A method, system, device and medium for long-time coherent accumulation of a motor target

Abstract

The application discloses a long-time coherent accumulation method, system, equipment and medium for a motorized target, relates to the technical field of radar signal processing, and comprises the following steps: the introduction of FDA allows a planar array to realize complete space coverage in the azimuth range dimension. The planar array utilizes three-dimensional information of a target, so that the planar array can obtain higher-dimensional information than coherent FDA. Subsequently, an azimuth-elevation-distance three-dimensional matching filter is designed, and fast matching of a waveform is realized. In view of the influence of the coherent accumulation process of a motorized target, finally, a second-order Keysone transform-LVD algorithm is adopted to compensate for distance migration and Doppler frequency migration in the detection process of a high-altitude motorized target, so that coherent accumulation of the target is realized. The application not only provides a novel radar array combining a PA and a FDA, but also is applied to the field of target detection, and is especially suitable for the detection of a high-altitude motorized target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radar signal processing, and in particular to a long-time coherent accumulation method, system, device and medium for a maneuvering target. BACKGROUND

[0002] With the development of stealth technology, detecting high-altitude maneuvering targets has gradually become a major challenge for radar systems. These targets are typically characterized by long distances, low observability, and high maneuverability. The detection performance of these targets is crucial for target imaging, identification, and tracking. However, the radar cross section (RCS) of such targets is small, and the observation distance 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 long-time coherent accumulation, the speed and acceleration of the target can cause significant cross-range and cross-Doppler effects, which negatively impact radar detection performance.

[0003] A new Radon Fourier Transform (RFT) has been proposed, which utilizes the coupling between the target's radial velocity and range migration (RM) during long-time coherent accumulation. By rescaling the time axis of each frequency using a first-order Keystone Transform (KT), linear range migration (LRM) is corrected, and coherent integration of high-speed moving targets is achieved. However, the presence of radial acceleration components can introduce Doppler frequency migration (DFM) and quadratic range migration (QRM), which reduces the performance of the above algorithm. For the detection of uniform high-speed targets, a second-order trapezoidal transform (SKT) is used to eliminate QRM and achieve coherent integration. The Radon fractional Fourier Transform (RFRFT) algorithm addresses the range migration problem by searching for velocity and acceleration, and uses fractional Fourier Transform (FRFT) for coherent accumulation. This algorithm has strong detection performance and can achieve long-term coherent integration. However, the requirement for parameter search in existing algorithms results in high computational complexity, leading to poor performance during coherent accumulation, especially when the search space is wide. SUMMARY

[0004] The present application aims to address the shortcomings of the prior art and provides a long-time coherent accumulation method, system, device and medium for a maneuvering target to solve the problems in the prior art.

[0005] The present application specifically provides the following technical solutions:

[0006] A long-time coherent accumulation method for a maneuvering target, comprising:

[0007] A radar planar array based on vertical phased array (PA) and horizontal frequency diverse array (FDA) is constructed, a left upper corner element of the radar planar array is selected as a reference element, and all transmitting signals of the elements are received by set row and column elements after being reflected by a target to obtain echo signals;

[0008] The echo signals are matched filtered, and fast Fourier transform of the matched filtered echo signals in a fast time dimension is performed to obtain a frequency domain expression of the echo signals;

[0009] In the frequency domain, range migration caused by target velocity in the echo signals is corrected, range curvature caused by target acceleration is corrected through second order Keystone transform, Doppler migration caused by acceleration in the echo signals is corrected through LVD algorithm, and after the range migration, range curvature and Doppler migration are corrected, inverse range Fourier transform and azimuth Fourier transform are performed to obtain target energy coherent accumulation results; the range curvature is quadratic range migration.

[0010] Preferably, the transmitting signals of all the elements are received by the set row and column elements after being reflected by the target, and specifically, the transmitting signals of all the elements are received by the set row and column elements after being reflected by the target.

[0011] The transmitting signals of the elements are described by fast time, frequency modulation and pulse time and rectangular window function. m Row n Column element transmitting signal , and a specific expression is as follows:

[0012] ;

[0013] Wherein t , μ and T p fast time, frequency modulation and pulse time respectively.

