A method and system for construction and operation of a distributed very long baseline transmitting array

Abstract

The application discloses a method for constructing and operating a distributed very long wave transmitting array, which comprises the following steps: S1, delimiting a geographical deployment area of the transmitting array, and discretizing the deployment area into a standard grid set containing a plurality of candidate nodes; S2, performing a random walk strategy based on a dynamic hopping mechanism to generate a first number of target deployment coordinates in the standard grid set; S3, deploying a corresponding movable very long wave transmitting unit at each target deployment coordinate; and S4, performing time synchronization and phase control on each very long wave transmitting unit based on a unified time reference, and controlling the phase of the signal transmitted by each very long wave transmitting unit so that the electromagnetic waves radiated thereby realize coherent power synthesis in a predetermined spatial direction. The application further discloses a distributed very long wave transmitting system. The embodiment of the application significantly improves the invincible survival capability of communication, and meets the requirements of long-distance communication on transmitting power and coverage range.

Description

Technical Field

[0001] This application relates to the fields of wireless communication and antenna engineering technology, and more specifically, to a method and system for constructing and operating a distributed very long wave transmitting array. Background Technology

[0002] Very Long Wave (VLF, 3kHz-30kHz) radio waves can propagate stably within a spherical waveguide formed by the Earth's surface and the lower boundary of the ionosphere. They possess unique advantages such as low atmospheric attenuation, phase stability, and the ability to penetrate tens of meters of seawater. They are a core means of achieving long-distance maritime communication, global emergency communication, and underground infrastructure communication, and their strategic importance is irreplaceable. Traditional VLF communication relies on centralized shore-based transmitting stations, using giant tower arrays and high-power amplifiers to achieve megawatt-level radiation power to meet global coverage requirements. The level of this technology directly determines the reliability and timeliness of long-distance communication.

[0003] However, existing very long wave (VLW) transmission systems have significant technical drawbacks: On the one hand, shore-based fixed stations adopt a centralized architecture, with antenna arrays covering several square kilometers and towers hundreds of meters high. These are easily identifiable targets with poor survivability. If core nodes such as tuning rooms and feeder systems are precisely targeted, the repair cycle can last for months, potentially leading to communication paralysis. On the other hand, existing mobile launch platforms, such as tethered balloons and UAV-borne antennas, are limited by cable insulation performance and current carrying capacity, resulting in a single unit radiated power generally below 100kW, making them unable to replace fixed stations for wide-area coverage. If multi-element arrays are used to synthesize power, regular arrays, such as uniform linear arrays, are easily predicted and targeted for destruction by the enemy. Traditional random deployment algorithms are prone to "deadlock" due to grid constraints, or near-field strong mutual coupling can burn out power amplifiers and far-field grating lobe energy leakage due to improper element spacing.

[0004] In summary, traditional very long wave communication faces a dilemma: either build ultra-large centralized transmitters to obtain sufficient communication power but poor survivability, or rely on small mobile transmitters to improve survivability but have insufficient power per unit and weak coverage, and can never meet the three major requirements of high power, high survivability and rapid deployment. Summary of the Invention

[0005] In view of at least one defect or improvement need in the prior art, this application provides a method and system for constructing and operating a distributed very long wave transmission array, which can solve at least one of the problems existing in the background art.

[0006] To achieve the above objectives, according to the first aspect of this application, a method for constructing and operating a distributed very long wave (VLS) transmitting array is provided, the method comprising the following steps: S1. Delineate the geographical deployment area of ​​the transmission array, and discretize the deployment area into a set of standard grids containing several candidate nodes; S2. Execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids; the dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. S3. Deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; S4. Based on a unified time reference, time synchronization and phase modulation are performed on each of the very long wave transmitting units to control the phase of the transmitted signal of each of the very long wave transmitting units, so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

[0007] Furthermore, the method for constructing and operating the aforementioned distributed very long wave transmission array, specifically including the execution of a random walk strategy based on a dynamic hopping mechanism, includes: S2.1 Randomly select a node from the standard grid set as the position of the first array element; S2.2 For the current last determined array element position, determine its geometric neighborhood, and remove nodes that are occupied or exceed the geographical deployment area from the geometric neighborhood to obtain a set of available candidates; S2.3 If the available candidate set is not empty, then randomly select a node from it as the next array element position; If the available candidate set is empty, it is determined to be in a local deadlock state, triggering the dynamic jump mechanism, randomly selecting a previously determined array element position as the new current node, and returning to S2.2; Repeat the above steps until the positions of the first number of array elements are determined.

