AIS abnormality warning system and warning method

Abstract

The embodiment of the present application provides an AIS abnormal warning system and warning method, which relates to the field of automatic identification technology of ships. The system includes: a signal receiving module; a signal processing module for separating at least two AIS channel data from the radio signal, and judging the starting point and end point of each AIS device occupied time slot based on occupancy detection and time slot detection; when any AIS channel is occupied, a demodulation request and a direction finding request are generated, the demodulation module is used to respond to the demodulation request to obtain the first relative direction of the AIS device relative to the monitoring point; the direction finding module is used to respond to the direction finding request to obtain the second relative direction of the AIS device relative to the monitoring point; the result display module is used to display based on an electronic map: the first relative direction, the second relative direction, and the warning information when the deviation of the first relative direction or the second relative direction exceeds the preset deviation threshold. The implementation method provided by the present application can effectively identify false AIS devices.

Description

Technical Field

[0001] The present application relates to the technical field of automatic identification of ships, and in particular to an AIS abnormality warning system and an AIS abnormality warning method. Background Art

[0002] The Automatic Identification System (AIS) is a technology used for inter-vessel communication and navigation. The AIS system communicates via VHF radio waves. Each vessel is assigned a unique MMSI number, similar to a telephone number, for identification. The system uses GPS to obtain information such as a vessel's position, speed, and heading, and transmits this information to other vessels or shore stations. The AIS system can also receive information from other vessels and shore stations, including the vessel's position, speed, heading, and destination.

[0003] The AIS system is widely used in areas such as ship navigation, vessel traffic management, maritime rescue, marine resource management, marine environmental monitoring, and ship management. However, in routine ship management, maritime authorities have discovered that some ships are fabricating AIS information, reporting inconsistent locations in the system to conceal their true operating status and illegal activities. This type of fabricated AIS information poses numerous challenges to ship management. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide an AIS anomaly warning system and warning method, which are intended to detect and respond to the behavior of concealing the actual location of a ship by falsifying longitude and latitude information, thereby improving the supervision and management capabilities of ships and solving at least some of the problems in the background technology.

[0005] To achieve the above objectives, the present application provides an AIS anomaly warning system, comprising: a signal receiving module for monitoring wireless signals; a signal processing module for separating at least two AIS channel data from the radio signals and, based on occupancy detection and time slot detection, determining the start and end points of each AIS device's occupied time slot; generating a demodulation request and a direction finding request when any AIS channel is occupied, and ensuring that the current direction finding operation is completed before the end of the AIS device's time slot; a demodulation module for, in response to the demodulation request, parsing the data content of the current time slot of the occupied AIS channel and, based on location information in the data content, obtaining a first relative direction of the AIS device relative to a monitoring point; a direction finding module for, in response to the direction finding request, performing direction finding on the radio signal belonging to the current time slot of the occupied AIS channel to obtain a second relative direction of the AIS device relative to the monitoring point; and a result display module for displaying, based on an electronic map, at least one of the following: the first relative direction, the second relative direction, and a warning message when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold; the warning message including identifying the AIS device as a false AIS.

[0006] Optionally, the signal processing module includes: a multi-channel DDC synchronous acquisition and output submodule, used to implement digital channel separation on the physical channel, realize real-time monitoring of two channels and time slot segmentation; an occupancy detection submodule, used to detect the occupancy of the time slot through a sliding trigger mode; a time slot detection submodule, used to determine the start and end points of the time slot by identifying a specific training header and start header of the AIS signal; and a request generation submodule, used to generate a demodulation request and a direction finding request when any AIS channel is occupied.

[0007] Optionally, the direction finding module includes a first direction finding submodule and a second direction finding submodule; when the system operates in fixed station mode, the first direction finding submodule is selected; when the system operates in mobile station mode, the second direction finding submodule is selected; the first direction finding submodule includes: a starting point judgment unit, configured to judge whether the triggering moment of the synchronous direction finding request is the time slot starting point of the AIS device, and trigger the time slot direction finding submodule to start working when the triggering moment is the time slot starting point of the AIS device; a time slot direction finding unit, configured to control the switching of the direction finding antenna and collect IQ data of different baselines, and then obtain the second relative direction of the AIS device relative to the monitoring point after calculation by a direction finding algorithm; and a data marking unit, configured to mark the second relative direction if it is detected that the time slot of the AIS channel is occupied during the operation of the time slot direction finding submodule;

[0008] The second direction-finding submodule includes: a starting point judgment unit, configured to judge whether the triggering moment of the synchronous direction-finding request is the starting point of the time slot of the AIS device, and trigger the time slot level calculation submodule to start working when the triggering moment is the starting point of the time slot of the AIS device; a time slot level calculation unit, configured to calculate the level of the corresponding time slot and add the demodulated data flag of the corresponding time slot for use by the electromagnetic situation positioning unit to summarize the data; a data calibration unit, configured to calibrate the calculated level value to be consistent with the actual received signal level; and an electromagnetic situation positioning unit: obtaining a second relative direction of the AIS device relative to the monitoring point based on the intensity distribution of the level value.

