Clutter-avoiding airborne radar target detection method, system, device and medium

Abstract

The application discloses a clutter-avoiding airborne radar target detection method, system, device and medium. The detection method comprises the following steps: collecting echo signals; grouping the echo signals according to a pulse repetition frequency to obtain a pulse repetition frequency signal group; performing Keystone transformation and Doppler ambiguity number compensation processing on all pulse repetition frequency signal groups, performing discrete Fourier transform at a slow-time sampling moment, performing first-layer detection threshold detection on a range-Doppler result, performing demodulation and coherent processing to obtain a coherent result; performing second-layer detection threshold detection on the coherent result, and performing target judgment and parameter estimation to obtain accurate range information of the target and speed information of the target. The detection method can effectively avoid the influence of clutter on the target and realize two-dimensional demodulation processing of the range-Doppler of the target, thereby effectively improving the detection accuracy of the target. The application can be widely applied to the technical field of radar detection.

Description

Technical Field

[0001] This invention relates to the field of radar detection technology, and in particular to an airborne radar target detection method, system, device, and medium for clutter avoidance. Background Technology

[0002] After decades of development, radar is now widely used in military and civilian fields such as target detection, tracking, and imaging, bringing great convenience to people's work and life. To address the look-down problem, airborne pulse-Doppler radar is widely used. However, range and velocity ambiguity are unavoidable problems during target detection. Simultaneously, radar receives strong clutter; when a moving radar is in different positions, the ambiguity from this clutter can obscure moving targets, reducing the radar's target detection probability. Because target and ground clutter echo signals may be ambiguous, using a single fixed PRF signal may not yield accurate target information.

[0003] Currently, the conventional method in the radar field is to use multiple pulse repetition frequencies (Multi-PRF) for detection, perform target detection based on the range-Doppler (RD) spectra of different PRF echoes, and use the Chinese remainder theorem to resolve range and velocity ambiguities, ultimately obtaining accurate range and velocity information for the target. Improving target detection accuracy, avoiding clutter, and performing two-dimensional unambiguation processing on the target's range-Doppler spectrum are pressing technical challenges that need to be addressed. Summary of the Invention

[0004] The purpose of this invention is to at least partially solve one of the technical problems existing in the related art.

[0005] Therefore, one objective of this invention is to provide an airborne radar target detection method that avoids clutter. This detection method can effectively avoid the influence of clutter on the target while achieving two-dimensional de-ambiguity processing of the target range Doppler, thereby effectively improving the target detection accuracy.

[0006] Another objective of this application is to provide an airborne radar detection system that avoids clutter.

[0007] To achieve the above-mentioned technical objectives, the technical solutions adopted in the embodiments of this application include:

[0008] In a first aspect, embodiments of this application provide an airborne radar detection method for clutter avoidance, including:

[0009] Collect the echo signal of the airborne radar;

[0010] The echo signals are grouped according to the pulse repetition frequency to obtain pulse repetition frequency signal groups;

[0011] For all pulse repetition frequency signal groups, Keystone transform and Doppler ambiguity number compensation processing are applied, and then discrete Fourier transform is performed at the slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group;

[0012] The distance Doppler results are subjected to a first-level detection threshold, followed by deblurring and coherent processing to obtain coherent results.

[0013] The coherent results are subjected to a second-layer detection threshold detection. Based on the obtained second-layer detection results, target determination and parameter estimation are performed to obtain the accurate distance and velocity information of the target.

[0014] In addition, the detection method according to the above embodiments of this application may also have the following additional technical features:

[0015] Furthermore, in one embodiment of this application, the airborne radar is used to generate a transmission signal, the transmission signal including pulses corresponding to the pulse repetition frequency group;

[0016] The first pulse between each of the transmitted signals is transmitted according to the first pulse interval corresponding to the pulse repetition frequency group, and the subsequent pulses of each of the transmitted signals are transmitted sequentially according to the pulse repetition frequency corresponding to the pulse repetition frequency in the pulse repetition frequency group, wherein the different transmitted signals are orthogonal to each other.

[0017] Furthermore, in one embodiment of this application, after grouping the echo signals according to the pulse repetition frequency to obtain pulse repetition frequency signal groups, the method further includes:

[0018] The pulse repetition frequency signal group is subjected to pulse compression processing.

[0019] Furthermore, in one embodiment of this application,

[0020] The Doppler sampling intervals of the pulse repetition frequency signal groups are the same.