[0008] Furthermore, in the above-mentioned method for constructing and operating a distributed very long wave transmission array, the standard grid set consists of square grids with a side length of d, and the geometric neighborhood is the eight neighborhoods of the current grid. The range of values ​​for the side length d is configured as follows: ,in The operating wavelength for very long wave transmitted signals; The minimum spacing between the very long wave transmitting units is or .

[0009] Furthermore, the method for constructing and operating the aforementioned distributed very long wave transmitting array, specifically including the realization of coherent power combining, includes: Each of the very long wave transmitting units independently receives timing signals from the global navigation satellite system and establishes a global synchronization clock in conjunction with a local atomic clock; Based on the spatial location coordinates of the target communication object and the target deployment coordinates of each VW transmitter, the required phase compensation amount for each VW transmitter is calculated. Each very long wave transmitting unit adjusts the phase of the excitation current according to the phase compensation amount to compensate for the phase delay caused by the spatial propagation path difference.

[0010] Furthermore, the above-mentioned method for constructing and operating a distributed very long wave transmitting array, after step S4, also includes a persistence assessment of the transmitting array: A random failure model for the very long wave transmitting unit is constructed, and the failure probability p of the transmitting unit is set. The relative gain distribution of the remaining array relative to the initial intact array was calculated using Monte Carlo simulation at the stated damage probability p. Calculate the median value of the relative gain distribution. If the median value is lower than a preset communication link threshold, increase the first quantity and repeat steps S2 to S4.

[0011] Furthermore, in the above-mentioned method for constructing and operating a distributed very long wave (VLW) transmitting array, the VLW transmitting unit adopts a vertical monopole antenna structure pulled by a tethered balloon, and resonant transmission at a specific frequency is achieved by adjusting the effective height of the tethered cable and the end tuning parameters.

[0012] According to a second aspect of this application, a system for constructing and operating a distributed very long wave (VLS) transmitting array is also provided, comprising: The grid partitioning module is used to delineate the geographical deployment area of ​​the transmission array and discretize the deployment area into a set of standard grids containing several candidate nodes; The path exploration module is used to execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids. The dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and to re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. The deployment module is used to deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; The control module is used to perform time synchronization and phase control on each of the very long wave transmitting units based on a unified time reference, and to control the phase of the transmitted signal of each of the very long wave transmitting units so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

[0013] Furthermore, the aforementioned distributed very long wave (VLS) transmitting array construction and operation system further includes a first number of spatially dispersed mobile transmitting units, the deployment locations of which are determined by a random walk strategy based on a dynamic hopping mechanism. Each of the mobile transmitting units includes: A floating platform is used to provide vertical height. The very long wave antenna assembly is towed and vertically suspended by the floating platform and is used as an electromagnetic wave radiator. The time synchronization module is used to obtain a high-precision unified time reference; The transmitter and tuning module are used to generate an excitation signal with a specific phase based on the time reference and target azimuth information and feed it into the very long wave antenna assembly to achieve power combining with other mobile transmitting units in space.

[0014] Furthermore, in the above-mentioned distributed very long wave transmitting array construction and operation system, the very long wave antenna component is integrated as the mooring cable of the floating platform, the mobile transmitting unit also includes a radial ground grid laid on the ground, and the transmitter and tuning module are connected between the mooring cable and the radial ground grid by bottom feeding.

