Maneuvering target long-time coherent accumulation method, system, equipment and medium

Abstract

The invention discloses a maneuvering target long-time coherent accumulation method, system and device and a medium, and relates to the technical field of radar signal processing, and the method comprises the steps: enabling a plane array to achieve the complete airspace coverage in the azimuth angle range dimension through the introduction of FDA; according to the planar array, three-dimensional information of a target is utilized, so that the target can obtain information with higher dimensionality than that of coherent FDA. Then, an azimuth angle-pitch angle-distance three-dimensional matching filter is designed, and rapid waveform matching is realized. The method aims at the influence of a maneuvering target phase-coherent accumulation process. And finally, compensating range migration and Doppler frequency migration in a high-altitude maneuvering target detection process by adopting a second-order Keysone transform-LVD algorithm to realize coherent accumulation of the target. The invention not only provides a novel radar array combining PA and FDA, but also is applied to the field of target detection, especially for complex detection conditions such as high-altitude maneuvering targets.

Description

Technical Field

[0001] The present invention relates to the field of radar signal processing technology, and in particular to a method, system, device and medium for long-term coherent integration of a maneuvering target. Background Art

[0002] With the advancement of stealth technology, detecting high-altitude, maneuvering targets has become a significant challenge for radar systems. These targets are typically characterized by long range, low observability, and high maneuverability. Detection performance of these targets is crucial for imaging, identification, and tracking. However, the radar cross section (RCS) of these targets is small, and the observation range is long, resulting in reduced echo energy. Therefore, radar systems must extend the observation time to accumulate higher energy to detect these targets. However, during the long coherent integration process, the target's velocity and acceleration can cause significant cross-range and cross-Doppler effects, negatively impacting radar detection performance.

[0003] A new Radon Fourier transform (RFT) is proposed, exploiting the coupling between target radial velocity and range migration (RM) during long-term coherent integration. Using a first-order Keystone Transform (KT), the time axis of each frequency is rescaled to correct for linear range migration (LRM), resulting in a coherent integration of high-speed moving targets. However, the presence of radial acceleration components introduces Doppler frequency shift (DFM) and quadratic range migration (QRM), which degrades the performance of the aforementioned algorithms. For the detection of uniform, high-speed targets, a second-order ladder transform (SKT) is used to eliminate QRM and achieve coherent integration. The Radon Fractional Fourier Transform (RFRFT) algorithm addresses range migration by searching for velocity and acceleration and uses a fractional Fourier transform (FRFT) for coherent integration. This algorithm offers strong detection performance and enables long-term coherent integration. However, the requirement for parameter search in existing algorithms leads to high computational complexity, resulting in poor coherent integration performance, especially when the search space is very large. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a method, system, device and medium for long-term coherent accumulation of maneuvering targets to solve the problems in the prior art.

[0005] The present invention specifically provides the following technical solutions: A long-term coherent integration method for a maneuvering target, comprising: A radar planar array based on a vertical phased array PA and a horizontal frequency-variable array FDA was constructed. The element in the upper left corner of the radar planar array was selected as the reference element. The transmitted signals of all elements were reflected by the target and then received by the set row and column elements to obtain the echo signal. Perform matched filtering on the echo signal, and perform fast Fourier transform on the echo signal after matched filtering in the fast time dimension to obtain the frequency domain expression of the echo signal; In the frequency domain, the range migration caused by target velocity in the echo signal is corrected, and the range curvature caused by target acceleration is corrected using a second-order Keystone transform. The Doppler migration caused by acceleration in the echo signal is corrected using the LVD algorithm. After correcting for range migration, range curvature, and Doppler migration, the range inverse Fourier transform and azimuth Fourier transform are performed to obtain the target energy coherent accumulation result. Range curvature is quadratic range migration.

