A radar networking anti-main lobe interference method and system based on JBSS

Abstract

The present application relates to the radar networking system anti main lobe suppression type interference technical field, specifically relates to a kind of radar networking anti main lobe interference method and system based on JBSS, echo signal received by each radar receiving station is transmitted to information fusion center, respectively with the received signal of each radar station as benchmark, the radar receiving signal of remaining each station is carried out delay estimation and compensation, complete time domain alignment, based on JBSS algorithm processing mode is carried out target signal and interference signal separation to the signal after time domain alignment, obtain separation signal, after separation signal is compressed, target channel accumulation, constant false alarm detection, obtain with each radar station as benchmark, after target signal main lobe interference suppression, target radial distance measurement information is obtained.Finally, through multi-station joint positioning, the real target space position is determined.The main lobe suppression interference effect of this method is strong, and target positioning precision is high.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of radar networking system anti-main lobe suppression jamming, and particularly relates to a radar networking anti-main lobe jamming method and system based on JBSS. BACKGROUND

[0002] In recent years, the anti-main lobe jamming method has become a difficult and hot problem in radar anti-jamming technology. The high-power suppression jamming and the Smeared Spectrum (SMSP) and Chopping & Interleaving (C&I) dense false target jamming enter the radar receiving opportunity from the main lobe of the antenna pattern, so that the radar target detection is seriously affected. The traditional suppression jamming suppression methods of a single radar, such as sidelobe cancellation and sidelobe concealment, are all invalid. At present, most of the main lobe suppression jamming suppression methods of a single station radar can only resist fixed types of jamming, and the anti-jamming performance deteriorates or even fails after the jamming parameters change or the jamming type changes. The anti-main lobe suppression jamming method of a multi-station radar system needs prior information such as the jamming angle and the jamming type or requires that the jamming power be much greater than the target echo power.

[0003] The blind source separation (BSS) method has also been used in the anti-jamming processing of radar systems in recent years, and its advantage is that prior information such as the angle and type of interference does not need to be known in advance. At present, the anti-main lobe suppression interference method based on BSS is mostly based on the joint approximation diagonalization of eigen matrices (JADE), which requires prior information such as the number of signal sources to be obtained in advance, and also needs to calculate high-order statistics, which requires a relatively high computing power of the running equipment. At present, Xiaofei Han, Huafeng He, Qi Zhang, Lihao Yang, Yaomin He and Zhen Li. et al. published the article Main-lobe jamming suppression method for phased array netted radar based on MSNR-BSS[J] in the journal IEEE Sensors Journal, 2022, 22(23): 22972-22984, which points out that each radar in the netted system separately completes the BSS processing of the received signal, pulse compression, target detection, and then multi-station fusion is performed on the target radial distance obtained by each radar to determine the target position. The method in this article is essentially a data-level fusion processing of the target radial distance after radar signal processing. Data-level fusion does not directly process the received signals of each station radar in the radar netted system, and the information loss is large, and the anti-jamming capability is limited. In addition, the MSNR-BSS method in this article has the problem of poor signal separation effect or even failure when the number of signal sources is greater than the number of observed signal channels. SUMMARY

[0004] The application provides a radar netting anti-main lobe interference method and system based on JBSS, which aims to solve the problem of poor anti-main lobe interference effect or even failure caused by the traditional BSS method when the number of signal sources is greater than the number of signal channels.

[0005] The purpose of the application is achieved by the following technical solutions:

[0006] A radar netting anti-main lobe interference method based on JBSS, comprising:

[0007] The echo signals received by each radar receiving station are transmitted to the information fusion center, and the radar receiving signals of the remaining receiving stations are delayed and compensated based on the received signals of each radar station, and time domain alignment is completed.

[0008] The JBSS algorithm-based processing method separates the target signal and interference signal from the time-domain aligned signal to obtain a separated signal, which includes the target signal.

[0009] After pulse compression, channel accumulation, and constant false alarm rate detection, the separated signal is used to obtain the target radial distance measurement information after the main lobe interference of the target signal is suppressed, with each radar station as the reference.

[0010] As a further improvement of the present invention, the calculation expression for the radar received signal of each receiving station is as follows:

[0011]

[0012] in, This indicates the transpose operation. Let be the received signal of the Lth element in the k-th radar, and t be the time variable. The expression for calculating the received signal of the element is:

[0013]

[0014] In the formula, Let be the amplitude of the target echo signal; exp{} is the exponential function; Indicates radar transmission signal; , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target; Indicates the first p The interference source to the first k The distance to the radar; Indicates the speed of electromagnetic wave propagation; Wavelength; The distance between array elements; l Indicates the current array element; Let be the direction of the arrival angle of the k-th radar reaching the target; For the first k The direction of the arrival angle of the radar signal interfering with the signal; With a mean of 0 and a variance of Complex Gaussian white noise, j Let M be the imaginary part, and M be the total number of targets. Let P be the amplitude of the interference signal, and P be the total number of interference signals. Indicates interference signal. T m For the target signal period, J p For the period of the interference signal, The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. The phase of the target echo signal obtained after quadrature demodulation. The phase difference caused by the target echo signal reaching different array elements of the k-th radar. The sum of the interference signals received after the interference signal returns to the k-th radar. The phase is obtained by orthogonal demodulation of the interference signal. The phase caused by the interference signal being transmitted to different array elements of the k-th radar.

