A navigation signal anti-interference method, system and device based on four beams

Abstract

The present invention belongs to the field of satellite navigation signal anti-interference, and specifically relates to a navigation signal anti-interference method, system and equipment based on four beams. It aims to solve the problems of traditional anti-interference methods such as difficulty in collaboratively suppressing composite interference and performance deterioration in the presence of interference within the beam pointing range. The present invention includes: selecting four satellites and calculating signal steering vectors, processing array signals in four channels, eigendecomposing the covariance matrix of each channel, detecting mainlobe interference based on eigenvector correlation, using oblique projection preprocessing to eliminate mainlobe interference, calculating weighting vectors, generating directional beams to track satellites and switching in real time to achieve dynamic anti-interference. The present invention adopts a narrow beam mode, main beam gain desired signal, adaptive zeroing to suppress high-power suppression interference, side lobes to suppress multi-source low-power deceptive interference, and using eigenvalue oblique projection preprocessing to deal with interference within the beam pointing range. It can collaboratively suppress composite interference and adapt to complex dynamic environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite navigation signal anti-interference, and in particular relates to a navigation signal anti-interference method, system and equipment based on four beams. Background Art

[0002] Satellite navigation signals are extremely susceptible to various interferences due to their weak signal strength and transparent system. The current main types of interference include suppressive interference and deceptive interference.

[0003] Extensive research has been conducted on suppressive anti-interference methods, resulting in a multi-domain fusion technology system encompassing time, frequency, and spatial domains, as well as joint space-time and space-frequency processing. Adaptive nulling antennas, an effective spatial anti-interference method, have been widely used in military applications such as drones. This method employs an array antenna and, through power inversion or its improved algorithms, generates a beam direction that covers the entire airspace but forms a null in the direction of interference, achieving adaptive suppression of high-power suppressive interference. However, due to its wide beam pattern, its gain in the signal direction is limited.

[0004] Compared to jamming suppression, deceptive jamming achieves active misdirection through information falsification. The jamming power is relatively low, making it ineffective against traditional spatial anti-jamming techniques such as power inversion. Current deception suppression techniques can also employ spatial nulling control, but this requires the direction of the deceptive jamming signal to be known. In dynamically changing interference environments, interference must be re-estimated and nulling adjusted, making it less suitable for receivers that require real-time deception suppression.

[0005] It is also worth noting that if the interference signal comes from a direction close to the satellite, that is, when the interference source is within the beam pointing range, there will be mainlobe interference. The traditional adaptive beamforming algorithm will generate a null in the mainlobe, causing the beam pointing to shift, gain reduction, or even loss of the target signal. At the same time, the sidelobe level will increase significantly, and the output signal-to-interference-noise ratio will deteriorate, seriously affecting the receiver's receiving capability and even causing positioning failure.

[0006] In modern battlefield electromagnetic environments, suppressive and deceptive jamming often interact in a complex manner. Traditional airspace anti-suppression technologies are inadequate for suppressing low-power deceptive jamming, while deceptive jamming airspace processing methods are prone to performance degradation in the presence of strong suppressive jamming. This synergistic interference mechanism severely challenges the battlefield applicability of existing single-mode countermeasure technologies. Furthermore, in the presence of mainlobe interference, traditional adaptive beamforming technology can deform the main beam and even weaken signal reception from target satellites, further degrading positioning performance. This combined interference mechanism severely impacts positioning accuracy due to existing countermeasure technologies, necessitating the urgent need for the development of new combined interference suppression technologies.

[0007] Based on this, the present invention proposes a navigation signal anti-interference method, system and device based on four beams. Summary of the Invention

[0008] In order to solve the above-mentioned problems in the prior art, namely, the difficulty of traditional airspace anti-interference technology in collaboratively suppressing combined interference of suppression and deception, and the performance deteriorating when encountering interference within the beam pointing range, which seriously affects the receiver's receiving capability and causes positioning failure, the present invention provides a navigation signal anti-interference method, system and device based on four beams.