[0014] The echo signals are obtained by receiving the transmitting signals reflected by the target by the specific row and column elements, and a specific expression is as follows:

[0015] ;

[0016] Wherein, N total column number; n 1 represents the first column; n m slow time; t time delay; pitch angle, azimuth angle; G T and G R transmitting pattern gain and receiving pattern gain respectively. ​

[0017] Preferably, the echo signal is matched filtered, specifically:

[0018] Based on the setting that the receiving pattern gain depends on the angle, the echo signal is matched filtered using a three-dimensional matched filter function, which is expressed as:

[0019]

[0020] Wherein conj represents a conjugate operation, represents a convolution operation, is a three-dimensional matched filter function, is the echo signal after receiving beam forming, is the echo signal after matched filtering.

[0021] Preferably, the matched filtered echo signal is subjected to fast Fourier transform in the fast time dimension to obtain a frequency domain expression of the echo signal, specifically:

[0022] The matched filtered echo signal is subjected to fast Fourier transform in the fast time dimension to 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 function of the velocity.

[0023] Preferably, the distance curvature caused by the target acceleration is corrected by a second-order Keystone transform, and the Doppler migration caused by the acceleration in the echo signal is corrected by an LVD algorithm, including:

[0024] A search velocity is set, and the search velocity is used as a compensation function, when the search velocity matches the target radial velocity in the echo signal, the distance migration caused by the target radial velocity is corrected;

[0025] After the distance migration is corrected, the second-order distance migration caused by the target acceleration is corrected by a second-order Keystone transform, and the slow time variable is replaced; wherein the second-order distance migration is the distance curvature;

[0026] After the second-order distance migration is corrected, inverse fast Fourier transform IFFT is performed on the fast Fourier transform FFT in the fast time dimension to obtain a frequency domain expression of the intermediate echo signal;

[0027] An estimated acceleration of the target is set, and the estimated acceleration is used as a compensation function to obtain the echo signal of the distance unit where the target is located in the intermediate echo signal only considering the azimuth echo;

[0028] 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 the time delay and the complex conjugate echo signal.​

[0029] The slow-time variable is equivalent to the ratio of the slow-time variable estimating acceleration to the time delay variable and the time delay constant. The equivalent parametric instantaneous autocorrelation function is obtained through the equivalent slow-time variable.

[0030] The target's acceleration is used as the energy peak value, and the energy peak value is used as the compensation function to correct the Doppler frequency modulation in the final echo signal.

[0031] The corrected echo signal is subjected to Fast Fourier Transform (FFT) for Doppler migration compensation.

[0032] Preferably, 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, through center frequency and column number n The sum of frequency differences of -1 yields the first... n The frequency of the array elements; where the frequency increment ∆ f Much smaller than the center frequency f 0.

[0033] Preferably, when selecting the upper left corner element of the radar planar array as the reference element, the method further includes:

[0034] Using the vertical direction of the radar planar array as the phased array, each array element in the vertical direction is assigned a weight that is consistent with the weight in the horizontal direction.

[0035] This invention provides a long-term coherent accumulation system for maneuvering targets, comprising:

[0036] The signal transmission module is used to construct a radar planar array based on a vertical phased array (PA) and a horizontal frequency-varying 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 received by the set row and column elements to obtain the echo signal.

[0037] The filtering module is used to perform matched filtering on the echo signal and to perform fast Fourier transform on the matched filtered echo signal in a fast time dimension to obtain the frequency domain expression of the echo signal.

[0038] The correction module is used to correct range migration caused by target velocity in the echo signal in the frequency domain, and to correct range curvature caused by target acceleration through second-order Keystone transform. It also corrects Doppler migration caused by acceleration in the echo signal through LVD algorithm. After correcting range migration, range curvature and Doppler migration, it performs inverse range Fourier transform and azimuth Fourier transform to obtain the coherent accumulation result of target energy; the range curvature is a second-order range migration.