[0015] Furthermore, in the aforementioned distributed VLSI transmission array construction and operation system, the distributed VLSI transmission system is configured such that when some mobile transmission units fail due to damage, the remaining surviving mobile transmission units automatically adjust their phase parameters according to the updated array topology.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived in this application can achieve the following beneficial effects: The method for constructing and operating a distributed very long wave (VLS) transmitting array provided in this application adopts the idea of ​​breaking down the whole into parts and spatial synthesis. It generates the array topology through a standard grid random walk algorithm with a dynamic jumping mechanism and combines it with spatial power synthesis technology. This solves the problems of poor survivability of traditional stations, low power of mobile single units, and easy locking of random arrays. It significantly improves the resilience of communication and meets the requirements of long-distance communication for transmission power and coverage. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for constructing and operating a distributed very long wave transmitting array, as provided in an embodiment of this application; Figure 2 A schematic diagram of the structure of the distributed very long wave transmitting array system provided in the embodiments of this application; Figure 3 A schematic diagram of a distributed very long wave transmission system architecture provided in an embodiment of this application; Figure 4 A schematic diagram of a random walk deployment method based on a dynamic jump mechanism is provided for embodiments of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0020] The terms "first," "second," "third," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0021] Figure 1 A flowchart illustrating the construction and operation method of a distributed very long wave transmitting array provided in this application embodiment is shown below. Figure 1 As shown in the figure, this application provides a method for constructing and operating a distributed very long wave (VLS) transmitting array, which includes the following steps: S1. Delineate the geographical deployment area of ​​the transmission array, and discretize the deployment area into a set of standard grids containing several candidate nodes; S2. Execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids; the dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. S3. Deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; S4. Based on a unified time reference, time synchronization and phase modulation are performed on each of the very long wave transmitting units to control the phase of the transmitted signal of each of the very long wave transmitting units, so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

[0022] Specifically, the distributed very long wave (VLW) transmitting array construction and operation method provided in this application solves the contradiction between power and survivability in traditional VLW communication by using a technical approach of breaking down the whole into parts, random deployment, and spatial synthesis.

[0023] Step S1 defines the physical basis and spatial constraints of the array construction, transforming the continuous geographic space into a discrete set of standardized grids. This discretization is a prerequisite for subsequent algorithm execution, and its key lies in the implicit adaptation to the physical characteristics of very long waves through the setting of grid side lengths. By standardizing the deployment area into grid nodes, the risk of strong near-field electromagnetic coupling caused by excessively close element spacing and the far-field grating lobe effect caused by excessively large spacing can be effectively avoided, thus providing a spatial framework for subsequent random deployment that meets both electrical safety requirements and radiation performance. The first number of target deployment coordinates can be N.

[0024] Step S2 aims to generate a highly persistent topology using intelligent algorithms. Traditional random deployment methods, when generating a large number of nodes within a limited area, are prone to local deadlock due to occupied available space, preventing the algorithm from generating the required number of array elements. The dynamic jump mechanism introduced in this step is an intelligent backtracking strategy. When the random walk path cannot continue beyond the current node, the system does not terminate but automatically backtracks to previously generated historical nodes and uses them as a new starting point to search the neighborhood again. This mechanism breaks the linear thinking of traditional algorithms, ensuring the stable generation of a predetermined number of target deployment coordinates under arbitrarily complex spatial constraints. Furthermore, the generated coordinates naturally possess an unpredictable random distribution, significantly increasing the difficulty for enemy prediction and targeted strikes.

[0025] Step S3 transforms the virtual topology into physical entities. This step emphasizes the mobility of the launching units. By deploying independent mobile units at the generated coordinate points, the system gains the ability to respond and reconfigure quickly. Each unit is physically distributed and independent, requiring no physical connection. This not only reduces the complexity of engineering deployment but also eliminates the risk of system paralysis due to a single point of failure at the physical level.

[0026] Step S4 ensures strict synchronization of all transmitting units on the time axis through a unified time reference, which is a prerequisite for achieving phase consistency. Based on this, phase modulation is used to precisely calibrate the transmitted signal of each unit, compensating for path differences caused by spatial variations. Ultimately, the electromagnetic waves radiated by all units are superimposed in phase in a predetermined direction, producing a coherent power combining effect. This combining makes multiple medium-power units equivalent to a single extremely high-power transmitter in the far field, thus achieving communication capabilities that replace traditional megawatt-class shore-based stations while ensuring high survivability.

[0027] The method for constructing and operating a distributed very long wave (VLS) transmitting array provided in this application adopts the idea of ​​breaking down the whole into parts and spatial synthesis. It generates the array topology through a standard grid random walk algorithm with a dynamic jumping mechanism and combines it with spatial power synthesis technology. This solves the problems of poor survivability of traditional stations, low power of mobile single units, and easy locking of random arrays. It significantly improves the resilience of communication and meets the requirements of long-distance communication for transmission power and coverage.