[0009] Optionally, the direction-finding antenna switching control, data collection and phase calculation in the time-slot direction-finding unit are processed by different processes in parallel.

[0010] Optionally, when the system operates in mobile station mode, the system is mounted on a vehicle or a ship, and a level trace of the AIS device is obtained by road testing, wherein the position corresponding to the maximum level is displayed in the level trace.

[0011] Optionally, the demodulation module includes: a digital demodulation submodule, configured to demodulate a digital signal on an occupied AIS channel using a digital signal; a content extraction submodule, configured to obtain data content including at least location information and an MMSI number; and a direction calculation submodule, configured to calculate a first relative direction of the AIS device relative to the monitoring point based on the location information and the location of the monitoring point.

[0012] Optionally, the method further includes: judging whether the AIS device is in a stationary state or in a moving state based on a movement pattern in the first relative direction or the second relative direction; when the AIS device is in a stationary state, when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold number of times or the duration exceeds a first proportional threshold, determining that the AIS device is in an abnormal state; when the AIS device is in a moving state, when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold number of times or the duration exceeds a second proportional threshold, determining that the AIS device is in an abnormal state; the second proportional threshold is greater than the first proportional threshold.

[0013] Optionally, the system further includes a cross-positioning module, which is configured to determine, when there are at least two monitoring points at different locations, the actual signal transmission position of the AIS device based on the intersection of the second relative directions of the at least two monitoring points, and generate early warning information based on the reported position of the AIS device parsed by the demodulation module, and when the reported position is inconsistent with the actual signal transmission position.

[0014] This application also provides an AIS abnormality warning method, which is implemented by the aforementioned AIS abnormality warning system. The method includes: monitoring wireless signals through a deployed direction-finding antenna. When the system operates in fixed station mode, the direction-finding antenna is a single integrated design, and the monitoring range covers the maritime service frequency band; when the system operates in mobile station mode, the direction-finding antenna is an ordinary monitoring antenna; inputting the monitored wireless signal into the AIS abnormality warning system; and obtaining an AIS abnormality warning based on the output information of the AIS abnormality warning system.

[0015] The present application also provides an electronic device comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the at least one processor implements the aforementioned AIS abnormality warning system by executing the instructions stored in the memory.

[0016] The present application also provides a machine-readable storage medium having instructions stored thereon. When the instructions are executed by a processor, the processor is configured to execute and implement the aforementioned AIS abnormality warning system.

[0017] The present application also provides a computer program product, comprising a computer program, which implements the aforementioned system when executed by a processor.

[0018] The above technical solution has the following beneficial effects:

[0019] (1) Through the synchronization mechanism, it is ensured that the direction finding process can clearly identify the ship for which signal direction finding and signal level calculation are performed, and that the collected data only comes from a single ship to avoid interference and misjudgment.

[0020] (2) Detect and respond to attempts to mask the actual location of a ship by falsifying its longitude and latitude information, thereby improving the ability to supervise and manage ships.

[0021] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0023] Figure 1 The structure diagram of the AIS abnormal warning system according to the embodiment of the present application is schematically shown;

[0024] Figure 2The following is a schematic diagram showing the steps of the AIS abnormality warning method according to the embodiment of the present application. DETAILED DESCRIPTION

[0025] The following describes the specific implementation of the embodiment of the present application in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present application and is not intended to limit the embodiment of the present application.