[0021] Furthermore, in one embodiment of this application, after performing Keystone transform and Doppler ambiguity number compensation processing on all pulse repetition frequency signal groups, and then performing slow-time discrete Fourier transform to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group, the method further includes:

[0022] Based on the distance Doppler results, a matching calculation is performed to obtain the correct Doppler information corresponding to the pulse repetition frequency signal group.

[0023] Furthermore, in one embodiment of this application, the step of performing defuzzification and coherent processing to obtain a coherent result further includes:

[0024] Coherent processing coefficients are constructed using the target's true Doppler frequencies;

[0025] Based on the true Doppler frequency, determine the fuzzy post-Doppler unit in the distance Doppler result that corresponds to the true Doppler frequency;

[0026] The blurred post-Doppler unit is subjected to coherent processing based on the coherent processing coefficients to determine the coherent result.

[0027] Furthermore, in one embodiment of this application, the step of performing a first-layer detection threshold detection on the distance Doppler result, followed by deblurring and coherent processing to obtain a coherent result, further includes determining the validity of the coherent accumulation;

[0028] The determination of the effectiveness of coherent accumulation includes:

[0029] The coherent processing coefficients are used to directly coherently process each frequency point in the range Doppler result, and false frequency points in the coherent processing result are removed according to the preset removal rules to obtain the direct coherent processing result.

[0030] The validity of the coherent accumulation is determined based on the direct coherent processing results and the coherent results.

[0031] Secondly, embodiments of this application provide an airborne radar target detection method, system, apparatus, and medium for clutter avoidance, including:

[0032] The acquisition module is used to acquire the echo signal of the airborne radar;

[0033] The grouping module is used to group the echo signal according to the pulse repetition frequency to obtain pulse repetition frequency signal groups;

[0034] The processing module is used to process all pulse repetition frequency signal groups using Keystone transform and Doppler ambiguity number compensation, and then perform discrete Fourier transform at the slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group.

[0035] The detection module is used to perform a first-level detection threshold detection on the distance Doppler results, and then perform deblurring and coherent processing to obtain coherent results;

[0036] The determination module is used to perform second-layer detection threshold detection on the coherent results, and to determine the target and estimate parameters based on the obtained second-layer detection results, so as to obtain the accurate distance and velocity information of the target.

[0037] Thirdly, embodiments of this application also provide an airborne radar target detection device for clutter avoidance, comprising:

[0038] At least one processor;

[0039] At least one memory for storing at least one program;

[0040] When the at least one program is executed by the at least one processor, the at least one processor implements the airborne radar target detection method for clutter avoidance described in the first aspect above.

[0041] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a processor-executable program, which, when executed by the processor, is used to implement the airborne radar target detection method for clutter avoidance described in the first aspect.

[0042] The advantages and beneficial effects of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application:

[0043] This application discloses an airborne radar target detection method, system, device, and medium for clutter avoidance. The method involves acquiring the echo signal from the airborne radar; grouping the echo signal according to the pulse repetition frequency to obtain pulse repetition frequency signal groups; applying Keystone transform and Doppler ambiguity compensation processing to all pulse repetition frequency signal groups, followed by discrete Fourier transform at slow sampling times to obtain range Doppler results corresponding to the pulse repetition frequency signal groups; performing first-level detection threshold detection on the range Doppler results, followed by deambiguation and coherent processing to obtain coherent results; performing second-level detection threshold detection on the coherent results; and performing target determination and parameter estimation based on the obtained second-level detection results to obtain the accurate range and velocity information of the target. This detection method can effectively avoid the influence of clutter on the target while achieving two-dimensional deambiguation processing of the target range Doppler, thereby effectively improving the target detection accuracy. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following description is provided with accompanying drawings of the relevant technical solutions in the embodiments of this application or the prior art. It should be understood that the accompanying drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions in this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0045] Figure 1A flowchart illustrating an airborne radar target detection method for clutter avoidance provided in an embodiment of this application;

[0046] Figure 2 A schematic diagram illustrating the principle of alternating transmission of multiple orthogonal signals by an airborne radar, provided for an embodiment of this application;

[0047] Figure 3 This is a two-dimensional schematic diagram of the range Doppler results for signal groups with different pulse repetition frequencies provided in an embodiment of this application;

[0048] Figure 4 A schematic diagram of the detection result of a first-layer detection threshold provided in an embodiment of this application;

[0049] Figure 5 A comparative schematic diagram illustrating the effectiveness of coherent accumulation provided for embodiments of this application;

[0050] Figure 6 A schematic diagram of the detection result of a second-layer detection threshold provided in an embodiment of this application;

[0051] Figure 7 A schematic diagram of Doppler resolution using a conventional Multi-PRF detection method is provided as an embodiment of this application.

