A ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels

Abstract

The present invention relates to a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels, belonging to the technical field of radar target characteristic modeling, and solving problems such as insufficient modeling granularity in existing electromagnetic models. The system comprises: radar equipment for conducting omnidirectional data acquisition experiments to obtain measured high-speed echo data; a normalized basis function determination module for generating normalized basis functions based on radar equipment parameters; a target characteristic extraction module for extracting target characteristics from the measured high-speed echo data based on the normalized basis functions to obtain target characteristic range-Doppler data; an omnidirectional stable scattering point sequence generation module for processing each frame of target characteristic range-Doppler data to obtain an omnidirectional stable scattering point sequence for each polarization channel; and a ship omnidirectional scattering point modeling module for performing omnidirectional scattering point modeling on the omnidirectional stable scattering point sequence for each polarization channel to obtain a ship omnidirectional scattering point model under multi-polarization channels.

Description

Technical Field

[0001] The present invention relates to the technical field of radar target characteristic modeling, and in particular to a ship target omnidirectional scattering point characteristic modeling system based on a multi-polarization channel. Background Art

[0002] Radar's target detection and recognition performance directly impacts the combat effectiveness of weapon systems. Improving radar's ability to identify ship targets in complex battlefield environments requires extensive ship target data. By accurately analyzing ship target characteristics and simulating their echo signals, we construct a model of the omnidirectional scattering characteristics of ship targets. This allows for scene reconstruction and data augmentation of high-speed ship echo data, fully tapping into the value of test data and providing massive data support for improving weapon combat effectiveness.

[0003] However, the existing measured data is costly and difficult to obtain, and the simulation of radar target and environmental characteristics is difficult; at the same time, electromagnetic models often have low realism due to insufficient modeling granularity, and there are few studies on characteristics based on measured data.

[0004] Therefore, how to design a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels is an urgent problem that needs to be solved. Summary of the Invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels to solve the problems of insufficient modeling granularity and low fidelity of electromagnetic models in the prior art.

[0006] The present invention discloses a ship target omnidirectional scattering point characteristic modeling system based on a multi-polarization channel, comprising:

[0007] Radar equipment, used to conduct omnidirectional data acquisition tests on ship targets in the field to obtain measured high-speed echo data;

[0008] a normalized basis function determination module, configured to obtain radar equipment parameters during the test and generate a normalized basis function based on the radar equipment parameters;

[0009] A target feature extraction module is used to extract target features of the target area in the range-Doppler data corresponding to each frame of measured high-speed echo data based on the normalized basis function, and obtain the corresponding target feature range-Doppler data;

[0010] The omnidirectional stable scattering point sequence generation module is used to process the target characteristic range-Doppler data of each frame to obtain the omnidirectional stable scattering point sequence of each polarization channel;

[0011] The ship omnidirectional scattering point modeling module is used to perform omnidirectional scattering point modeling on the omnidirectional stable scattering point sequence of each polarization channel respectively, and obtain the ship omnidirectional scattering point model under multi-polarization channels.

[0012] On the basis of the above solution, the present invention also makes the following improvements:

[0013] Furthermore, the normalized basis function determination module includes:

[0014] A baseband transmission signal determination submodule is used to determine the baseband transmission signal according to the radar equipment parameters;

[0015] The basis function determination submodule obtains the corresponding basis function set by convolving the baseband transmit signal with itself;

[0016] The normalized function acquisition submodule is used to perform coherent accumulation and normalization processing on the basis function set to obtain the normalized basis function.

[0017] Furthermore, the target feature extraction module includes:

[0018] The target information annotation submodule is used to select the target area of ​​the range-Doppler data corresponding to each frame of measured high-speed echo data, and to annotate the target information of the selected target area;

[0019] The target scattering point acquisition submodule is used to obtain all target scattering points in the range-Doppler data of the target area;

[0020] The target characteristic range-Doppler data generation submodule is used to superimpose the characteristic data of all target scattering points and perform radar-target centroid distance normalization processing to obtain the target characteristic range-Doppler data of the current frame.

[0021] Furthermore, in the target scattering point acquisition submodule, the following operations are performed:

[0022] Obtain the scattering point with the largest amplitude in the range-Doppler data of the target area;

[0023] Determine whether the amplitude of the scattering point is greater than or equal to the clutter amplitude threshold,

[0024] If yes, the scattering point is extracted as a target scattering point, and the product of the amplitude of the scattering point and the normalized basis function is used as the characteristic data of the target scattering point;

[0025] Update the total number of target scattering points and determine whether the total number of target scattering points is greater than or equal to the preset number of target scattering points.

[0026] If yes, then end and obtain the characteristic data of all target scattering points;

[0027] Otherwise, the target scattering point is removed from the range-Doppler data of the target area, the range-Doppler data of the target area is updated, and the scattering point with the largest amplitude in the range-Doppler data of the target area is re-acquired;

[0028] Otherwise, end and obtain the characteristic data of all target scattering points.

