Satellite-borne AIS payload full-link simulation and ship detection probability assessment system

Abstract

The invention discloses a satellite-borne AIS payload full-link simulation and ship detection probability assessment system, comprising a satellite-borne AIS payload full-link simulation and ship detection probability assessment system, the satellite-borne AIS payload full-link simulation and ship detection probability assessment system comprising scene and baseband signal generation software, satellite-borne AIS data processing software and ship detection probability assessment software, the scene and baseband signal generation software generates the distribution of satellites and multiple ships on the sea surface, and calculates parameters such as time delay, Doppler frequency shift, phase difference, power difference, etc. according to the relative position relationship between the satellite and the ship; the invention can establish a ship distribution model in areas with different ship densities through the system; establish a launch model of a ship-borne AIS system; simulate multiple satellite-borne receiving systems; simulate satellite-to-ground channels of different orbit types; evaluate the detection probability of different receiving systems and time slot conflict resolution algorithms; and evaluate the detection probability when parameters such as the number of ships, observation time, and the number of receiving channels are variable.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite-borne AIS payload full-link simulation and ship detection probability assessment, and in particular to a satellite-borne AIS payload full-link simulation and ship detection probability assessment system. Background Art

[0002] The Automatic Identification System for Ships is a ship-to-shore and ship-to-ship communication, positioning and auxiliary navigation system based on self-organizing time division multiple access as the core technology for maritime traffic safety and dispatching command. The AIS system broadcasts the ship's dynamic information (ship position, speed, heading, etc.), static information (ship name, identification code, destination port, etc.), voyage information, safety short messages and other related information to other ships around it using very high frequency digital communication to achieve automatic identification between ships and monitoring of ships by the ship traffic management center.

[0003] In the prior art, the automatic ship identification system cannot intuitively perform full-link simulation of satellite-borne AIS payloads and ship detection probability assessment. It is difficult to simulate and analyze ship detection probability indicators with different satellite orbit parameters, different satellite-borne AIS antenna forms, and different observation times. It cannot intuitively assess the detection probability when parameters such as the number of ships, observation time, and number of receiving channels are variable. Therefore, a satellite-borne AIS payload full-link simulation and ship detection probability assessment system is needed. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a satellite-borne AIS payload full-link simulation and ship detection probability assessment system to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention proposes a satellite-borne AIS payload full-link simulation and ship detection probability assessment system, including a scene and baseband signal generation software to generate the distribution of satellites and multiple ships on the sea surface, calculate the time delay, Doppler frequency shift, phase difference, power difference and other parameters according to the relative position relationship between the satellite and the ship, and generate an AIS baseband signal waveform data file in a SOTDMA mode, wherein the SOTDMA mode is a self-organizing time division multiple access mode;

[0006] The satellite-borne AIS data processing software reads the waveform data file of the satellite and ship distribution scene and the baseband signal generation software, performs single-channel or multi-channel signal separation, demodulation, and decoding to obtain the information data of the target ship;

[0007] The ship detection probability assessment software reads the true value of the ship information generated by the scene and baseband signal generation software and the processing result of the AIS data processing software, and compares them, and counts the demodulation accuracy and number of ships and other information for system performance evaluation.

[0008] Preferably, the scenario and baseband signal generation software consists of a ship distribution model, a multi-cell ship AIS transmission model, a signal power distribution model, a Doppler frequency shift distribution model, a multi-channel phase difference model, a multi-channel delay model and an AIS signal generation model;

[0009] The ship distribution model mainly simulates the distribution pattern of ships at sea. Since the distribution pattern of ships is different in different sea areas or ports, through statistical analysis, a variety of ship distribution models are designed to simulate the actual situation to the greatest extent, so as to obtain a more realistic ship detection probability index.

[0010] The multi-cell ship AIS transmission model mainly simulates the SOTDMA communication protocol model of the AIS and LAIS systems, and generates the transmission rules and transmission time slot numbers of each ship according to the distribution of ships.

