A nanosecond-level synchronization method and device for underground cable distributed monitoring nodes

Abstract

The application discloses a kind of nanosecond level synchronization method and device of underground cable distributed monitoring node, belong to electric power equipment state monitoring technical field.This method is by constructing "two-way question and answer" mechanism between master node and slave node, and introduces time stamp, when calculating relative clock difference, signal propagation time is naturally cancelled in equation set as intermediate variable, without knowing or estimating signal propagation speed in cable in advance, high-precision clock synchronization can be realized;By requiring slave node to delay a predetermined time after receiving synchronization start signal and reply with unique identity coding reply signal, the master node can explicitly identify and record the valid response from a specific node, ensure that the synchronization process is only established between the master node and the target slave node, so that reliable nanosecond level synchronization can still be maintained in complex cable network environment, and high-precision distributed measurement comparable to satellite synchronization is realized.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring technology, specifically to a nanosecond-level synchronization method and device for distributed monitoring nodes of underground cables. Background Technology

[0002] With the continuous improvement of urban power grid intelligence, real-time and accurate distributed monitoring of the operating status of underground cables has become a key link in ensuring power supply reliability. Whether it's achieving rapid fault location, precise analysis of circulating current distribution, early warning of temperature field hotspots, or accurate location of early signs of insulation degradation such as partial discharge, the core technology relies on multiple detector nodes deployed along the cable line to collect signals with strict time-series correlation. These analysis methods, based on traveling wave principles or multi-point data fusion, require that the time of each node within the entire distributed monitoring network be highly consistent. The synchronization accuracy directly determines the accuracy and effectiveness of the monitoring results. Therefore, achieving nanosecond-level time synchronization is a fundamental technical challenge supporting these advanced monitoring applications.

[0003] Currently, time synchronization primarily relies on the Global Positioning System (GPS) or the BeiDou Navigation Satellite System. However, in underground cable tunnels, pipe racks, or direct-buried environments, GPS or BeiDou signals cannot provide effective coverage, preventing distributed monitoring nodes from achieving high-precision synchronization via satellite. In existing technologies, the one-way pulse synchronization method is an alternative, where the master node broadcasts a synchronization pulse, and slave nodes calibrate their clocks based on the difference between the pulse's arrival time and the master node's transmission time. However, this method has a fundamental flaw: its time synchronization accuracy depends entirely on the precise knowledge of the signal propagation speed in the cable. In reality, the signal propagation speed is affected by factors such as cable structure, insulation materials, aging conditions, and environmental temperature and humidity, and is not constant throughout the network and is difficult to measure accurately. This deviation in wave velocity estimation directly and without compensation translates into clock synchronization errors between nodes, leading to a significant decrease in positioning accuracy. Furthermore, in actual cable networks with multiple branches and joints, pulse reflections generate complex interference signals.

[0004] Therefore, in multi-node cable networks without communication coordination, how to design a reliable mechanism that enables nodes to accurately identify synchronization pulse sources and effectively deal with the inherent pulse reflection interference in cable networks remains an unsolved technical problem. Summary of the Invention

[0005] The purpose of this invention is to provide a nanosecond-level synchronization method and related device for distributed monitoring nodes of underground cables, so as to overcome the problem that existing technologies are unable to eliminate the influence of wave velocity estimation errors in underground cable networks without GPS / BeiDou positioning systems and without communication capabilities between nodes.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a nanosecond-level synchronization method for distributed monitoring nodes of underground cables, applied in an underground cable network comprising one master node and N slave nodes. Within a time window of the master node, a synchronization start signal is broadcast to all slave nodes, and the first timestamp is recorded. ; After receiving the synchronization start signal, the current slave node records the second timestamp. , where n indicates that the current slave node is the nth slave node, and the value of n ranges from 1 to N; Based on the response delay time pre-stored by the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. ; After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; Based on the obtained timestamps, the relative clock difference of each slave node is calculated to correct the local clock of the slave node, thereby achieving nanosecond-level synchronization of distributed monitoring nodes.