[0039] The application provides a computer device, comprising a memory and a processor, the memory stores a program, and the program is executed by the processor to make the processor execute the steps of the long-time coherent accumulation method of the motor target.

[0040] The application provides a storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the long-time coherent accumulation method of the motor target.

[0041] Compared with the prior art, the application has the following remarkable advantages:

[0042] In the detection of the high-altitude motor target, the method of combining the vertical phased array and the horizontal frequency diversity array PA-FDA is used, so that the plane array can realize full coverage in the azimuth dimension compared with the conventional phased array, the information of the higher one-dimensional target can be used, the wide-range parameter traversal search on the speed and acceleration is not needed, the problem of the sharp increase of the calculation complexity caused by the parameter search of the RFRFT is fundamentally avoided, the efficiency of the coherent accumulation process is significantly improved, and the plane array is used to transmit signals to detect the target, even in the complex dynamic scene (the search space is very wide) of the high-altitude motor target, the echo received can still be calculated and processed, so that the range migration (RM) and the Doppler migration (DFM) caused by the speed and acceleration of the motor target in the detection process are solved, the long-time coherent accumulation of the motor target is realized, and the target energy is well focused. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 FIG. 1 is an antenna structure schematic diagram of the motor target long-time coherent accumulation method based on the vertical PA and the horizontal FDA plane array of the application;

[0044] Figure 2 FIG. 2 is an array surface structure schematic diagram in the embodiment of the application;

[0045] Figure 3 FIG. 3 is a transmitting direction pattern of the array surface in the embodiment of the application; wherein Figure 3 (a) of FIG. 3 is a transmitting direction pattern, Figure 3 (b) of FIG. 3 is a change diagram of the transmitting direction angle, Figure 3 (c) of FIG. 3 is a transmitting direction pattern feature of the FDA, Figure 3 (d) of FIG. 3 is a transmitting direction pattern feature of the PA;

[0046] Figure 4 FIG. 4 is a three-dimensional schematic diagram of the matched filtering result of the target in the embodiment of the application; and Figure 4(a) is a three-dimensional diagram. Figure 4 (b) is a two-dimensional schematic diagram of the angular direction. Figure 4 (c) is a two-dimensional schematic diagram of time and angular direction. Figure 4 (d) is a two-dimensional schematic diagram of time and phase angle direction;

[0047] Figure 5 This is an image of the coherent accumulation process of a high-altitude maneuvering target in the simulation of this invention; Figure 5 (a) is a coherent accumulation diagram. Figure 5 (b) is the image after LRM correction of the target. 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 a Fast Fourier Transform (FFT) on the Doppler image;

[0048] Figure 6 The flowchart illustrates a long-term coherent accumulation method for maneuvering targets provided by this invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0050] Phased array (PA) radar offers fast antenna beam scanning and spatial filtering capabilities. Frequency-changing array (FDA) radar features automatic scanning of the transmitted beam pattern and provides wide spatial coverage. Based on these advantages, this invention proposes a planar array combining elements of both radar systems. In the planar array of the horizontal frequency-changing array (FDA), each column of elements can be considered as a PA radar, with only one phase difference. The planar array has M rows and N columns, and each row of elements can be considered as an FDA radar, specifically as follows... Figure 2 As shown, there is only one frequency difference ∆f between the array elements. Let the center frequency of the first element in each column of the planar array be... f 0, through center frequency and column number n The sum of frequency differences of -1 yields the first... n The frequency of the array elements; where the frequency increment ∆ f Much smaller than the center frequency f 0.

[0051] ;

[0052] Wherein, frequency increment ∆ f Much smaller than the center frequencyf 0.