[0011] The signal power distribution model is mainly a model for calculating the signal power of each ship based on the information such as the transmitting antenna pattern, transmitting antenna gain, transmitting power of the shipborne AIS and the receiving antenna pattern, receiving antenna gain, receiver sensitivity, etc.

[0012] The Doppler frequency shift distribution model mainly calculates the Doppler frequency shift of each ship received by the satellite based on the ephemeris position and speed of the satellite movement and the position of each ship.

[0013] The multi-channel phase difference model and time delay model mainly calculate the multi-channel phase difference and time delay of each ship received by multiple receiving antennas and channels of the satellite based on the posture and position of the satellite movement and the position of each ship.

[0014] The AIS signal generation model mainly generates AIS signal data corresponding to each time slot of each ship based on the signal power, Doppler frequency shift, multi-channel phase difference, and delay calculated above, and based on the ship number, position, speed, time slot, and other information of the ship distribution model.

[0015] Preferably, the satellite-borne AIS data processing software includes a comprehensive display module, a data reading module, a data calculation and generation module and a data demodulation module.

[0016] The comprehensive display module displays information such as a list of E0B data to be processed, data calculation results, data demodulation processing progress, and data demodulation results.

[0017] The data reading module obtains the E0B data list to be processed according to the folder path or file path imported by the user.

[0018] The data calculation and generation module is responsible for parsing AIS sampling data and on-board demodulation data from the AIS satellite raw reconnaissance data, converting the data into packet formats and time frame alignment, and separating the two frequency points of 161.975MHz and 162.025MHz and LAIS data; according to the unified GPS clock, the sampling data is divided into time slots to ensure the integrity of the signals arriving at the satellite receiver from ships at different positions within the satellite's field of view.

[0019] The data demodulation module is responsible for the demodulation of AIS signal data. First, the carrier frequency is estimated and the Doppler frequency shift introduced by the relative motion between the satellite and the ship is estimated. Then, the possible single signal and time slot conflict environment is considered and each segment of data is demodulated in combination with the carrier frequency estimation result. The long pulse data occupying multiple time slots is extracted and the demodulation mode is adjusted accordingly according to its data format to obtain the AIS signal information sequence. The AIS information sequence obtained by demodulation is verified with reference to the AIS signal coding format to determine its correctness. The information sequence that fails the verification is error corrected to improve the probability of correct demodulation.

[0020] The ship detection probability evaluation software includes ship detection probability theoretical statistics and ship detection probability simulation statistics.

[0021] The ship detection probability theoretical statistics module mainly calculates the number of time slot overlaps and the probability of ship overlap based on the time slots and scene distribution statistics of theoretical simulation.

[0022] The ship detection probability simulation statistics module compares the MMSI number parsed by the satellite-borne AIS data processing software with the MMSI number generated by simulation to obtain the ship detection probability.

[0023] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has detection probability assessment functions of different receiving systems and time slot conflict resolution algorithms.

[0024] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has a detection probability assessment function when parameters such as the number of ships, observation time, and number of receiving channels are variable.

[0025] The satellite-borne AIS load full-link simulation and ship detection probability assessment system has the statistical function of time slot overlap number and ship overlap probability.

[0026] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system proposed by the present invention can bring the following beneficial effects:

[0027] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system can be used to establish ship distribution models in areas with different ship densities; establish a launch model for the ship-borne AIS system; simulate a variety of satellite-borne receiving systems; simulate satellite-to-ground channels of different orbital types; evaluate the detection probability of different receiving systems and time slot conflict resolution algorithms; and evaluate the detection probability when parameters such as the number of ships, observation time, and number of receiving channels are variable.