[0007] A further improvement of this invention lies in that, based on the obtained timestamp, the calculation of the relative clock difference of the slave node is specifically as follows:

[0008] in, The relative clock difference between the master node and the nth slave node.

[0009] A further improvement of the present invention is that the response delay time pre-stored by the current slave node is calculated based on the estimated propagation time of the signal between the current slave node and the master node, so that the response signals of all slave nodes arrive at the master node in a sequential order in time and do not overlap.

[0010] A further improvement of this invention is that, if the nanosecond-level synchronization of the underground cable distributed monitoring node is the first execution, then the pre-stored response delay time of the nth slave node... Specifically:

[0011] in, The distance from the master node to the slave node n; The distance from the master node to the farthest slave node N; For the signal propagation speed of engineering cables; The preset time for the signal reflection wave to fully attenuate; If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is not the first execution, then the pre-stored response delay time of the nth slave node... Specifically:

[0012] in, The signal propagation time from the master node to the slave node n obtained during the last synchronization execution; The signal propagation time from the master node to the farthest slave node N, obtained from the last synchronization execution.

[0013] A further improvement of the present invention is that the synchronization start signal and the response signal are signals containing a single synchronization pulse and a specific digital code, the specific digital code being a square wave following the synchronization pulse; the specific digital code of the master node and each slave node is unique and different, and is used for identity authentication.

[0014] A further improvement of the present invention is that, within a time window of the master node, if the master node does not receive response signals from all slave nodes, it closes the current time window, enters a silent period, records the current error information, and enters the next time window after the silent period ends.

[0015] This invention also provides a nanosecond-level synchronization system for distributed monitoring nodes of underground cables, comprising: The first module is used to broadcast a synchronization start signal to all slave nodes within a time window of the master node and record the first timestamp. After receiving the synchronization start signal, the current slave node records the second timestamp. 'n' indicates that the current slave node is the nth slave node, and the value of 'n' ranges from 1 to N; based on the pre-stored response delay time of the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; The second module is used to calculate the relative clock difference of each slave node based on the obtained timestamp, which is used to correct the local clock of the slave node and realize nanosecond-level synchronization of distributed monitoring nodes.

[0016] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the nanosecond-level synchronization method for distributed monitoring nodes as described above.

[0017] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the nanosecond-level synchronization method for distributed monitoring nodes as described above.

[0018] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the nanosecond-level synchronization method for distributed monitoring nodes as described above.

[0019] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The nanosecond-level synchronization method for distributed monitoring nodes of underground cables provided by this invention establishes a "two-way question-and-answer" mechanism between the master node and the slave node and introduces timestamps. When calculating the relative clock difference, the signal propagation time is naturally canceled out as an intermediate variable in the equation system. Therefore, high-precision clock synchronization can be achieved without prior knowledge or estimation of the signal propagation speed in the cable. By requiring the slave node to delay for a predetermined time after receiving the synchronization start signal and reply with a response signal with a unique identification code, the master node can clearly identify and record the valid response from the specific node. This effectively filters out incoherent reflection pulses and noise interference, ensuring that the synchronization process is effectively established only between the master node and the target slave node. As a result, reliable nanosecond-level synchronization can still be maintained in complex cable network environments. This enables high-precision distributed measurement comparable to satellite synchronization in underground cable environments where GPS / BeiDou signals cannot cover. Attached Figure Description

[0020] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a flowchart illustrating the overall workflow of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to the present invention.

[0022] Figure 2 This is a hardware system architecture diagram of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to the present invention.

[0023] Figure 3 This is a timing diagram of a single interaction of the bidirectional time synchronization method for the nanosecond-level synchronization method of the distributed monitoring node of underground cable of the present invention.

[0024] Figure 4 This is a schematic diagram of the waveforms of pulse signals and digital codes in an embodiment of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to the present invention.

[0025] Figure 5 This is a block diagram of the internal hardware functional units of the monitoring node in the nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to the present invention.

[0026] Figure 6 This is a schematic diagram of the deployment of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to the present invention in a practical system. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0029] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0031] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This is an explanation of the present invention and not a limitation thereof.