[0053] The transmitted beam pattern of the planar array was simulated and analyzed, and three-dimensional matched filtering of azimuth-elevation-range was implemented. The filtering results are as follows. Figure 4 As shown, the introduction of FDA allows planar arrays to achieve full airspace coverage in the azimuth range. This planar array utilizes three-dimensional target information (azimuth, elevation, and range), enabling it to acquire higher-dimensional information than coherent FDA. Subsequently, a three-dimensional matched filter (azimuth-elevation-range) was designed to achieve rapid waveform matching. To address the impact of the coherent accumulation process of moving targets, a second-order trapezoidal transform-LVD (SKT-LVD) algorithm was used to compensate for range offset (RM) and Doppler frequency offset (DFM) during moving target detection, achieving coherent accumulation of the target and effectively focusing the target energy.

[0054] This embodiment provides a long-term coherent accumulation method for maneuvering targets, comprising the following steps:

[0055] Step S1: Construct a radar planar array based on a vertical phased array (PA) and a horizontal frequency-varying array (FDA). Select the upper left corner element 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.

[0056] First, the characteristics of the surface are analyzed, considering a linear frequency modulation (LFM) signal. The first characteristic is described by fast time, frequency modulation, pulse time, and a rectangular window function. m OK n Array element transmits signal The specific expression is:

[0057] ;

[0058] in t , μ and T p These are fast time, frequency modulation, and pulse time, respectively.

[0059] Choose the element at the top left corner of the array as the reference element. Consider a moving target in three-dimensional space. The signal originates from the... M (m1=1,2,...,M) rows and the first N The echo signals emitted by the (n1=1,2,…,N) column elements and scattered are received by antennas m2 and n2. for:

[0060] ;

[0061] like Figure 1As 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 plane of the radar plane array is phased, a weight consistent with the weight in the horizontal direction is set for each array element in the vertical direction, and then the echo signal is obtained, and the transmitting direction pattern of the plane array is obtained from the echo signal , which can be expressed as

[0062] ;

[0063] The transmitting direction pattern of the array can be analyzed, and it is modulated by the azimuth angle, the elevation angle and the distance, and because the horizontal direction of the array is FDA, the introduction of FDA enables full coverage in the azimuth angle dimension. By slicing the direction pattern in the azimuth angle-distance and elevation angle-fast time dimensions, the transmitting direction pattern characteristics of the frequency diversity array radar FDA and the phased array radar PA can be observed.

[0064] In the plane array system, the received echo signal is considered by column. The echo signal is obtained by receiving the reflected signal by the target by a specific row-column array element, and the echo signal after mixing the obtained echo signal , which can be expressed as

[0065] ;

[0066] , wherein N represents the total number of columns; n 1 represents the first n 1 column; t m represents slow time; represents time delay; represents the elevation angle, represents the azimuth angle; G T and G R are the transmitting direction pattern gain and the receiving direction pattern gain, is the wavelength, and the specific expression is

[0067] ;

[0068] ;

[0069] Step S2: Match filtering the echo signal, and performing fast Fourier transform on the fast time dimension of the matched filtered echo signal to obtain the frequency domain expression of the echo signal.

[0070] Because it is based on the vertical phased array PA and the horizontal frequency diversity array FDA, the conventional beam forming technology is used at the receiving end, and for the beam pointing and Two weight vectors are set for row and column respectively 、 Two weight vectors can be expressed as:

[0071] ;

[0072] ;

[0073] Therefore, the beam weight vector can be expressed in the following form, where denotes the Kronecker product, and the specific expression is:

[0074] ;

[0075] The received beam-formed echo signal can be expressed as:

[0076] ;

[0077] From the receiving pattern, it can be seen that the receiving beam pattern is only related to the angle, and therefore the beam forming has no effect on the time-domain echo waveform. The angle includes the azimuth angle and the elevation angle. In order to realize the matched filtering of any point in space, a matched filtering function needs to be designed to match each angle in space, and the matched filtering can be written as:

[0078] ;

[0079] where is a transmitting pattern matching function, which can be expressed as:

[0080] ;

[0081] where denotes the matched filtering form of an arbitrary waveform, and for a given angle, the matched filtering function is affected by the transmitting beam pattern. Therefore, based on the setting that the receiving pattern depends on the angle in the receiving pattern gain, the echo signal is matched filtered using a three-dimensional matched filtering function, and the expression is:

[0082] ;

[0083] where conj denotes the conjugate operation, denotes the convolution operation, which allows the target to be matched filtered in a three-dimensional space, where is a three-dimensional matched filtering function, is a received beam-formed echo signal, is a matched filtered echo signal.