[0009] In a first aspect of the present invention, a navigation signal anti-interference method based on four beams is proposed, the method comprising:

[0010] Step S1, select four target satellites and perform beamforming, calculate the satellite directions of the four target satellites, and calculate the signal steering vectors of the four target satellites respectively;

[0011] Step S2: splitting the signals received by the N array elements of the array antenna into four independent channels, performing eigendecomposition on the covariance matrix of the signal of each independent channel, and extracting the interference signal eigenvector;

[0012] Step S3, calculating the correlation between the interference signal eigenvector and the signal steering vector, and judging whether there is main lobe interference in each channel based on the correlation; if so, jump to step S4; otherwise, jump to step S5;

[0013] Step S4: construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weight vector of each independent channel based on the signal steering vector in step S1, and jump to step S6;

[0014] Step S5, calculating the weighted vector of each independent channel based on the signal steering vector in step S1 and the covariance matrix in step S2, and jumping to step S6;

[0015] Step S6: weighting the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtaining the signals output by the four independent channels, and then performing capture and tracking processing on them respectively;

[0016] Step S7, determining whether to switch satellites, if yes, jumping to step S1, and repeating steps S1 to S6 to achieve real-time anti-interference.

[0017] Furthermore, the satellite direction is calculated as follows:

[0018] According to the receiver's position information, four visible satellites with elevation angles higher than a preset angle and evenly distributed azimuth angles are selected as target satellites;

[0019] The satellite directions of the four target satellites are calculated based on the undisturbed ephemeris.

[0020] Furthermore, the signal steering vector is calculated based on the spacing between adjacent array elements, the wavelength of the received signal, and the phase difference between the incident signal reaching each array element and the first array element.

[0021] Furthermore, the covariance matrix of the signal of each independent channel is eigendecomposed, the eigenvalues ​​and the eigenvectors corresponding to the eigenvalues ​​are extracted, the eigenvalues ​​are sorted from large to small, and based on the characteristic that the interference power is greater than the noise power, the eigenvectors corresponding to the first Q eigenvalues ​​are selected from the arranged eigenvalues ​​as the eigenvectors of the interference signal, and the correlation is calculated based on the Q eigenvectors and the signal-guided vector.

[0022] Furthermore, based on the correlation, it is determined whether main lobe interference exists in each channel, and the method is specifically as follows:

[0023] It is determined whether the correlation exceeds a set threshold. If so, the output is that main lobe interference exists. If not, the output is that main lobe interference does not exist and only side lobe interference exists.

[0024] Furthermore, an eigenvalue oblique projection preprocessing matrix is ​​constructed to filter out the main lobe interference, and the covariance matrix of the preprocessed signal is solved and diagonal loading is performed to eliminate matrix mismatch. The specific method is as follows:

[0025] Step S41, based on the channel determined to have main lobe interference in step S3, extracting the subspace spanned by the main lobe interference feature vector;

[0026] Step S42, combining the orthogonal complement space of the subspace spanned by the mainlobe interference eigenvector and the subspace spanned by the sidelobe interference eigenvector and the target signal steering vector to generate an oblique projection matrix;

[0027] Step S43, multiplying the oblique projection matrix with the received signal to filter out the main lobe interference component;

[0028] Step S44 , solving the covariance matrix of the signal after filtering out the main lobe interference component, and performing diagonal loading processing to eliminate the covariance matrix mismatch.

[0029] Furthermore, in step S6, after aligning the main lobe direction of the narrow beam to four satellites respectively, the method further includes: strongly suppressing the existing high-power suppression interference through adaptive zeroing, and suppressing the low-power deceptive interference through the side lobe.

[0030] Furthermore, the method for determining whether to switch satellites is as follows:

[0031] Calculate the satellite's real-time position and future trajectory based on the satellite's ephemeris information and the receiver's own position;

[0032] When the elevation angle of any target satellite is predicted to be lower than a preset threshold, it is determined that satellite switching is required, and the beam pointing is adjusted to select a new visible satellite.

[0033] In a second aspect of the present invention, a navigation signal anti-interference system based on four beams is proposed, the system comprising:

[0034] a signal steering vector calculation module, configured to select four target satellites and perform beamforming, calculate the satellite directions of the four target satellites, and respectively calculate the signal steering vectors of the four target satellites;

[0035] A branching and feature extraction module is configured to branch the signals received by the N array elements of the array antenna into four independent channels, perform feature decomposition on the covariance matrix of the signal of each independent channel, and extract the interference signal feature vector interference;

[0036] a mainlobe interference judgment module, configured to calculate the correlation between the interference signal characteristic vector and the signal steering vector, and judge whether there is mainlobe interference in each channel based on the correlation; if so, jump to the interference filtering and weighted vector calculation module; otherwise, jump to the weighted vector calculation module;

[0037] Interference filtering and weighted vector calculation module, which is configured to construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weighted vector of each independent channel in combination with the signal steering vector in the signal steering vector calculation module, and jump to the weighting and tracking module;