[0033] This invention provides a nanosecond-level synchronization method for distributed monitoring nodes of underground cables, applied in an underground cable network comprising one master node and N slave nodes. Within a time window of the master node, a synchronization start signal is broadcast to all slave nodes, and the first timestamp is recorded. ; After receiving the synchronization start signal, the current slave node records the second timestamp. , where n indicates that the current slave node is the nth slave node, and the value of n ranges from 1 to N; Based on the response delay time pre-stored by the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. ; After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; Based on the obtained timestamps, the relative clock difference of each slave node is calculated to correct the local clock of the slave node, thereby achieving nanosecond-level synchronization of distributed monitoring nodes.

[0034] This method directly solves the relative clock difference through a specific computational model, fundamentally eliminating the dependence on signal propagation speed. It adopts a master-slave parallel polling architecture, in which the master node completes bidirectional synchronization with all slave nodes in one cycle, without the need for direct communication between nodes, and is highly robust and scalable.

[0035] By establishing a "two-way question-and-answer" mechanism between the master and slave nodes, and introducing four precise timestamps ( In calculating relative clock difference, the signal propagation time, as an intermediate variable, is naturally canceled out in the equations. This eliminates the need to know or estimate the signal propagation speed in the cable beforehand, achieving high-precision clock synchronization and significantly improving the robustness and adaptability of the synchronization system. By requiring slave nodes to delay for a predetermined time after receiving the synchronization start signal and reply with a uniquely identified code, the master node can clearly identify and record valid responses from specific nodes. This mechanism effectively filters out incoherent reflected pulses and noise interference, ensuring that the synchronization process is only effectively established between the master node and the target slave node. This allows for reliable nanosecond-level synchronization even in complex cable network environments, providing a solid technical foundation for cable condition monitoring based on traveling wave positioning and multi-point data fusion (such as precise fault location, circulation analysis, temperature field reconstruction, and early warning of insulation degradation). It also enables high-precision distributed measurement comparable to satellite synchronization in underground cable environments where GPS / BeiDou signals cannot reach, thus comprehensively improving the intelligent operation and maintenance level and power supply reliability of urban power grids.

[0036] Specifically, based on the obtained timestamp, the propagation time of the signal from the master node to the slave node n is calculated using the following mathematical formula. Relative clock bias :

[0037]

[0038] in, The relative clock difference between the master node and the nth slave node.

[0039] Furthermore, the distance from the master node to the slave node n can be used. l n (Given) The average propagation speed of the signal from the master node to the slave node n is obtained. .

[0040] Specifically, the response delay time pre-stored by the current slave node is calculated based on the estimated propagation time of the signal between the current slave node and the master node, so that the response signals of all slave nodes arrive at the master node in a sequential and non-overlapping manner.

[0041] By using a timing strategy with a preset delayed response, attenuation time is provided for the pulse reflection wave, which together with the coding mechanism constitutes an anti-interference guarantee.

[0042] Specifically, if the nanosecond-level synchronization of the underground cable distributed monitoring nodes is the first execution, then the pre-stored response delay time of the nth slave node... Specifically:

[0043] in, The distance from the master node to the slave node n; The distance from the master node to the farthest slave node N; This refers to the commonly used cable signal propagation speed in engineering, specifically 1.7 × 10⁻⁶. 8 m / s; The preset time for the signal reflection wave to fully attenuate; If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is not the first execution, then the pre-stored response delay time of the nth slave node... Specifically:

[0044] in, The signal propagation time from the master node to the slave node n obtained during the last synchronization execution; This is the signal propagation time from the master node to the farthest slave node N, obtained from the last synchronization execution.

[0045] For the first time synchronization of this underground cable network, the propagation speed and propagation time of the signal at the master and slave nodes are unknown. The commonly used cable signal propagation speed in engineering is adopted. To estimate the propagation speed, let's assume there are N slave nodes in the cable, and slave node 1 is the closest to the master node. From node 2 onwards, for And so on, from node N to the master node the distance is the farthest, which is... .