[0006] Preferably, the step of reflecting the transmission signals of all array elements by the target and receiving them by array elements in set rows and columns is specifically as follows: The first is described by fast time, frequency modulation, pulse time and rectangular window function m OK n Array element transmits signal , the specific expression is: ; in t 、 μ and T p They are fast time, frequency modulation and pulse time respectively; The transmitted signal is reflected by the target and received by the specific rows and columns of array elements to obtain the echo signal, which is specifically expressed as: ; in, N Indicates the total number of columns; n 1 means the n 1 column; t m Indicates slow time; Indicates delay; represents the pitch angle, Indicates azimuth; G T and G R are the transmit pattern gain and receive pattern gain, respectively.

[0007] Preferably, the matched filtering of the echo signal is specifically performed as follows: Based on the setting that the receiving pattern in the receiving pattern gain depends on the angle, a three-dimensional matched filter function is used to perform matched filtering on the echo signal. Its expression is: ; in conj represents the conjugate operation, represents the convolution operation, is the three-dimensional matched filter function, is the echo signal after receiving beamforming, is the echo signal after matched filtering.

[0008] Preferably, the fast Fourier transform in the fast time dimension is performed on the echo signal after matched filtering to obtain the frequency domain expression of the echo signal, specifically: The matched filtered echo signal is subjected to fast Fourier transform (FFT) in the fast time dimension, and the echo signal received in the frequency domain is represented by the product of the gain brought by the planar array, the rectangular window function of the range frequency, the azimuth window function, and the e-index function of the velocity.

[0009] Preferably, the correcting of the range curvature caused by the target acceleration by the second-order Keystone transform and the correcting of the Doppler migration caused by the acceleration in the echo signal by the LVD algorithm include: Set the search speed and use it as a compensation function. When the search speed matches the target radial velocity in the echo signal, the range migration caused by the target radial velocity is corrected. After correcting the range migration, the second-order Keystone transform is used to correct the secondary range migration caused by the target acceleration and replace the slow time variable; the secondary range migration is the range curvature; After correcting the quadratic range migration, the fast Fourier transform (FFT) in the fast time dimension is subjected to the inverse fast Fourier transform (IFFT) to obtain the frequency domain expression of the intermediate echo signal. Set the estimated acceleration of the target and use the estimated acceleration as a compensation function to obtain the echo signal of the range unit where the target is located when only the azimuth echo is considered in the intermediate echo signal; According to the LVD algorithm, the time delay variable and the time delay constant are used as the time delay of the echo signal, and the parameter symmetric instantaneous autocorrelation function is constructed by the product of the echo signal with time delay and the complex conjugate echo signal; The slow time variable is equivalent to the ratio of the slow time variable of the estimated acceleration to the time delay variable and the time delay constant, and the equivalent parameter symmetric instantaneous autocorrelation function is obtained through the equivalent slow time variable; The acceleration of the target is taken as the energy peak, and the energy peak is used as the compensation function to correct the Doppler frequency modulation in the final echo signal; Perform Fast Fourier Transform (FFT) on the corrected echo signal and perform Doppler migration (DFM) compensation.

[0010] Preferably, in the radar plane array of the horizontal frequency variation array FDA, there is only a fixed frequency difference ∆ between the array elements. f , let the center frequency of the first element in each column of the planar array be f 0, by center frequency and number of columns nThe sum of the frequency differences of -1 is obtained n The frequency of the array element; where the frequency increment ∆ f Much smaller than the center frequency f 0.

[0011] Preferably, when selecting the upper left corner array element of the radar planar array as the reference array element, the method further includes: The vertical direction of the radar plane array is used as a phased array, and a weight that is consistent with the weight in the horizontal direction is set for each array element in the vertical direction.