[0038] a weighted vector calculation module configured to calculate a weighted vector for each independent channel based on the signal-steering vector in the signal-steering vector calculation module and the covariance matrix in the branching and feature extraction module, and jump to the weighting and tracking module;

[0039] A weighting and tracking module is configured to perform weighted processing on the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtain the signals output by the four independent channels, and then perform capture and tracking processing on them separately;

[0040] The real-time monitoring module is configured to determine whether to switch satellites. If so, it jumps to the signal steering vector calculation module and repeatedly executes the signal steering vector calculation module to the weighting and tracking module to achieve real-time anti-interference.

[0041] A third aspect of the present invention provides an electronic device, comprising:

[0042] at least one processor; and

[0043] a memory communicatively connected to at least one of the processors; wherein,

[0044] The memory stores instructions that can be executed by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned four-beam-based navigation signal anti-interference method.

[0045] Beneficial effects of the present invention:

[0046] 1. Conventional power-inversion adaptive nulling antennas are primarily used for high-power suppression jamming and are not suitable for low-power, highly concealed deceptive jamming. Furthermore, due to their wide beam pattern, their directional gain is limited. The present invention utilizes a narrow beam pattern, resulting in a focused beam and high gain in the desired direction.

[0047] 2. Spatial nulling control for deceptive jamming requires the known direction of the jamming signal. For dynamically changing jamming environments, the jamming direction must be re-estimated and the nulling adjusted. The presence of sidelobes in this invention can address multiple deceptive jamming signals from all undesired directions, regardless of the desired jamming direction.

[0048] 3. In complex electromagnetic environments where deceptive interference and suppression interference coexist, traditional interference suppression methods cannot achieve simultaneous suppression. The present invention combines four-beam diversity processing with the eigenvalue oblique projection preprocessing matrix. For interference within the beam pointing range, the main lobe interference is suppressed through eigenvalue oblique projection preprocessing. Without affecting the reception of the desired signal, the interference within the beam pointing range is accurately suppressed. For interference outside the beam pointing range, the present invention strongly suppresses the existing high-power suppression interference through adaptive zeroing. At the same time, it can also well suppress low-power deceptive interference through the side lobes, thereby effectively suppressing various types of interference in non-desired directions, solving the performance limitations of traditional single anti-interference technology in complex interference scenarios, significantly improving the overall suppression efficiency of collaborative interference, and being more practical in actual scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0050] Figure 1 It is a flow chart of a navigation signal anti-interference method based on four beams of the present invention;

[0051] Figure 2This is a four-beam forming principle diagram of a four-beam navigation signal anti-interference method based on the present invention;

[0052] Figure 3 The beam pattern of the power inversion anti-interference antenna in the present invention;

[0053] Figure 4 is the beam pattern of the adaptive beamforming anti-interference antenna in the present invention;

[0054] Figure 5 It is a beam pattern formed by a channel aligned with one of the satellites in the navigation signal anti-interference method based on four beams of the present invention when interference exists. DETAILED DESCRIPTION

[0055] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0056] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0057] A first embodiment of the present invention provides a navigation signal anti-interference method based on four beams, the method comprising:

[0058] Step S1, select four target satellites and perform beamforming, calculate the satellite directions of the four target satellites, and calculate the signal steering vectors of the four target satellites respectively;

[0059] Step S2: splitting the signals received by the N array elements of the array antenna into four independent channels, performing eigendecomposition on the covariance matrix of the signal of each independent channel, and extracting the interference signal eigenvector;

[0060] Step S3, calculating the correlation between the interference signal eigenvector and the signal steering vector, and judging whether there is main lobe interference in each channel based on the correlation; if so, jump to step S4; otherwise, jump to step S5;

[0061] Step S4: construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weight vector of each independent channel based on the signal steering vector in step S1, and jump to step S6;

[0062] Step S5, calculating the weighted vector of each independent channel based on the signal steering vector in step S1 and the covariance matrix in step S2, and jumping to step S6;

[0063] Step S6: weighting the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtaining the signals output by the four independent channels, and then performing capture and tracking processing on them respectively;

[0064] Step S7, determining whether to switch satellites, if yes, jumping to step S1, and repeating steps S1 to S6 to achieve real-time anti-interference.