[0046] The master node sends a synchronization start signal at time t=t1, and the slave node n receives the synchronization start signal at time t=t1. Set the time for the master node to receive the first reply signal from the slave node as For the ideal time, among which, t 0 represents a pre-defined timeframe for sufficient attenuation of reflected waves in the cable. This means that after the farthest node in the cable receives the signal, there is a delay of one... t 0, at this point, it is ideal for the response signal from node 1 to reach the master node.

[0047] To meet this requirement, the response time from node 1 is... The response delay from node 1 is Similarly, the ideal time for the master node to receive the reply signal from slave node n is... This indicates that the time interval between each slave node's response signal arriving at the master node is 1. t 0, to ensure that the reflected wave of the previous signal is sufficiently attenuated in the cable. Based on this, the response delay time from node n can be deduced to be... Each slave node calculates its own response delay time according to this formula, which ensures that the response signals of each slave node arrive at the master node in a sequential order without overlap.

[0048] For the second and subsequent synchronizations of this underground cable, the signal propagation time from the master node to slave node n, calculated from the previous time synchronization, is used. From the above derivation process, a more accurate response delay time for node n can be obtained as follows: .

[0049] Specifically, the synchronization start signal and response signal are signals containing a single synchronization pulse and a specific digital code, with the specific digital code following the synchronization pulse in the form of a square wave; the specific digital code of the master node and each slave node is unique and different, and is used for identity authentication.

[0050] By combining a unique digital code with a synchronization pulse, nodes can uniquely identify the source of the synchronization pulse, effectively solving the problem of misidentification.

[0051] Specifically, within a time window of the master node, if the master node does not receive response signals from all slave nodes, it closes the current time window, enters a silent period, records the current error information, and enters the next time window after the silent period ends.

[0052] This invention also provides a nanosecond-level synchronization system for distributed monitoring nodes of underground cables, comprising: The first module is used to broadcast a synchronization start signal to all slave nodes within a time window of the master node and record the first timestamp. After receiving the synchronization start signal, the current slave node records the second timestamp. 'n' indicates that the current slave node is the nth slave node, and the value of 'n' ranges from 1 to N; based on the pre-stored response delay time of the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; The second module is used to calculate the relative clock difference of each slave node based on the obtained timestamp, which is used to correct the local clock of the slave node and realize nanosecond-level synchronization of distributed monitoring nodes.

[0053] The nanosecond-level synchronization system for distributed monitoring nodes of underground cables provided by this invention boasts high synchronization accuracy and fundamentally eliminates system errors. Employing a bidirectional time synchronization mechanism, since the signal travels along the same path, same-mode propagation errors can be canceled out, ensuring synchronization accuracy is unaffected by wave velocity uncertainties caused by inconsistent cable parameters or environmental changes, thus providing a theoretical guarantee for achieving nanosecond-level synchronization. It also exhibits strong anti-interference capabilities and high robustness: by assigning a unique digital code to each node, the master and slave nodes can clearly identify the communication object, avoiding misinterpreting pulses or reflected waves from irrelevant nodes as synchronization signals. Furthermore, by introducing the response delay time of each slave node and a global silent waiting time, sufficient attenuation time is provided for pulse reflections. The method combines coding verification to form a dual filtering, effectively solving the problem of misidentification caused by pulse reflection in complex cable networks; it requires no inter-node communication, has high reliability and low cost: the entire synchronization process relies only on the propagation of pulses in the cable body, without the need to deploy additional high-speed communication networks (such as fiber optic or wireless modules), which reduces system complexity and cost, and avoids synchronization failure due to communication link failure, making it very suitable for deployment in underground environments with weak communication infrastructure; the method is flexible and highly scalable: adding a slave node only requires pre-allocating a new code and its response delay time, adding it to the cable network, and extending the time window for the master node to wait for the response signal pair, without changing the hardware or logic of the existing nodes, making system expansion simple.