[0012] The present invention provides a long-term coherent integration system for a maneuvering target, comprising: The signal transmission module is used to construct a radar planar array based on a vertical phased array PA and a horizontal frequency-variable array FDA. The upper left corner element of the radar planar array is selected as the reference element. The transmitted signals of all elements are reflected by the target and then received by the set row and column elements to obtain the echo signal. The filtering module is used to perform matched filtering on the echo signal and perform fast Fourier transform in the fast time dimension on the echo signal after matched filtering to obtain the frequency domain expression of the echo signal; The correction module corrects the range migration caused by target velocity in the echo signal in the frequency domain, corrects the range curvature caused by target acceleration using a second-order Keystone transform, corrects the Doppler migration caused by acceleration in the echo signal using the LVD algorithm, and performs an inverse Fourier transform of range and an inverse Fourier transform of azimuth after corrections for range migration, range curvature, and Doppler migration to obtain the target energy coherent accumulation result. Range curvature is quadratic range migration.

[0013] The present invention provides a computer device, comprising a memory and a processor, wherein a program is stored in the memory, and when the program is executed by the processor, the processor executes the steps of the above-mentioned long-term coherent accumulation method for a maneuvering target.

[0014] The present invention provides a storage medium storing a computer program, which implements the steps of the above-mentioned long-term coherent accumulation method for a maneuvering target when the computer program is executed by a processor.

[0015] Compared with the prior art, the present invention has the following significant advantages: In complex detection scenarios such as high-altitude maneuvering targets, the present invention combines a vertical phased array with a horizontal frequency diversity array (PA-FDA). This allows the planar array to achieve full airspace coverage in the azimuth dimension, compared to traditional phased arrays. This allows the array to utilize higher-dimensional target information, eliminating the need to rely on extensive parameter searches for velocity and acceleration. This fundamentally avoids the computational complexity surge caused by parameter searches in RFRFT, significantly improving the efficiency of the coherent accumulation process. Furthermore, by combining the vertical phased array with the horizontal frequency diversity array (PA-FDA), the planar array transmits signals to detect targets. Even in complex dynamic scenarios involving high-altitude maneuvering targets (where the search space is extensive), post-processing of received echoes is performed, thereby addressing range migration (RM) and Doppler migration (DFM) caused by the velocity and acceleration of the target during detection. This allows for long-term coherent accumulation of the target, effectively focusing the target energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the antenna structure involved in the method of long-term coherent integration of maneuvering targets based on vertical PA and horizontal FDA array of the present invention; Figure 2 2. It is a schematic diagram of the array structure in an embodiment of the present invention; Figure 3 is the emission pattern of the array in the embodiment of the present invention; Figure 3 (a) is the emission pattern, Figure 3 (b) is the angle change diagram of the emission direction, Figure 3 (c) is the emission pattern characteristic of FDA, Figure 3 (d) is the emission pattern characteristic of PA; Figure 4 is a three-dimensional schematic diagram of the matched filtering result of the target in an embodiment of the present invention; Figure 4 (a) is a three-dimensional graph, Figure 4 (b) is a two-dimensional schematic diagram of the angle direction. Figure 4 (c) is a two-dimensional schematic diagram of time and angle direction, Figure 4 (d) is a two-dimensional schematic diagram of time and phase angle directions; Figure 5 It is an image of the coherent accumulation process of the high-altitude maneuvering target in the simulation of the present invention; Figure 5 (a) is the coherent accumulation diagram, Figure 5 (b) is the image after the LRM of the target is corrected. Figure 5 (c) is the image after QRM is corrected by the second-order Keystone transform. Figure 5 (d) is the graph obtained by performing fast Fourier transform FFT on the Doppler dimension; Figure 6 The present invention provides a flow chart of a long-term coherent integration method for a maneuvering target. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0018] Since phased array (PA) radar provides fast antenna beam scanning and spatial filtering capabilities. Frequency varying array (FDA) radar is characterized by automatically scanning the transmission beam pattern and providing wide spatial coverage. Based on these advantages, the present invention proposes a planar array that combines the elements of the two radar systems. In the radar planar array of the horizontal frequency varying array FDA, each row of array elements on the array surface can be regarded as a PA radar, with only one phase difference. The number of rows of the planar array is M, the number of columns is N, and each row of array elements can be regarded as an FDA radar. Specifically, Figure 2 As shown, there is only a frequency difference ∆f between the array elements. Let the center frequency of the first array element in each column of the planar array be f 0, by center frequency and number of columns n The sum of the frequency differences of -1 is obtained n The frequency of the array element; where the frequency increment ∆ f Much smaller than the center frequency f 0.

