A method and device for estimating DOA of low-orbit satellite based on phased array

Abstract

The present application provides a method and device for estimating the DOA of a low-orbit satellite based on a phased array. The method provided by the present application includes: adjusting the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix characterizes the response of the antenna unit of the phased array in multiple directions; wherein the phase weight corresponding to each channel of the antenna unit of the phased array is changed based on the multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; the steering matrix is ​​determined based on the steering vector; the steering matrix is ​​eigen-decomposed, and the DOA estimation result is determined based on the decomposition result; the motion trajectory of the low-orbit satellite is determined based on the DOA estimation result, and the DOA estimation result is updated based on the target tracking algorithm. The method and device provided by the present application are used to realize the DOA estimation of low-orbit satellites in maritime communication scenarios based on multi-beam phased arrays.

Description

Technical Field

[0001] The present application relates to the field of satellite communication technology, and in particular to a phased array-based low-orbit satellite DOA estimation method and device. Background Art

[0002] Satellite communication (SATCOM) networks have become the primary solution for achieving ubiquitous marine communications. The latest generation of low earth orbit (LEO) SATCOM systems have superior attributes such as higher throughput, lower latency, and lower cost compared to traditional geostationary orbit (GEO) SATCOM systems. Phased array terminals with reconfigurable multi-beams have potential advantages in LEO SATCOM.

[0003] In order to develop a multi-beam phased array terminal, the receiver adopts a compact variable gain phase shift and active combination scheme. However, the coupling of amplitude weighting and phase weighting will damage the accuracy in the low gain state and increase the complexity of on-chip beam table storage. At the same time, due to factors such as manufacturing errors, production inaccuracies, and non-uniform mutual coupling between antennas, the amplitude and phase between channels are inconsistent, forming a beam that deviates from the expected value. In order to solve this problem, methods for estimating the initial amplitude and phase errors when all array elements are activated have been proposed and widely used, including single-element methods and multi-element methods. However, the accuracy and practical applicability of these algorithms are still insufficient. And when the phased array is used in maritime communication scenarios, the movement of ships and satellites increases the complexity of target capture, limits the positioning accuracy of fast-moving low-orbit satellites, and the coupled movement of ships and low-orbit satellites affects the quality of the wireless link.

[0004] In recent years, research aims to combine direction of arrival (DOA) estimation methods with tracking algorithms to improve efficiency and accuracy. However, these methods have encountered challenges in maintaining real-time performance, especially in planar phased arrays. The proposed combination of sparse Bayesian learning (SBL) and state update filters is used to reduce computational complexity and achieve off-grid DOA estimation, but only focuses on one-dimensional DOA estimation scenarios. For multi-beam analog phased arrays with fully connected structures, a real-time two-dimensional DOA estimation algorithm is required. At the same time, the signal received by each array element is summed and output, and cannot be obtained separately. Therefore, we can only use a composite signal equivalent to the number of output beams for DOA estimation. This limitation makes traditional DOA estimation algorithms unusable in maritime communication scenarios. Therefore, there is an urgent need for a method to achieve DOA estimation of low-orbit satellites in maritime communication scenarios based on multi-beam phased arrays. Summary of the invention

[0005] In view of this, the present application provides a phased array-based low-orbit satellite DOA estimation method and device, which is used to realize DOA estimation of low-orbit satellites in maritime communication scenarios based on a multi-beam phased array.

[0006] Specifically, the present application is implemented through the following technical solutions:

[0007] The first aspect of the present application provides a phased array-based low-orbit satellite DOA estimation method, the method comprising:

[0008] The calibrated fully connected multi-beam phased array is adjusted based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna units of the phased array in multiple directions;

[0009] The phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector;

[0010] constructing a received signal model based on the steering matrix, performing eigendecomposition on the received signal model, and determining a DOA estimation result based on the decomposition result;

[0011] The motion trajectory of the low-orbit satellite is determined based on the DOA estimation result, and the DOA estimation result is updated based on a target tracking algorithm.