[0065] The present invention is based on an antenna array and a beamforming algorithm. Through precise beam control technology, four narrow beam main lobes can be respectively aimed at four different satellites, which is equivalent to establishing four relatively independent receiving links. Since the formed beam is very narrow, a natural filtering mechanism is formed in space. For the narrow beam aimed at the satellite, it has a high gain in the desired satellite communication direction. When the interference source is outside the beam pointing range, the existing high-power suppression interference is strongly suppressed by adaptive zeroing. At the same time, the low-power deceptive interference can also be well suppressed by the side lobes, thereby effectively suppressing various types of interference in the undesired direction. When the interference signal comes from the direction close to the satellite, the interference source is within the beam pointing range and there is main lobe interference. By constructing an eigenvalue oblique projection preprocessing matrix to filter out the main lobe interference, the main lobe interference and the impact on the target satellite signal are effectively suppressed.

[0066] The four-beam design employed in this invention is the minimum requirement for accurate positioning. If the mainlobe directions of multiple satellites are interfered with, the receiver may not be able to obtain sufficient valid satellites, resulting in positioning interruption. To ensure effective receiver performance, research on mainlobe interference resistance is essential.

[0067] In order to more clearly illustrate the navigation signal anti-interference method based on four beams of the present invention, the following is combined with Figure 1-Figure 5 Each step in the embodiment of the present invention is described in detail.

[0068] A navigation signal anti-interference method based on four beams according to a first embodiment of the present invention includes steps S1 to S6, each of which is described in detail as follows:

[0069] Step S1, select four target satellites and perform beamforming, calculate the satellite directions of the four target satellites, and calculate the signal steering vectors of the four target satellites respectively;

[0070] In this embodiment, four visible satellites with elevation angles higher than a preset angle and uniform azimuth distribution are selected as target satellites based on the receiver position information;

[0071] Calculate the satellite directions of the four target satellites based on the undisturbed ephemeris , , Indicates the number of satellites. The four-beam design is directly related to the minimum positioning requirements of the navigation system. Selecting four visible satellites ensures that the receiver can maintain basic positioning capabilities in interference environments, reduces the risk of multipath interference and signal conflicts, and simplifies the complexity of beam management, avoiding the waste of hardware resources and the surge in algorithm computation caused by too many beams.

[0072] In this embodiment, the real-time azimuth and elevation of the satellite are calculated using a satellite orbit model (such as the Kepler equation) based on the orbital parameters in the ephemeris (such as the satellite orbit inclination, right ascension of the ascending node, and average angular velocity), combined with the receiver's geographic location and timestamp.

[0073] The satellite's direction vector in space is determined using a coordinate transformation (e.g., geocentric to receiver local coordinates).

[0074] In this embodiment, the signal steering vector is calculated based on the spacing between adjacent array elements, the wavelength of the received signal, and the phase difference between the incident signal reaching each array element and the first array element. Specifically:

[0075] Calculate the satellite signal steering vector based on the satellite direction For an antenna array with a fixed array element distribution, the position of reference element 1 is taken as the origin, and the position coordinates of the nth array element are , , when the antenna array receives the incoming When the satellite signal is received, the steering vector of the formed beam aimed at the target satellite is:

[0076] ;

[0077] in, is the path difference between the received signal of the nth array element and the reference array element, and its analytical expression is:

[0078] ;

[0079] Where c is the speed of light, is the signal center frequency.

[0080] See also Figure 2 , step S2, splitting the signals received by the N array elements of the array antenna into four independent channels, performing eigendecomposition on the covariance matrix of the signal of each independent channel, and extracting the interference signal eigenvector;

[0081] In this embodiment, the signal after branching is expressed as: ,in To receive a signal in the Mth channel, The signal received by the nth array element in each channel is expressed as: . Wherein, the nth array element receives the signal in the Mth channel.

[0082] Step S2: splitting the signals received by the N array elements of the array antenna into four independent channels, performing eigendecomposition on the covariance matrix of the signal of each independent channel, and extracting the interference signal eigenvector;

[0083] Solve the sampling covariance matrix of the four received signals when the number of snapshots is K respectively Then perform eigendecomposition on the covariance matrix of the four received signals: .in, and Represents the first order of the sampling covariance matrix of the received signal in each channel eigenvalues ​​and eigenvectors, are N eigenvalues ​​arranged in descending order, is the eigenvector corresponding to the eigenvalue.