[0019] ; Where, the frequency increment ∆ f Much smaller than the center frequency f 0.

[0020] The transmit beam pattern of the planar array was simulated and analyzed, and the three-dimensional matched filtering of azimuth angle, elevation angle and distance was realized. The filtering results are shown in the figure below. Figure 4 As shown in the figure. The introduction of FDA allows the planar array to achieve full spatial coverage in the azimuth range dimension. This planar array utilizes three-dimensional target information (azimuth, elevation, and range), enabling it to obtain higher-dimensional information than coherent FDA. Subsequently, a three-dimensional azimuth-elevation-range matched filter was designed to achieve fast waveform matching. To address the influence of the coherent accumulation process of maneuvering targets, a second-order ladder transform-level distribution (SKT-LVD) algorithm was used to compensate for the range shift (RM) and Doppler frequency shift (DFM) during the moving target detection process, achieving coherent accumulation of the target and effectively focusing the target energy.

[0021] In this embodiment, a long-term coherent integration method for a maneuvering target includes the following steps: Step S1: Construct a radar planar array based on a vertical phased array PA and a horizontal frequency-variable array FDA. Select the element in the upper left corner of the radar planar array as the reference element. After the transmitted signals of all elements are reflected by the target, they are received by the set row and column elements to obtain the echo signal.

[0022] First, the characteristics of the array are analyzed. Considering the linear frequency modulation (LFM) signal, the fast time, modulation frequency, pulse time and rectangular window function are used to describe the first m OK n Array element transmits signal , the specific expression is: ; in t 、 μ and T p They are fast time, frequency modulation and pulse time respectively.

[0023] Select the element at the upper left corner of the array as the reference element. Consider a moving target in three-dimensional space. The signal is from M (m1=1,2,…,M) rows and N (n1=1,2,…,N) columns of units transmit, and after scattering, the echo signals received by the m2 and n2 antennas for: ; like Figure 1 As shown, considering the characteristics of the array, the vertical direction is a phased array radar, and a weight is set for each array element in the vertical direction, that is, the vertical direction of the array of the radar plane array is used as a phased array, and a weight is set for each array element in the vertical direction that is consistent with the weight in the horizontal direction, and then the echo signal is obtained, and the emission pattern of the array is obtained from the echo signal. , which can be expressed as: ; Analysis of the array's transmit pattern reveals that it is modulated by azimuth, elevation, and range. Furthermore, because the array's horizontal direction is FDA, its introduction enables full spatial coverage in the azimuth dimension. By slicing the pattern in the azimuth-range and elevation-fast time dimensions, the transmit pattern characteristics of the frequency-diversity array radar's FDA and phased array radar's PA can be observed.

[0024] In a planar array system, the echo signal is received by columns. The transmitted signal is reflected by the target and then received by the array elements in specific rows and columns to obtain the echo signal. The echo signal is obtained and mixed. It can be expressed as: ; in, N Indicates the total number of columns; n 1 means the n 1 column; t m Indicates slow time; Indicates delay; represents the pitch angle, Indicates azimuth; G T and G R are the transmit pattern gain and receive pattern gain, respectively, is the wavelength, and the specific expression is: ; ; Step S2: performing matched filtering on the echo signal, and performing fast Fourier transform in the fast time dimension on the echo signal after matched filtering to obtain a frequency domain expression of the echo signal.