[0012] The second aspect of the present application provides a low-orbit satellite DOA estimation device based on a phased array, the device comprising: an adjustment module, a determination module and an update module; wherein,

[0013] The adjustment module is used to adjust the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna unit of the phased array in multiple directions;

[0014] The phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector;

[0015] The determination module is used to construct a received signal model based on the steering matrix, perform eigendecomposition on the received signal model, and determine the DOA estimation result based on the decomposition result;

[0016] The updating module is used to determine the motion trajectory of the low-orbit satellite based on the DOA estimation result, and to update the DOA estimation result based on a target tracking algorithm.

[0017] The DOA estimation method and device for low-orbit satellites based on phased array provided in the present application adjust the calibrated phased array based on multi-channel phase weighting to obtain a steering matrix. On the one hand, by adjusting the phase weight of the phased array, the overall beam characteristics of the phased array can be changed, and different synthetic beam outputs corresponding to the number of beams can be generated, so that DOA estimation can be achieved when the signal received by each antenna unit alone cannot be obtained. On the other hand, since the multi-channel phase weighting designs the phase weighting matrix based on the Hadamard matrix, reconstructs the array factor of each antenna unit, and significantly reduces the correlation between each output beam, it is easier to obtain the target direction information under a limited number of output beams, thereby obtaining a more accurate DOA estimation result and improving the success rate of DOA estimation. On the third hand, since the steering matrix obtained describes the response characteristics of the antenna unit based on two directional angles (pitch angle and azimuth angle), when the received signal model is subsequently constructed based on the steering matrix and the received signal model is eigen-decomposed to determine the DOA estimation result, the decomposition result also includes the estimation of the two directional angles, that is, it includes the angle information of two dimensions. Compared with the traditional DOA estimation algorithm, the present application realizes two-dimensional DOA estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flowchart of a first embodiment of a phased array-based low-orbit satellite DOA estimation method provided in this application;

[0019] Figure 2 This is a schematic diagram of the structure of a low-orbit satellite communication system at sea according to an exemplary embodiment of the present application;

[0020] Figure 3 This is a schematic diagram of the structure of a fully connected multi-beam phased array shown in an exemplary embodiment of the present application;

[0021] Figure 4 This is a structural schematic diagram of Embodiment 1 of the phased array-based low-orbit satellite DOA estimation device provided in this application. DETAILED DESCRIPTION

[0022] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0023] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0024] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0025] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0026] Figure 1 This is a flow chart of the first embodiment of the phased array based low-orbit satellite DOA estimation method provided by this application. Figure 1 , the method provided in this embodiment may include:

[0027] S101. Adjust the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna units of the phased array in multiple directions.

[0028] Specifically, a phased array refers to an antenna system composed of multiple antenna units. In a phased array, each antenna unit has a corresponding phase weight. In this application, the phased array used is a fully connected multi-beam phased array, in which each antenna unit is fully connected to multiple beamformers, which allows multiple independent beams to be formed in the same array and transmit or receive signals in different directions.

[0029] It should be noted that in the subsequent embodiments of the present application, the phased array refers to a fully connected multi-beam phased array.

[0030] Furthermore, multi-channel phase weighting refers to setting a suitable phase weight for the phase shifter in each channel of each antenna unit to control the beam direction and radiation pattern of the phased array. Multi-channel refers to the path of each antenna unit to process the signal. The steering matrix represents the phase difference of the antenna unit of the phased array in a certain direction due to the antenna arrangement distance. The steering matrix is ​​usually a complex matrix, and each element represents the phase difference of the antenna unit in a certain direction due to the antenna arrangement distance.

[0031] It should be noted that the steering matrix usually describes the response characteristics of the antenna unit based on two directional angles (elevation angle and azimuth angle). When the received signal model is subsequently constructed based on the steering matrix and the received signal model is eigendecomposed to determine the DOA estimation result, the decomposition result also includes the estimation of these two directional angles, that is, it contains angle information in two dimensions.

[0032] Optionally, the phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector.

[0033] In a specific implementation, the calibrated fully connected multi-beam phased array is adjusted based on multi-channel phase weighting to reconstruct the steering matrix, including:

[0034] (1) Determining the phase weight of the antenna unit based on relevant parameters of the phased array.

[0035] Specifically, the relevant parameters of the phased array include at least the dimension and the number of beams of the phased array.