[0052] Figure 8 A schematic diagram of Doppler resolution for an embodiment of this application using the detection method of this application;

[0053] Figure 9 This application provides a target detection probability comparison chart as an embodiment.

[0054] Figure 10 A speed estimation accuracy comparison chart provided for embodiments of this application;

[0055] Figure 11 A schematic diagram of the structure of an airborne radar target detection system for clutter avoidance provided in an embodiment of this application;

[0056] Figure 12 This is a schematic diagram of the structure of an airborne radar target detection device for clutter avoidance provided in an embodiment of this application. Detailed Implementation

[0057] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0059] Currently, the conventional method in the radar field is to use multiple pulse repetition frequencies (Multi-PRF) for detection, perform target detection based on the range-Doppler (RD) spectra of different PRF echoes, and use the Chinese remainder theorem to resolve range and velocity ambiguities, ultimately obtaining accurate range and velocity information for the target. Improving target detection accuracy, avoiding clutter, and performing two-dimensional unambiguation processing on the target's range-Doppler spectrum are pressing technical challenges that need to be addressed.

[0060] To address the challenges of clutter avoidance and target detection under range Doppler two-dimensional ambiguity in radar systems, numerous scholars have conducted related research. Currently, commonly used target detection techniques mainly include:

[0061] 1) Each PRF signal group in the Multi-PRF is detected independently;

[0062] 2) A detection method that uses multiple sets of signal RD results for non-coherent processing.

[0063] Because each PRF signal group in a traditional Multi-PRF performs target detection separately and independently, it cannot utilize the energy of the entire beam's main time, resulting in a decrease in target detection performance at low signal-to-noise ratios. Furthermore, traditional Multi-PRF suffers from the problem of non-coherent processing of multiple signal groups. When the RD results of multiple signal groups are processed non-coherently, the time interval between each PRF group is relatively large. For high-speed targets, the starting position of the target in the echoes of different PRFs may be significantly coherent, causing inconsistencies in the range cells of the target in different PRF signals. This leads to the inability to achieve effective non-coherent target accumulation, and the existence of matching errors makes it difficult to resolve the target's range and Doppler ambiguity.

[0064] In view of this, embodiments of the present invention provide an airborne radar target detection method for clutter avoidance. This detection method can effectively avoid the influence of clutter on the target while realizing two-dimensional de-ambiguation processing of the target range Doppler, thereby effectively improving the target detection accuracy.

[0065] Reference Figure 1 In this application embodiment, a clutter-avoidance airborne radar target detection method includes:

[0066] Step 110: Collect the echo signal of the airborne radar;

[0067] Specifically, in some embodiments, the airborne radar is used to generate a transmission signal, the transmission signal including pulses corresponding to the pulse repetition frequency group;

[0068] The first pulse between each of the transmitted signals is transmitted according to the first pulse interval corresponding to the pulse repetition frequency group, and the subsequent pulses of each of the transmitted signals are transmitted sequentially according to the pulse repetition frequency corresponding to the pulse repetition frequency in the pulse repetition frequency group, wherein the different transmitted signals are orthogonal to each other.

[0069] It is understood that airborne radar refers to any airborne radar in the relevant technology. It is understood that the airborne radar emits a signal, which is then received again by the airborne radar as an echo signal. Collecting the echo signal from the airborne radar is to facilitate the detection of the target's position and velocity in subsequent steps.

[0070] Specifically, refer to Figure 2 The pulse repetition frequency group includes the pulse frequency and pulse interval of each transmitted signal. When the airborne radar transmits a signal, the first pulse of a certain transmitted signal is transmitted according to the first pulse interval corresponding to the pulse repetition frequency group. Subsequent pulses are transmitted sequentially according to the corresponding pulse repetition frequencies in the pulse repetition frequency group, and so on for other transmitted signals. This application will not elaborate further. In addition, the different transmitted signals are orthogonal to each other, which can improve the channel utilization.