[0025] Since it is a planar array based on vertical phased array PA and horizontal frequency diversity array FDA, conventional beamforming technology is used at the receiving end. and , set two weight vectors for rows and columns respectively 、 , the two weight vectors can be expressed as: ; ; Therefore, the beam weight vector It can be expressed as follows, where represents the Kronecker product, and its specific expression is: ; The echo signal after receiving beamforming can be expressed as: ; As can be seen from the receive pattern, the receive beam pattern is only related to the angle, so beamforming has no effect on the time domain echo waveform. Angles include azimuth and elevation. To implement matched filtering for any point in space, a matched filter function must be designed to match every angle in space. Matched filtering can be written as: ; in is the transmission pattern matching function, which can be expressed as: ; in Represents the matched filtering form of an arbitrary waveform. For a given angle, the matched filter function is affected by the transmit beam pattern. Therefore, based on the setting that the receive pattern in the receive pattern gain depends on the angle, a three-dimensional matched filter function is used to match the echo signal. Its expression is: ; in conj represents the conjugate operation, Represents the convolution operation, which allows matched filtering of the target in three-dimensional space, where is the three-dimensional matched filter function, is the echo signal after receiving beamforming, is the echo signal after matched filtering.

[0026] Since targets are in motion during detection, detecting maneuvering targets at high altitudes results in low echo energy. To improve the signal-to-noise ratio, continuous observation of the target is necessary to accumulate the target echo energy. The target's velocity and acceleration can cause range and Doppler shifts, requiring correction for these errors.

[0027] Perform fast Fourier transform (FFT) on the matched filtered echo in the fast time dimension, and the signal received in the range frequency domain is: Perform fast Fourier transform (FFT) on the matched filtered echo signal in the fast time dimension, and express the echo signal received in the frequency domain as the product of the gain brought by the planar array, the rectangular window function of the range frequency, the azimuth window function, and the e-index function of the speed. The specific expression is: ; in and represent the range frequency and azimuth window functions respectively, is the gain brought by the planar array.

[0028] From the frequency domain expression of the fast time dimension, it can be seen that the radial velocity v of the maneuvering target is coupled with the range frequency f, thus generating linear range migration LRM. At the same time, the existence of the target's acceleration will also be coupled with the range frequency f and center frequency f 0 coupling, which respectively causes secondary range migration QRM (also called range bending) and Doppler migration DFM. Therefore, in order to eliminate the influence of target motion during observation, it is necessary to correct these errors caused by the motion process.

[0029] Step S3: In the frequency domain, the range migration caused by the target velocity in the echo signal is corrected, and the range curvature caused by the target acceleration is corrected using a second-order Keystone transform. The Doppler migration caused by acceleration in the echo signal is corrected using the LVD algorithm. After the range migration, range curvature, and Doppler migration corrections are made, the range inverse Fourier transform and azimuth Fourier transform are performed to obtain the target energy coherent accumulation result; range curvature is quadratic range migration.

[0030] The matched filtered signal is processed in the frequency domain to compensate for the errors caused by the velocity and acceleration of the maneuvering target during the observation process, thereby achieving the focusing effect of the target.

[0031] The range curvature caused by target acceleration is corrected using the second-order Keystone transform, and the Doppler shift caused by acceleration in the echo signal is corrected using the LVD algorithm, including: According to the frequency domain of the fast time dimension above, a compensation function can be set, that is, the search speed is set and used as the compensation function. When the search speed matches the radial velocity of the target in the echo signal, the range migration caused by the radial velocity of the target is corrected. , expressed as: ; in Indicates the search speed.