[0054] In a specific embodiment of the present invention, the present invention provides a nanosecond-level synchronization method for distributed monitoring nodes of underground cables. Under the condition that it does not rely on the Global Positioning System (GPS / BeiDou) and there is no direct communication network between nodes, the master node completes synchronization with multiple slave nodes within a synchronization cycle through a single interaction process. Specifically, the method includes the following steps: The master node broadcasts a synchronization start signal to the cable network. Each slave node, based on the time it receives the synchronization start signal, injects a reply signal with a unique identification code into the cable network at a time point after delaying its own unique reply delay. The master node receives and distinguishes the reply signals from different slave nodes, and calculates the relative clock difference with each slave node by analyzing its four unique timestamps. The specific calculation method for the unique reply delay pre-stored by each slave node is as follows: it calculates the estimated propagation time of the signal between itself and the master node, ensuring that all slave node reply signals arrive at the master node sequentially without overlap. In principle, the reply signal from the slave node closest to the master node arrives first, and the reply signal from the slave node farthest from the master node arrives last. The four timestamps include: The local time at which the master node transmits the synchronization start signal t 1; The local time at which a certain slave node n receives the synchronization start signal The local time of the reply signal transmitted from node n The local time at which the master node receives the reply signal from the slave node n. The relative clock difference That is, the time difference between the local clock of the master node and the local clock of the slave node n, expressed by the formula Calculations show that both the synchronization start signal and the slave node's response signal contain a single synchronization pulse and a specific digital code. The digital code for each slave node is unique and distinct, used for authentication. The digital code follows the synchronization pulse in square wave form. The arrival time of the first slave node's response signal to the master node is estimated to be after all slave nodes have received the synchronization start signal, and the synchronization start signal must be sufficiently attenuated in the cable network. The interval between the arrival times of each slave node's response signal to the master node should be sufficient to ensure that the reflected wave of the previous response signal is sufficiently attenuated in the cable network. After the master node sends the synchronization start signal, the total time window for waiting for each slave node's response signal is: [The time window is calculated as follows]. The system architecture calculates the arrival time of the last slave node's reply signal based on the cable network, allowing for a certain margin. If the master node fails to recognize all slave node reply signals within the time window for receiving them, it closes the time window and records the error information. At the end of a synchronization cycle, after the master node closes the time window for receiving each slave node's reply signal, a certain silence time is allowed before the start of the next synchronization cycle. This silence time ensures that the reflected waves of all reply signals are sufficiently attenuated in the cable network. Both the master and slave nodes in the system architecture have hardware functional architectures including transmitters, detectors, highly stable clocks, and processing control units, thus supporting any node in the network to be configured as a master node.

[0055] A nanosecond-level synchronization method for distributed monitoring nodes in underground cable networks is proposed. The system consists of a master node and several slave nodes, which do not have the ability to communicate with each other. The synchronization accuracy is achieved based on the principle of bidirectional time synchronization to eliminate wave velocity estimation errors. The reliability of synchronization is achieved through a digital coding identification mechanism and a timing scheduling strategy to deal with pulse reflection interference.

[0056] In this method, the master node triggers a coordinated response from all slave nodes via a single broadcast synchronization start signal, completing time synchronization of all nodes in the network within one synchronization cycle. Time synchronization between the master node and any slave node is achieved by recording the local time of pulse transmission and reception during a single bidirectional analog-to-digital pulse exchange. A specific calculation model is used to directly calculate the relative clock deviation using the four timestamps obtained, thus eliminating dependence on the signal propagation speed in the cable. To address pulse reflection interference and misidentification issues in the cable network, a unique digital code is used for authentication, and precise pre-set time slot allocation avoids signal conflicts. This invention achieves nanosecond-level time synchronization of distributed monitoring nodes in environments without GPS / BeiDou positioning system signals. It boasts advantages such as high accuracy, strong anti-interference capability, and no need for additional communication networks, providing a reliable technical foundation for distributed synchronous monitoring of underground cables.

[0057] The concept of this invention is based on the following core components and principles: synchronous system architecture, bidirectional time synchronization and deviation calculation principle, encoding recognition and addressing mechanism, and time-series scheduling strategy to resist reflection interference.

[0058] The synchronization system adopts a master-slave architecture. The master node serves as the synchronization reference and scheduling center, and has a built-in highly stable local clock. Each slave node has pulse transmission, signal detection, code recognition, and timestamp recording functions. All nodes are coupled to each other via the cable body, eliminating the need for an additional communication network.