[0036] Optionally, a phase weighting matrix is ​​constructed based on relevant parameters of the phased array; the phase weights of each output channel of the antenna unit are determined based on the phase weighting matrix; the relevant parameters include at least the number of array elements and the number of output channels of the phased array; the dimension of the phase weighting matrix is ​​the same as the number of array elements and the number of output channels of the phased array; the elements of the phase weighting matrix correspond to the phase weights of each output channel of the antenna unit.

[0037] In a specific implementation, determining the phase weight of the antenna unit based on the relevant parameters of the phased array includes:

[0038] (i) Determine the Hadamard matrix based on the dimensions of the phased array.

[0039] Specifically, the Hadamard matrix is ​​a square matrix composed of +1 and -1, which has good orthogonal properties. The dimension of the Hadamard matrix is ​​the same as the dimension of the phased array.

[0040] In specific implementation, the calibrated phased array is measured to determine its dimension. Based on the determined dimension of the phased array, a Hadamard matrix of the same dimension is constructed according to the distribution rule of the Hadamard matrix elements. For example, when the dimension of the phased array is two-dimensional, the Hadamard matrix H can be expressed as:

[0041] ,

[0042] (ii) Based on a mapping relationship, the elements in the Hadamard matrix are converted into phases to obtain a phase weighting matrix; the mapping relationship represents the corresponding relationship between the elements in the Hadamard matrix and the phases.

[0043] Specifically, the mapping relationship represents the correspondence between the elements and the phase in the Hardmard matrix. The mapping relationship is set according to actual needs, and in this embodiment, it is not limited to this. For example, in one embodiment, the mapping relationship is to map -1 in the Hardmard matrix to a phase of 180 degrees, and to map +1 in the Hardmard matrix to a phase of 0 degrees. The dimension of the phase-weighted matrix is ​​the same as the dimension of the Hardmard matrix. Combined with the above description, the dimension of the Hardmard matrix is ​​the same as the dimension of the phased array, and the dimension of the phase-weighted matrix is ​​the same as the dimension of the phased array. Furthermore, each element of the phase-weighted matrix corresponds to the response of a certain antenna unit in a specific direction.

[0044] In specific implementation, each element in the Hardmard matrix is ​​traversed, and based on the determined mapping relationship, each element in the Hardmard matrix is ​​mapped to a phase, and the mapped matrix is ​​determined as a phase weighted matrix W.

[0045] (iii) determining phase weights of antenna elements based on the phase weighting matrix.

[0046] Specifically, the phase weight of each output channel of each antenna element corresponds to an element in the phase weighting matrix. By applying these phase weights to each antenna element of the phased array, each output beam of the antenna element can be controlled and adjusted, thereby solving the DOA estimation result.

[0047] In a specific implementation, each element in the phase weighting matrix is ​​traversed, and based on the phase represented by each element, the phase weight of the antenna unit corresponding to the element is determined.

[0048] (2) Performing phase weighting on the received signal of the antenna unit based on the phase weight of the antenna unit to obtain a weighted steering vector.

[0049] Specifically, the steering vector represents the phase difference of the antenna unit in the target direction caused by the antenna arrangement distance.

[0050] In specific implementation, the phase difference of the first array element is set to 0, and the phase difference between each antenna unit and the first array element in the target direction is calculated to obtain the steering vector.

[0051] (3) Constructing a steering matrix based on the steering vector.

[0052] Specifically, in combination with the above description, the steering matrix represents the phase difference of the antenna units of the phased array in a certain direction caused by the antenna arrangement matrix.

[0053] In specific implementation, based on the number of antenna units in the phased array and the number of directions of the antenna units, the steering vectors of all antenna units in all directions are combined to obtain a steering matrix. The steering matrix can be expressed as:

[0054] ,

[0055] ,

[0056] ,

[0057] ,

[0058] Among them, the is the guiding matrix; is the pitch angle of the Lth signal; is the azimuth of the Lth signal; is the spacing between elements in a row; is the element spacing between columns; is an imaginary unit, ; The N is the number of elements in the phased array on the X-axis; the is the number of array elements of the phased array on the Y axis; is the wavelength.

