein the voltage display is connected in parallel to both ends of the first end stepped power supply and is used to display the output voltage of the first end stepped 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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