[0059] The principle of bidirectional time synchronization and deviation calculation states that for any slave node, assuming it is numbered n, its synchronization with the master node is achieved through a complete bidirectional analog-digital hybrid pulse exchange. This process generates four key timestamps: the master node's transmission time... t 1. Receive time from node Node launch time Master node reception time The propagation time of the signal from the master node to the slave node n is calculated using the following mathematical formula. With clock deviation :

[0060]

[0061] The encoding and addressing mechanism enables accurate addressing even without communication. A unique digital code is pre-configured for the master node and each slave node: the master node code is used by slave nodes to identify the synchronization start signal, and the slave node code is used by slave nodes to verify their identity with the master node. This mechanism ensures that in an environment with multiple nodes coexisting, each node can uniquely identify its own synchronization command or response, avoiding misidentification.

[0062] Anti-reflection interference timing scheduling strategies are used to address pulse reflections in cable networks. The system employs a parallel cooperative scheduling mechanism based on estimated propagation delays: the master node initiates the entire synchronization process through a single broadcast, and all slave nodes initiate responses in parallel based on their pre-stored, unique reply delay times. Through a unique delay design, the reply signals from all slave nodes arrive at the master node sequentially on the time axis without overlapping, thus naturally forming a conflict-free reply signal sequence within a short time window. The inherent time interval between reply signals provides an attenuation window for reflection interference. The system has a quiet period before the start of a synchronization cycle, which provides attenuation time for the reflected wave of the last reply signal, ensuring that it does not interfere with the next synchronization cycle.

[0063] See Figure 1 At the start of the synchronization cycle, the master node triggers a coordinated response from all slave nodes via a single broadcast synchronization start signal. Each slave node, based on its pre-stored unique response delay time, injects a response signal with a unique identification code into the cable network at a precisely calculated time. The master node receives the response signals from all slave nodes within a preset waiting window and calculates the relative clock difference by analyzing the four timestamps corresponding to each slave node. After the synchronization cycle ends, the system enters a preset silent waiting time to ensure sufficient attenuation of reflected waves in the cable network, providing a clean signal environment for the next synchronization cycle. This parallel architecture enables time synchronization of all nodes in the network within a single synchronization cycle, significantly improving synchronization efficiency.

[0064] See Figure 2The hardware system architecture of this invention adopts a unified and modular design. The system consists of a master node and several slave nodes, all connected through an underground cable network to form a distributed monitoring network. Each node contains four core modules: a processing control unit, a detector, a transmitter, and a high-stability clock. This unified hardware design ensures the interchangeability of nodes, meaning that any node in the network can be configured as the master node as needed. The processing control unit is responsible for code recognition and generation, timing control, and data processing; the detector is specifically responsible for signal sensing, converting analog signals on the cable into digital waveforms; the transmitter focuses on power driving, converting digital commands into high-voltage pulses; and the high-stability clock provides a unified time reference. All modules are connected through standard interfaces to form a collaborative and efficient hardware system.

[0065] See Figure 3 For any slave node n, its synchronization with the master node is achieved through a complete bidirectional pulse exchange, which generates four key timestamps: the local time t1 when the master node transmits the synchronization start signal, the local time t2 when the slave node n receives the synchronization start signal, and the local time t3 when the master node transmits the synchronization start signal. The local time of the reply signal transmitted from node n The local time at which the master node receives the reply signal from slave node n. Subsequent data processing will be based entirely on these four timestamps, eliminating dependence on wave velocity. The propagation time T of the signal from the master node to the slave node n is calculated using the formula... Furthermore, the relative clock difference between the master node and the slave node n can be obtained. Furthermore, this can be calculated from the distance from the master node to the slave node n. l n (Assuming it is known) Obtain the average propagation speed of the signal from the master node to the slave node n. .