[0059] Optionally, the process of establishing the calibrated fully-connected multi-beam phased array includes: measuring the received signal of the antenna under test in the fully-connected multi-beam phased array to obtain measurement data of the fully-connected multi-beam phased array; wherein the phased array is deployed in a low-orbit satellite communication system at sea, and the phased array includes a multi-beam integrated circuit; the measurement data includes at least phase and amplitude; converting the measurement data to obtain image data; wherein the image data includes data from three channels; inputting the image data into a trained calibration model to obtain a phase amplitude error; and calibrating the phased array based on the phase amplitude error to obtain a calibrated fully-connected multi-beam phased array.

[0060] Specifically, Figure 2 A schematic diagram of the structure of a maritime low-orbit satellite communication system shown as an exemplary embodiment of the present application. Figure 3 This is a schematic diagram of the structure of a fully connected multi-beam phased array shown in an exemplary embodiment of the present application. Figure 2, the fully connected multi-beam phased array is deployed in the maritime low-orbit satellite communication system, the ship-borne terminal establishes a direct connection with the low-orbit satellite, and the maritime observation point establishes a connection with the low-orbit satellite through the drone. This configuration is conducive to communication between different nodes in the network and realizes efficient data exchange and transmission between maritime and low-orbit satellites.

[0061] For further information, please refer to Figure 3 , the fully connected multi-beam phased array includes a multi-beam integrated circuit, where the left side is a plurality of antenna units, which are processed by a low noise amplifier, a phase shifter, and an attenuator in sequence, and then output to different beam ports. It supports space division duplexing with the maximum available antenna aperture. The multi-beam integrated circuit is used to process signals of multiple bands, allocate multiple beams to different areas, and control the reception or transmission of each beam by adjusting the phase and gain based on the determined direction of each beam.

[0062] It should be noted that the phased array is designed as a multi-beam integrated circuit through the fusion phase-shifting synthesis technology, which has low power consumption and small size, reduces electromagnetic coupling, reduces design complexity, realizes seamless beam switching, ensures the quality of the communication link, and improves beam control accuracy.

[0063] Furthermore, the measurement data of the fully connected multi-beam phased array includes at least phase and amplitude. The image data includes data of three channels.

[0064] In the specific implementation, the fully connected multi-beam phased array is deployed in a microwave darkroom to ensure a high signal-to-noise ratio during calibration and improve the calibration success rate. Furthermore, the measurement data of the signals received by each antenna unit of the fully connected multi-beam phased array is recorded by a vector network analyzer, and the measurement data consists of amplitude and phase. The signal vectors of all antenna units in the measurement data are combined to obtain the signal vector of the fully connected multi-beam phased array. Based on the signal conversion method, the signal vector is mapped to the three channels of RGB to obtain image data. Furthermore, the image data is input into the trained calibration model, and the calibration model outputs the phase amplitude error. The fully connected multi-beam phased array is calibrated based on the phase amplitude error to obtain a calibrated fully connected multi-beam phased array.

[0065] The method provided in this embodiment, on the one hand, calculates the phase amplitude error by using the calibration model (residual neural network), and then calibrates the fully connected multi-beam phased array, so that the calibrated fully connected multi-beam phased array can compensate for the amplitude and phase errors that may exist between antenna units, and achieve more accurate beam control. When the fully connected multi-beam phased array is applied in actual scenarios, the accuracy of the DOA estimation results of low-orbit satellites can be improved, and a more accurate calibration algorithm can be achieved. On the other hand, by converting the measurement data into visual RGB image data, the spatial relationship of the image can be used to capture the correlation between adjacent antenna units, effectively capture and analyze spatial patterns and local features, and capture more implicit phase error features, which helps to improve the calibration accuracy of the fully connected multi-beam phased array; and, because the image data can contain multiple information at the same time, it can retain and enhance important phase error features. In the case of limited measurement data, the measurement data can be maximized to capture more comprehensive radiation phase error features, thereby improving the efficiency of calibration and error analysis.

[0066] S102: construct a received signal model based on the steering matrix, perform eigendecomposition on the received signal model, and determine a DOA estimation result based on the decomposition result.