[0026] Figure 1 The schematic diagram shows the structure of the AIS abnormal warning system according to the embodiment of the present application. Figure 1 As shown, an AIS abnormality warning system includes:

[0027] A signal receiving module for monitoring wireless signals;

[0028] a signal processing module configured to separate at least two AIS channel data from the radio signal and determine the start and end points of each AIS device's occupied time slot based on occupancy detection and time slot detection; generate a demodulation request and a direction finding request when any AIS channel is occupied, and ensure that the direction finding operation is completed before the end of the AIS device's time slot;

[0029] a demodulation module, configured to parse data content on a current time slot of the occupied AIS channel in response to the demodulation request, and obtain a first relative direction of the AIS device relative to the monitoring point based on position information in the data content;

[0030] a direction finding module, configured to, in response to the direction finding request, perform direction finding on a radio signal belonging to a current time slot of the occupied AIS channel, to obtain a second relative direction of the AIS device relative to the monitoring point;

[0031] A result display module is configured to display at least one of the following based on an electronic map: the first relative direction, the second relative direction, and a warning message when a deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold; the warning message includes identifying the AIS device as a false AIS.

[0032] Through the above implementation, time slot processing ensures strict synchronization between information parsing in the demodulation module and direction finding or level control in the direction finding module, improving data acquisition consistency. By ensuring that the direction finding operation is completed before the end of the AIS device's time slot, the timeliness of direction finding is guaranteed, ensuring that the direction finding task is completed within a single time slot. Furthermore, the direction finding results are coordinated with the message results to determine the legitimacy of the AIS signal.

[0033] In some embodiments of the present application, the signal processing module includes: a multi-channel DDC synchronous acquisition and output submodule for implementing digital channel separation on the physical channel, enabling real-time monitoring and time slot segmentation of the two channels; an occupancy detection submodule for detecting time slot occupancy using a sliding trigger mode; a time slot detection submodule for determining the start and end points of a time slot by identifying the specific training header and start header of the AIS signal; and a request generation submodule for generating a demodulation request and a direction finding request when any AIS channel is occupied. Existing AIS systems use two channels for communication. Although time slot allocation is synchronized, the manner in which individual ships occupy time slots is random and asynchronous. To ensure the integrity and accuracy of AIS signal data, multi-channel DDC technology is employed to achieve real-time monitoring and time slot segmentation of the two channels on a single physical channel, thereby ensuring efficient data demodulation. DDC (Direct Digital Controller) downconverts signals in digital systems, converting them from RF (intermediate frequency) signals to baseband signals.

[0034] In some embodiments of the present application, the direction-finding module includes a first direction-finding submodule and a second direction-finding submodule. When the system operates in fixed station mode, the first direction-finding submodule is selected; when the system operates in mobile station mode, the second direction-finding submodule is selected. The AIS anomaly warning system provided in this embodiment can be applied to two operating modes: fixed station mode and mobile station mode. In different operating modes, corresponding direction-finding submodules need to be selected. The first direction-finding submodule is primarily used to determine the second relative direction using direction-finding technology at a fixed monitoring point. The second direction-finding submodule is primarily used to determine the second relative direction at a mobile monitoring point by changing its own position to obtain different power levels. Specifically, the first direction-finding submodule includes: a starting point determination unit, configured to determine whether the triggering moment of the synchronous direction-finding request is the starting point of the AIS device's time slot, and triggering the time slot direction-finding submodule to begin operation when the triggering moment is the starting point of the AIS device's time slot; a time slot direction-finding unit, configured to control the switching of the direction-finding antenna and acquire IQ data from different baselines, and then calculate the second relative direction of the AIS device relative to the monitoring point through a direction-finding algorithm; and a data marking unit, configured to mark the second relative direction if the time slot direction-finding submodule detects that the AIS channel's time slot is occupied. The time slot direction-finding unit can utilize a time slot correlation interferometer, and its workflow includes: controlling the switching of the direction-finding antenna and acquiring data, determining whether the direction-finding baseline is the last set of baselines, and repeating the aforementioned process of controlling the switching of the direction-finding antenna and acquiring data if it is the last set of baselines; and obtaining a table of phase differences between different baselines if it is the last set of baselines. One of the difficulties in developing this system lies in detecting the time slot intervals of the AIS device. Compared to AIS base stations, our system uses a non-cooperative demodulation approach, requiring the individual detection of all time slots within the detection range and accurate identification of the start and end points of each AIS device's time slot. This embodiment utilizes a sliding trigger mode, combined with precise time slot interval division, to detect the presence and disappearance of signals within a time slot in real time. Furthermore, by identifying the specific training header and start header of the AIS signal, the signal's validity can be effectively determined, thereby accurately determining the start and end points of each device's time slot. Furthermore, the second direction-finding submodule includes: a start point determination unit, configured to determine whether the trigger moment of the synchronous direction-finding request is the start point of the AIS device's time slot, and triggering the time slot level calculation submodule to begin operation when the trigger moment is the start point of the AIS device's time slot; a time slot level calculation unit, configured to calculate the level of the corresponding time slot and add a demodulated data flag to the corresponding time slot for use by the electromagnetic situation location unit in data aggregation; a data calibration unit, configured to calibrate the calculated level value to be consistent with the actual received signal level; and an electromagnetic situation location unit, configured to determine a second relative direction of the AIS device relative to the monitoring point based on the intensity distribution of the level values.The second direction-finding submodule is primarily used in driving tests (DT) and can also be installed on ships. Its device maintains an integrated design, meeting the requirements for mounting on mobile platforms such as vehicles or ships, facilitating mobile monitoring. When the system operates in mobile station mode, it is mounted on a mobile platform such as a vehicle or ship, and a level trace of the AIS device is obtained through drive testing. The level trace shows the position corresponding to the maximum level. The approximate location of the AIS device is determined based on the maximum level position, which is then compared with the output position of the demodulation module to obtain a judgment result.