[0029] Furthermore, the target characteristic range-Doppler data C of the rth frame r Expressed as:

[0030]

[0031] d r =rangegate+D r .fbl (4)

[0032] Among them, d s is the target feature normalized distance, d r represents the actual distance between the radar and the center of mass of the ship target corresponding to the range-Doppler data of the rth frame, rangegate represents the gate position, and D r represents the range image position of the center of mass of the ship target in the rth frame of range-Doppler data, fbl represents the range resolution of the radar, and n is the total number of frames.

[0033] Furthermore, the omnidirectional stable scattering point sequence generation module includes:

[0034] A main polarization channel processing submodule is used to obtain an omnidirectional stable scattering point sequence of the main polarization channel based on the target characteristic range-Doppler data component of each frame of target characteristic range-Doppler data in the main polarization channel;

[0035] The other polarization channel processing submodule is used to map the omnidirectional stable scattering point sequence of the main polarization channel to other polarization channels to obtain the omnidirectional stable scattering point sequence of other polarization channels.

[0036] Furthermore, in the main polarization channel processing submodule, the omnidirectional stable scattering point sequence of the main polarization channel is obtained by performing the following operations:

[0037] Perform decoherence processing on the target characteristic range-Doppler data components of each frame of the main polarization channel, and take the prt with the largest amplitude as the one-dimensional range image of the frame under the main polarization channel;

[0038] Determine, based on the one-dimensional range image of each frame in the main polarization channel and its corresponding sideways angle, a one-dimensional range image sequence of a vertical sideways frame interval in the main polarization channel and a one-dimensional range image sequence of a non-vertical sideways frame interval;

[0039] Target characteristics are correlated for the one-dimensional range images of each frame in the non-perpendicular sideways frame interval to obtain a stable scattering point sequence in the non-perpendicular sideways frame interval under the main polarization channel;

[0040] Based on the stable scattering point sequence in the non-vertical sideways frame interval under the main polarization channel, a stable scattering point sequence in the vertical sideways frame interval under the main polarization channel is obtained;

[0041] The stable scattering point sequences in the non-vertical and vertical sideways frame intervals under the main polarization channel are sorted according to the frame sequence number to obtain the omnidirectional stable scattering point sequence of the main polarization channel.

[0042] Furthermore, in the main polarization channel processing submodule, a stable scattering point sequence in a non-vertical sideways frame interval under the main polarization channel is obtained by performing the following operations:

[0043] According to the preset number of associated segment frames, the temporally adjacent one-dimensional range images in the non-vertical side frame interval are segmented, and the one-dimensional range images of each frame in the segment are sequentially spliced ​​according to the frame sequence number to obtain a plurality of segment data;

[0044] Preprocess each fragment data to obtain corresponding stable scattering point fragment data;

[0045] Perform range image principal component analysis and cluster analysis on each stable scattering point segment data, and output the stable scattering point sequence and cluster center associated between frames in the corresponding segment;

[0046] According to the stable scattering point sequence and cluster center associated between frames in each segment, inter-segment correlation is performed to obtain the stable scattering point sequence in the non-vertical sideways frame interval under the main polarization channel.

[0047] Furthermore, in the omnidirectional stable scattering point sequence, the stable scattering point information of each stable scattering point includes: frame number, side angle, range image position, scattering point phase and scattering point amplitude

[0048] Furthermore, in the other polarization channel processing submodule, the following operations are performed to obtain the omnidirectional stable scattering point sequences of the other polarization channels:

[0049] According to the range image position of each stable scattering point in the omnidirectional stable scattering point sequence of the main polarization channel, it is mapped to the one-dimensional range image of other polarization channels;

[0050] The omnidirectional stable scattering point sequences of other polarization channels are obtained through the corresponding one-dimensional range images of other polarization channels.

[0051] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0052] The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels proposed in the present invention has the following beneficial effects:

[0053] First, the ship target characteristics of the radar high-speed echo data are extracted through the normalized basis function determination module and the target characteristic extraction module, and the scattering point overlap problem in the association under the main polarization channel is solved through normalization calculation and hull geometry analysis. After the omnidirectional stable scattering point sequence under the main polarization channel is determined, the omnidirectional stable scattering point sequence of the main polarization channel is mapped to other polarization channels to obtain the omnidirectional stable scattering point sequence of other polarization channels, thereby realizing the omnidirectional scattering point modeling of the omnidirectional stable scattering point sequence of each polarization channel separately, and obtaining the final omnidirectional scattering point model of the ship under the multi-polarization channel, realizing the reconstruction of the ship target omnidirectional scattering point characteristics and echo signal simulation based on the multi-polarization channel.

[0054] Second, the ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels in the present invention can effectively enhance the modeling granularity and improve the realism, thereby solving the problem of low realism of the electromagnetic model due to insufficient modeling granularity.

[0055] Third, engineering practice has proved that the ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels proposed in the present invention can obtain a full-angle characterization model of the ship's azimuth, realize scene reconstruction and data augmentation of ship high-speed echo data, and provide a large amount of data support for radar target detection and recognition algorithm training, ultimately improving the radar's ability to identify ship targets and the combat effectiveness of weapons in complex battlefield environments.