[0084] Because the target is in motion state in the process of target detection, the detection of the high-altitude moving target will result in low echo energy; in order to improve the signal-to-noise ratio, the target needs to be continuously observed to accumulate the target echo energy. However, the speed and acceleration of the target will cause range migration and Doppler migration, and therefore the errors caused by the speed and acceleration of the target need to be corrected.

[0085] The matched filtered echo is subjected to fast Fourier transform (FFT) in the fast time dimension, and the signal received in the range frequency domain is:

[0086] 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 expressed by the product of the gain brought by the planar array, the range frequency rectangular window function, the azimuth window function, and the velocity e index function The specific expression is:

[0087] ;

[0088] Wherein and respectively represent the range frequency and the azimuth window function, is the gain brought by the planar array.

[0089] As can be seen from the frequency domain expression in the fast time dimension, the radial velocity v of the moving target is coupled with the range frequency f, thereby causing linear range migration (LRM). Meanwhile, the existence of the acceleration of the target is coupled with the range frequency f and the center frequency f 0, thereby respectively causing quadratic range migration (QRM, also referred to as range curvature) and Doppler migration (DFM), and therefore in order to eliminate the influence caused by the motion of the target in the observation process, the errors caused by the motion of the target need to be corrected.

[0090] Step S3: in the frequency domain, the range migration caused by the speed of the target in the echo signal is corrected, the range curvature caused by the acceleration of the target is corrected through the second Keystone transform, the Doppler migration caused by the acceleration of the target in the echo signal is corrected through the LVD algorithm, and after the range migration, the range curvature and the Doppler migration are corrected, inverse range Fourier transform and azimuth Fourier transform are performed to obtain the target energy coherent accumulation result; the range curvature is quadratic range migration.

[0091] The matched filtered signal is processed in the frequency domain, and the errors caused by the speed and acceleration of the moving target in the observation process are compensated, so that the focusing effect of the target can be obtained.

[0092] The range curvature caused by the acceleration of the target is corrected through the second Keystone transform, and the Doppler migration caused by the acceleration of the target in the echo signal is corrected through the LVD algorithm, including:

[0093] According to the frequency domain of the fast time dimension, a compensation function can be set, that is, a search velocity is set, and the search velocity is taken as the compensation function, when the search velocity matches the target radial velocity in the echo signal, the distance migration caused by the target radial velocity is corrected , which is expressed as:

[0094] ;

[0095] Wherein represents the search velocity.

[0096] After correcting the distance migration, a second-order Keystone (SKT) transform is used to correct the quadratic range migration (QRM) caused by the target acceleration; wherein the quadratic range migration is a distance curvature. The SKT is equivalent to replacing the slow time variable, and the relationship between the variables can be written as:

[0097] ;

[0098] Wherein τ m is a new slow time variable, after the quadratic range migration is corrected, an inverse fast Fourier transform IFFT is performed on the fast time dimension to obtain a frequency domain expression of the intermediate echo signal , and the expression is:

[0099] ;

[0100] Wherein it is seen that the QRM caused by the target acceleration a is eliminated, and the LRM caused by the target velocity v is reduced by half. After compensating for the RM, it is necessary to accurately correct the Doppler frequency modulation (DFM) effect in the LFM signal to realize accurate focusing of the energy of the moving target. In order to correct the DFM, a compensation function can be constructed according to 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, taking the estimated acceleration as the compensation function, obtaining the echo signal of the distance unit where the target is located when only considering the azimuth echo in the intermediate echo signal, the echo signal of the distance unit where the target is located can be written as:

[0101] ;

[0102] Wherein A represents the amplitude of the signal, according to the definition of LVD, the time delay variable and the time delay constant are taken as the time delay of the echo signal, and the parameter symmetric instantaneous autocorrelation function (PSIAF) is constructed by the product of the echo signal with the time delay and the complex conjugate echo signal , which can be expressed as:

[0103] ;

[0104] wherein, is a time delay variable, and has the same interval, is a time delay constant.