[0067] Specifically, the received signal model characterizes the association between the signal received by the antenna unit and the signal source in different directions. The DOA (Direction of Arrival) estimation result characterizes the direction between the antenna unit of the phased array and the signal source of the low-orbit satellite. Based on the steering matrix and the received signal model construction method, the received signal model is constructed. The received signal model can be expressed as:

[0068] ,

[0069] Among them, the is a received signal model; is the phase weighting matrix; is the guiding matrix; is a signal matrix; is the noise matrix; is the reconstructed steering matrix.

[0070] In a specific implementation, the feature decomposition of the received signal model is performed, and the DOA estimation result is determined based on the decomposition result, including: performing feature decomposition of the received signal model based on a multi-signal classification algorithm, and determining the spatial spectrum function based on the decomposition result; determining the peak value in the spatial spectrum function based on peak search, and determining the DOA estimation result based on the position of the peak value.

[0071] Specifically, the multiple signal classification algorithm is also called the MUSIC (Multiple Signal Classification) algorithm, which achieves accurate estimation of the arrival direction of multiple signal sources by separating the signal subspace and the noise subspace. The decomposition results include the eigenvector matrix of the signal subspace, the eigenvalue diagonal matrix of the signal subspace, the eigenvector matrix of the noise subspace, and the eigenvalue diagonal matrix of the noise subspace. The spatial spectrum function characterizes the orthogonality of the eigenvector matrix of the steering vector and the noise subspace.

[0072] In specific implementation, the received signal model is feature decomposed based on the multi-signal classification algorithm to obtain a decomposition result. A spatial spectrum function is constructed based on the eigenvector matrix of the noise subspace in the decomposition result and the reconstructed steering vector. A two-dimensional angle search is performed on the spatial spectrum function to determine a preset number (the preset number is set according to actual needs, and this is not limited in this embodiment) of peaks, and the DOA estimation result of the spatial spectrum function is obtained based on the positions of these peaks, and all the results are solved to obtain the final DOA estimation result.

[0073] S103: Determine the motion trajectory of the low-orbit satellite based on the DOA estimation result, and update the DOA estimation result based on a target tracking algorithm.

[0074] Specifically, in actual application scenarios, the high dynamic motion between the LEO satellite and the phased array will affect the beam alignment. Therefore, after determining the position of the LEO satellite, a target tracking algorithm is used to ensure that the beam pointing is continuously aligned with the LEO satellite.

[0075] In a specific implementation, the motion trajectory of the low-orbit satellite is determined based on the DOA estimation result, and the DOA estimation result is updated based on a target tracking algorithm, including: determining the position of the low-orbit satellite based on the DOA estimation result, and tracking the low-orbit satellite based on the position; during the tracking process, the state parameters of the low-orbit satellite are calculated based on the target tracking algorithm, and the DOA estimation result is updated based on the state parameters; the state parameters include at least the position of the low-orbit satellite.

[0076] Specifically, the state parameters of the low-orbit satellite include at least the position, velocity, acceleration and orbital parameters of the low-orbit satellite.

[0077] In specific implementation, the position of each antenna unit is determined based on the geometric layout of the phased array. Based on the DOA estimation results and the signal reception model, the direction information is converted into coordinate information (the actual position of the low-orbit satellite is determined by triangulation using the DOA estimation results corresponding to each antenna unit and the position of each antenna unit). Furthermore, the low-orbit satellite is tracked based on the position of the low-orbit satellite, and the state parameters of the low-orbit satellite are calculated in real time during the tracking process. The DOA estimation results are updated based on the current state parameters.

[0078] Optionally, when the target tracking algorithm is an unscented Kalman filter, the state parameters of the low-orbit satellite are collected based on the target tracking algorithm during the tracking process, and the DOA estimation result is updated based on the state parameters, including: establishing a dynamic model based on the collected state parameters of the low-orbit satellite; the dynamic model characterizes the state parameters of the low-orbit satellite at different times; based on the state parameters of the low-orbit satellite at the current time and the dynamic model, predicting the state parameters of the low-orbit satellite at the next time; adjusting the DOA estimation result of the low-orbit satellite at the next time based on the state parameters of the low-orbit satellite at the next time, and updating the DOA estimation result.

[0079] Specifically, the dynamic model is used to describe the motion state of the low-orbit satellite at different times, including position, velocity, and acceleration.