[0028] Optionally, the execution of the random walk strategy based on the dynamic jump mechanism specifically includes: S2.1 Randomly select a node from the standard grid set as the position of the first array element; S2.2 For the current last determined array element position, determine its geometric neighborhood, and remove nodes that are occupied or exceed the geographical deployment area from the geometric neighborhood to obtain a set of available candidates; S2.3 If the available candidate set is not empty, then randomly select a node from it as the next array element position; If the available candidate set is empty, it is determined to be in a local deadlock state, triggering the dynamic jump mechanism, randomly selecting a previously determined array element position as the new current node, and returning to S2.2; Repeat the above steps until the positions of the first number of array elements are determined.

[0029] Optionally, in the method for constructing and operating a distributed very long wave transmitting array provided in this application embodiment, the standard grid set is composed of square grids with a side length of d, and the geometric neighborhood is the eight neighborhoods of the current grid; The range of values ​​for the side length d is configured as follows: ,in The operating wavelength for very long wave transmitted signals; The minimum spacing between the very long wave transmitting units is or .

[0030] Optionally, the method for constructing and operating a distributed very long wave transmitting array provided in this application embodiment, wherein the coherent power combining is specifically included: Each of the very long wave transmitting units independently receives timing signals from the global navigation satellite system and establishes a global synchronization clock in conjunction with a local atomic clock; Based on the spatial location coordinates of the target communication object and the target deployment coordinates of each VW transmitter, the required phase compensation amount for each VW transmitter is calculated. Each very long wave transmitting unit adjusts the phase of the excitation current according to the phase compensation amount to compensate for the phase delay caused by the spatial propagation path difference.

[0031] Optionally, the method for constructing and operating a distributed very long wave (VLS) transmitting array provided in this application embodiment further includes, after step S4, a persistence evaluation of the transmitting array: A random failure model for the very long wave transmitting unit is constructed, and the failure probability p of the transmitting unit is set. The relative gain distribution of the remaining array relative to the initial intact array was calculated using Monte Carlo simulation at the stated damage probability p. Calculate the median value of the relative gain distribution. If the median value is lower than a preset communication link threshold, increase the first quantity and repeat steps S2 to S4.

[0032] Optionally, the method for constructing and operating a distributed very long wave (VLW) transmitting array provided in this application embodiment uses a vertical monopole antenna structure pulled by a tethered balloon in the VLW transmitting unit. By adjusting the effective height of the tethered cable and the end tuning parameters, resonant transmission at a specific frequency is achieved.

[0033] Specifically, consider a distributed array consisting of N vertical monopoles, distributed on the plane xOy. The coordinates of the Nth cell are (x... n y n The feed current is I. n The excitation phase is β n Assume the effective height of each antenna element is h. n Then the array in the far field direction Far-field total radiation field It can be represented as:

[0034] in: Angular frequency; The vacuum permeability; Distance from observation point For wave number, Wavelength; The observation angle in spherical coordinates; Let the spatial phase difference of the i-th cell relative to the origin be defined as...

[0035] To make the array be in the desired target direction To achieve beam maximization and in-phase synthesis (i.e., forming the main beam), phase compensation needs to be applied to each element:

[0036] 2. Statistical properties and applications of the central limit theorem Define array gain The ratio of the array's directional radiation capability to its omnidirectional radiation capability:

[0037] Among them, the array factor is defined. for:

[0038] in This represents the difference between the actual spatial phase and the compensated phase. In the target direction... , The array factor reaches its maximum value. .

[0039] This application employs random deployment, in the non-main lobe direction, due to coordinate... It is a random variable generated by the random walk algorithm. It can be regarded as in Random variables that are approximately uniformly distributed.

[0040] According to the central limit theorem, when the number of array elements N is sufficiently large, the array factor increases in the non-target direction. It can be regarded as the sum of a large number of independent random variables, with both the real and imaginary parts approaching a Gaussian distribution with zero mean.

[0041] Based on statistical properties, the array factor amplitude It follows a Rayleigh distribution, and its power It approximately follows an exponential distribution.

[0042] Due to array gain The denominator (total radiated power) involves an integral over the entire spatial domain, containing a large number of weakly correlated random variables, and can be viewed as a weighted sum of these variables. According to the law of large numbers, the denominator tends to a constant. Therefore, this application derives the conclusion that the array gain of a large-scale randomly distributed array... It approximately follows a Gaussian distribution.

[0043] This leads to an important conclusion: the array gain of the random array constructed in this application statistically follows a Gaussian distribution.

[0044] 3. Persistence Assessment Indicators To quantify resilience, this application introduces a unit random failure vector. ,in Let represent the state of the nth unit, which follows a Bernoulli distribution. If the unit is destroyed, If they survive, Let the damage rate be p, then .