[0084] In this embodiment, the covariance matrix of the signal of each independent channel is eigendecomposed, the eigenvalues ​​and the eigenvectors corresponding to the eigenvalues ​​are extracted, and the eigenvalues ​​are sorted from large to small. Based on the characteristic that the interference power is greater than the noise power, the eigenvectors corresponding to the first Q eigenvalues ​​are selected from the arranged eigenvalues ​​as the eigenvectors of the interference signal, and the correlation is calculated based on the Q eigenvectors and the signal steering vector. Specifically:

[0085] Since the interference power is greater than the noise power, the diagonal matrix composed of Q large eigenvalues Represents the eigenvalue matrix of the interference signal, which corresponds to is the subspace spanned by the interference signal. The remaining eigenvalues ​​constitute the eigenvalue matrix of the noise , and its corresponding noise subspace is: .

[0086] The Q in this embodiment is estimated based on the AIC criterion. Specifically:

[0087] Construct the AIC curve: ,in is the parameter vector containing interference feature information, is the number of possible interferences. The first term in the formula represents the deviation between the constructed model and the true distribution, and the second term is the penalty function added to prevent overestimation. The smaller the AIC value, the higher the degree of fit of the model. Therefore, exist Optimize within the range, and the formula value is the smallest The value is an estimate of the number of large eigenvalues: .

[0088] Step S3, calculating the correlation between the interference signal eigenvector and the signal steering vector, and judging whether there is main lobe interference in each channel based on the correlation; if so, jump to step S4; otherwise, jump to step S5;

[0089] In this embodiment, based on the correlation, it is determined whether there is main lobe interference in each channel. The specific method is as follows:

[0090] It is determined whether the correlation exceeds a set threshold. If so, the output is that main lobe interference exists. If not, the output is that main lobe interference does not exist and only side lobe interference exists.

[0091] The correlation , which is calculated as follows:

[0092] Since the main lobe interference is closest to the target satellite , so the characteristic vector of the main lobe interference is highly correlated with the target satellite steering vector. It means to find the second norm of the correlation vector.

[0093] Each channel is judged separately, and the characteristic vectors corresponding to the Q large eigenvalues ​​obtained in step S2 are correlated with the steering vector of the target satellite obtained in step S1. If the correlation value between them is higher than the set threshold (the threshold is set at 0.9), it indicates that the channel has main lobe interference, and the characteristic vector at this time is the characteristic vector of the main lobe interference. If it is lower than the set threshold, it indicates that only sidelobe interference exists in the channel.

[0094] Step S4: construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weight vector of each independent channel based on the signal steering vector in step S1, and jump to step S6;

[0095] In this embodiment, an eigenvalue oblique projection preprocessing matrix is ​​constructed to filter out main lobe interference, and the covariance matrix is ​​solved and diagonal loading is performed on the preprocessed signal to eliminate matrix mismatch. The specific method is as follows:

[0096] Step S41: based on the channel determined to have main lobe interference in step S3, extract the subspace spanned by the main lobe interference feature vector. ,in , P represents the number of main lobe interferences.

[0097] Step S42, generating an oblique projection matrix by combining the orthogonal complement space of the subspace spanned by the mainlobe interference eigenvector and the subspace spanned by the sidelobe interference eigenvector and the target signal steering vector;

[0098] The subspace spanned by the sidelobe interference eigenvector and the target signal steering vector is: ;

[0099] in, Represents the subspace spanned by the sidelobe interference, generating the oblique projection matrix ;

[0100] Among them, the orthogonal complement space of the main lobe interference subspace can be expressed as: , H is the conjugate transpose.

[0101] Oblique projection matrix .

[0102] Since the calculation process of constructing the above-mentioned eigenvalue oblique projection preprocessing matrix relies on operations such as matrix inversion, the computational complexity is relatively high. Therefore, an iterative algorithm is used to gradually approximate the exact solution, which can reduce the computational complexity of the oblique projection operator and improve the running speed of the algorithm, making it more suitable for systems with high real-time requirements.

[0103] Among them, we can also introduce super-relaxation iteration to gradually iteratively approximate the exact value of the inverse matrix to more efficiently calculate the oblique projection matrix. Specifically:

[0104] Super-relaxation iterative method for solving linear equations , and its iterative formula is .in, , D is a diagonal matrix consisting of the diagonal elements of A; L is the matrix obtained by taking the negation of the strictly lower triangular part of A; U is the matrix obtained by taking the negation of the strictly upper triangular part of A; is the relaxation factor.