[0028] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system is used to establish the observation model of the satellite-borne AIS subsystem, analyze the time slot conflict probability faced by the satellite-borne AIS subsystem, and combine the satellite-borne AIS signal reception and processing technology simulation and test system to simulate and analyze the ship detection probability indicators with different satellite orbit parameters, different satellite-borne AIS antenna forms, and different observation times, providing a reference for the overall scheme design, antenna scheme design, and ground experimental verification of the wide-band SAR satellite AIS subsystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the satellite-borne AIS payload full-link simulation and ship detection probability assessment system of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the flow chart of the satellite-borne AIS payload full-link simulation and ship detection probability assessment system of the present invention;

[0032] Figure 3 It is a schematic diagram of the structure of the scenario and baseband signal generation software of the present invention;

[0033] Figure 4 It is a schematic diagram of the main workflow structure of the scenario and baseband signal generation software of the present invention;

[0034] Figure 5 A schematic diagram of the structure of the satellite-borne AIS data processing software of the present invention;

[0035] Figure 6 The present invention is a schematic diagram of the structure of the integrated display function module;

[0036] Figure 7 The present invention is a schematic diagram of the integrated display module processing flow structure;

[0037] Figure 8 The present invention is a schematic diagram of the data reading module processing flow structure;

[0038] Fig. 9 A schematic diagram of the structure of the module selection module of the present invention;

[0039] Fig.10 This is a schematic diagram of the structure of the data demodulation module of the present invention;

[0040] Fig.11 It is a schematic diagram of the processing flow structure of the data demodulation module of the present invention. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below in an exemplary manner in conjunction with the accompanying drawings.

[0042] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0043] Embodiment is as follows, the present invention provides as Figure 1-Figure 11 The satellite-borne AIS payload full-link simulation and ship detection probability assessment system shown in the figure includes scenario and baseband signal generation software to generate the distribution of satellites and multiple ships on the sea surface, calculate the delay, Doppler frequency shift, phase difference, power difference and other parameters according to the relative position relationship between the satellite and the ship, and generate the AIS baseband signal waveform data file in SOTDMA mode, which is a self-organizing time division multiple access mode; AIS is a ship positioning technology, and SOTDMA is a time division multiple access algorithm with the ability to avoid and resolve communication conflicts. It is a new type of communication technology, applied to mobile stations operating in autonomous and continuous modes, and aims to provide an access algorithm that can quickly resolve conflicts without the intervention of the control console.

[0044] The satellite-borne AIS data processing software reads the waveform data files of the satellite and ship distribution scene and baseband signal generation software, performs single-channel or multi-channel signal separation, demodulation, and decoding to obtain the information data of the target ship;

[0045] The ship detection probability assessment software reads the true value of the ship information generated by the scene and baseband signal generation software and the processing results of the AIS data processing software, and compares them, and statistics the demodulation accuracy and number of ships and other information for system performance evaluation.

[0046] The workflow of the satellite-borne AIS payload full-link simulation and ship detection probability assessment system is as follows:

[0047] 1. The operator sets the scene and parameters, inputs the selected satellite orbit, simulated area, chart file name and other scene parameters;

[0048] 2. Read the ephemeris file and chart file through the external file interface, and read the chart ship data file through the chart ship data interface. The ephemeris file interface reads the ephemeris file, which is a standard double-line root number TLE file;

[0049] 3. The scene and baseband signal generation software generates the distribution of satellites and multiple ships on the sea surface, and then generates the AIS baseband signal waveform data file according to the SOTDMA method based on the relative position relationship between the satellite and the ship:

[0050] 4. Demodulate the AIS baseband signal waveform data file using the AIS demodulation software to obtain the demodulated ship information file;

[0051] 5. The AIS demodulation performance evaluation software reads the AIS scene true value file and the demodulated ship information file, and performs comparative statistics, including the number of time slot overlaps, the overlap probability statistics of ships, and the statistics of ship demodulation probability.

[0052] Furthermore, the scenario and baseband signal generation software consists of a ship distribution model, a multi-cell ship AIS transmission model, a signal power distribution model, a Doppler frequency shift distribution model, a multi-channel phase difference and delay model, and an AIS signal data generation model;

[0053] The ship distribution model mainly simulates the distribution pattern of ships at sea. Since the distribution pattern of ships is different in different sea areas or ports, through statistical analysis and design of a variety of ship distribution models, the actual situation can be simulated to the greatest extent in order to obtain a more realistic ship detection probability index.