[0080] In specific implementation, a state model is established based on state parameters and a selected orbit model (such as the Kepler orbit model, the earth gravity model, etc.). The established state model can be a linear model or a nonlinear model. Furthermore, based on the state parameters of the low-orbit satellite at the current moment, the state parameters collected are input into the state model to obtain the state parameters of the low-orbit satellite at the next moment. By calculating the difference between the state parameters of the low-orbit satellite at the next moment and the DOA estimation result of the low-orbit satellite at the next moment, when the difference is greater than the preset value, the state parameters and the DOA estimation result are adjusted by the weighted average method to update the DOA estimation result.

[0081] As an optional embodiment, before the adjustment of the calibrated phased array based on multi-channel phase weighting, it includes: installing a phased array antenna to a shipborne terminal, the phased array antenna is used to communicate with a low-orbit satellite; the phased array antenna includes a multi-beam chip of the first band, and the interval time between two adjacent beams emitted by the multi-beam chip is zero; the multi-beam chip communicates with the low-orbit satellite based on multiple adjacent beams to generate a phased array; calibrating the phased array to obtain a calibrated phased array. The method provided by the present invention establishes a direct connection between a shipborne terminal composed of a multi-beam chip capable of seamless switching and a low-orbit satellite, and a maritime observation node establishes a connection with a low-orbit satellite through an unmanned aerial vehicle (UAV). This configuration is conducive to communication between different nodes in the network and realizes efficient data exchange and transmission between maritime and satellite platforms. On the other hand, since the flight time of a low-earth orbit satellite is only a few minutes, the multi-beam seamless switching operation can effectively improve the communication capacity and obtain a phased array with a large information capacity.

[0082] The method provided in this embodiment determines the motion trajectory of the low-orbit satellite based on the DOA estimation result, and updates the DOA estimation result based on the target tracking algorithm. On the one hand, by continuously updating the DOA estimation result, the position and direction of the low-orbit satellite can be corrected in real time, thereby improving the accuracy of low-orbit satellite tracking, eliminating the error caused by the coupled motion between the ship and the low-orbit satellite, and obtaining a more accurate DOA estimation result. On the other hand, the DOA estimation result directly affects the pointing direction of the beam. By updating the DOA estimation result, the beam direction of the phased array antenna unit can be accurately adjusted to achieve precise alignment of the beam with the low-orbit satellite, thereby improving the strength and quality of signal reception, which is of great significance for realizing application scenarios that require high precision.

[0083] The phased array-based low-orbit satellite DOA estimation method provided in this embodiment adjusts the calibrated phased array based on multi-channel phase weighting to reconstruct the steering matrix. On the one hand, by adjusting the phase weight of the phased array, the overall beam characteristics of the phased array can be changed, and different synthetic beam outputs corresponding to the number of beams can be generated, so that DOA estimation can be achieved when the signal received by each antenna unit alone cannot be obtained. On the other hand, since the multi-channel phase weighting designs the phase weighting matrix based on the Hadamard matrix, the array factor of each antenna unit is reconstructed, and the correlation between each output beam is significantly reduced. It is easier to obtain the target direction information under a limited number of output beams, thereby obtaining a more accurate DOA estimation result and improving the success rate of DOA estimation. On the third hand, since the steering matrix obtained describes the response characteristics of the antenna unit based on two directional angles (pitch angle and azimuth angle), when the received signal model is subsequently constructed based on the steering matrix and the received signal model is characteristically decomposed to determine the DOA estimation result, the decomposition result also includes the estimation of the two directional angles, that is, it includes the angle information of two dimensions. Compared with the traditional DOA estimation algorithm, the present application realizes two-dimensional DOA estimation. Fourthly, the motion trajectory of the low-orbit satellite is determined based on the DOA estimation results, and the DOA estimation results are updated based on the target tracking algorithm. By continuously updating the DOA estimation results, the position and direction of the low-orbit satellite can be corrected in real time, the accuracy of low-orbit satellite tracking can be improved, the error caused by the coupled motion between the ship and the low-orbit satellite can be eliminated, and a more accurate DOA estimation result can be obtained. Fifthly, the DOA estimation result directly affects the direction of the beam. By updating the DOA estimation result, the beam direction of the phased array antenna unit can be accurately adjusted to achieve precise alignment of the beam with the low-orbit satellite, improve the strength and quality of signal reception, and have great significance for realizing application scenarios that require high precision. Sixthly, the phased array is designed as a multi-beam integrated circuit through the fusion phase shift synthesis technology, which has low power consumption and small size, reduces electromagnetic coupling, reduces design complexity, realizes seamless beam switching, ensures the quality of the communication link, and improves beam control accuracy. In addition, by using the calibration model (residual neural network) to calculate the phase amplitude error and then calibrating the phased array, the calibrated phased array can compensate for the amplitude and phase errors that may exist between antenna units and achieve more precise beam control. When the phased array is applied in actual scenarios, the accuracy of the DOA estimation results of low-orbit satellites can be improved, thus achieving a more accurate calibration algorithm.Furthermore, by converting the measurement data into visual RGB image data, the spatial relationship of the image can be used to capture the correlation between adjacent antenna units, effectively capture and analyze spatial patterns and local features, and capture more implicit spatial relationships and phase error features, which helps to improve the calibration accuracy of the phased array. Furthermore, since image data can contain multiple types of information at the same time, important phase error features can be retained and enhanced. In the case of limited measurement data, the measurement data can be maximized to capture more comprehensive radiation phase error features, thereby improving the efficiency of calibration and error analysis.