[0105] The slow time variable is equivalent to the slow time variable of the estimated acceleration and the time delay variable, the time delay constant and the ratio of, the equivalent parameter symmetric instantaneous autocorrelation function is obtained by the equivalent slow time variable, specifically:

[0106] After that, in order to decouple, It can be changed to:

[0107] ;

[0108] wherein, h is the equivalent slow time normalization coefficient. After replacement, the parameter symmetric instantaneous autocorrelation function (PSIAF) can be written as , the specific expression is expression can be written as:

[0109] ;

[0110] From the above formula, the coupling between the slow time variable and the time delay variable has been eliminated. Then, the processed echo signal is subjected to two-dimensional (2-D) FFT to obtain the target energy coherent accumulation , which can be expressed as:

[0111] ;

[0112] It can be seen that LVD involves three steps: correlation, decoupling and two-dimensional FFT. In these steps, the correlation extends the direction echo energy of the target from one dimension to two dimensions. Then, the decoupling eliminates the coupling between the variables. Finally, the energy accumulation of the signal is realized by 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 value, so as to construct a compensation function to correct the DFM. That is, the acceleration of the target is taken as the energy peak value, and the energy peak value is taken as the compensation function, and the Doppler frequency modulation in the final echo signal is corrected, and the compensation function can be written as:

[0113] ;

[0114] The corrected echo signal is subjected to fast Fourier transform (FFT), and the Doppler migration (DFM) compensation is performed, and the result can be expressed as:

[0115] ;

[0116] in f g For slow time variables The corresponding Doppler frequency variable is used to achieve DFM compensation and coherent accumulation.

[0117] The invention will now be further described with reference to simulation diagrams.

[0118] 1. Simulation parameters:

[0119] Simulation parameters are shown in Table 1:

[0120] Table 1. Overview of Simulation Parameters

[0121]

[0122] 2. Simulation content and result analysis:

[0123] Under the simulation parameters in Table 1 above, the radiation pattern of a planar array combining a vertical phased array and a horizontal frequency diversity array was analyzed using the technology of this invention. The transmission radiation pattern is as follows: Figure 3 As shown, the introduction of the FDA enables it to achieve full airspace coverage in the azimuth dimension, and the slice diagrams show the launch pattern characteristics of the FDA and PA respectively.

[0124] Figure 5 To utilize this array for coherent accumulation of data on maneuvering targets, the target's LRM is first corrected. The corrected image is shown below. Figure 5 (b) Secondly, the QRM is corrected using the second-order Keystone Transform (SKT), and the corrected effect is as follows. Figure 5 (c) Finally, the DFM problem is solved using LVD, and a Fast Fourier Transform (FFT) is performed on the Dopplerweiss to obtain... Figure 5 (d) The target has a good focusing effect.

[0125] Based on the above method, this invention proposes a long-term coherent accumulation system for maneuvering targets, comprising: a signal transmission module, a filtering module, and a correction module.

[0126] The signal sending module is configured to construct a radar planar array based on a vertical phased array (PA) and a horizontal frequency diversity array (FDA), select a top-left element of the array surface of the radar planar array as a reference element, receive, by the set row and column elements, the transmission signals of all elements after being reflected by a target to obtain a return signal, and the filter module is configured to perform fast Fourier transform on the received return signal in a fast time dimension to obtain a frequency domain of the return signal, design a three-dimensional matched filter function to perform matched filtering on the return signal to obtain a frequency domain expression after matched filtering, the correction module is configured to correct, in the frequency domain, range migration caused by a target speed, correct range curvature caused by a target acceleration through a second-order Keystone transform, correct Doppler migration caused by the acceleration in the return signal through an LVD algorithm, and perform inverse range Fourier transform and azimuth Fourier transform after correction of the range migration, the range curvature and the Doppler migration to obtain a target energy coherent integration result, and the range curvature is quadratic range migration.