[0056] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0058] Figure 1 A schematic diagram of the structure of a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels provided by an embodiment of the present invention;

[0059] Figure 2 Schematic diagram of the correspondence between the range image position of the kth stable scattering point and the range image position of the center of mass of the ship target in the current frame when the broadside angle is 0° in the example;

[0060] Figure 3 Schematic diagram of the correspondence between the range image position of the kth stable scattering point and the range image position of the center of mass of the ship target in the current frame when the broadside angle is 45° in the example;

[0061] Figure 4 Schematic diagram of the method for obtaining the radial velocity of the stable scattering point in the beam direction in the example.

[0062] Figure 5 Schematic diagram of the ship's omnidirectional scattering point model structure. DETAILED DESCRIPTION

[0063] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0064] A specific embodiment of the present invention discloses a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels, the structural diagram of which is shown in FIG. Figure 1 Shown, including:

[0065] Radar equipment, used to conduct omnidirectional data acquisition tests on ship targets in the field to obtain measured high-speed echo data;

[0066] a normalized basis function determination module, configured to obtain radar equipment parameters during the test and generate a normalized basis function based on the radar equipment parameters;

[0067] A target feature extraction module is used to extract target features of the target area in the range-Doppler data corresponding to each frame of measured high-speed echo data based on the normalized basis function, and obtain the corresponding target feature range-Doppler data;

[0068] The omnidirectional stable scattering point sequence generation module is used to process the target characteristic range-Doppler data of each frame to obtain the omnidirectional stable scattering point sequence of each polarization channel;

[0069] The ship omnidirectional scattering point modeling module is used to perform omnidirectional scattering point modeling on the omnidirectional stable scattering point sequence of each polarization channel respectively, and obtain the ship omnidirectional scattering point model under multi-polarization channels.

[0070] In this embodiment, since the normalized basis function determination module, the target characteristic extraction module, the omnidirectional stable scattering point sequence generation module and the ship omnidirectional scattering point modeling module mainly perform data calculation processing and data storage operations, these modules can be based on a CPU or other hardware with strong computing power and large memory space to better implement the corresponding functions.

[0071] It should be noted that in the field test scenarios constructed in this embodiment, each field test scenario only contains one ship target. At the same time, after the field test scenario is constructed, the radar collects echo data in the field test scenario by emitting radar transmission signals and receiving radar echo signals fed back by the ship target, which is used as the corresponding field-measured high-speed echo data. Since the omnidirectional scattering point characteristics of the ship target on each polarization channel are obtained based on the high-speed echo data in the full polarization state, and in order to effectively utilize the test conditions of the field test scenario, the polarization state of the radar should be set to full polarization in the field test scenario. During the omnidirectional data acquisition test, the ship target rotates in a circle, so the entire time sequence of the measured high-speed echo data obtained corresponds to a broadside angle of 0-360°.

[0072] In the normalized basis function determination module, it includes:

[0073] The baseband transmit signal determination submodule is used to determine the baseband transmit signal based on radar equipment parameters. During omnidirectional testing of a ship target in a field test scenario, the radar equipment parameters remain unchanged. In this embodiment, the radar equipment parameters include information such as radar operating status, polarization mode, operating frequency band, signal bandwidth, and code type.

[0074] The basis function determination submodule obtains the corresponding basis function set by convolving the baseband transmit signal with itself;

[0075] Specifically, the baseband transmission signal st is convolved with itself to find the PRT basis function set of the current frame, where the basis function Base of the i-th PRT is recorded as i for:

[0076]

[0077] Where Window is the matched filter window function, i = 1, 2, ..., m, m is the number of pulse accumulation, and the current frame basis function set Base is as follows:

[0078] Base=fft([Base1; Base2; ...; Base m ]) (2)

[0079] The normalization function acquisition submodule is used to perform coherent accumulation and normalization processing on the basis function set to obtain a normalized basis function. In this embodiment, the normalized basis function is denoted as NBase.

[0080] The target characteristic extraction module includes a target information annotation submodule, a target scattering point acquisition submodule and a target characteristic range-Doppler data generation submodule.

[0081] The target information labeling submodule is used to select the target area of ​​the range-Doppler data corresponding to each frame of measured high-speed echo data, and label the target information of the selected target area; specifically,

[0082] In the target information labeling submodule, the corresponding range-Doppler data is obtained by performing pulse compression and coherent accumulation processing on each frame of measured high-speed echo data; then, based on the mapping relationship between the field test scene and each frame of range-Doppler data, the target area can be framed out from each frame of range-Doppler data. After the target area is framed out, the target area can be labeled with target information. In this embodiment, the labeled target information includes: target attribute information, target location information, and target scene information; among them,

[0083] Target attribute information includes target type and hull number / model; for example, target type includes warship and civilian ship, and hull number / model includes 835, etc.

[0084] The target location information refers to the range Doppler area where the target area is located;

[0085] Target parameter information includes: side angle, heading, speed and ship geometry (such as length, width and height);

[0086] Target scene information refers to the meteorological information of the field test scene, such as weather, sea conditions, wind speed, wind direction, ocean currents, ocean direction, etc.

[0087] Since in this embodiment, omnidirectional data collection is required for a ship target in an outdoor test scenario, each omnidirectional data collection test involves only one ship target. Accordingly, only one target area can be selected from the range-Doppler data.