[0015] As a further improvement of the present invention, the expression for calculating the time-domain aligned signal is as follows:

[0016]

[0017] in, The target echo signal vector after time delay compensation. For interference signal vectors, The noise vector is the target echo signal vector, and the target echo signal vector is:

[0018]

[0019] The interference signal vector is:

[0020]

[0021] In the formula, The amplitude of the target echo signal, Indicates radar transmission signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target For wavelength, The distance between array elements. - For the first radar to the first K Each radar unit was positioned in the direction of the target's angle of arrival. The amplitude of the interference signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first p The distance to the interference source, - Let M be the angle of arrival of the jamming signal from radars 1 through K, respectively, and let c be the electromagnetic wave propagation speed. l Where P is the current array element and P is the total number of interference signals. T m For the target signal period, J p For the period of the interference signal, - The transmissions were transmitted from the first radar station to the second radar station. K The received signal delay difference, where t is a time variable and K is the total number of radar stations, K≥2. The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. The phase of the target echo signal obtained after quadrature demodulation. The phase difference caused by the target echo signal reaching different array elements of the k-th radar. The sum of the interference signals received after the interference signal returns to the k-th radar. The phase is obtained by orthogonal demodulation of the interference signal. The phase caused by the interference signal transmitted to different array elements of the k-th radar. The sum of the interference signals received after the delayed interference signal returns to the k-th radar is given. This is the sum of the received signals from the target echo signal returned to the k-th radar after time delay compensation.

[0022] As a further improvement of the present invention, the expression for calculating the signal after delay compensation is as follows:

[0023]

[0024] in, This indicates the transpose operation. Let be the delay-compensated signal corresponding to the i-th radar station, with dimension . , Where K is the number of snapshots, L is the total number of radar stations, and L is the total number of array elements. For the first i Radar station transmits to the first k The signal delay difference received by the radar station satisfies:

[0025]

[0026] In the formula, To find the function that maximizes the signal delay difference, For Kronecker product, Let be the adjoint matrix of the signal corresponding to the k-th radar station after time compensation, where t is the time variable.

[0027] As a further improvement of the present invention, after completing the time-domain alignment, the method further includes a preprocessing step for the time-domain aligned signal. The preprocessing includes zero-meaning and whitening. The zero-meaning is used to remove the DC component from the signal, and the whitening is used to decorrelate the signal. The expression for calculating the whitened signal is as follows:

[0028]

[0029] wherein, is the whitened signal, is the whitening matrix, is the time-delay compensated signal corresponding to the kth radar station, and the whitening matrix is:

[0030]

[0031] wherein, is the conjugate transpose, is a diagonal matrix composed of eigenvalues, is an eigenmatrix, is the conjugate transpose of the eigenmatrix B, and the eigenmatrix B satisfies the relationship: wherein B satisfies:

[0032]

[0033] wherein, is the conjugate transpose of the time-delay compensated signal corresponding to the kth radar station, and E is an identity matrix.

[0034] As a further improvement of the present application, the time-domain aligned signal is separated into target signals and interference signals based on the JBSS algorithm, comprising:

[0035] a signal-to-noise ratio function is constructed, a separation matrix is calculated according to the signal-to-noise ratio function, and a separation signal is obtained based on the separation matrix, and the calculation expression of the signal-to-noise ratio function is:

[0036]

[0037] wherein,

[0038] is the separation signal, which is defined as , is the signal after sliding average, which is defined as , W is the separation matrix, is the preprocessed received signal, is the signal after sliding average based on the received signal, is the transpose of the separation matrix, is the transpose of the signal after sliding average, is the transpose of the preprocessed received signal, and the separation matrix satisfies:

[0039]

[0040] wherein, the separation signal calculation expression is:

[0041]

[0042] C is a first matrix, ; a second matrix, ; V is a third matrix, ; U is a fourth matrix, .

[0043] As a further improvement of the present application, the calculation expression of pulse compression of the separated signals is:

[0044]

[0045] wherein, is the compressed signal, is the first k part of the pulse compressed signal of the first l channel, is the radar linear frequency modulation signal, t is the time variable, and T is the signal period, is the integral calculation symbol.