[0084] Corresponding to the aforementioned embodiment of a method for estimating DOA of a low-orbit satellite based on a phased array, the present application also provides an embodiment of a device for estimating DOA of a low-orbit satellite based on a phased array.

[0085] Figure 4 This is a schematic diagram of the structure of the first embodiment of the low-orbit satellite DOA device based on phased array provided by this application. Figure 4 The device provided in this embodiment includes: an adjustment module 410, a determination module 420 and an update module 430; wherein,

[0086] The adjustment module 410 is used to adjust the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna units of the phased array in multiple directions;

[0087] The phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector;

[0088] The determination module 420 is used to construct a received signal model based on the steering matrix, perform eigendecomposition on the received signal model, and determine a DOA estimation result based on the decomposition result;

[0089] The updating module 430 is used to determine the motion trajectory of the low-orbit satellite based on the DOA estimation result, and update the DOA estimation result based on a target tracking algorithm.

[0090] The device of this embodiment can be used to perform Figure 1 The steps, specific implementation principles and implementation processes of the method embodiment shown are similar and will not be repeated here.

[0091] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0092] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0093] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A phased array based low-orbit satellite DOA estimation method, characterized in that: The method comprises: The calibrated fully connected multi-beam phased array is adjusted based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna unit of the phased array in multiple directions, and the steering matrix represents the response of the phased array to different directions by generating multiple beams, and the direction corresponding to each beam is represented by an elevation angle and an azimuth angle; The phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector; constructing a received signal model based on the steering matrix, performing eigendecomposition on the received signal model, and determining a DOA estimation result based on the decomposition result; The motion trajectory of the low-orbit satellite is determined based on the DOA estimation result, and the DOA estimation result is updated based on a target tracking algorithm.

2. The method according to claim 1, characterized in that The method of adjusting the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct the steering matrix includes: Determining the phase weight of the antenna unit based on relevant parameters of the phased array; Wherein, a phase weighting matrix is ​​constructed based on relevant parameters of the phased array; the phase weights of each output channel of the antenna unit are determined based on the phase weighting matrix; the relevant parameters include at least the number of array elements and the number of output channels of the phased array; the dimension of the phase weighting matrix is ​​the same as the number of array elements and the number of output channels of the phased array; the elements of the phase weighting matrix correspond to the phase weights of each output channel of the antenna unit; performing phase weighting on a received signal of the antenna unit based on a phase weight of the antenna unit to obtain a weighted steering vector; A steering matrix is ​​constructed based on the steering vector.

3. The method according to claim 2, characterized in that The determining the phase weight of the antenna unit based on the relevant parameters of the phased array includes: determining a Hadamard matrix based on the dimensions of the phased array; Based on a mapping relationship, the elements in the Hadamard matrix are converted into phases to obtain a phase weighting matrix; the mapping relationship represents the corresponding relationship between the elements in the Hadamard matrix and the phase; Phase weights of antenna elements are determined based on the phase weighting matrix.