[0045] The orientation coefficient of the remaining array is:

[0046] For a given damage rate p Define relative gain It is the ratio (dB) of the residual array orientation coefficient to the initial intact array orientation coefficient, and the median value of its cumulative distribution function is used as the core indicator for measuring persistence.

[0047]

[0048] Compared to the average, the median provides a more robust reflection of the system's actual performance under most circumstances. This metric indicates that, given a certain probability of damage, the array's performance is better than this value 50% of the time, providing an objective assessment of the array's "bottom line" of resilience.

[0049] The beneficial effects of this application are as follows: 1. Extremely high survivability: Compared to regular arrays, the randomly distributed array of this application exhibits a more gradual decrease in array gain when some cells fail due to an attack. Statistics show that, at a 50% cell destruction rate, the median relative gain of the surviving array is superior to that of a regular array of the same size, and it can still maintain effective communication capabilities, possessing an indestructible and unbreakable survivability.

[0050] 2. Breaking through power limits: Through spatial power synthesis, multiple independent low-power (such as 16 50kW units) mobile units can generate more than 5000kW of radiated power in the far field, which has the ability to replace traditional megawatt-level fixed stations.

[0051] 3. Solved the deadlock problem in random deployment: The proposed dynamic jump mechanism effectively solves the deadlock phenomenon in gridded random walks, making it possible to generate dense random arrays that satisfy electrical spacing constraints within a limited area, thus avoiding strong coupling and gate lobe problems.

[0052] 4. Flexible Deployment and Rapid Reconfiguration: Each launch unit is relatively small and can be moved by vehicle. It can be quickly deployed in any open area using tethered balloons, eliminating the need for complex towers and ground networks. The array employs a random deployment method, adapting to complex terrains such as mountains and forests, fully utilizing terrain-protected units to reduce the probability of enemy detection and location. If a unit is damaged, the remaining units can be redeployed to a safe location as replacements or their operation can be reduced by adjusting the array, significantly shortening recovery time.

[0053] 5. Excellent System Scalability: The architecture of this application allows for flexible adjustment of the number of transmitting units, increasing or decreasing the total power as needed. More units can further enhance the synthetic gain (theoretically, the gain increases with N, and the statistical distribution tends towards a more stable normal distribution), thereby achieving longer communication distances or stronger anti-interference capabilities. Simultaneously, the system also supports beam scanning and shaping by adjusting the unit phases, pointing the main lobe in different directions within a certain range, possessing some functions of traditional phased arrays. This is highly advantageous for tracking moving targets or multi-target communication over wide areas.

[0054] This application also provides a system for constructing and operating a distributed very long wave transmitting array, such as... Figure 2 As shown, it includes: The grid partitioning module is used to delineate the geographical deployment area of ​​the transmission array and discretize the deployment area into a set of standard grids containing several candidate nodes; The path exploration module is used to execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids. The dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and to re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. The deployment module is used to deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; The control module is used to perform time synchronization and phase control on each of the very long wave transmitting units based on a unified time reference, and to control the phase of the transmitted signal of each of the very long wave transmitting units so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

[0055] Optionally, the distributed very long wave (VLS) transmitting array construction and operation system provided in this application embodiment further includes a first number of spatially dispersed mobile transmitting units, the deployment locations of which are determined by a random walk strategy based on a dynamic hopping mechanism. Each mobile transmitting unit includes: A floating platform is used to provide vertical height. The very long wave antenna assembly is towed and vertically suspended by the floating platform and is used as an electromagnetic wave radiator. The time synchronization module is used to obtain a high-precision unified time reference; The transmitter and tuning module are used to generate an excitation signal with a specific phase based on the time reference and target azimuth information and feed it into the very long wave antenna assembly to achieve power combining with other mobile transmitting units in space.

[0056] Specifically, this application provides a distributed very long wave transmission system with high survivability, such as... Figure 3 As shown, the system comprises N spatially distributed mobile transmitting units, each equipped with a floating platform (such as a tethered balloon), a vertical monopole antenna, a time synchronization module, an RF power amplifier module, and a tuning matching network. The system is capable of maintaining a high level of radiated power by reconfiguring the remaining units even if some units are damaged (e.g., 50% failure).