[0088] In particular, if the outdoor scene also contains non-cooperative targets, the non-cooperative targets in the range-Doppler data are removed and replaced with background clutter;

[0089] Since non-cooperative targets (i.e., non-predetermined ship-like targets) inevitably appear in field measurement data, such as unknown small fishing boats and drilling platforms, they are marked as non-cooperative targets during data annotation. When extracting ship target characteristics, these non-cooperative targets need to be removed. Here, background clutter replacement is used to remove non-cooperative targets. Specifically, after the target area is selected and the target information is annotated, the range-Doppler range of the ship target and other non-cooperative targets is determined based on the annotated information of all targets in the current frame's range-Doppler data. The non-cooperative targets in the range-Doppler data are then removed and replaced with background clutter.

[0090] The target scattering point acquisition submodule is used to acquire all target scattering points in the range-Doppler data of the target area. Specifically, the following operations are performed in this submodule:

[0091] Step 1-1: Obtain the scattering point with the largest amplitude in the range-Doppler data of the target area;

[0092] Specifically, in step 1-1, when the process is first executed, the range-Doppler data of the target area is determined based on the target position information of the marked target area. When the process is not first executed, the range-Doppler data of the target area refers to the range-Doppler data of the target area updated in step 1-2.

[0093] Step 1-2: Determine whether the amplitude of the scattering point is greater than or equal to the clutter amplitude threshold.

[0094] If yes, the scattering point is extracted as a target scattering point, and the product of the amplitude of the scattering point and the normalized basis function is used as the characteristic data of the target scattering point;

[0095] Update the total number of target scattering points and determine whether the total number of target scattering points is greater than or equal to the preset number of target scattering points.

[0096] If so, then end;

[0097] Otherwise, the target scattering point is removed from the range-Doppler data of the target area, and the range-Doppler data of the target area is updated, and the process jumps to step 1-1, that is, searching for the scattering point with the largest amplitude again in the updated range-Doppler data of the target area;

[0098] Otherwise, end;

[0099] After executing the above cycle, the characteristic data of all target scattering points can be obtained.

[0100] In step 1-2, the corresponding clutter amplitude threshold is determined based on the clutter data in the current frame range-Doppler data and the preset clutter probability threshold. Specifically, the clutter amplitude threshold is determined in the following manner: the clutter amplitude threshold β is calculated from the cumulative probability distribution P of the clutter data Z in the current frame range-Doppler data. The relationship between the clutter probability threshold α and the clutter amplitude threshold β is expressed as α=P(Z≤β), that is, the clutter probability threshold α is the probability that the clutter Z is less than or equal to the clutter amplitude threshold β. Therefore, when the clutter probability threshold is predetermined, the clutter amplitude threshold can be determined based on the clutter data in the current frame range-Doppler data. α∈(0,1], the higher the limit on the number of extracted target scattering points, the higher the value of the corresponding clutter probability threshold. At the same time, the amplitude of the extracted scattering points must be greater than the clutter amplitude threshold at the α quantile.

[0101] In step 1-2, the process of obtaining characteristic data of the target scattering point based on the normalized basis function and removing the target scattering point from the range-Doppler data of the target area is described as follows:

[0102] The scattering points are extracted in descending order according to the amplitude of the target scattering points in the range-Doppler data. Assume that the amplitude of the j-th target scattering point in the target area is I j , the coordinates are (a, b), the normalized basis function NBase is matrix translated (the redundant and missing parts are spliced ​​end to end after the translation), the basis of the translation is to move the maximum amplitude point of the normalized basis function NBase to (a, b), and the moved basis function is recorded as NBase j , will I j *NBase j As the characteristic data of the jth target scattering point in the current target area, I is then filtered out from the target area. j *NBase j , in order to eliminate the target scattering point from the range-Doppler data of the target area.

[0103] The target characteristic range-Doppler data generation submodule is used to superimpose the characteristic data of all target scattering points and perform radar-target centroid distance normalization processing to obtain the target characteristic range-Doppler data of the current frame.

[0104] For example, the target characteristic range-Doppler data C of the rth frame r Expressed as:

[0105]

[0106] d r =rangegate+D r .fbl (4)

[0107] Among them, d s is the target feature normalized distance, d r represents the actual distance between the radar and the center of mass of the ship target corresponding to the range-Doppler data of the rth frame, rangegate represents the gate position, and D r Indicates the range image position of the center of mass of the ship target in the range-Doppler data of the rth frame, fbl represents the range resolution of the radar, and n is the total number of frames. r It includes the data information of all target scattering points that constitute the target characteristics of the frame data. It is a two-dimensional RD complex matrix, which contains the distance, Doppler position and phase information of all target scattering points that constitute the target characteristics.

[0108] Preferably, the omnidirectional stable scattering point sequence generation module includes: a main polarization channel processing submodule and other polarization channel processing submodules; wherein the main polarization channel processing submodule is configured to obtain an omnidirectional stable scattering point sequence of the main polarization channel based on the target characteristic range-Doppler data component of each frame of target characteristic range-Doppler data in the main polarization channel; and the other polarization channel processing submodule is configured to map the omnidirectional stable scattering point sequence of the main polarization channel to other polarization channels to obtain omnidirectional stable scattering point sequences of the other polarization channels.