[0071] Step 120: Group the echo signals according to the pulse repetition frequency to obtain pulse repetition frequency signal groups;

[0072] Step 120, grouping the echo signals according to the pulse repetition frequency to obtain pulse repetition frequency signal groups, further includes:

[0073] Step 121: Perform pulse compression processing on the pulse repetition frequency signal group.

[0074] Understandably, when an airborne radar acquires an echo signal, it can group the echo signals according to the pulse repetition frequency of each pulse in the pulse repetition frequency group when the airborne radar transmits the signal, thus obtaining a pulse repetition frequency signal group. Subsequently, a matched filter can be used to perform pulse compression processing on each pulse repetition frequency signal group to reduce the influence of clutter signals and improve the target detection performance in the echo signal.

[0075] Specifically, in the embodiments of this application, the pulse repetition frequency signal group can be represented by the following formula:

[0076]

[0077] Among them, u n (t) represents the Discrete Frequency Coded (DFC) signal corresponding to the nth pulse repetition frequency signal group; n is the pulse repetition frequency group number index; t is the sum of the fast time and the slow time; T sp Time width for each frequency chip; f m,n M is the encoded sequence of the transmitted pulse in the nth pulse repetition frequency group; M is the number of frequency chips in a pulse; and m is the index value of the frequency chip number in a pulse.

[0078] Step 130: For all pulse repetition frequency signal groups, use Keystone transform and Doppler ambiguity number compensation processing, and then perform discrete Fourier transform at the slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group;

[0079] In this step, when the airborne radar receives the echo signal, the target often crosses multiple range gates within one airborne radar processing cycle (CPI), necessitating the elimination of the impact of target range migration. In this embodiment, based on the pulse repetition frequency grouping, Keystone transform and Doppler ambiguity compensation are applied to each pulse repetition frequency group, and then a discrete Fourier transform is performed at the slow-time sampling moment to obtain the range Doppler result, thereby eliminating the influence of target range ambiguity.

[0080] Specifically, in the embodiments of this application, the target echo signal in each pulse repetition frequency signal group can be represented by the following formula:

[0081]

[0082] Among them, s k,t (t,t n,k R(t) represents the target echo signal of a certain pulse repetition frequency signal group; n,k R represents the distance to the target at the k-th pulse moment; t,0 v represents the initial distance to the target.t The velocity of the target; Δt n The first pulse interval of the target echo signal; c is the speed of light constant; n is the pulse repetition frequency group number index; t is the sum of the fast time and the slow time; Δt n t represents the start time of the transmission of the nth pulse repetition frequency group signal; n,k Used to characterize the transmission time of the k-th transmitted pulse signal in the n-th pulse repetition frequency group; f d,t The product of the number of ambiguities in the nth pulse repetition frequency signal group and the maximum unambiguous Doppler frequency of the nth pulse repetition frequency signal group, plus the sum of the ambiguity Doppler frequencies of the nth pulse repetition frequency signal group; σ t The radar cross-section (RCS) of the target.

[0083] It is understandable that the number of ambiguities, the maximum unambiguous Doppler frequency, and the ambiguous Doppler frequency of the nth pulse repetition frequency signal group are parameters that can be determined by certain technical means, and this application will not elaborate further here.

[0084] After Keystone transform and Doppler ambiguity compensation, and after performing Discrete Fourier Transform (or IFFT transform) at slow sampling times, the resulting range-Doppler distance can be expressed by the following formula:

[0085]

[0086] Among them, s k,t (t,t n,k R represents the target echo signal of a certain pulse repetition frequency signal group; t,0 v represents the initial distance to the target. t The velocity of the target; Δt n The first pulse interval of the target echo signal; c is the speed of light constant; n is the pulse repetition frequency group number index; t is the sum of the fast time and the slow time Δt. n is the start time of the transmission of the nth pulse repetition frequency group signal; k is the index value of the kth transmitted pulse signal; σ is the fuzzy Doppler frequency of the nth pulse repetition frequency signal group; t The radar cross-section (RCS) of the target; f is the frequency in the fast time domain; f c t is the center frequency of the radar; n,k B is used to characterize the transmission time of the kth transmitted pulse signal in the nth pulse repetition frequency group; B is the radar system bandwidth.

[0087] Specifically, in some embodiments, the Doppler sampling intervals of the pulse repetition frequency signal groups are the same.