[0057] This application employs a distributed phased array approach, distributing the previously concentrated transmission power across multiple mobile, medium-power transmitting units. Specifically, the system consists of several (e.g., 16) independent VLF (Very Long Wave) transmitting units, each equipped with a floating platform (such as a tethered balloon), a vertical monopole antenna, a time synchronization module, an RF power amplifier module, and a tuning matching network. These transmitting units are randomly distributed within a predetermined area, wirelessly independent of each other and requiring no physical connection. All units within the same system maintain strict synchronization using GNSS satellite timing and atomic clocks, transmitting VLF communication signals at the same frequency according to a unified phase reference. By coordinating the transmission phase of each unit, their signals in the far-field target direction are made phase-consistent and amplitude-added, forming a directional radiation gain and achieving spatial power combining. Thus, the equivalent radiated power of the entire distributed array in the main lobe direction can reach hundreds to thousands of kilowatts, rather than a simple sum of the power of each unit.

[0058] Because the transmitting units are geographically dispersed, it is difficult for the enemy to destroy all units in one strike. When some units are damaged, the remaining units can continue to operate and maintain synchronization. By adjusting the phase-compensated array pattern, the remaining array can ensure sufficient effective radiated power in the main communication direction. This application specifically introduces a random deployment topology and redundant configuration to avoid the problem of severe beam distortion or even failure to form due to the damage of a critical node in a regular array, thus significantly improving the overall system's fault tolerance and resilience. Simulation statistics show that, in the extreme case where 50% of the units are destroyed, the combined gain of the remaining units relative to the median of the complete array can reach -2.5 dB, and the equivalent radiated power of the remaining array relative to the median of the complete array can be maintained above -6 dB. Therefore, this application provides an "unbreakable VLF transmitter" that can significantly improve the reliability of long-distance communication.

[0059] Optionally, in the distributed very long wave transmitting array construction and operation system provided in this application embodiment, the very long wave antenna component is integrated as a mooring cable for the floating platform, the mobile transmitting unit also includes a radial ground grid laid on the ground, and the transmitter and tuning module are connected between the mooring cable and the radial ground grid by bottom feeding.

[0060] Optionally, in the distributed very long wave transmitting array construction and operation system provided in this application embodiment, the timing and synchronization module is configured to use the timing signal of the Global Navigation Satellite System to discipline the local clock, so that the time synchronization error between each mobile transmitting unit is less than the first delay, and the remaining phase error at the 20kHz operating frequency is less than a preset threshold.

[0061] Optionally, the distributed VLSI transmission array construction and operation system provided in this application embodiment is configured such that when some mobile transmission units fail due to damage, the remaining surviving mobile transmission units automatically adjust their phase parameters according to the updated array topology.

[0062] The following is a specific embodiment illustrating the construction and operation method of the distributed very long wave transmission array provided in this application. This embodiment describes in detail how to generate a random array topology that satisfies spacing constraints and is free from deadlock.

[0063] Step 1: Region Discretization The deployment area of ​​the transmission array is set as a two-dimensional plane. The region is discretized using a square grid with a side length of d.

[0064] The grid set is denoted as .

[0065] Key parameter selection: The grid side length d directly determines the element spacing (the adjacent distance is d or...). Coupling problem: If d is too small (e.g.) The extremely high voltage (up to hundreds of kilovolts) of very long wave antennas can create strong mutual coupling between adjacent antennas, leading to drastic changes in input impedance and even power backflow that burns out the transmitter. Grid lobe problem: If d is too large (e.g., The array factor can cause grating lobes to disperse the main beam energy during scanning. To avoid strong near-field coupling (requiring a relatively small spacing) and suppress far-field grating lobes (requiring a relatively large spacing), the grid side length d is configured as follows: For example, for a 24kHz signal ( ), take d=5.3km.

[0066] Step 2: Random walk with dynamic jump mechanism Traditional random walks are prone to deadlock when the grid is constrained (i.e., all eight surrounding cells are occupied or the grid is out of bounds). This application introduces a "dynamic jump" mechanism to solve this problem. Figure 4 As shown: 1. Initialization: From A grid is randomly and uniformly selected from the middle. As the first array element, it is marked as occupied.

[0067] 2. Neighborhood Expansion: Let the last element placed be... Define its eight-neighbor set .

[0068] 3. Availability check: From After removing occupied and out-of-bounds grids, a candidate set is obtained. .