[0035] In some embodiments of the present application, the direction-finding antenna switching control, data acquisition, and phase calculation in the time-slot direction-finding unit are handled using separate parallel processes. To meet the AIS system's requirement to complete direction-finding within a single time slot, this embodiment employs a parallel processing flow for antenna control, data acquisition, and phase calculation. Through these technical measures, an efficient digital signal processing flow is successfully implemented, achieving a single direction-finding time of approximately 18 ms at a 50 kHz sampling rate. This addresses the limited direction-finding performance of traditional direction-finding systems at low sampling rates.

[0036] In some embodiments of the present application, the demodulation module includes: a digital demodulation submodule for demodulating the digital signal on the occupied AIS channel using a digital signal; a content extraction submodule for obtaining data content including at least location information and the MMSI number; and a direction calculation submodule for calculating a first relative direction of the AIS device relative to the monitoring point based on the location information and the location of the monitoring point. In this embodiment, the demodulation module is triggered by a demodulation request to initiate channel demodulation, obtain bitstream data, and then perform data decoding on the bitstream data to obtain information such as the MMSI, location, and speed of the AIS device. The calculation then determines the first relative direction of the AIS device relative to the monitoring point.

[0037] In some embodiments of the present application, the method further includes: judging whether the AIS device is in a stationary state or in a moving state based on the movement pattern of the first relative direction or the second relative direction; when the AIS device is in a stationary state, when the deviation between the first relative direction and the second relative direction exceeds the preset deviation threshold number of times or the duration exceeds the first ratio threshold, determining that the AIS device is in an abnormal state; when the AIS device is in a moving state, when the deviation between the first relative direction and the second relative direction exceeds the preset deviation threshold number of times or the duration exceeds the second ratio threshold, determining that the AIS device is in an abnormal state; the second ratio threshold is greater than the first ratio threshold. However, since the position of a ship in motion is more difficult to measure accurately, a larger deviation threshold is used to overcome the occurrence of false alarms. This embodiment automatically matches different ratios based on the motion state of the trajectory point, which can improve the accuracy of abnormality judgment.

[0038] In different scenarios of static state and moving state, the judgment rules of the AIS device also include the following changes. When the AIS device is in a static state, the preset deviation threshold value is the first deviation threshold value; when the AIS device is in a moving state, the preset deviation threshold value is the second deviation threshold value; the second deviation threshold value is greater than the first deviation threshold value. When the ship where the AIS device is located is a moored ship, it can accurately perform direction finding at this time, and it is found that the position reported by the ship completely matches the direction finding position, and the system determines it to be normal. When the ship where the AIS device is located is a moving ship, the motion trajectory can be tracked at this time, and the legality of each trajectory point can be determined, and the system determines it to be normal. However, since the position of a ship in motion is more difficult to measure accurately, a larger deviation threshold value is used to overcome the occurrence of false alarms. This embodiment automatically matches different thresholds based on the motion state of the trajectory point, which can improve the accuracy of abnormal judgment.

[0039] In some embodiments of the present application, the result display module is further configured to: display a first graphic identifier starting from the monitoring point on the electronic map for indicating the first relative direction using a first color; display a second graphic identifier starting from the monitoring point on the electronic map for indicating the second relative direction using a second color; display a third graphic identifier of the AIS device on the electronic map when the deviation between the first relative direction and the second relative direction does not exceed a preset deviation threshold using a third color; and display a third graphic identifier of the AIS device on the electronic map when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold using a fourth color. This embodiment provides a color-based display scheme that facilitates intuitive and accurate display of direction results and abnormal results.