[0066] See Figure 4The encoding recognition and anti-interference mechanism employs a hybrid signal design combining pulse and digital encoding. Both the synchronization start signal and the slave node's response signal are composite signals containing a single synchronization pulse and a specific digital code. The digital code for each master node and each slave node is unique and distinct. This encoded signal follows the high-voltage pulse in square wave form, together forming a complete signal. For example, when the master node sends a synchronization start signal, the pulse is followed by the code "0xA5" for all slave nodes to identify; while when slave node 1 responds, its pulse is followed by the code "0x5A", and so on. Upon detecting a pulse, the receiver decodes and verifies the subsequent encoding. Only pulses with matching codes are considered valid synchronization signals; pulses with mismatched codes or those that cannot be decoded (likely reflected waves or noise) are discarded. This mechanism has two advantages: First, it avoids the need for each monitoring node to have an independent communication network to schedule the synchronization order. Each slave node only needs to identify the master node's code to determine whether to respond, which greatly reduces the deployment difficulty. Second, it avoids the misidentification of signals. Even if a slave node does not respond normally, the master node can correctly determine the response status, which greatly improves the robustness of the system.

[0067] See Figure 5 The internal hardware of the monitoring node in this invention adopts a modular architecture with functional separation. The detector, as the signal sensing front end, consists of coupling and protection circuits, signal conditioning circuits, and an analog-to-digital converter, specifically responsible for coupling signals from the cable and converting them into digital waveforms. The transmitter, as the power output front end, consists of a digital-to-analog converter, a driver amplifier, and a power output stage, focusing on converting digital commands into high-voltage pulses and injecting them into the cable. Both modules connect to the processing and control unit via a standard interface, forming a clear signal chain.

[0068] In a practical system deployment diagram, the master node is typically installed in a location easily maintained, such as at the entrance of a substation or cable trench. Slave nodes are distributed and deployed along the cable route at key locations based on monitoring needs, including cable joints, branch boxes, and terminals. (See also...) Figure 6Let's assume that the distance from node 1 to the master node is the shortest, followed by node 2, and so on, with node n being the farthest. At time t=t1, the master node broadcasts a synchronization start signal to the cable network. Each slave node receives this signal sequentially and begins its own unique response delay time. At a certain moment, all nodes receive the synchronization start signal. After receiving the synchronization start signal and delaying its own response delay, each slave node injects a response signal with its own code into the cable. This ensures that the master node receives the response signals from each slave node sequentially on the time axis without overlap. The interval between each slave node's response signal arriving at the master node should ensure sufficient attenuation of the previous signal in the cable. The master node's waiting time window for the response signal should ensure that it receives the response signal from the last slave node under normal circumstances, with a certain margin. After this time window closes, the system enters a silent period to ensure sufficient signal attenuation in the cable before entering the next synchronization cycle, ensuring continuous synchronization of the master and slave node clocks and minimizing clock deviation. After each round of synchronization, the relative clock difference between the master node and slave node n is calculated. Each slave node sequentially adjusts its local clock to [the desired value]. ,in For the synchronized local clock, This is the local clock before synchronization. The synchronized local clock can achieve nanosecond-level synchronization with the master node's local clock.

[0069] Based on the same inventive concept, this application provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of a nanosecond-level synchronization method for distributed monitoring nodes. The memory may include main memory, such as high-speed random access memory, or it may also include non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which may be an industry-standard architecture bus, a peripheral component interconnection standard bus, an extended industry-standard architecture bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory stores the program; specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0070] Based on the same inventive concept, embodiments of this application provide a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the steps of a nanosecond-level synchronization method for the distributed monitoring nodes. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include RAM (Random Access Memory) and / or cache memory, etc. The non-volatile memory may include ROM (Read-Only Memory), hard disk, flash memory, optical disk, magnetic disk, etc.

[0071] Based on the same inventive concept, this application provides a computer program product, which includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions, which, when executed by a computer device, cause the computer device to perform the steps of the above-described nanosecond-level synchronization method for distributed monitoring nodes.

[0072] Those skilled in the art will understand that embodiments of the present invention can be provided as methods or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM (Compact Disc Read-Only Memory), optical storage, etc.) containing computer-usable program code.