[0054] The target location can be generated according to two distribution models: the chart data distribution model and the uniform distribution model at sea:

[0055] 1. The chart data distribution model reads the instance distribution of ship positions in the chart according to the real-time AIS distribution data of the chart, and generates multiple distributions of ships. There are two cases. One is that the number of ships M in the chart is greater than or equal to the set number of simulated ships N, then the ship data of N charts are randomly extracted to generate information such as the position and speed of simulated ships; the other is that the number of ships M in the chart is less than the set number of simulated ships. In this case, only the uniform distribution model at sea can be used to generate MN ships to make up for the deficiencies in the chart data;

[0056] 2. After simulating and generating N targets, some targets will inevitably be out of the satellite's field of view, so this part must be removed. In addition, since the satellite is moving at high speed, the satellite field of view is different at different times. How to determine whether it is within the total range of the satellite field of view over a period of time is a key simulation problem that needs to be solved.

[0057] The method for determining the field of view is as follows. Assume that in the Earth-Fixed (ECEF) coordinate system, the satellite position vector is , the target position vector is , the local elevation angle of the ship can be calculated as

[0058] ;

[0059] If the local elevation angle is less than a certain critical value

[0060] ;

[0061] If the target is not visible, the geometry is considered invisible. Otherwise, the geometry is visible. To this end, we use a method to randomly select the required number N targets according to the target position field of view. The method is as follows:

[0062] 1. First, generate M times the required number of targets, so that the targets are evenly distributed in the area;

[0063] 2. Eliminate land targets based on coastline distribution and retain sea targets;

[0064] 2. For each target, calculate its geometric visibility with respect to the satellite at different times and eliminate invisible targets;

[0065] 3. Assign a uniformly distributed random number to each ship, arrange all the random numbers from small to large, take the required N targets, and find the serial numbers of the N targets;

[0066] 4. By intercepting N target numbers, you can get the required N targets.

[0067] The multi-cell ship AIS transmission model mainly simulates the SOTDMA communication protocol model of the AIS and LAIS systems, and generates the transmission rules and transmission time slot numbers of each ship according to the distribution of ships.

[0068] For multiple ships on the sea, since each ship transmits according to the SOTDMA mechanism, the simulation can be carried out according to the following logic:

[0069] 1. First, the first ship randomly selects a time slot within its transmission interval to transmit, and then determines all the time slots at the following moments in sequence according to the transmission interval and the first transmission time slot;

[0070] 2. The nth ship behind first determines whether there is a ship within its field of view;

[0071] 3. The nth ship randomly selects the first transmission time slot and determines the subsequent time slots based on the transmission interval;

[0072] 4. Determine whether all the transmission time slots of the nth ship conflict with the time slots occupied by ships in its field of view cell;

[0073] 5. If there is no conflict, generate the next ship. If there is a conflict, return to step (3) until there is no conflict.

[0074] 6. All ships are generated, record the launch time of each ship and the occupied time slot number .

[0075] The signal power distribution model is mainly used to calculate the signal power of each ship based on the transmitting antenna pattern, gain, transmitting power of the shipborne AIS and the receiving antenna pattern, gain, receiver sensitivity and other information.

[0076] According to the reconnaissance equation, the received signal power is calculated as follows:

[0077] ;

[0078] Where P rk,i is the received signal power, P T is the known shipborne AIS transmission power, is the wavelength of AIS signal, G rk,i The shipborne AIS transmitting antenna is at t k,i The gain in the direction of the satellite pointing at all times. The empirical calculation formula for the gain of a typical shipborne AIS antenna is as follows

[0079] ;

[0080] in is the local elevation angle of the ship where the satellite is located, and its calculation formula is

[0081] ;

[0082] in and are the satellite and the kth ship at t k,i The three-dimensional position in the Earth-centered Earth-fixed (ECF) coordinate system at that moment, " represents the 2 norm, r k,i is the distance between the satellite and the ship:

[0083] ;

[0084] In the above formula, Grk,i is the satellite receiving antenna at t k,i The gain in the pointing direction of the kth ship at the moment.

[0085] Considering that the satellite-borne AIS antenna is installed at a certain side angle, the directional pattern data of the satellite-borne AIS antenna is first read.