[0032] After correcting for range migration, the second-order Keystone transform (SKT) is used to correct for the quadratic range migration (QRM) caused by target acceleration. Quadratic range migration is range curvature. SKT is equivalent to replacing the slow-time variable, and the relationship between the variables can be written as: ; in τ m It is a new slow-time variable. After the quadratic range migration is corrected, the fast-time dimension is subjected to inverse fast Fourier transform IFFT to obtain the frequency domain expression of the intermediate echo signal. , the expression is: ; It can be seen that the target acceleration aThe QRM caused by the velocity v is eliminated, and the LRM caused by the target velocity v is reduced by half. After compensating for the RM, the Doppler frequency modulation (DFM) effect in the LFM signal needs to be accurately corrected to achieve accurate focusing of the energy of the moving target. In order to correct the DFM, a compensation function can be constructed based on the estimated acceleration of the target. The error in the fast time dimension has been corrected, so the next step only needs to consider the azimuth echo and correct the error in this dimension, that is, use the estimated acceleration as the compensation function to obtain the echo signal of the distance unit where the target is located when only the azimuth echo is considered in the intermediate echo signal, and the echo signal of the distance unit where the target is located is obtained. can be written as: ; Where A represents the amplitude of the signal. According to the definition of LVD, the delay variable and the delay constant are used as the delay of the echo signal. The parametric symmetric instantaneous autocorrelation function (PSIAF) is constructed by the product of the echo signal with delay and the complex conjugate echo signal. , which can be expressed as: ; in, is the delay variable, and With the same interval, is the delay constant.

[0033] Equivalent slow-time variables to slow-time variables for estimating acceleration Delay variable, delay constant The ratio of and is obtained by the equivalent slow time variable to obtain the equivalent parameter symmetric instantaneous autocorrelation function, specifically: Then, to decouple, Can be changed to: ; Where h is the equivalent slow-time normalization coefficient. After replacement, the parameter symmetric instantaneous autocorrelation function (PSIAF) Can be written as , the specific expression can be written as: ; From the above formula, we can see that the slow time variable With delay variables The coupling between them has been eliminated. Then the processed echo signal is subjected to a two-dimensional (2-D) FFT to obtain the target energy coherent accumulation , which can be expressed as: ; It can be seen that LVD involves three steps: correlation, decoupling, and two-dimensional FFT. In these steps, correlation expands the target's directional echo energy from a one-dimensional straight line to a two-dimensional plane. Then, decoupling eliminates the coupling between variables. Finally, the energy accumulation of the signal is achieved through two-dimensional FFT. In the γ dimension, the energy peak corresponds to the acceleration of the target. Therefore, the acceleration of the target can be estimated from this peak, and a compensation function can be constructed to correct DFM. That is, the acceleration of the target is used as the energy peak, and the energy peak is used as the compensation function to correct the Doppler frequency modulation in the final echo signal. The compensation function can be written as: ; Perform Fast Fourier Transform (FFT) on the corrected echo signal and perform Doppler migration (DFM) compensation. The result can be expressed as: ; in f g Slow time variable The corresponding Doppler frequency variable is obtained, thereby achieving DFM compensation and coherent accumulation.

[0034] The present invention will be further described below with reference to simulation diagrams.

[0035] 1. Simulation parameters: The simulation parameters are shown in Table 1: Table 1 Simulation parameters list

[0036] 2. Simulation content and result analysis: Under the simulation parameters in Table 1 above, the technology of the present invention is used to analyze the directional pattern of the planar array combining the vertical phased array and the horizontal frequency diversity array. The transmission directional pattern is as follows: Figure 3 As shown, it can be seen that the introduction of FDA enables it to achieve full spatial coverage in the azimuth dimension, where the slice diagrams show the emission pattern characteristics of FDA and PA respectively.

[0037] Figure 5 In order to utilize the coherent accumulation process of the array to the maneuvering target, the LRM of the target is first corrected. The corrected image is as follows: Figure 5 (b), and then the QRM is corrected by the second-order Keystone transform (SKT). ​​The effect after correction is as follows Figure 5 (c), finally solve the DFM problem by LVD, and finally perform fast Fourier transform FFT on the Doppler dimension to obtain Figure 5 (d) Objective good focusing effect.

[0038] Based on the above method, the present invention proposes a long-term coherent integration system for maneuvering targets, including: a signal sending module, a filtering module and a correction module.