[0109] In the main polarization channel processing submodule, the following process is performed:

[0110] This embodiment involves four polarization channels: HH, HV, VH, and VV. In actual implementation, the polarization channel with the highest signal-to-noise ratio (SNR) of the target characteristic range-Doppler data is selected as the primary polarization channel. Because data from the same polarization channel has identical characteristics, to simplify implementation, the polarization channel with the highest SNR of the target characteristic range-Doppler data in the first frame can be directly selected as the primary polarization channel.

[0111] In this step, perform the following operations:

[0112] Step 2-1: Perform decoherence processing on the target characteristic range-Doppler data components of each frame of the main polarization channel, and take the prt with the largest amplitude (corresponding to a row in the decoherence data) as the one-dimensional range image of the frame in the main polarization channel;

[0113] Step 2-2: Determine a one-dimensional range image sequence of a perpendicular sideways frame interval and a one-dimensional range image sequence of a non-perpendicular sideways frame interval in the main polarization channel based on the one-dimensional range image of each frame in the main polarization channel and its corresponding sideways angle; wherein the non-perpendicular sideways frame interval refers to a frame interval in other sideways except the perpendicular sideways frame interval.

[0114] Since the radial size of the ship is the smallest in the vertical broadside frame interval (around plus or minus 90 degrees), the range images of the various target scattering points will overlap. Therefore, in the main polarization channel, the one-dimensional range images of the vertical broadside frame interval and the non-vertical broadside frame interval can be divided by judging whether the one-dimensional range images corresponding to each broadside angle overlap. At the same time, to solve this problem, this embodiment implements two different correlation technology solutions for the target characteristic range-Doppler data components in the non-vertical broadside frame interval and the vertical broadside frame interval respectively. Specifically,

[0115] Step 2-3: Perform target characteristic correlation on the one-dimensional range images of each frame in the non-perpendicular sideways frame interval to obtain a stable scattering point sequence in the non-perpendicular sideways frame interval under the main polarization channel;

[0116] Step 2-3-1: Divide the temporally adjacent one-dimensional range images in the non-vertical side frame interval into segments according to the preset number of associated segment frames, and sequentially splice the one-dimensional range images of each frame in the segment according to the frame sequence number to obtain a number of segment data;

[0117] Step 2-3-2: Preprocess each segment data to obtain the corresponding stable scattering point segment data;

[0118] Since the scattering point characteristics do not necessarily exist at all broadside angles, the extracted target characteristic range-Doppler data component contains several target scattering points with discontinuous and unstable time series. Therefore, it is necessary to preprocess each data segment, including outlier removal and missing value interpolation, to solve the problem of discontinuous and unstable time series of target scattering point data.

[0119] Outlier removal: Using the existing MAD algorithm, the target scattering point is judged as an outlier by determining whether the deviation between the range image of each target scattering point and the median value of the range images of all target scattering points is within a reasonable range. By executing this process, unstable target scattering points can be removed and the remaining target scattering points can be regarded as stable scattering points.

[0120] Missing value interpolation: Using the filling method of regression analysis, missing values ​​are calculated by fitting the regression mathematical model, that is, missing stable scattering points are filled.

[0121] After the preprocessing is completed, the stable scattering point segment data can be obtained. At this time, the intra-segment inter-frame correlation is performed first, and then the inter-segment correlation is performed to solve the problem that the omnidirectional data scattering points with large spans are difficult to distinguish, effectively reducing the correlation difficulty and improving the accuracy of the correlation results. Specifically,

[0122] Step 2-3-3: Perform range image principal component analysis and cluster analysis on each stable scattering point segment data, and output the stable scattering point sequence and cluster center associated between frames within the corresponding segment;

[0123] For each stable scattering point segment, first, principal component analysis (PCA) is performed on the range images of all stable scattering points within the segment to maximize their discrimination within the range image. Then, K-means clustering is performed on the range image using the PCA results, with the number of clustering categories equal to the number of stable scattering points. This results in a stable scattering point subsequence and its cluster center associated with each stable scattering point within the current segment. The stable scattering point subsequence records the stable scattering point information for each stable scattering point in each frame. This stable scattering point information includes: frame number, sideways angle, range image position, scattering point phase, and scattering point amplitude. The range image position, scattering point phase, and scattering point amplitude are obtained from the corresponding one-dimensional range image. The frame number refers to the frame data corresponding to the measured high-speed echo data collected in the field test scenario. The stable scattering point subsequences associated with each stable scattering point within the current segment are summarized to form a stable scattering point sequence associated with each stable scattering point within the corresponding segment.

[0124] Step 2-3-4: Based on the stable scattering point sequence and cluster center associated between frames in each segment, perform inter-segment correlation to obtain the stable scattering point sequence in the non-vertical side frame interval under the main polarization channel.