[0086] Then the WGS-84 coordinate system satellite target line of sight unit vector

[0087] ;

[0088] According to the ephemeris position and the current satellite attitude matrix, the target's sight vector can be converted to the stellar coordinate system.

[0089] ;

[0090] Then, according to the following formula and the antenna installation rotation matrix, the target line of sight vector is converted to the line of sight vector relative to the antenna installation coordinate system:

[0091]

[0092] The azimuth and elevation angles of the target can be calculated by converting the target sight vector into the sight vector relative to the antenna installation coordinate system.

[0093] ;

[0094] According to the antenna pattern read, the azimuth and elevation angles are interpolated in two dimensions to obtain the receiving antenna gain value G rk,i .

[0095] The Doppler frequency shift distribution model mainly calculates the Doppler frequency shift received by the satellite for each ship based on the ephemeris position and speed of the satellite movement and the position of each ship.

[0096] Assume the satellite position is , the position of the ship is , The satellites are k,i The three-dimensional velocity in the Earth-centered Earth-fixed (ECF) coordinate system at the moment, ignoring the speed of the ship, the Doppler frequency shift f dk,i The calculation formula is as follows

[0097] ; .

[0098] The multi-channel phase difference model and time delay model mainly calculate the multi-channel phase difference and time delay of each ship received by multiple receiving antennas and channels of the satellite based on the attitude and position of the satellite movement and the position of each ship.

[0099] Since the connection direction of the dual-channel antenna is consistent with the direction of satellite movement, the phase difference between the two antennas can be calculated as

[0100] ;

[0101] in .

[0102] According to the distance from each target to the satellite, the signal time delay of each time slot signal can be calculated as:

[0103] ;

[0104] Where c is the speed of light.

[0105] The AIS signal generation model mainly generates the corresponding AIS signal data for each time slot of each ship based on the signal power, frequency shift, phase difference, and delay value calculated above, as well as the ship number, position, speed, and time slot information of the ship distribution model.

[0106] Furthermore, after turning on the computer, the user starts the scene and baseband signal data generation software, sets the scene parameters and clicks to start simulation. The software then starts to calculate the visible range according to the set satellite motion scenario, generates multiple ship targets within the visible range, and performs SOTDMA time slot simulation. Then, the AIS signal is generated according to the time slot specified for each target, the multi-target signals are superimposed, the multi-target superimposed baseband signal data is generated and stored on the disk, and then the corresponding signal data file is loaded and output through the signal loading software.

[0107] Furthermore, the satellite-borne AIS data processing software includes a comprehensive display module, a data reading module, a data calculation and generation module and a data demodulation module.

[0108] The comprehensive display module displays the list of E0B data to be processed, data calculation results, data demodulation processing progress, data demodulation results and other information.

[0109] According to the functional requirements, the comprehensive display module can be divided into sub-modules such as file selection and display, data import result display, data demodulation progress display, and demodulation result display; the file selection and display sub-module provides a tool for manually selecting a data path. After the selection is completed, the file list under the path is displayed, and a single file selection addition and file list management functions are provided; the mode selection module is responsible for displaying information such as the demodulation algorithm, number of channels, and pulse extraction method; the demodulation progress display sub-module is responsible for receiving the demodulation progress information sent by the data demodulation module; the demodulation result display sub-module is responsible for receiving the demodulation result and demodulation status information sent by the data demodulation module.

[0110] The detailed processing flow of the integrated display module is as follows:

[0111] 1. Perform data selection operations and set the path of the data to be processed;

[0112] 2. Display the data path and the data list under the path;

[0113] 3. The operator sets the storage path and sends the storage path to the result storage module;

[0114] 4. After receiving the splitting result sent by the data splitting module, display it;

[0115] 5. After receiving the progress and result information sent by the data demodulation module, display it.

[0116] The data reading module obtains the list of data to be processed according to the folder path or file path imported by the user and the file name format, and sends it to the comprehensive display module; it reads the files in the data list in turn and sends the content to the data demodulation module for processing. According to the functional requirements, the data reading module can be divided into sub-modules such as file screening, file list management, and source package data reading.