[0046] As a further improvement of the present application, the constant false alarm detection mode is: detecting each channel of the pulse compressed separated signals, accumulating the channels in which the target signal is detected, and performing constant false alarm probability detection on the accumulated target signal to obtain the target radial distance measurement value.

[0047] As a further improvement of the present application, after obtaining the target radial distance measurement information after the target signal main lobe interference suppression based on each radar station, the method further comprises using the obtained target radial distance to perform multi-station joint positioning, using the target radial distance values of the multi-stations to perform joint positioning by using the three-ball positioning principle to determine the spatial information of the target.

[0048] The present method further provides a JBSS-based radar networking anti-main lobe interference system, comprising:

[0049] a data acquisition module, the data acquisition module being configured to acquire the received signals corresponding to each radar receiving station;

[0050] a data processing module, the data processing module being configured to process the received signals corresponding to each radar receiving station to implement the JBSS-based radar networking anti-main lobe interference method as described above.

[0051] The beneficial effects of the present application are that: the radar networking anti-main lobe interference method based on JBSS of the present application, through signal level fusion processing of the received signals of all radar stations in the networking system in the same fusion center, delay estimation and compensation of the radar received signals of the remaining radar receiving stations are carried out based on the received signals of each radar station, time domain alignment is completed, and then the signals after time domain alignment are processed by the joint blind source separation JBSS algorithm to separate the target signals and interference signals, so that the separated signals are obtained, and the main lobe suppression interference of the signals is suppressed through pulse compression, channel accumulation and constant false alarm detection. The method solves the problem that the prior art anti-main lobe interference method needs to know the prior information such as interference type, interference angle and signal source number in advance, expands the number of observation signal channels, avoids the problem that the signal separation effect of the BSS method is poor when the number of signal sources is greater than the number of observation signal channels, and improves the anti-interference performance and target positioning accuracy of the networking system. The present application is also applicable to noise amplitude modulation interference, noise frequency modulation interference, noise phase modulation interference, spectral dispersion interference, slicing interference and other main lobe suppression interference suppression methods independent of radar target echo. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0053] Figure 1 is a flowchart of the radar networking anti-main lobe interference method based on JBSS in the embodiments of the present application;

[0054] Figure 2 is a schematic diagram of the radar networking system anti-main lobe interference scene in the embodiments of the present application;

[0055] Figure 3(a) is a schematic diagram of pulse compression results before signal time domain alignment in the embodiments of the present application;

[0056] Figure 3(b) is a schematic diagram of pulse compression results after signal time domain alignment with radar station 1 as the reference in the embodiments of the present application;

[0057] Figure 3(c) is a schematic diagram of pulse compression results after signal time domain alignment with radar station 2 as the reference in the embodiments of the present application;

[0058] Figure 3(d) is a schematic diagram of pulse compression results after signal time domain alignment with radar station 3 as the reference in the embodiments of the present application;

[0059] Figure 4This is a schematic diagram of the signal pulse compression results of each channel without JBSS in an embodiment of the present invention;

[0060] Figure 5 This is a schematic diagram of the signal pulse compression results of each channel after JBSS processing in an embodiment of the present invention;

[0061] Figure 6 This is a schematic diagram of the target detection results of each channel signal after JBSS processing in an embodiment of the present invention;

[0062] Figure 7 This is a schematic diagram illustrating the noise amplitude modulation interference suppression effect in an embodiment of the present invention;

[0063] Figure 8 This is a schematic diagram of the final constant false alarm rate (CFAR) detection result after target channel superposition in an embodiment of the present invention;

[0064] Figure 9 This is a schematic diagram illustrating the variation of PSLR with SNR in an embodiment of the present invention;

[0065] Figure 10 This is a schematic diagram illustrating the variation of PSLR with JNR in an embodiment of the present invention;

[0066] Figure 11 This is an embodiment of the present invention. Schematic diagram showing the variation of SNR;

[0067] Figure 12 This is an embodiment of the present invention. A schematic diagram showing how JNR changes. Detailed Implementation

[0068] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0069] Terminology Explanation:

[0070] JBSS: Joint Blind Source Separation Algorithm;

[0071] SNR: Signal-to-noise ratio;

[0072] PSLR: Peak-to-Side-Lobe Ratio, which represents the ratio of the signal's peak value to its side lobes, is an important indicator for evaluating signal processing performance.

[0073] JNR: Signal-to-noise ratio;

[0074] PRF: Pulse Repetition Frequency;

[0075] MSNR-BSS: Blind Source Separation Algorithm;

[0076] CFAR: Constant False Alarm Rate;

[0077] Monte Carlo: Monte Carlo method, also known as random sampling or statistical test method.