[0125] After all inter-frame correlations within each segment are completed, for adjacent stable scattering point segment data, the cluster centers of each stable scattering point segment data are predicted based on the ship's geometry and the stable scattering point positional relationships. Based on the distance relationship between the predicted cluster centers of each segment data and the cluster centers obtained by cluster analysis (performing steps 2-3-3), the corresponding relationship between the same stable scattering point in each stable scattering point segment data is determined. Based on this corresponding relationship, inter-segment correlation is performed to obtain the stable scattering point sequence in the non-vertical sideways frame interval under the main polarization channel. Specifically, the inter-segment correlation method is as follows:

[0126] For the same target scattering point, the stable scattering point subsequences in different stable scattering point segments are spliced ​​according to the frame sequence number to form the stable scattering point sequence of the stable scattering point in the non-vertical sideways frame interval; the stable scattering point sequences of all stable scattering points in the non-vertical sideways frame interval are summarized to form the final stable scattering point sequence in the non-vertical sideways frame interval.

[0127] For the correlation of target characteristic data components in the vertical broadside frame interval, since the radial size of the ship is the smallest in the vertical broadside frame interval, the range images of each target scattering point overlap. Therefore, it is necessary to combine the frequency domain information to correlate the stable scattering points. The specific steps are as follows:

[0128] Step 2-4: Based on the stable scattering point sequence in the non-vertical sideways frame interval under the main polarization channel, obtain the stable scattering point sequence in the vertical sideways frame interval under the main polarization channel; specifically,

[0129] Step 2-4-1: Based on the stable scattering point sequence in the non-vertical sideways frame interval and the hull geometry, establish the hull scattering position geometry model; specifically,

[0130] Based on the hull geometric structure, establish a hull geometric model;

[0131] For each stable scattering point, a plurality of frames of stable scattering point information are selected from a stable scattering point sequence in a non-perpendicular broadside frame interval to determine the physical position of the stable scattering point in establishing the hull geometric model; for each stable scattering point, each frame of stable scattering point information is selected to determine the linear position of the stable scattering point at the current broadside angle based on the corresponding relationship between the broadside angle and the range image position corresponding to the frame and the range image position of the center of mass of the ship target in the current frame; based on the linear positions of the stable scattering point at multiple broadside angles, the physical position of the stable scattering point in the hull geometric model can be determined;

[0132] For example, for the kth stable scattering point, it is assumed that the stable scattering point sequence in the non-vertical sideways frame interval contains stable scattering point information with sideways angles of 0° and 45°; when the sideways angle is 0°, as Figure 2 As shown in , according to the correspondence between the range image position of the kth stable scattering point and the range image position of the center of mass of the ship target in the current frame, the radial position of the stable scattering point can be obtained. It can be seen that the kth scattering point is on a straight line in the hull that is perpendicular to the beam direction at this time. When the broadside angle is 45°, as Figure 3 As shown, it can be seen that the kth stable scattering point is located on another straight line in the hull that is perpendicular to the beam direction at this time. The intersection of these two lines is the physical location of the stable scattering point in the hull geometric model. More precisely, stable scattering point information corresponding to more broadside angles can be selected to more accurately determine the physical location of the stable scattering point in the hull geometric model. Similarly, the physical locations of all stable scattering points in the hull geometric model can be determined using this method.

[0133] According to the physical position of each stable scattering point in the hull geometric model, a hull scattering position geometric model is established.

[0134] Step 2-4-2: Determine the stable scattering point information of each stable scattering point at each broadside angle within the vertical broadside frame interval based on the ship scattering position geometry model, the speed and heading of the ship target;

[0135] Specifically, for each stable scattering point at each broadside angle within the vertical broadside frame interval, the following operations are performed:

[0136] According to the geometric model of the hull scattering position, the speed and heading of the ship target, the radial velocity of the stable scattering point in the beam direction is calculated, and the radial velocity is converted into the corresponding Doppler channel number;

[0137] Example: Calculate the stable scattering points (such as Figure 4 The Doppler channel number corresponding to the kth stable scattering point is shown in the figure (using the kth stable scattering point as an example): After obtaining the ship's motion state (speed and heading) for that frame, the velocity vector is projected onto the beam direction based on the ship's scattering position geometry model to obtain the radial velocity of the stable scattering point in the beam direction. The radial velocity is then converted to the corresponding Doppler channel number l according to the following formula:

[0138]

[0139] Where v is the radial velocity, PRT is the pulse repetition period, N is the Doppler dimension, and λ is the carrier wavelength.

[0140] The Doppler channel number is mapped to the target characteristic range-Doppler data component of the corresponding frame under the main polarization channel to determine the range position of the stable scattering point; the target scattering point corresponding to the range position is located as the stable scattering point from the one-dimensional range image of the corresponding frame under the main polarization channel, and stable scattering point information of the located stable scattering point is obtained.

[0141] This process can solve the overlapping problem of the range images of the stable scattering point positions in the vertical side frame interval.

[0142] Step 2-4-3: Based on the obtained stable scattering point information of each stable scattering point in the vertical sideways frame interval, obtain the stable scattering point sequence in the vertical sideways frame interval under the main polarization channel.

[0143] In the vertical sideways frame interval, for the same stable scattering point, the stable scattering point information is spliced ​​according to the frame sequence number to form a stable scattering point sequence of the stable scattering point in the vertical sideways frame interval under the main polarization channel; the stable scattering point sequences of all stable scattering points in the vertical sideways frame interval are summarized to form a final stable scattering point sequence in the vertical sideways frame interval under the main polarization channel.