[0039] Among them, the signal transmission module is used to construct a radar planar array based on a vertical phased array (PA) and a horizontal frequency-variable array (FDA). The array element in the upper left corner of the radar planar array is selected as the reference array element. The transmitted signals of all array elements are reflected by the target and then received by the set row and column array elements to obtain the echo signal. The filtering module is used to perform a fast Fourier transform (FFT) on the received echo signal in the fast time dimension to obtain the frequency domain of the echo. A three-dimensional matched filter function is designed to perform matched filtering on the echo signal to obtain the frequency domain expression after matched filtering. The correction module is used to correct the range migration caused by the target velocity in the echo signal in the frequency domain, and to correct the range curvature caused by the target acceleration through a second-order Keystone transform. The Doppler migration caused by acceleration in the echo signal is corrected through the LVD algorithm. After the range migration, range curvature, and Doppler migration corrections, the range inverse Fourier transform and azimuth Fourier transform are performed to obtain the target energy coherent accumulation result. The range curvature is quadratic range migration.

[0040] The present invention also provides a computer device, including a memory and a processor, wherein a program is stored in the memory, and when the program is executed by the processor, the processor executes the steps of a long-term coherent accumulation method for a maneuvering target.

[0041] According to the disclosed embodiments, a computing device may communicate with one or more external devices (e.g., keyboards, pointing devices, Bluetooth communications, etc.), or any device (e.g., routers, modems, etc.) that enables a computing device to communicate with one or more other computing devices.

[0042] The present invention also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of a long-term coherent accumulation method for a maneuvering target are implemented.

[0043] According to the disclosed embodiments, the storage medium may be a non-volatile computer-readable storage medium, such as, but not limited to, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. For purposes of the present invention, the storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, apparatus, or device.

[0044] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. For those skilled in the art to which the present invention belongs, several simple deductions or replacements can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A long-term coherent integration method for a maneuvering target, characterized in that: include: A radar planar array based on a vertical phased array PA and a horizontal frequency-variable array FDA was constructed. The element in the upper left corner of the radar planar array was selected as the reference element. The transmitted signals of all elements were reflected by the target and then received by the set row and column elements to obtain the echo signal. Perform matched filtering on the echo signal, and perform fast Fourier transform on the echo signal after matched filtering in the fast time dimension to obtain the frequency domain expression of the echo signal; In the frequency domain, the range migration caused by target velocity in the echo signal is corrected, and the range curvature caused by target acceleration is corrected using a second-order Keystone transform. The Doppler migration caused by acceleration in the echo signal is corrected using the LVD algorithm. After correcting for range migration, range curvature, and Doppler migration, the range inverse Fourier transform and the azimuth Fourier transform are performed to obtain the target energy coherent accumulation result. Range bending is quadratic range migration.

2. The long-term coherent integration method for a maneuvering target according to claim 1, characterized in that: The transmission signals of all array elements are reflected by the target and then received by array elements in set rows and columns, specifically: The first is described by fast time, frequency modulation, pulse time and rectangular window function m OK n Array element transmits signal , the specific expression is: ； in t 、 μ and T p They are fast time, frequency modulation and pulse time respectively; The transmitted signal is reflected by the target and received by the specific rows and columns of array elements to obtain the echo signal, which is specifically expressed as: ； in, N Indicates the total number of columns; n 1 means the n 1 column; t m Indicates slow time; Indicates delay; represents the pitch angle, Indicates azimuth; G T and G R are the transmit pattern gain and receive pattern gain, respectively.

3. The long-term coherent integration method for a maneuvering target according to claim 2, characterized in that: The matched filtering of the echo signal is specifically performed as follows: Based on the setting that the receiving pattern in the receiving pattern gain depends on the angle, a three-dimensional matched filter function is used to perform matched filtering on the echo signal. Its expression is: ； in conj represents the conjugate operation, represents the convolution operation, is the three-dimensional matched filter function, is the echo signal after receiving beamforming, is the echo signal after matched filtering.