[0127] The application further provides a computer device comprising a memory and a processor, the memory storing a program, and the program being executed by the processor to make the processor execute the steps of the long-time coherent integration method for a maneuvering target.

[0128] According to the disclosed embodiments, the computer device can communicate with one or more external devices (such as a keyboard, a pointing device, a Bluetooth communication, etc.), or communicate with any device (such as a router, a demodulator, etc.) that enables the computer device to communicate with one or more other computer devices.

[0129] The application further provides a storage medium storing a computer program, and the computer program being executed by the processor to implement the steps of the long-time coherent integration method for a maneuvering target.

[0130] According to the disclosed embodiments, the storage medium can be a non-volatile computer readable storage medium, which can include but is not limited to a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the present application, the storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus or device.

[0131] The above is a further detailed description of the application in combination with the specific preferred embodiments, and for those skilled in the art, without departing from the concept of the application, a number of simple deductions or substitutions can also be made, which should be considered as falling within the protection scope of the application.

Claims

1. A method for long-time coherent accumulation of a motorized target, characterized in that, The application relates to a radar plane array based on a vertical phased array (PA) and a horizontal frequency variable array (FDA), a reference array element is selected at the left upper corner of the array plane of the radar plane array, the transmitting signals of all array elements are received by set row and column array elements after being reflected by a target to obtain echo signals, the echo signals are matched filtered, and fast Fourier transform (FFT) of the fast time dimension of the matched filtered echo signals is carried out to obtain a frequency domain expression of the echo signals. In the frequency domain, distance migration caused by target speed in the echo signals is corrected, distance curvature caused by target acceleration is corrected through a second Keystone transform, Doppler migration caused by acceleration in the echo signals is corrected through an LVD algorithm, and after the distance migration, the distance curvature and the Doppler migration are corrected, inverse distance Fourier transform and azimuth Fourier transform are carried out to obtain target energy coherent accumulation results; the distance curvature is quadratic distance migration. The method for correcting the distance curvature caused by target acceleration through the second Keystone transform and correcting the Doppler migration caused by acceleration in the echo signals through the LVD algorithm comprises the following steps: A search speed is set, and the search speed is used as a compensation function; when the search speed matches the target radial speed in the echo signals, the distance migration caused by the target radial speed is corrected. After the distance migration is corrected, the second distance migration caused by target acceleration is corrected through the second Keystone transform, and a slow time variable is replaced; wherein the second distance migration is the distance curvature. After the second distance migration is corrected, inverse fast Fourier transform (IFFT) of fast Fourier transform (FFT) of the fast time dimension is carried out to obtain a frequency domain expression of an intermediate echo signal. An estimated acceleration of the target is set, and the estimated acceleration is used as a compensation function to obtain echo signals of a distance unit where the target is located in the intermediate echo signals only considering azimuth echoes. According to the LVD algorithm, a time delay variable and a time delay constant are used as time delays of the echo signals, and a parameter symmetric instantaneous autocorrelation function is constructed through the product of the echo signals with the time delays and a complex conjugate echo signal. The slow time variable is equivalent to the ratio of the slow time variable of the estimated acceleration to the sum of the time delay variable, the time delay constant and the time delay constant, and an equivalent parameter symmetric instantaneous autocorrelation function is obtained through the equivalent slow time variable. The acceleration of the target is used as an energy peak value, and the energy peak value is used as a compensation function to correct Doppler frequency modulation in a final echo signal. Fast Fourier transform (FFT) is carried out on the corrected echo signal to carry out Doppler migration (DFM) compensation. The transmitting signals of all array elements are received by set row and column array elements after being reflected by a target to obtain echo signals. The transmitting signals of all array elements are received by set row and column array elements after being reflected by a target to obtain echo signals.