[0073] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer apparatus or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0074] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer device or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0075] These computer program instructions may also be loaded onto a computer device or other programmable data processing equipment to cause a series of operational steps to be performed on the computer device or other programmable equipment to produce a process implemented by the computer device, thereby providing instructions that execute on the computer device or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0076] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0077] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A nanosecond-level synchronization method for distributed monitoring nodes of underground cables, characterized in that, This is applied in underground cable networks, which include one master node and N slave nodes. Within a time window, the master node broadcasts a synchronization start signal to all slave nodes and records the first timestamp. ; After receiving the synchronization start signal, the current slave node records the second timestamp. , where n indicates that the current slave node is the nth slave node, and the value of n ranges from 1 to N; Based on the response delay time pre-stored by the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. ; After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; Based on the obtained timestamps, the relative clock difference of each slave node is calculated to correct the local clock of the slave node, thereby achieving nanosecond-level synchronization of the distributed monitoring nodes of underground cables. The response delay time pre-stored by the current slave node is calculated based on the estimated propagation time of the signal between the current slave node and the master node, so that the response signals of all slave nodes arrive at the master node in a sequential and non-overlapping manner in time. If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is the first execution, then the pre-stored response delay time of the nth slave node... Specifically: in, The distance from the master node to the slave node n; The distance from the master node to the farthest slave node N; For the signal propagation speed of engineering cables; The preset time for the signal reflection wave to fully attenuate; If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is not the first execution, then the pre-stored response delay time of the nth slave node... Specifically: in, The signal propagation time from the master node to the slave node n obtained during the last synchronization execution; This is the signal propagation time from the master node to the farthest slave node N, obtained from the last synchronization execution.

2. The nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to claim 1, characterized in that, Based on the obtained timestamps, the relative clock difference of the slave nodes is calculated as follows: in, The relative clock difference between the master node and the nth slave node.

3. The nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to claim 1, characterized in that, The synchronization start signal and response signal are signals containing a single synchronization pulse and a specific digital code, with the specific digital code following the synchronization pulse in the form of a square wave; the specific digital code of the master node and each slave node is unique and different, and is used for identity authentication.

4. The nanosecond-level synchronization method for distributed monitoring nodes of underground cables according to claim 1, characterized in that, If the master node does not receive response signals from all slave nodes within a time window, it closes the current time window, enters a silent period, records the current error information, and enters the next time window after the silent period ends.

5. A nanosecond-level synchronization system for distributed monitoring nodes of underground cables, characterized in that, include: The first module is used to broadcast a synchronization start signal to all slave nodes within a time window of the master node and record the first timestamp. After receiving the synchronization start signal, the current slave node records the second timestamp. 'n' indicates that the current slave node is the nth slave node, and the value of 'n' ranges from 1 to N; based on the pre-stored response delay time of the current slave node, a response signal with a unique identification code is sent to the master node, and a third timestamp is recorded. After receiving the reply signal from the current slave node, the master node records the fourth timestamp. ; The response delay time pre-stored by the current slave node is calculated based on the estimated propagation time of the signal between the current slave node and the master node, so that the response signals of all slave nodes arrive at the master node in a sequential and non-overlapping manner in time. If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is the first execution, then the pre-stored response delay time of the nth slave node... Specifically: in, The distance from the master node to the slave node n; The distance from the master node to the farthest slave node N; For the signal propagation speed of engineering cables; The preset time for the signal reflection wave to fully attenuate; If the nanosecond-level synchronization of the underground cable distributed monitoring nodes is not the first execution, then the pre-stored response delay time of the nth slave node... Specifically: in, The signal propagation time from the master node to the slave node n obtained during the last synchronization execution; The signal propagation time from the master node to the farthest slave node N, obtained from the last synchronization execution; The second module is used to calculate the relative clock difference of each slave node based on the obtained timestamp, which is used to correct the local clock of the slave node and realize nanosecond-level synchronization of the distributed monitoring nodes of underground cables.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables as described in any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables as described in any one of claims 1 to 4.

8. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the nanosecond-level synchronization method for distributed monitoring nodes of underground cables as described in any one of claims 1 to 4.

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