[0078] The concept of the present application is to provide a JBSS-based radar networking anti-main lobe interference method and system, which comprises the following steps:

[0079] The interference suppression principle of the present application is that the received signals of each radar station are taken as the reference to estimate and compensate the received signals of the remaining radar stations, and time domain alignment is completed. Based on the combination of signal time domain alignment and joint blind source separation algorithm, the channel number of target observation signal can be expanded, the target signal can be separated, and the main lobe interference of the radar received signal can be suppressed.

[0080] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments, wherein the described embodiments are only a part of the embodiments of the present application, but not all the embodiments.

[0081] Embodiment 1:

[0082] As shown in a JBSS-based radar networking anti-main lobe interference method, the method mainly comprises the following steps: Figure 1 Firstly, the received echo signals of each radar receiving station are transmitted to the information fusion center, and the received signals of each radar station are taken as the reference to estimate and compensate the received signals of the remaining radar stations, and time domain alignment is completed.

[0083] In this embodiment, each radar receiving station in the radar networking system is taken as an example to resist the main lobe suppression interference. The radar networking system comprises a plurality of radar receiving stations. The received signals of the plurality of radar receiving stations are transmitted to the information fusion center. As shown in the figure,

[0084] As shown in the figure, one radar in the networking system can be responsible for radiating signals and receiving signals, and the remaining radars only receive signals, and a plurality of radars can detect the same target area. Figure 2

[0085] ​In this embodiment, the number of array elements in the adversarial scenario is... L of K Radar station, exists P One source of interference and M One real target. Using each radar receiving station in the radar network system as a reference station, delay estimation and compensation are performed on the received signals of each station. K ≥2 , P, M ≥1.

[0086] The calculation expression for the received signal is as follows:

[0087]

[0088] Where t is the time variable, Let L be the received signal of the Lth element in the k-th radar. The transpose operation is indicated by the following expression for calculating the signal received by the array element:

[0089]

[0090] In the formula, The amplitude of the target echo signal; Indicates radar transmission signal; , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target; Indicates the first p The interference source to the first k The distance of each radar; Indicates the speed of electromagnetic wave propagation; Wavelength; The distance between array elements; l Indicates the current array element; Let be the direction of the angle of arrival from the k-th radar station to the target; For the first k The direction of arrival angle of the radar station to the jamming signal; With a mean of 0 and a variance of Complex Gaussian white noise, j Let M be the imaginary part, and M be the total number of targets. Let P be the amplitude of the interference signal, and P be the total number of interference signals. Indicates interference signal. T m For the target signal period, J p For the period of the interference signal, The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. the phase of the target echo signal after quadrature demodulation, the phase of the target echo signal after being transmitted to the kth radar array element, the sum of the interference signals received after the interference signals are returned to the kth radar, the phase of the interference signal after quadrature demodulation, the phase of the interference signal after being transmitted to the kth radar array element.

[0091] Because the distances of the same target or interference to different radar receiving stations are different, there is a certain delay difference between the received signals of the receiving stations, and therefore, before the signal-level fusion uniform processing based on the JBSS algorithm processing method is performed, the received signals of the receiving stations need to be time-domain aligned. The delay difference between the signals of different receiving stations can be estimated through the cross-correlation function between the received signals of different radar receiving stations. Taking the first radar station as an example, the signal after delay compensation can be expressed as:

[0092]

[0093] In the formula, is the signal after delay compensation corresponding to the ith radar station, and the dimension is , is the number of fast snapshots, K is the total number of radar stations, and L is the total number of array elements, is the signal delay difference between the signals received by the ith radar station and the kth radar station, k the cross-correlation function between the signals received by the ith radar station (in this embodiment, the first radar station is taken as an example for description) and the kth radar station is calculated, k the time delay difference between the signals of the two radar stations is , which is the maximum value of the cross-correlation function between the signals of the two radar stations, and the signal delay difference satisfies:

[0094]

[0095] In the formula, is a function for finding the maximum signal delay difference, is the Kronecker product, is the companion matrix of the signal after delay compensation corresponding to the kth radar station, and t is a time variable.