2. A method for long-time coherent integration of a motorized target as claimed in claim 1, characterized in that, The echo signals are matched filtered. The signals transmitted by the array elements are described by fast time, frequency and pulse time and a rectangular window function m row n array element transmit signals The specific expression is: ； wherein t , Based on the setting that the receiving direction pattern depends on the angle in the receiving direction pattern gain, a three-dimensional matched filtering function is used to match filter the echo signals, and the expression is as follows: and T p are fast time, frequency modulation rate and pulse time, respectively; The echo signals are matched filtered. ； wherein, N represents the total number of columns; n 1 represents the first n column; t m represents a slow time; The echo signals are matched filtered. represents a time delay; represents a pitch angle, represents an azimuth angle; G T and G R are the transmit and receive pattern gains, respectively.

3. A method for long-time coherent integration of a motorized target as claimed in claim 2, characterized in that, ​ ​ ； wherein ​ represents a convolution operation, is a three-dimensional matched filter function, is a received beamformed echo signal, is a matched filtered echo signal.

4. A method of long-time coherent integration of a motorized target as claimed in claim 3, characterized in that, ​ Performing fast Fourier transform (FFT) on the matched filtered echo signal in the fast time dimension to represent the received echo signal in the frequency domain as the product of the gain of the planar array, the range frequency rectangular window function, the azimuth window function, and the velocity e-function.

5. A method for long-time coherent integration of a motorized target as claimed in 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, through center frequency and column number n The sum of frequency differences of -1 yields the first... n The frequency of the array elements; where the frequency increment Δ f much less than the center frequency f 0.

6. A method for long-time coherent integration of a motorized target as claimed in claim 1, characterized in that, When the upper left corner element of the radar planar array is selected as the reference element, the method further comprises: Taking the vertical direction of the radar planar array as the phased array, a weight consistent with the weight in the horizontal direction is set for each element in the vertical direction.

7. A motional target long coherent integration system, characterized by, The method comprises: The signal sending module is configured to construct a radar planar array based on a vertical phased array (PA) and a horizontal frequency diversity array (FDA), select the upper left corner element of the radar planar array as the reference element, and receive the echo signal of all the elements after the transmission signals of all the elements are reflected by a target. The filtering module is configured to perform matched filtering on the echo signal, and perform fast Fourier transform (FFT) on the matched filtered echo signal in the fast time dimension to obtain the frequency domain expression of the echo signal. The correction module is configured to correct the range migration caused by the target velocity in the echo signal in the frequency domain, correct the range curvature caused by the target acceleration by performing second-order Keystone transform, correct the Doppler migration caused by the target acceleration in the echo signal by using the LVD algorithm, and perform range inverse Fourier transform and azimuth Fourier transform after the correction of the range migration, the range curvature, and the Doppler migration to obtain the target energy coherent integration result. The range curvature is the second-order range migration. The method comprises: The search velocity is set as the compensation function, and the range migration caused by the target radial velocity is corrected when the search velocity matches the target radial velocity in the echo signal. After the correction of the range migration, the second-order range migration caused by the target acceleration is corrected by using the second-order Keystone transform to replace the slow time variable. The second-order range migration is the range curvature. After the correction of the second-order range migration, inverse fast Fourier transform (IFFT) is performed on the fast Fourier transform (FFT) in the fast time dimension to obtain the frequency domain expression of the intermediate echo signal. The estimated acceleration of the target is set as the compensation function, and the echo signal of the target in the distance unit considering only the azimuth echo in the intermediate echo signal is obtained. According to the LVD algorithm, the time delay variable and the time delay constant are set 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 the 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 sum of the time delay variable, the time delay constant, and 1, and the equivalent parameter symmetric instantaneous autocorrelation function is obtained by using the equivalent slow time variable. The acceleration of the target is set as the energy peak value, and the Doppler frequency modulation in the final echo signal is corrected by using the energy peak value as the compensation function. The corrected echo signal is subjected to fast Fourier transform (FFT) to perform Doppler migration (DFM) compensation.

8. A computer device, comprising: The computer program is executed by a processor to implement the steps of the long-time coherent accumulation method of a motorized target according to any one of claims 1 to 6.

9. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by a processor to implement the steps of the long-time coherent accumulation method of a motorized target according to any one of claims 1 to 6.

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