[0040] In some embodiments of the present application, the system further includes a cross-positioning module, which is used to determine the actual signal transmission position of the AIS device based on the intersection of the second relative directions of the at least two monitoring points when there are at least two monitoring points in different positions, determine the reported position of the AIS device based on the intersection of the second relative directions of the at least two monitoring points, and generate an early warning message when the reported position is inconsistent with the actual signal transmission position. When there are at least two monitoring points, the two monitoring points can be used to further locate the abnormal AIS. For normal AIS devices, based on the intersection positioning test, it can be seen that the intersection of the two-station direction-finding lines crosses the station report position, that is, the actual transmission position. For false AIS devices, the intersection of their direction-finding lines indicates the actual signal transmission position, but there is a large deviation in the reported position of their AIS devices, and an early warning message is generated at this time.

[0041] Through the above implementation, the direction finding control process and processing efficiency are optimized, so that it can be completed within a time slot. At the same time, the direction finding results are coordinated with the message results to realize the legitimacy judgment of the AIS signal.

[0042] Based on the same inventive concept, the embodiment of the present application also provides an AIS abnormality early warning method. Figure 2 The following schematically shows the steps of the AIS abnormal warning method according to the embodiment of the present application. Figure 2 As shown, the method is implemented based on the aforementioned AIS abnormal warning system, and the method includes:

[0043] S01. Monitoring wireless signals through a deployed direction-finding antenna. When the system operates in fixed station mode, the direction-finding antenna is a single integrated design, and the monitoring range covers the maritime service frequency band; when the system operates in mobile station mode, the direction-finding antenna is a common monitoring antenna.

[0044] S02. Inputting the monitored wireless signal into the AIS abnormal warning system;

[0045] S03. Obtaining an AIS abnormality warning based on output information of the AIS abnormality warning system.

[0046] Through the above implementation methods, it is also possible to detect and respond to the behavior of concealing the actual position of a ship by falsifying latitude and longitude information, thereby improving the supervision and management capabilities of ships.

[0047] The specific steps of obtaining the AIS abnormal warning system based on the output information of the AIS abnormal warning system in S03 refer to the description of the AIS abnormal warning system, which will not be repeated here.

[0048] The specific definitions of the various functional modules in the above-mentioned AIS anomaly warning system can also be found in the above-mentioned definitions of the AIS anomaly warning method, and will not be repeated here. Each module in the above-mentioned system can be implemented in whole or in part through software, hardware, or a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of the above-mentioned modules. It is also based on the characteristics of the AIS system and combines the current mature signal analysis and direction finding methods to achieve the coordination of direction finding results and message results, and realize the effect of determining the legitimacy of the AIS signal.

[0049] In some embodiments of the present application, an electronic device is further provided, comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the at least one processor executes the aforementioned AIS abnormal warning system. The control module or processor herein has the functions of numerical calculation and logical operation, and has at least a central processing unit (CPU) with data processing capabilities, a random access memory (RAM), a read-only memory (ROM), multiple I / O ports, and an interrupt system. The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be provided, and the aforementioned method can be implemented by adjusting kernel parameters. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0050] In one embodiment provided in the present application, a machine-readable storage medium is provided. The machine-readable storage medium stores instructions. When the instructions are executed by a processor, the processor is configured to execute the aforementioned AIS abnormality warning system.

[0051] In one embodiment provided in the present application, a computer program product is provided, including a computer program, which implements the aforementioned AIS abnormality warning system when executed by a processor.

[0052] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0053] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0054] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0055] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0056] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0057] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0058] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0059] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0060] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. An AIS abnormality warning system, characterized in that: The system includes: A signal receiving module for monitoring wireless signals; a signal processing module configured to separate at least two AIS channel data from the radio signal and determine the start and end points of each AIS device's occupied time slot based on occupancy detection and time slot detection; generate a demodulation request and a direction finding request when any AIS channel is occupied, and ensure that the direction finding operation is completed before the end of the AIS device's time slot; a demodulation module, configured to parse data content on a current time slot of the occupied AIS channel in response to the demodulation request, and obtain a first relative direction of the AIS device relative to the monitoring point based on position information in the data content; a direction finding module, configured to, in response to the direction finding request, perform direction finding on a radio signal belonging to a current time slot of the occupied AIS channel, to obtain a second relative direction of the AIS device relative to the monitoring point; a result display module configured to display at least one of the following based on the electronic map: the first relative direction, the second relative direction, and a warning message when a deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold; the warning message including identifying the AIS device as a false AIS; The signal processing module includes: Multi-channel DDC synchronous acquisition and output submodule is used to realize digital channel separation on the physical channel, and realize real-time monitoring and time slot division of two channels; An occupancy detection submodule is used to detect the occupancy of the time slot through a sliding trigger mode; A timeslot detection submodule, configured to determine the start and end points of a timeslot by identifying a specific training header and start header of an AIS signal; and The request generation submodule is used to generate a demodulation request and a direction finding request when any AIS channel is occupied.