[0096] The time-domain aligned signal after delay compensation is:

[0097]

[0098] In the formula, is the target echo signal vector after delay compensation, is the interference signal vector, is the noise vector, and the target echo signal vector is:

[0099]

[0100] The interference signal vector is:

[0101]

[0102] In the formula, The amplitude of the target echo signal, Indicates radar transmission signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target For wavelength, The distance between array elements. - For the first radar to the first K Each radar unit was positioned in the direction of the target's angle of arrival. The amplitude of the interference signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first p The distance to the interference source, - Let M be the angle of arrival of the jamming signal from radars 1 through K, respectively, and let c be the electromagnetic wave propagation speed. l Where P is the current array element and P is the total number of interference signals. T m For the target signal period, J p For the period of the interference signal, - The transmissions were transmitted from the first radar station to the second radar station. K The received signal delay difference, where t is a time variable and K is the total number of radar stations. The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. The phase of the target echo signal obtained after quadrature demodulation. The phase difference caused by the target echo signal reaching different array elements of the k-th radar. The sum of the interference signals received after the interference signal returns to the k-th radar. The phase is obtained by orthogonal demodulation of the interference signal. The phase caused by the interference signal transmitted to different array elements of the k-th radar. The sum of the interference signals received after the delayed interference signal returns to the k-th radar is given. The sum of the return signals of the target echo signals after time delay compensation to the receiving signals of the kth radar.

[0103] Secondly, the target signal and the interference signal are separated based on the processing mode of the JBSS algorithm to obtain a separated signal.

[0104] Specifically, before the signal separation, the time domain aligned signal is preprocessed, and the preprocessing process includes zero mean processing and whitening processing. The zero mean processing is used to remove the direct current component in the received signal, and the zero mean processing is usually realized by subtracting the mean of the observation vector. The whitening processing is used to decorrelate the radar received signal (that is, the original radar observation signal), so that the whitened observation signal covariance matrix is a unit matrix. The calculation expression of the whitened signal is:

[0105]

[0106] wherein, denotes the transposition operation, is the whitened signal, is the signal after time delay compensation corresponding to the kth radar station, is a whitening matrix, and the whitening matrix is obtained by multiplying the whitening matrix and the original radar observation signal , and the whitening matrix is obtained by performing eigenvalue decomposition on the covariance matrix of the original radar observation signal

[0107] wherein the eigenvalue decomposition of the covariance matrix of the original radar observation signal is represented as:

[0108]

[0109] The calculation expression of the whitening matrix is:

[0110]

[0111] wherein, is the conjugate transpose, is a diagonal matrix composed of eigenvalues, is an eigenmatrix.

[0112] ​The purpose of using the JBSS algorithm is to solve for a separation matrix W. This separation matrix is ​​then multiplied by the mixed signal received by the radar network system to ultimately separate the target echo signal, interference signal, and noise signal into different channels. In this embodiment, the ideal signal after separation of the target, interference, and noise is called the source signal, and the actual signal obtained after separation is called the separated signal.

[0113] Among these, a higher signal-to-noise ratio (SNR) results in better separation. This embodiment constructs a signal-to-noise ratio (SNR) function and a noise ratio function based on this. The calculation expression is:

[0114]

[0115] In the formula, For the separation of signals, This is the separation signal after moving average. This is the preprocessed mixed echo signal. Indicates to The signal after moving average is represented by W, which is the separation matrix. The noise ratio function is calculated based on the noise signal and the source signal.

[0116] Specifically, the initial expression for calculating the noise ratio function SNR is:

[0117]

[0118] in, For noise signals, defined as , The source signal is an unknown signal. The separated signal is an estimated signal of the source signal. This separated signal contains noise, therefore the separated signal after moving average is... As the source signal, the noise ratio function is further expressed as:

[0119]

[0120] In the formula, the separated signal Defined as Separation signal after moving average Defined as ,in, This is the preprocessed mixed signal (i.e., the received signal after time domain alignment). Indicates to The signal after moving average. The expression for calculating the signal after moving average is:

[0121]

[0122] In the formula denotes the size of the sliding average window. The noise ratio function can be further written as:

[0123]

[0124] wherein, is the noise ratio function, is a logarithm function, is a sliding average signal defined as , W is a separation matrix, is a pre-processed received signal, is a sliding average signal based on the received signal, is a transpose of the separation matrix, is a transpose of the sliding average signal, is a transpose of the pre-processed received signal, the embodiment further defines a first matrix: , a second matrix: , a third matrix: , and a fourth matrix: , then:

[0125]

[0126] In the formula, the separation matrix is the independent variable, and the gradient of both sides of the above formula is taken:

[0127]

[0128] The extreme point of the objective function is the zero point of the above formula, i.e.

[0129]

[0130] The separation matrix can be obtained by solving the above formula. The solution in the formula is composed of the eigenvectors of the matrix , and the dimension of is . The separation signal is:

[0131]

[0132] In the formula, each row of represents an estimated signal of a signal source.

[0133] Finally, after pulse compression, channel accumulation, and constant false alarm detection, the separation signal obtains target radial distance measurement information based on each radar station and after target signal main lobe interference suppression.