[0069] 4. Branch decision: Scenario A (Normal Wandering): If Not empty, from Randomly select a grid as the (k+1)th element, and set k = k+1, then continue to the next round.

[0070] Scenario B (Dynamic Jump - Innovation Point): If If the search result is empty (i.e., deadlock, all neighbors are occupied, and the algorithm has reached a dead end), the algorithm does not terminate but triggers a dynamic jump mechanism. From the k historically generated nodes, a node is randomly selected as the new "current node" and the search is restarted within its neighborhood.

[0071] 5. Iteration: Repeat the above process until N (e.g., 16) element coordinates are successfully generated.

[0072] Step 3: Deployment and Verification The generated coordinates represent the predetermined positions of the moving launch units. This algorithm ensures that the distance between any two adjacent units is at least d, and that the array as a whole exhibits random distribution characteristics, making it difficult for the enemy to predict its position through patterns.

[0073] III. Example 2: Highly Resilient Distributed Very Long Wave Transmission System This embodiment describes the physical system hardware architecture constructed based on the above method.

[0074] 1. System Composition The system consists of 16 independent mobile transmission units distributed over an area of ​​tens of square kilometers. Each unit contains: Aerial platform: Utilizes streamlined tethered balloons to provide lift.

[0075] Antenna assembly: The tether cable of the tethered balloon is used as a vertical monopole antenna, with an effective altitude set at 2000m. The cable integrates high-voltage conductors and is covered by an anti-corona sheath.

[0076] Grounding network system: 24 radial conductors, each 100m long, are deployed on the ground and connected to the soil through grounding stakes to form a low-loss grounding network.

[0077] Time synchronization module: Core control component. Built-in GNSS receiver and rubidium atomic clock. Function: Uses GNSS second pulses (1PPS) to discipline the local atomic clock, correcting time synchronization errors among distributed units. Phase control: At 20kHz, an 80ns time jitter corresponds to only about 0.57° of phase error, which meets the requirements. The requirement for high-precision coherent synthesis.

[0078] 2. Power combining and radiation efficiency Input power per unit: 50kW.

[0079] Radiation efficiency: Simulation calculations show that a 2000m altitude antenna at 24kHz with a grid side length of 5300m (approximately...) yields the best radiation efficiency. Under the configuration of ), the radiation power of a single array element (Input 50kW, efficiency >50%).

[0080] Synthetic efficiency: The equivalent radiated power (ERP) of the 16 elements in the main lobe direction is calculated as follows:

[0081] Although spatial dispersion leads to mutual coupling effects and the actual gain is slightly lower than the theoretical value, simulations show that the system can achieve an equivalent radiated power (ERP) of over 5000 kW, sufficient to cover global communications. This far exceeds any existing single VLF station (typically in the 1000 kW-2000 kW range).

[0082] 3. Persistence Analysis The scenario was set up so that 50% of the launch units were randomly destroyed (i.e., 8 units remained).

[0083] Reconfiguration process: The remaining 8 units do not need to exchange survival status or move physically. They only need to receive the target location information from the command center, calculate their respective phase compensation, and continue to carry out the launch mission.

[0084] Resilience: Monte Carlo simulations of the system in this application show that, at a 50% failure rate, the median relative gain of the surviving array is -2.5 dB. This means that the median total equivalent radiated power drops by less than 6 dB, still remaining above 1500 kW (equivalent to the full power level of a Cutler array).

[0085] Conclusion: Even under severe conditions with half of the components damaged, the proposed solution still exhibits excellent survivability.

[0086] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0087] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0088] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some service interface; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0089] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0090] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0091] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for constructing and operating a distributed very long wave (VLS) transmitting array, characterized in that, The method includes the following steps: S1. Delineate the geographical deployment area of ​​the transmission array, and discretize the deployment area into a set of standard grids containing several candidate nodes; S2. Execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids; the dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. S3. Deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; S4. Based on a unified time reference, time synchronization and phase modulation are performed on each of the very long wave transmitting units to control the phase of the transmitted signal of each of the very long wave transmitting units, so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

2. The method for constructing and operating a distributed very long wave transmission array as described in claim 1, characterized in that, The execution of the random walk strategy based on the dynamic jump mechanism specifically includes: S2.1 Randomly select a node from the standard grid set as the position of the first array element; S2.2 For the current last determined array element position, determine its geometric neighborhood, and remove nodes that are occupied or exceed the geographical deployment area from the geometric neighborhood to obtain a set of available candidates; S2.3 If the available candidate set is not empty, then a node is randomly selected from it as the next array element position; If the available candidate set is empty, it is determined to be in a local deadlock state, triggering the dynamic jump mechanism, randomly selecting a previously determined array element position as the new current node, and returning to S2.2; Repeat the above steps until the positions of the first number of array elements are determined.