[0105] Assumptions , , which is considered as the coefficient matrix in the super-relaxation iterative method , ,right , Decompose, that is , , solving the inverse matrix is ​​equivalent to solving the linear equations ,but The iterative calculation can be expressed as: ,in for No. k The approximate value of the iterations, Iis the identity matrix. The iterative calculation of can be obtained in the same way.

[0106] Step S43: multiply the oblique projection matrix by the received signal to filter out the main lobe interference component:

[0107] ,in, It is the signal after filtering out the main lobe interference component.

[0108] Step S44, solving the covariance matrix of the signal after filtering out the main lobe interference component, and performing diagonal loading processing to eliminate the covariance matrix mismatch:

[0109] The sampling covariance matrix of the signal after oblique projection preprocessing in the channel with main lobe interference is solved again: , and then perform diagonal loading on the preprocessed covariance matrix to eliminate the covariance matrix mismatch: , is the loading amount for diagonal loading treatment, is the identity matrix.

[0110] The weight vectors for each beamforming are designed as: , design four different weight vectors for the four channels .

[0111] Step S5, calculating the weighted vector of each independent channel based on the signal steering vector in step S1 and the covariance matrix in step S2, and jumping to step S6;

[0112] Using the steering vector obtained in step S1, the weight vectors for each beamforming path are designed: ;

[0113] in, Represents the correlation matrix The inverse matrix of . Design four different weights for the four channels The weight coefficient of the nth array element in each channel is expressed as: .in The weight coefficient set for the nth array element in the Mth channel.

[0114] See also Figure 2 In step S6, the signals of the four independent channels are weighted based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites to obtain the signals output by the four independent channels, and then the signals are captured and tracked separately. After the main lobe directions of the narrow beams are respectively aimed at the four satellites, the method further includes: strongly suppressing the existing high-power suppression interference through adaptive zeroing, and suppressing low-power deceptive interference through side lobes.

[0115] The received signals after the branching in step S2 are weighted and processed respectively. The processed signals are expressed as follows: .

[0116] The narrow beam mentioned in the present invention is in contrast to the wide beam generated by the traditional power inversion type adaptive nulling antenna. This beam usually does not have a clear main lobe, and the energy may be dispersed in multiple directions, showing the overall characteristics of a wide beam. Therefore, compared with the wide beam formed in this way, the beam generated by the present invention can be regarded as a narrow beam. Taking a uniform linear array as an example, the number of array elements is N, the array element spacing is d, and the desired signal direction is , the half-power main beamwidth is expressed as: , the maximum sidelobe gain of the uniform linear array is less than -13dB. At this time, the half-power main beam width of the beam is less than or equal to , a uniform linear array can be defined as a narrow beam if its maximum sidelobe gain is no higher than -13dB.

[0117] Step S7, determining whether to switch satellites, if yes, jumping to step S1, and repeating steps S1 to S6 to achieve real-time anti-interference.

[0118] In this embodiment, the method for determining whether to switch satellites is as follows:

[0119] Calculate the satellite's real-time position and future trajectory based on the satellite's ephemeris information and the receiver's own position;

[0120] When the elevation angle of any target satellite is predicted to be lower than a preset threshold, it is determined that satellite switching is required, and the beam pointing is adjusted to select a new visible satellite.

[0121] Because satellite directions are constantly changing, the receiver calculates the satellite's real-time position and future trajectory based on the satellite's ephemeris information and the receiver's own position. It then predicts when the satellite's elevation angle will fall below a preset threshold to determine if the satellite is passing. If so, it's necessary to switch satellites and adjust the beam pointing.

[0122] like Figure 3-5 As shown, Figure 3 It realizes adaptive suppression of high-power interference. Due to its wide beam mode, the gain in the signal direction is limited. Figure 4 When mainlobe interference exists, the traditional adaptive beamforming algorithm will generate a null in the mainlobe, causing the beam pointing to shift, the gain to decrease, or even the loss of the target signal. At the same time, the sidelobe level will increase significantly. At this time, the output signal-to-interference-and-noise ratio will deteriorate, seriously affecting the receiver's receiving capability and even causing positioning failure.

[0123] and Figure 3 and Figure 4 compared to, Figure 5 It is a beam pattern formed by a channel aligned with one of the satellites in the navigation signal anti-interference method based on four beams of the present invention when interference exists, Figure 5 It can be seen that this method is able to generate a deep null in the direction of the interference while keeping the main lobe aligned with the direction of the desired signal. Figure 4 The traditional adaptive beamforming algorithm avoids the main beam offset caused by main lobe interference, resulting in reduced gain, increased sidelobe levels, and a deterioration in the output signal-to-interference-noise ratio, ensuring efficient reception of target signals. The four-beam design achieves high-gain directional reception through multi-beam joint optimization. It provides wider spatial coverage and can dynamically adapt to complex electromagnetic environments, making it particularly suitable for collaborative suppression of multiple interference sources in multi-satellite navigation scenarios.