2. The system according to claim 1, wherein: The direction finding module includes a first direction finding submodule and a second direction finding submodule; when the system operates in a fixed station mode, the first direction finding submodule is selected; When the system operates in mobile station mode, selecting a second direction finding submodule; The first direction finding submodule includes: A starting point judgment unit is used to judge whether the triggering moment of the synchronous direction finding request is the time slot starting point of the AIS device, and trigger the time slot direction finding submodule to start working when the triggering moment is the time slot starting point of the AIS device; A time slot direction finding unit, configured to control the switching of the direction finding antenna and collect IQ data of different baselines, and then calculate the second relative direction of the AIS device relative to the monitoring point through a direction finding algorithm; and a data marking unit, configured to mark the second relative direction if it is detected that the time slot of the AIS channel is occupied during the operation of the time slot direction finding submodule; The second direction finding submodule includes: A starting point judgment unit is used to judge whether the triggering moment of the synchronous direction finding request is the starting point of the time slot of the AIS device, and trigger the time slot level calculation submodule to start working when the triggering moment is the starting point of the time slot of the AIS device; The time slot level calculation unit is used to calculate the level of the corresponding time slot and add the demodulated data mark of the corresponding time slot for the electromagnetic situation positioning unit to summarize the data; a data calibration unit, configured to calibrate the calculated level value to be consistent with the actual received signal level; and The electromagnetic situation positioning unit is used to obtain a second relative direction of the AIS device relative to the monitoring point based on the intensity distribution of the level value.

3. The system according to claim 2, characterized in that The direction-finding antenna switching control, data collection and phase calculation in the time-slot direction-finding unit are processed by different processes in parallel.

4. The system according to claim 2, wherein: When the system operates in mobile station mode, the system is mounted on a vehicle or a ship, and a level trace of the AIS device is obtained by road testing. The level trace displays a position corresponding to a maximum level.

5. The system according to claim 1, wherein: The demodulation module includes: A digital demodulation submodule is used to demodulate the digital signal on the occupied AIS channel using a digital signal; a content extraction submodule, configured to obtain data content including at least location information and an MMSI number; The direction calculation submodule is used to calculate a first relative direction of the AIS device relative to the monitoring point based on the position information and the position of the monitoring point.

6. The system according to claim 1, wherein: The system further comprises: determining whether the AIS device is in a stationary state or in a moving state according to a movement pattern in the first relative direction or the second relative direction; When the AIS device is in a stationary state, when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold number of times or the duration exceeds a first proportional threshold, determining that the AIS device is in an abnormal state; When the AIS device is in a moving state, when the deviation between the first relative direction and the second relative direction exceeds a preset deviation threshold number of times or the duration exceeds a second proportional threshold, determining that the AIS device is in an abnormal state; The second ratio threshold is greater than the first ratio threshold.

7. The system according to claim 1, wherein: The system further includes a cross-location module configured to, when there are at least two monitoring points at different locations, determine the actual signal transmission location of the AIS device based on an intersection of a second relative direction of the at least two monitoring points, and generate warning information based on the reported location of the AIS device parsed by the demodulation module, if the reported location is inconsistent with the actual signal transmission location.

8. An AIS abnormality early warning method, characterized in that: Based on the implementation of the AIS abnormality warning system in any one of claims 1 to 7, the method includes: Wireless signals are monitored by deploying direction-finding antennas. When the system operates in fixed station mode, the direction-finding antenna is a single integrated design, and the monitoring range covers the maritime service frequency band; when the system operates in mobile station mode, the direction-finding antenna is a common monitoring antenna; Inputting the monitored wireless signal into the AIS abnormal warning system; An AIS abnormality warning is obtained based on the output information of the AIS abnormality warning system.

9. An electronic device, characterized in that: include: at least one processor; a memory connected to the at least one processor; The memory stores instructions that can be executed by the at least one processor, and the at least one processor implements the AIS abnormality warning system according to any one of claims 1 to 7 or the AIS abnormality warning method according to claim 8 by executing the instructions stored in the memory.

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