4. The method according to claim 1, characterized in that Determining the motion trajectory of the low-orbit satellite based on the DOA estimation result, and updating the DOA estimation result based on a target tracking algorithm, includes: Determine a position of a low-orbit satellite based on the DOA estimation result, and track the low-orbit satellite based on the position; During the tracking process, the state parameters of the low-orbit satellite are calculated based on the target tracking algorithm, and the DOA estimation result is updated based on the state parameters; the state parameters at least include the position of the low-orbit satellite.

5. The method according to claim 4, characterized in that When the target tracking algorithm is an unscented Kalman filter, collecting the state parameters of the low-orbit satellite based on the target tracking algorithm during the tracking process, and updating the DOA estimation result based on the state parameters, includes: Establishing a dynamic model based on the collected state parameters of the low-orbit satellite; the dynamic model represents the state parameters of the low-orbit satellite at different times; Based on the state parameters of the low-orbit satellite at the current moment and the dynamic model, predicting the state parameters of the low-orbit satellite at the next moment; The DOA estimation result of the low-orbit satellite at the next moment is adjusted based on the state parameters of the low-orbit satellite at the next moment, and the DOA estimation result is updated.

6. The method according to claim 1, characterized in that The process of establishing the calibrated fully connected multi-beam phased array includes: Measuring a received signal of an antenna under test in a fully connected multi-beam phased array to obtain measurement data of the fully connected multi-beam phased array; wherein the phased array is deployed in a maritime low-orbit satellite communication system, and the phased array includes a multi-beam integrated circuit; and the measurement data includes at least phase and amplitude; Converting the measurement data to obtain image data; wherein the image data includes data of three channels; Inputting the image data into a trained calibration model to obtain a phase amplitude error; The phased array is calibrated based on the phase amplitude error to obtain a calibrated fully connected multi-beam phased array.

7. The method according to claim 6, characterized in that The multi-beam integrated circuit is used to process signals of multiple bands, allocate multiple beams to different areas, and control the reception or transmission of each beam by adjusting the phase and gain based on the determined direction of each beam.

8. The method according to claim 1, characterized in that The performing characteristic decomposition on the received signal model and determining the DOA estimation result based on the decomposition result includes: Performing feature decomposition on the received signal model based on a multi-signal classification algorithm, and determining a spatial spectrum function based on the decomposition result; A peak value in the spatial spectrum function is determined based on a peak search, and a DOA estimation result is determined based on the position of the peak value.

9. The method according to any one of claims 1 to 8, characterized in that Before adjusting the calibrated phased array based on multi-channel phase weighting, the method includes: Installing a phased array antenna on the shipboard terminal, wherein the phased array antenna is used for communication connection with a low-orbit satellite; Wherein, the phased array antenna includes a multi-beam chip of a first band, and the interval time between two adjacent beams emitted by the multi-beam chip is zero; The multi-beam chip communicates with the low-orbit satellite based on multiple adjacent beams to generate a phased array; The phased array is calibrated to obtain a calibrated phased array.

10. A low-orbit satellite DOA estimation device based on phased array, characterized in that: The device comprises: an adjustment module, a determination module and an update module; wherein, The adjustment module is used to adjust the calibrated fully connected multi-beam phased array based on multi-channel phase weighting to reconstruct a steering matrix; the steering matrix represents the response of the antenna unit of the phased array in multiple directions, and the steering matrix represents the response of the phased array to different directions by generating multiple beams, and the direction corresponding to each beam is represented by a pitch angle and an azimuth angle; The phase weight corresponding to each channel of the antenna unit of the phased array is changed based on multi-channel phase weighting, and the steering vector of the received signal in the antenna unit is reconstructed based on the phase weight; and the steering matrix is ​​determined based on the steering vector; The determination module is used to construct a received signal model based on the steering matrix, perform eigendecomposition on the received signal model, and determine the DOA estimation result based on the decomposition result; The updating module is used to determine the motion trajectory of the low-orbit satellite based on the DOA estimation result, and to update the DOA estimation result based on a target tracking algorithm.

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