3. The method for constructing and operating a distributed very long wave transmission array as described in claim 2, characterized in that, The standard grid set consists of square grids with side length d, and the geometric neighborhood is the eight neighborhoods of the current grid. The range of values ​​for the side length d is configured as follows: ,in The operating wavelength for very long wave transmitted signals; The minimum spacing between the very long wave transmitting units is or .

4. The method for constructing and operating a distributed very long wave transmitting array as described in claim 1, characterized in that, The implementation of coherent power combining specifically includes: Each of the very long wave transmitting units independently receives timing signals from the global navigation satellite system and establishes a global synchronization clock in conjunction with a local atomic clock; Based on the spatial location coordinates of the target communication object and the target deployment coordinates of each VW transmitter, the required phase compensation amount for each VW transmitter is calculated. Each very long wave transmitting unit adjusts the phase of the excitation current according to the phase compensation amount to compensate for the phase delay caused by the spatial propagation path difference.

5. The method for constructing and operating a distributed very long wave transmitting array as described in claim 1, characterized in that, Following step S4, a persistence assessment of the transmit array is also included: A random failure model for the very long wave transmitting unit is constructed, and the failure probability p of the transmitting unit is set. The relative gain distribution of the remaining array relative to the initial intact array was calculated using Monte Carlo simulation at the stated damage probability p. Calculate the median value of the relative gain distribution. If the median value is lower than a preset communication link threshold, increase the first quantity and repeat steps S2 to S4.

6. The method for constructing and operating a distributed very long wave transmitting array as described in claim 1, characterized in that, The very long wave transmitting unit adopts a vertical monopole antenna structure pulled by a tethered balloon. By adjusting the effective height of the tethered cable and the end tuning parameters, resonant transmission at a specific frequency can be achieved.

7. A system for constructing and operating a distributed very long wave transmitting array, characterized in that, include: The grid partitioning module is used to delineate the geographical deployment area of ​​the transmission array and discretize the deployment area into a set of standard grids containing several candidate nodes; The path exploration module is used to execute a random walk strategy based on a dynamic jump mechanism to generate a first number of target deployment coordinates in the set of standard grids. The dynamic jump mechanism is configured to automatically select a backtracking node from the generated historical nodes when the current node is detected to be in a local dead state during the random walk generation process, and to re-search the path in the neighborhood of the backtracking node until the number of generated coordinates reaches the first number. The deployment module is used to deploy a corresponding movable very long wave transmitting unit at each of the target deployment coordinates; The control module is used to perform time synchronization and phase control on each of the very long wave transmitting units based on a unified time reference, and to control the phase of the transmitted signal of each of the very long wave transmitting units so that the electromagnetic waves radiated by them can achieve coherent power synthesis in a predetermined spatial direction.

8. The system for constructing and operating a distributed very long wave transmitting array as described in claim 7, characterized in that, The system also includes a first number of spatially distributed mobile transmission units, the deployment locations of which are determined by a random walk strategy based on a dynamic hopping mechanism, each of the mobile transmission units comprising: A floating platform is used to provide vertical height. The very long wave antenna assembly is towed and vertically suspended by the floating platform and is used as an electromagnetic wave radiator. The time synchronization module is used to obtain a high-precision unified time reference; The transmitter and tuning module are used to generate an excitation signal with a specific phase based on the time reference and target azimuth information and feed it into the very long wave antenna assembly to achieve power combining with other mobile transmitting units in space.

9. The system for constructing and operating a distributed very long wave transmitting array as described in claim 8, characterized in that, The very long wave antenna assembly is integrated as a mooring cable for the floating platform. The mobile transmitting unit also includes a radial ground grid laid on the ground. The transmitter and tuning module are connected between the mooring cable and the radial ground grid by bottom feeding.

10. The system for constructing and operating a distributed very long wave transmission array as described in claim 8, characterized in that, The distributed very long wave transmission system is configured such that when some mobile transmitting units fail due to damage, the remaining surviving mobile transmitting units automatically adjust their phase parameters according to the updated array topology.

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