[0117] The file screening submodule selects the files to be processed according to the selected path and file name format; the file list management submodule numbers the selected files to be processed, adds them to the queue to be processed, and sends the data queue to the comprehensive display module; the source packet data reading submodule reads the file contents in the queue to be processed in turn, and sends them to the data splitting module for processing; click the function button to read AIS signal data, select the file to be processed through the data file path, and complete the input of the original data; the AIS signal data file is a binary file, and the software can choose whether the input data rate is 4 times the sampling rate or 8 times the sampling rate to resolve time slot conflicts.

[0118] The detailed processing flow of the data reading module is as follows:

[0119] 1. Get the set data path;

[0120] 2. Filter files that meet the file name format specifications;

[0121] 3. Generate a file list and send it to the data splitting module.

[0122] The data calculation and generation module is responsible for parsing the AIS sampling data and on-board demodulation data from the AIS satellite's original reconnaissance data, converting the data into packet formats and time frame alignment, and separating the two frequency points of 161.975MHz and 162.025MHz and the LAIS data; based on the unified GPS clock, the sampling data is divided into time slots to ensure the integrity of the signals arriving at the satellite receiver from ships at different locations within the satellite's field of view.

[0123] The data demodulation module is responsible for the demodulation of AIS signal data. First, the carrier frequency is estimated and the Doppler frequency shift introduced by the relative motion between the satellite and the ship is estimated. Then, the possible single signal and time slot conflict environment is considered, and each segment of data is demodulated in combination with the carrier frequency estimation result. The long pulse data occupying multiple time slots is extracted, and the demodulation method is adjusted accordingly according to its data format to obtain the AIS signal information sequence. The demodulated AIS information sequence is verified with reference to the AIS signal coding format to determine its correctness. Error correction is performed on the information sequence that does not pass the verification to improve the probability of correct demodulation.

[0124] The detailed processing flow of the data demodulation module is as follows:

[0125] 1. Receive AIS signals;

[0126] 2. Use the signal separation algorithm to separate the AIS signal to obtain multiple AIS signals;

[0127] 3. Demodulate the single AIS signal;

[0128] 4. Display and store demodulation results.

[0129] Furthermore, the ship detection probability evaluation software includes ship detection probability theoretical statistics and ship detection probability simulation statistics.

[0130] The ship detection probability theoretical statistics module mainly calculates the number of time slot overlaps and the probability of ship overlap based on the time slot and scenario distribution statistics of theoretical simulation.

[0131] Statistics of timeslot overlap

[0132] For the entire simulation time period, each time slot is numbered starting from 1, and the number of times each time slot number is occupied by each ship is counted.

[0133] ;

[0134] in

[0135]

[0136] By counting the number of times s(k,i)=0, 1, 2, ..., we can get the statistics of the number of time slot overlaps.

[0137] Statistics of ship overlap probability

[0138] For the kth target in time slot i, the ship statistical probability is

[0139] ;

[0140] Count all the times n k=1, 2, ..., we can get the statistics of the number of overlapping ships. Dividing by the total number of ships, we can get the ratio of the number of overlapping ships of different types.

[0141] The ship detection probability simulation statistics module compares the MMSI number parsed by the satellite-borne AIS data processing software with the MMSI number generated by the simulation to obtain the ship detection probability.

[0142] During the simulation, the MMSI number is output and used to represent the ship. The MMSI number parsed by the satellite-borne AIS data processing software is compared with the MMSI number generated by the simulation, and the ratio obtained is the ship detection probability.

[0143] The ship detection probability statistics results are displayed on the interface.

[0144] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has the detection probability assessment function of different receiving systems and time slot conflict resolution algorithms.

[0145] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has the function of detecting probability assessment when the number of ships, observation time, number of receiving channels and other parameters are variable.

[0146] The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has the statistical function of time slot overlap number and ship overlap probability.