[0144] Step 2-5: Sort the stable scattering point sequences in the non-vertical and vertical sideways frame intervals of the main polarization channel according to the frame sequence number to obtain the omnidirectional stable scattering point sequence of the main polarization channel.

[0145] In the obtained omnidirectional stable scattering point sequence, assuming that the main polarization channel is the HH channel, the main polarization channel omnidirectional stable scattering point sequence of the kth stable scattering point is S HH_k , S HH_k It can be expressed as follows: HH_k1 ,S HH_k2 ,...,S HH_kr ,...,S HH_kn}; k = 1, 2, ..., K, K is the total number of stable scattering points; where S HH_kr Indicates the stable scattering point information of the kth stable scattering point in the rth frame of range-Doppler data under the HH channel.

[0146] In the other polarization channel processing submodule, the following operations are performed to obtain omnidirectional stable scattering point sequences for other polarization channels: the position of each stable scattering point in the omnidirectional stable scattering point sequence of the main polarization channel is mapped to the one-dimensional range image of the other polarization channel; and the omnidirectional stable scattering point sequence for the other polarization channel is obtained using the corresponding one-dimensional range image of the other polarization channel. It should be noted that the stable scattering points have the same range image position on the one-dimensional range image of different polarization channels, but different scattering point phases and scattering point amplitudes. Therefore, the scattering point phases and scattering point amplitudes of each scattering point in the other polarization channel can be obtained using the corresponding one-dimensional range image of the other polarization channel, ultimately forming an omnidirectional stable scattering point sequence for the other polarization channel.

[0147] In the ship omnidirectional scattering point modeling module, in the omnidirectional stable scattering point sequence of each polarization channel, the deviation of the sideways angle corresponding to two adjacent frames may be relatively large. In this case, it is necessary to interpolate the omnidirectional stable scattering point sequence based on the sideways angle, fit the sideways angle, range image position, scattering point phase and scattering point amplitude, and adjust the frame number to achieve omnidirectional scattering point modeling for each polarization channel. The omnidirectional scattering point modeling results of each polarization channel are summarized to form an omnidirectional scattering point model of the ship target under multi-polarization channels.

[0148] For example, the grid search method is used to select the corresponding fitting function to obtain the mathematical model of each scattering point of the ship target under each polarization channel, and the omnidirectional scattering point model of the corresponding polarization channel is modeled to obtain the full-angle characterization model of the ship azimuth, that is, the omnidirectional scattering point model of the ship target under multi-polarization channels. The model structure diagram is shown in the figure below. Figure 5 Based on this model, target characteristics can be reconstructed according to the broadside angle, achieving incremental expansion of typical ship target sample data and scene reconstruction.

[0149] In summary, the present invention proposes a ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels, which realizes the ship target characteristic extraction of radar high-speed echo data through the normalized basis function determination module and the target characteristic extraction module, and solves the scattering point overlap problem in the association under the main polarization channel through normalization calculation and hull geometry analysis. After the omnidirectional stable scattering point sequence under the main polarization channel is determined, the omnidirectional stable scattering point sequence of the main polarization channel is corresponded to other polarization channels to obtain the omnidirectional stable scattering point sequence of other polarization channels, thereby realizing omnidirectional scattering point modeling of the omnidirectional stable scattering point sequence of each polarization channel respectively, and obtaining the final ship omnidirectional scattering point model under the multi-polarization channel, realizing the ship target omnidirectional scattering point characteristic reconstruction and echo signal simulation based on the multi-polarization channel. Engineering practice has proved that the ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels proposed in the present invention can obtain a full-angle characterization model of the ship's azimuth, realize scene reconstruction and data augmentation of ship high-speed echo data, and provide a large amount of data support for radar target detection and recognition algorithm training, ultimately improving the radar's ability to identify ship targets and the combat effectiveness of weapons in complex battlefield environments.

[0150] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0151] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels, characterized by: include: Radar equipment, used to conduct omnidirectional data acquisition tests on ship targets in the field to obtain measured high-speed echo data; a normalized basis function determination module, configured to obtain radar equipment parameters during the test and generate a normalized basis function based on the radar equipment parameters; A target feature extraction module is used to extract target features of the target area in the range-Doppler data corresponding to each frame of measured high-speed echo data based on the normalized basis function, and obtain the corresponding target feature range-Doppler data; The omnidirectional stable scattering point sequence generation module is used to process the target characteristic range-Doppler data of each frame to obtain the omnidirectional stable scattering point sequence of each polarization channel; The ship omnidirectional scattering point modeling module is used to perform omnidirectional scattering point modeling on the omnidirectional stable scattering point sequence of each polarization channel to obtain the ship omnidirectional scattering point model under multi-polarization channels; The omnidirectional stable scattering point sequence generation module includes: A main polarization channel processing submodule is used to obtain an omnidirectional stable scattering point sequence of the main polarization channel based on the target characteristic range-Doppler data component of each frame of target characteristic range-Doppler data in the main polarization channel; Other polarization channel processing submodules, used to map the omnidirectional stable scattering point sequence of the main polarization channel to other polarization channels, and obtain the omnidirectional stable scattering point sequences of other polarization channels; In the main polarization channel processing submodule, the omnidirectional stable scattering point sequence of the main polarization channel is obtained by performing the following operations: Perform decoherence processing on the target characteristic range-Doppler data components of each frame of the main polarization channel, and take the prt with the largest amplitude as the one-dimensional range image of the frame under the main polarization channel; Determine, based on the one-dimensional range image of each frame in the main polarization channel and its corresponding sideways angle, a one-dimensional range image sequence of a vertical sideways frame interval in the main polarization channel and a one-dimensional range image sequence of a non-vertical sideways frame interval; Target characteristics are correlated for the one-dimensional range images of each frame in the non-perpendicular sideways frame interval to obtain a stable scattering point sequence in the non-perpendicular sideways frame interval under the main polarization channel; Based on the stable scattering point sequence in the non-vertical sideways frame interval under the main polarization channel, a stable scattering point sequence in the vertical sideways frame interval under the main polarization channel is obtained; The stable scattering point sequences in the non-vertical and vertical sideways frame intervals under the main polarization channel are sorted according to the frame sequence number to obtain the omnidirectional stable scattering point sequence of the main polarization channel.

2. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 1 is characterized in that: The normalized basis function determination module includes: A baseband transmission signal determination submodule is used to determine the baseband transmission signal according to the radar equipment parameters; The basis function determination submodule obtains the corresponding basis function set by convolving the baseband transmit signal with itself; The normalized function acquisition submodule is used to perform coherent accumulation and normalization processing on the basis function set to obtain the normalized basis function.

3. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 1 is characterized in that: The target feature extraction module includes: The target information annotation submodule is used to select the target area of ​​the range-Doppler data corresponding to each frame of measured high-speed echo data, and to annotate the target information of the selected target area; The target scattering point acquisition submodule is used to obtain all target scattering points in the range-Doppler data of the target area; The target characteristic range-Doppler data generation submodule is used to superimpose the characteristic data of all target scattering points and perform radar-target centroid distance normalization processing to obtain the target characteristic range-Doppler data of the current frame.

4. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 3 is characterized in that: In the target scattering point acquisition submodule, the following operations are performed: Obtain the scattering point with the largest amplitude in the range-Doppler data of the target area; Determine whether the amplitude of the scattering point is greater than or equal to the clutter amplitude threshold, If yes, the scattering point is extracted as a target scattering point, and the product of the amplitude of the scattering point and the normalized basis function is used as the characteristic data of the target scattering point; Update the total number of target scattering points and determine whether the total number of target scattering points is greater than or equal to the preset number of target scattering points. If yes, then end and obtain the characteristic data of all target scattering points; Otherwise, the target scattering point is removed from the range-Doppler data of the target area. updating the range-Doppler data of the target area and reacquiring the scattering point with the largest amplitude in the range-Doppler data of the target area; Otherwise, end and obtain the characteristic data of all target scattering points.

5. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 4 is characterized in that: The target characteristic range-Doppler data C of the rth frame r Expressed as: d r =rangegate+D r .fbl (4) Among them, d s is the target feature normalized distance, d r I represents the actual distance between the radar and the center of mass of the ship target corresponding to the range-Doppler data of the rth frame; j Represents the amplitude of the j-th target scattering point in the target area; the normalized basis function NBase is matrix translated. The basis of the translation is to move the point with the maximum amplitude of the normalized basis function NBase to the coordinate (a, b) of the j-th target scattering point. The moved basis function is recorded as NBase j ; rangegate represents the gate position, D r represents the range image position of the center of mass of the ship target in the rth frame of range-Doppler data, fbl represents the range resolution of the radar, and n is the total number of frames.

6. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to any one of claims 1 to 5, characterized in that: In the main polarization channel processing submodule, a stable scattering point sequence in a non-vertical sideways frame interval under the main polarization channel is obtained by performing the following operations: According to the preset number of associated segment frames, the temporally adjacent one-dimensional range images in the non-vertical side frame interval are segmented, and the one-dimensional range images of each frame in the segment are sequentially spliced ​​according to the frame sequence number to obtain a plurality of segment data; Preprocess each fragment data to obtain corresponding stable scattering point fragment data; Perform range image principal component analysis and cluster analysis on each stable scattering point segment data, and output the stable scattering point sequence and cluster center associated between frames in the corresponding segment; According to the stable scattering point sequence and cluster center of the inter-frame correlation in each segment, the inter-segment correlation is performed to obtain the stable scattering point sequence in the non-vertical side frame interval under the main polarization channel.

7. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 6 is characterized in that: In the omnidirectional stable scattering point sequence, the stable scattering point information of each stable scattering point includes: frame number, side angle, range image position, scattering point phase and scattering point amplitude.

8. The ship target omnidirectional scattering point characteristic modeling system based on multi-polarization channels according to claim 7 is characterized in that: In the other polarization channel processing submodule, the following operations are performed to obtain the omnidirectional stable scattering point sequences of other polarization channels: According to the range image position of each stable scattering point in the omnidirectional stable scattering point sequence of the main polarization channel, it is mapped to the one-dimensional range image of other polarization channels; The omnidirectional stable scattering point sequences of other polarization channels are obtained through the corresponding one-dimensional range images of other polarization channels.

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