4. The long-term coherent integration method for a maneuvering target according to claim 3, characterized in that: The fast Fourier transform of the echo signal after matched filtering is performed in the fast time dimension to obtain the frequency domain expression of the echo signal, specifically: The matched filtered echo signal is subjected to fast Fourier transform (FFT) in the fast time dimension, and the echo signal received in the frequency domain is represented by the product of the gain brought by the planar array, the rectangular window function of the range frequency, the azimuth window function, and the e-index function of the velocity.

5. The long-term coherent integration method for a maneuvering target according to claim 1, characterized in that: The correction of the range curvature caused by the target acceleration by the second-order Keystone transform and the correction of the Doppler migration caused by the acceleration in the echo signal by the LVD algorithm include: Set the search speed and use it as a compensation function. When the search speed matches the target radial velocity in the echo signal, the range migration caused by the target radial velocity is corrected. After correcting the range migration, the second-order Keystone transform is used to correct the secondary range migration caused by the target acceleration and replace the slow time variable; the secondary range migration is the range curvature; After correcting the quadratic range migration, the fast Fourier transform (FFT) in the fast time dimension is subjected to the inverse fast Fourier transform (IFFT) to obtain the frequency domain expression of the intermediate echo signal. Set the estimated acceleration of the target and use the estimated acceleration as a compensation function to obtain the echo signal of the range unit where the target is located when only the azimuth echo is considered in the intermediate echo signal; According to the LVD algorithm, the time delay variable and the time delay constant are used as the time delay of the echo signal, and the parameter symmetric instantaneous autocorrelation function is constructed by the product of the echo signal with time delay and the complex conjugate echo signal; The slow time variable is equivalent to the ratio of the slow time variable of the estimated acceleration to the time delay variable and the time delay constant, and the equivalent parameter symmetric instantaneous autocorrelation function is obtained through the equivalent slow time variable; The acceleration of the target is taken as the energy peak, and the energy peak is used as the compensation function to correct the Doppler frequency modulation in the final echo signal; Perform Fast Fourier Transform (FFT) on the corrected echo signal and perform Doppler migration (DFM) compensation.

6. The long-term coherent integration method for a maneuvering target according to claim 1, characterized in that: In the radar planar array of the horizontal frequency variation array FDA, there is only a fixed frequency difference ∆ between the array elements. f , let the center frequency of the first element in each column of the planar array be f 0, by center frequency and number of columns n The sum of the frequency differences of -1 is obtained n Frequency of array elements; The frequency increment ∆ f Much smaller than the center frequency f 0.

7. The long-term coherent integration method for a maneuvering target according to claim 1, characterized in that: When the array element at the upper left corner of the radar planar array is selected as the reference array element, the method further includes: The vertical direction of the radar plane array is used as a phased array, and a weight that is consistent with the weight in the horizontal direction is set for each array element in the vertical direction.

8. A long-term coherent integration system for maneuvering targets, characterized in that: include: The signal transmission module is used to construct a radar planar array based on a vertical phased array PA and a horizontal frequency-variable array FDA. The upper left corner element of the radar planar array is selected as the reference element. The transmitted signals of all elements are reflected by the target and then received by the set row and column elements to obtain the echo signal. The filtering module is used to perform matched filtering on the echo signal and perform fast Fourier transform in the fast time dimension on the echo signal after matched filtering to obtain the frequency domain expression of the echo signal; The correction module is used to correct the range migration caused by the target velocity in the echo signal in the frequency domain, and to correct the range curvature caused by the target acceleration through the second-order Keystone transform. The Doppler migration caused by the acceleration in the echo signal is corrected through the LVD algorithm. After the range migration, range curvature, and Doppler migration corrections are made, the range inverse Fourier transform and the azimuth Fourier transform are performed to obtain the target energy coherent accumulation result. Range bending is quadratic range migration.

9. A computer device, characterized in that: The method comprises a memory and a processor, wherein a program is stored in the memory, and when the program is executed by the processor, the processor executes the steps of a long-term coherent accumulation method for a maneuvering target as claimed in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a long-term coherent integration method for a maneuvering target according to any one of claims 1 to 7 are implemented.

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