[0147] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0148] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. Satellite-borne AIS payload full-link simulation and ship detection probability assessment system, including: The satellite-borne AIS payload full-link simulation and ship detection probability assessment system includes scene and baseband signal generation software, satellite-borne AIS data processing software and ship detection probability assessment software; The feature is that: the scene and baseband signal generation software generates the distribution of satellites and multiple ships on the sea surface, calculates the time delay, Doppler frequency shift, phase difference, and power difference parameters according to the relative position relationship between the satellite and the ship, and generates an AIS baseband signal waveform data file in a SOTDMA mode, wherein the SOTDMA mode is a self-organizing time division multiple access mode; The satellite-borne AIS data processing software reads the waveform data file of the satellite and ship distribution scene and the baseband signal generation software, performs single-channel or multi-channel signal separation, demodulation, and decoding to obtain the information data of the target ship; The ship detection probability assessment software reads the true value of the ship information generated by the scene and baseband signal generation software and the processing result of the satellite-borne AIS data processing software, and compares them, and statistically calculates the demodulation accuracy and ship number information for system performance evaluation; The scenario and baseband signal generation software consists of a ship distribution model, a multi-cell ship AIS transmission model, a signal power distribution model, a Doppler frequency shift distribution model, a multi-channel phase difference model, a multi-channel delay model and an AIS signal generation model; The ship distribution model simulates the distribution pattern of ships at sea; The multi-cell ship AIS transmission model simulates the SOTDMA communication protocol model of the AIS and LAIS systems, and generates the transmission rules and transmission time slot number of each ship according to the distribution of ships; The signal power distribution model is a model for calculating the signal power of each ship based on the transmitting antenna pattern, gain, transmitting power and the receiving antenna pattern, gain, and receiver sensitivity information of the shipborne AIS; The Doppler frequency shift distribution model calculates the Doppler frequency shift of each ship received by the satellite according to the ephemeris position and speed of the satellite movement and the position of each ship; The multi-channel phase difference model and time delay model calculate the multi-channel phase difference and time delay of each ship received by multiple receiving antennas and channels of the satellite according to the attitude and position of the satellite movement and the position of each ship; The AIS signal generation model generates AIS signal data corresponding to each time slot of each ship according to the signal power, frequency shift, phase difference, and delay value calculated above, and according to the ship number, position, speed, and time slot information of the ship distribution model; The satellite-borne AIS data processing software includes a comprehensive display module, a data reading module, a data calculation and generation module and a data demodulation module; The integrated display module displays the list of E0B data to be processed, data calculation results, data demodulation processing progress, and data demodulation result information; The data reading module obtains the E0B data list to be processed according to the folder path or file path imported by the user; The data calculation and generation module is responsible for parsing AIS sampling data and on-board demodulation data from the AIS satellite raw reconnaissance data, converting the data into packet formats and aligning the time frames, and separating the two frequency points of 161.975MHz and 162.025MHz and the LAIS data; The data demodulation module is responsible for the demodulation processing of AIS signal data; The ship detection probability assessment software includes ship detection probability theoretical statistics and ship detection probability simulation statistics; The ship detection probability theoretical statistics module calculates the number of time slot overlaps and the probability of ship overlap according to the time slots and scene distribution statistics of theoretical simulation; The ship detection probability simulation statistics module compares the MMSI number parsed by the satellite-borne AIS data processing software with the MMSI number generated by simulation to obtain the ship detection probability.

2. The satellite-borne AIS payload full-link simulation and ship detection probability assessment system according to claim 1 is characterized in that: The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has detection probability assessment functions of different receiving systems and time slot conflict resolution algorithms.

3. The satellite-borne AIS payload full-link simulation and ship detection probability assessment system according to claim 1 is characterized in that: The satellite-borne AIS payload full-link simulation and ship detection probability assessment system has a detection probability assessment function when the number of ships, observation time, and number of receiving channels are variable.

4. The satellite-borne AIS payload full-link simulation and ship detection probability assessment system according to claim 1 is characterized in that: The satellite-borne AIS load full-link simulation and ship detection probability assessment system has the statistical function of time slot overlap number and ship overlap probability.

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