[0134] Specifically, after signal preprocessing and JBSS algorithm processing, the target echo signal and the interference signal are separated in different channels, so it is necessary to further determine the channel where the target echo is located, and to suppress the interference signal and the noise signal. Pulse compression is performed on the signals of all separated channels, and the calculation expression of pulse compression of the separated signals is:

[0135]

[0136] In the formula, is the compressed signal, is the pulse compressed signal of the first channel, k is the pulse compressed signal of the second channel, l is the pulse compressed signal of the nth channel, is the radar linear frequency modulation signal, t is the time variable, and T is the signal period after pulse compression, is the integral calculation symbol.

[0137] In order to determine the target signal channel, constant false alarm detection is performed on each channel. The constant false alarm detection method is as follows: the separated signals of each channel after pulse compression are detected, the channels where the target signals are detected are accumulated, and the accumulated target signals are detected again to obtain the target radial distance. The above steps are repeated with different receiving stations in the network as reference stations, and the target radial distance values of the target from the first radar station to the nth radar station are obtained K . k The number of radar stations in the network system is . K

[0138] After obtaining the target radial distance measurement information based on each radar station, the method further includes a method of using the obtained target radial distance for multi-station joint positioning. The target radial distance values of the multi-stations are used to perform joint positioning based on the three-ball positioning principle to determine the spatial information of the target. Taking three radars as an example, the network system composed of three radars obtains three target distance values , , after the above signal level fusion processing. The first radar station is a transmitting / receiving station, and the remaining two radar stations only receive signals. Based on the three-ball positioning principle, the target is jointly positioned, so it is necessary to obtain the distance information of the target relative to each receiving station. The calculation expression of the distance information is as follows:

[0139]

[0140] In the formula, is the distance information of the target relative to each receiving station, is the distance value of the target to the kth radar station. ​

[0141] Then based on the spatial locations of the three receiving stations radial distance from the target to each station The target spatial location is determined by solving the following formula. :

[0142]

[0143] The exact spatial location of the target can be obtained using this formula.

[0144] To verify the effectiveness of the method in this embodiment, simulation experiments were also conducted. Taking noise amplitude modulation interference as an example, the simulation assumes that there are 3 radars in the network system, and their spatial distribution is shown in Table 1:

[0145] Table 1: Spatial Distribution Locations of Radar

[0146]

[0147] As shown in Table 1, the target location is The first radar transmits a linear frequency modulated signal, and the parameter settings are shown in Table 2.

[0148] Table 2 Radar Parameter Settings

[0149]

[0150] To facilitate observation of the signal alignment results across each channel, the number of array elements for all three radars was set to 1, with SNR and JNR of 10dB and 15dB, respectively. The angles at which the target signal and interference signal arrive at the main lobe of each radar are as follows: , Figures 3(a) and 3(d) show the normalized results of the received signals from all channels of the network system after direct pulse compression, and the normalized results of the received signals from all channels after time-domain alignment and pulse compression, with the three radar stations as reference stations, respectively. It can be seen that the signals of each channel with the three radar stations as reference stations have been aligned in the time domain.

[0151] Each radar is configured with 4 array elements, and the total number of signal-level processing channels after networking the three radars is 12. The number of snapshots is set to 4096, and the angles at which target signals and interference signals arrive at the main lobe of each radar are [missing information]. , .when , At that time, taking the first radar as an example, the simulation verified the anti-noise amplitude modulation main lobe interference effect.

[0152] The pulse compression results for each channel signal, which only underwent time-domain alignment and did not undergo JBSS algorithm processing, are as follows: Figure 4As shown, the target is submerged in interference in all channels, and cannot be detected by pulse compression alone. Figure 5 The image shows the pulse compression results of each channel signal after time-domain alignment and JBSS algorithm processing. It can be seen that after JBSS, the target is distributed in each channel. The target detection results of each channel signal after JBSS processing are as follows: Figure 6 As shown.

[0153] Depend on Figure 6 As can be seen, after using CFAR detection to separate the signals in each channel for target detection, both the first and eleventh channels detected the target. After confirming the target channels, all target channels are superimposed, and finally, CFAR detection is performed again to determine the target distance. Figure 7 The figure shows the main lobe interference suppression effect of this method. Figure 8 The image shows the CFAR detection results after superimposing the target channel signals. Figure 7 It can be seen that the target is still submerged in interference after direct pulse compression, and the interference suppression effect of the method in this embodiment is obvious. Figure 8 The network system shown, with the first radar as the reference station, receives a signal that, after processing by the JBSS algorithm, detects a target distance of 32373.12m. The target distance set for radar station 1 in the simulation is... The radial distance estimated by this method is quite close to the true value.

[0154] To verify the anti-jamming performance of this method, this embodiment simultaneously simulates the peak sidelobe ratio (PSLR) and target localization error of the method in this embodiment and the existing MSNR-BSS-based radar networking anti-main lobe jamming method. PSLR refers to the ratio of the peak intensity of the main lobe to that of the side lobes. In the... k In a radar system, the PSLR of the signal after interference suppression can be expressed as:

[0155]

[0156] In the formula, Indicates the first k Radar No. n The PSLR value of the Monte Carlo simulation results; in this example, K is 3.