[0124] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0125] A second embodiment of the present invention provides a navigation signal anti-interference system based on four beams and a navigation signal anti-interference method based on four beams. The system includes:

[0126] a signal steering vector calculation module, configured to select four target satellites and perform beamforming, calculate the satellite directions of the four target satellites, and respectively calculate the signal steering vectors of the four target satellites;

[0127] A branching and feature extraction module is configured to branch the signals received by the N array elements of the array antenna into four independent channels, perform feature decomposition on the covariance matrix of the signal of each independent channel, and extract the interference signal feature vector;

[0128] a mainlobe interference judgment module, configured to calculate the correlation between the interference signal characteristic vector and the signal steering vector, and judge whether there is mainlobe interference in each channel based on the correlation; if so, jump to the interference filtering and weighted vector calculation module; otherwise, jump to the weighted vector calculation module;

[0129] Interference filtering and weighted vector calculation module, which is configured to construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weighted vector of each independent channel in combination with the signal steering vector in the signal steering vector calculation module, and jump to the weighting and tracking module;

[0130] a weighted vector calculation module configured to calculate a weighted vector for each independent channel based on the signal-steering vector in the signal-steering vector calculation module and the covariance matrix in the branching and feature extraction module, and jump to the weighting and tracking module;

[0131] A weighting and tracking module is configured to perform weighted processing on the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtain the signals output by the four independent channels, and then perform capture and tracking processing on them separately;

[0132] The real-time monitoring module is configured to determine whether to switch satellites. If so, it jumps to the signal steering vector calculation module and repeatedly executes the signal steering vector calculation module to the weighting and tracking module to achieve real-time anti-interference.

[0133] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the system described above can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0134] It should be noted that the four-beam navigation signal anti-interference system provided in the above embodiment is only illustrated by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be combined into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the modules or steps and are not regarded as improper limitations on the present invention.

[0135] An electronic device according to a third embodiment of the present invention includes:

[0136] at least one processor; and

[0137] a memory communicatively connected to at least one of the processors; wherein,

[0138] The memory stores instructions that can be executed by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned four-beam-based navigation signal anti-interference method.

[0139] A computer-readable storage medium according to a fourth embodiment of the present invention stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned four-beam-based navigation signal anti-interference method.

[0140] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes and related instructions of the storage device and processing device described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0141] Those skilled in the art should be able to appreciate that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two, and the programs corresponding to the software modules and method steps can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. In order to clearly illustrate the interchangeability of electronic hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0142] The terms "first", "second", etc. are used to distinguish similar objects, rather than to describe or indicate a particular order or sequence.

[0143] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0144] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A navigation signal anti-interference method based on four beams, characterized in that: The method includes: Step S1, select four target satellites and perform beam control, calculate the satellite directions of the four target satellites, and calculate the signal steering vectors of the four target satellites respectively; Step S2: splitting the signals received by the N array elements of the array antenna into four independent channels, performing eigendecomposition on the covariance matrix of the signal of each independent channel, and extracting the interference signal eigenvector; Step S3, calculating the correlation between the interference signal eigenvector and the signal steering vector, and judging whether there is main lobe interference in each channel based on the correlation; if so, jump to step S4; otherwise, jump to step S5; Step S4: construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weight vector of each independent channel based on the signal steering vector in step S1, and jump to step S6; Step S5, calculating the weighted vector of each independent channel based on the signal steering vector in step S1 and the covariance matrix in step S2, and jumping to step S6; Step S6: weighting the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtaining the signals output by the four independent channels, and then performing capture and tracking processing on them respectively; Step S7, determining whether to switch satellites, if yes, jumping to step S1, and repeating steps S1 to S6 to achieve real-time anti-interference.

2. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: The satellite direction is calculated as follows: According to the receiver's position information, four visible satellites with elevation angles higher than a preset angle and evenly distributed azimuth angles are selected as target satellites; The satellite directions of the four target satellites are calculated based on the undisturbed ephemeris.

3. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: The signal steering vector is calculated based on the spacing between adjacent array elements, the wavelength of the received signal, and the phase difference between the incident signal arriving at each array element and the first array element.

4. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: The covariance matrix of the signal of each independent channel is subjected to eigendecomposition, and the eigenvalues ​​and the eigenvectors corresponding to the eigenvalues ​​are extracted. The eigenvalues ​​are sorted from large to small. Based on the characteristic that the interference power is greater than the noise power, the eigenvectors corresponding to the first Q eigenvalues ​​are selected from the arranged eigenvalues ​​as the eigenvectors of the interference signal, and the correlation is calculated based on the Q eigenvectors and the signal-guided vector.

5. The navigation signal anti-interference method based on four beams according to claim 4, characterized in that: Based on the correlation, it is determined whether there is main lobe interference in each channel. The specific method is as follows: It is determined whether the correlation exceeds a set threshold. If so, the output is that main lobe interference exists. If not, the output is that main lobe interference does not exist and only side lobe interference exists.

6. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: The eigenvalue oblique projection preprocessing matrix is ​​constructed to filter out the main lobe interference, and the covariance matrix of the preprocessed signal is solved and the diagonal loading process is performed to eliminate the matrix mismatch. The specific method is as follows: Step S41, based on the channel determined to have main lobe interference in step S3, extracting the subspace spanned by the main lobe interference feature vector; Step S42, combining the orthogonal complement space of the subspace spanned by the mainlobe interference eigenvector and the subspace spanned by the sidelobe interference eigenvector and the target signal steering vector to generate an oblique projection matrix; Step S43, multiplying the oblique projection matrix with the received signal to filter out the main lobe interference component; Step S44 , solving the covariance matrix of the signal after filtering out the main lobe interference component, and performing diagonal loading processing to eliminate the covariance matrix mismatch.

7. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: In step S6, after the main lobe direction of the narrow beam is respectively directed toward four satellites, the method further includes: strongly suppressing the existing high-power suppression interference through adaptive nulling, and suppressing the low-power deceptive interference through the side lobe.

8. The navigation signal anti-interference method based on four beams according to claim 1, characterized in that: To determine whether to switch satellites, the method is: Calculate the satellite's real-time position and future trajectory based on the satellite's ephemeris information and the receiver's own position; When the elevation angle of any target satellite is predicted to be lower than a preset threshold, it is determined that satellite switching is required, and the beam pointing is adjusted to select a new visible satellite.

9. A navigation signal anti-interference system based on four beams, based on the navigation signal anti-interference method based on four beams according to any one of claims 1 to 8, characterized in that: The system includes: a signal steering vector calculation module configured to select four target satellites and perform beam steering, calculate the satellite directions of the four target satellites, and respectively calculate the signal steering vectors of the four target satellites; A branching and feature extraction module is configured to branch the signals received by the N array elements of the array antenna into four independent channels, perform feature decomposition on the covariance matrix of the signal of each independent channel, and extract the interference signal feature vector; a mainlobe interference judgment module, configured to calculate the correlation between the interference signal characteristic vector and the signal steering vector, and judge whether there is mainlobe interference in each channel based on the correlation; if so, jump to the interference filtering and weighted vector calculation module; otherwise, jump to the weighted vector calculation module; Interference filtering and weighted vector calculation module, which is configured to construct an eigenvalue oblique projection preprocessing matrix to filter out mainlobe interference, solve the covariance matrix of the preprocessed signal and perform diagonal loading processing to eliminate matrix mismatch, calculate the weighted vector of each independent channel in combination with the signal steering vector in the signal steering vector calculation module, and jump to the weighting and tracking module; a weighted vector calculation module configured to calculate a weighted vector for each independent channel based on the signal-steering vector in the signal-steering vector calculation module and the covariance matrix in the branching and feature extraction module, and jump to the weighting and tracking module; A weighting and tracking module is configured to perform weighted processing on the signals of the four independent channels based on the weighting vector to form four independent narrow beams, which are respectively aimed at the four target satellites, obtain the signals output by the four independent channels, and then perform capture and tracking processing on them separately; The real-time monitoring module is configured to determine whether to switch satellites. If so, it jumps to the signal steering vector calculation module and repeatedly executes the signal steering vector calculation module to the weighting and tracking module to achieve real-time anti-interference.

10. An electronic device, characterized in that: include: at least one processor; as well as a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions that can be executed by the processor, and the instructions are used to be executed by the processor to implement the four-beam navigation signal anti-interference method according to any one of claims 1-8.

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