[0157] Target positioning error of radar network system It can be calculated using the following formula:

[0158]

[0159]

[0160] In the formula, Indicates the firstn Target positioning accuracy of the secondary Monte Carlo simulation experiment, represents the target position coordinates determined by the multi-station joint positioning data level fusion method, represents the true target position coordinates set in the simulation experiment.

[0161] The simulation experiment parameter setting is the same as the above parameter setting, and Monte Carlo simulation is performed 1000 times. When JNR=50dB, the SNR is increased from 5dB to 15dB; when SNR=10dB is fixed, JNR is increased from 0dB to 100dB. In the above two cases, PSLR is analyzed, The simulation results are shown in Figures 9-12 .

[0162] It can be seen from Figure 9 that the PSLR of the method and the existing method decreases with the increase of SNR, and the PSLR of the method is always lower than that of the existing method. It can be seen from Figure 10 that with the gradual increase of JNR, the PSLR of the method and the existing method increases slightly, and the PSLR of the method is always lower than that of the existing method, which shows that the two methods have good anti-large-power main lobe interference effect, and the anti-main lobe suppression interference performance of the method is better than that of the existing method.

[0163] It can be seen from Figure 11 that with the increase of SNR, the target positioning error of the existing method gradually decreases, while the target positioning error of the method changes slightly. It can be seen from Figure 12 that the target positioning error of the two methods increases slightly with the increase of JNR. Combined with Figure 11 and Figure 12 , it can be found that the target positioning effect of the method is always better than that of the existing method.

[0164] Embodiment 2:

[0165] The radar networking anti-main lobe interference system based on JBSS in the embodiment comprises a data acquisition module and a data processing module. The data acquisition module is used to acquire the received signals corresponding to each radar receiving station, and the data processing module is used to process the received signals corresponding to each radar receiving station to realize the radar networking anti-main lobe interference method based on JBSS. The radar networking anti-main lobe interference method based on JBSS in the embodiment has been described in detail in the radar networking anti-main lobe interference method based on JBSS embodiment, and will not be repeated here.

Claims

1. A method for radar networking to resist main lobe interference based on JBSS, characterized in that, include: The echo signals received by each radar receiving station are transmitted to the information fusion center. Based on the received signal of each radar station, the delay of the radar received signals of the other radar receiving stations is estimated and compensated to complete the time domain alignment. Based on the JBSS algorithm, the target signal and interference signal are separated from the time-domain aligned signal to obtain the separated signal, which includes the target signal; After the separated signals are sequentially processed through pulse compression, channel accumulation, and constant false alarm rate detection, the radial distance measurement information of the target is obtained based on each radar station and after the main lobe interference of the target signal is suppressed.

2. The JBSS-based radar networking anti-main lobe interference method according to claim 1, characterized in that, The calculation formula for the radar received signal at each receiving station is as follows: in, This indicates the transpose operation. Let be the received signal of the Lth element in the k-th radar, and t be the time variable. The expression for calculating the received signal of the element is: In the formula, The amplitude of the target echo signal; Indicates radar transmission signal; , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target; Indicates the first p The interference source to the first k Distance to the radar station; Indicates the speed of electromagnetic wave propagation; Wavelength; The distance between array elements; l Indicates the current array element; Let be the direction of the arrival angle of the k-th radar reaching the target; For the first k The direction of arrival angle of the radar station to the jamming signal; With a mean of 0 and a variance of Complex Gaussian white noise, j Let M be the imaginary part, and M be the total number of targets. Let P be the amplitude of the interference signal, and P be the total number of interference signals. Indicates interference signal. T m For the target signal period, J p For the period of the interference signal, The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. The phase of the target echo signal obtained after quadrature demodulation. The phase difference caused by the target echo signal reaching different array elements of the k-th radar. The sum of the interference signals received after the interference signal returns to the k-th radar. The phase is obtained by orthogonal demodulation of the interference signal. The phase caused by the interference signal being transmitted to different array elements of the k-th radar.

3. The JBSS-based radar networking anti-main lobe interference method according to claim 2, characterized in that, The time-domain aligned signal calculation expression is as follows: in, The target echo signal vector after time delay compensation. For interference signal vectors, The noise vector is the target echo signal vector, and the target echo signal vector is: The interference signal vector is: In the formula, The amplitude of the target echo signal, Indicates radar transmission signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first m Distance to the target For wavelength, The distance between array elements. - For the first radar to the first K Each radar unit was positioned in the direction of the target's angle of arrival. The amplitude of the interference signal, , They represent the first radar station and the second radar station, respectively. k Radar station to the first p The distance to the interference source, - Let M be the angle of arrival of the jamming signal from radars 1 through K, respectively, and let c be the electromagnetic wave propagation speed. l Where P is the current array element and P is the total number of interference signals. T m For the target signal period, J p For the period of the interference signal, - The transmissions were transmitted from the first radar station to the second radar station. K The received signal delay difference, where t is a time variable and K is the total number of radar stations, K≥2. The sum of the signals transmitted by each radar and the echo signals received by the k-th radar is given by the echo signals. The phase of the target echo signal obtained after quadrature demodulation. The phase difference caused by the target echo signal reaching different array elements of the k-th radar. The sum of the interference signals received after the interference signal returns to the k-th radar. The phase is obtained by orthogonal demodulation of the interference signal. The phase caused by the interference signal transmitted to different array elements of the k-th radar. The sum of the interference signals received after the delayed interference signal returns to the k-th radar is given. This is the sum of the received signals from the target echo signal returned to the k-th radar after time delay compensation.

4. The JBSS-based radar networking anti-main lobe interference method according to claim 3, characterized in that, The expression for calculating the signal after delay compensation is: in, This indicates the transpose operation. Let be the delay-compensated signal corresponding to the i-th radar station, with dimension . , Where K is the number of snapshots, L is the total number of radar stations, and L is the total number of array elements. For the first i Radar station transmits to the first k The signal delay difference received by the radar station satisfies: In the formula, To find the function that maximizes the signal delay difference, For Kronecker product, Let be the adjoint matrix of the delayed-compensated signal corresponding to the k-th radar station, where t is the time variable.

5. The JBSS-based radar networking anti-main lobe interference method according to claim 1 or 3, characterized in that, After completing the time-domain alignment, the process further includes a preprocessing step for the time-domain aligned signal. This preprocessing includes zero-mean normalization and whitening. Zero-mean normalization removes the DC component from the signal, and whitening performs decorrelation on the signal. The expression for the whitened signal is as follows: in, This is the signal after whitening. For whitening matrix, For the delay-compensated signal corresponding to the k-th radar station, the whitening matrix is: In the formula, It is the conjugate transpose. It is a diagonal matrix composed of eigenvalues. The characteristic matrix, The characteristic matrix B is the conjugate transpose of the characteristic matrix, and the characteristic matrix B satisfies the following relation: In the formula, Let E be the conjugate transpose of the delay-compensated signal corresponding to the k-th radar station, and let E be the identity matrix.

6. The JBSS-based radar networking anti-main lobe interference method according to claim 1, characterized in that, The separation of target signal and interference signal from the time-domain aligned signal based on the JBSS algorithm includes: A signal-to-noise ratio (SNR) function is constructed, a separation matrix is ​​calculated based on the SNR function, and the separated signal is obtained based on the separation matrix. The expression for calculating the SNR function is as follows: in, The separation signal is defined as follows: , The signal after moving average is defined as follows: , W For the separation matrix, The received signal after preprocessing. The signal is based on the moving average of the received signal. For the transpose of the separation matrix, This is the transpose of the signal after the moving average. This is the transpose of the preprocessed received signal. As a logarithmic function, the separating matrix satisfies: The expression for calculating the separated signal is as follows: In the formula, C is the first matrix. ; Second matrix, V is the third matrix. U is the fourth matrix. .

7. The JBSS-based radar networking anti-main lobe interference method according to claim 1, characterized in that, The calculation expression for pulse compression of the separated signal is: In the formula, The signal is compressed. For the first k Department No. l The pulse-compressed signal of each channel, The signal is a radar linear frequency modulated signal, where t is the time variable and T is the signal period. This is the symbol for integral calculation.

8. The JBSS-based radar networking anti-main lobe interference method according to claim 1, characterized in that, The constant false alarm probability detection method is as follows: the separated signal of each channel after pulse compression is detected, the channel where the target signal is detected is accumulated, and the accumulated target signal is detected again with constant false alarm probability to obtain the target radial distance measurement value.

9. The JBSS-based radar networking anti-main lobe interference method according to claim 1, characterized in that, After obtaining the target radial distance measurement information based on each radar station and after suppressing the main lobe interference of the target signal, the method also includes a multi-station joint positioning method using the obtained target radial distance. The target radial distance values ​​of multiple stations are used to perform joint positioning using the three-sphere positioning principle to determine the spatial information of the target.

10. A radar networking anti-main lobe interference system based on JBSS, characterized in that, include: The data acquisition module is used to acquire the received signals corresponding to each radar receiving station; The data processing module is used to process the received signals corresponding to each radar receiving station to realize the radar networking anti-main lobe interference method based on JBSS as described in any one of claims 1-9.

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