[0088] Understandably, because the slow-time sampling times of different pulse repetition frequency signal groups are different, directly applying Fourier transform to each pulse repetition frequency signal group would cause spectral leakage, resulting in inconsistent phases among the pulse repetition frequency signals. Therefore, DFT processing can be performed on the slow-time sampling times to ensure that the Doppler sampling intervals of the pulse repetition frequency signal groups are the same, thereby guaranteeing the phase consistency of the pulse repetition frequency signals.

[0089] Step 130, after processing all pulse repetition frequency signal groups using Keystone transform and Doppler ambiguity compensation, and then performing slow-time discrete Fourier transform to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group, the method further includes:

[0090] Step 131: Perform matching calculations based on the distance Doppler results to obtain the correct Doppler information corresponding to the pulse repetition frequency signal group.

[0091] Understandably, referring to Figure 3 The pulse repetition frequency signals of different pulse repetition frequency signal groups are in Figure 3 Since the positions are consistent, the range Doppler results can be used to perform matching calculations on the pulse repetition frequency signal to obtain the correct Doppler information of the target echo signal and the correct Doppler information of the clutter signal in the pulse repetition frequency signal group.

[0092] Step 140: Perform first-layer detection threshold detection on the distance Doppler result, then perform deblurring and coherent processing to obtain a coherent result; Step 140, performing deblurring and coherent processing to obtain a coherent result, includes:

[0093] Step 141: Construct coherent processing coefficients using the target's true Doppler frequencies;

[0094] Step 142: Based on the true Doppler frequency, determine the fuzzy post-Doppler unit in the distance Doppler result that corresponds to the true Doppler frequency;

[0095] Step 143: Perform coherent processing on the blurred post-Doppler unit according to the coherent processing coefficients to determine the coherent result.

[0096] Understandably, referring to Figure 4 The first detection threshold can be a low detection threshold. Specifically, in the embodiments of this application, the first detection threshold can be 7dB. When performing the first detection threshold detection on the distance Doppler results, in order to reduce the computational load of target detection, a certain amount of false alarms is allowed in the detection results.

[0097] It is understood that, in the embodiments of this application, the coherent processing coefficients can be represented by the following formula:

[0098] W n (f r )=exp(j2πf r Δt n )

[0099] Among them, W n (f r ) represents the coherent processing coefficient; n represents the index value of the pulse repetition frequency group; Δt n f is the start time of the transmission of the nth pulse repetition frequency group signal; r The true Doppler frequency of the target.

[0100] It is understandable that the range-Doppler results can be displayed as a two-dimensional graph, thus the ambiguous post-Doppler element corresponding to the target's true Doppler frequency in the range-Doppler results can be determined based on the Doppler frequency. Furthermore, since both range deblurring and Doppler deblurring can be processed using the Chinese Remainder Theorem in the radar field, in the step of obtaining coherent results through deblurring and coherent processing in this embodiment, the coherent processing can simultaneously complete the Doppler deblurring process, which is reflected in the formula representing the coherent results. Specifically, the coherent results can be represented by the following formula:

[0101]

[0102] Where N is the number of pulse repetition frequency signal groups. For the coherent result, s k,n,FC (t,f d The distance-Doppler result, W, is obtained by performing Doppler ambiguity number compensation and inverse Fourier transform (which acts as a matched filter) on the fast time-frequency domain signal after Doppler blurring. n (f r ) represents the coherent processing coefficient, f r R is the true Doppler frequency of the target. t,0 Let Δt be the initial distance to the target. n Let be the start time of the signal transmission for the nth pulse repetition frequency group, c be the speed of light constant, λ be the wavelength of the radar system, and t be time. σ represents the radar fast time over distance, n is the pulse repetition frequency group number index value, k is the number index value of the kth transmitted pulse signal, and σ is the radar fast time over distance. t T is the radar cross-section (RCS) of the target. R Accumulate time for coherence, B is the Doppler frequency of the radar's center frequency after the blurring of each pulse frequency signal group, and B is the radar system bandwidth.

[0103] Step 140 involves performing a first-layer detection threshold detection on the distance Doppler result, deblurring and coherent processing on the detected frequency points to obtain coherent results, and also includes determining the validity of coherent accumulation.

[0104] The determination of the effectiveness of coherent accumulation includes:

[0105] Step 144: Perform coherent processing on each frequency point in the range Doppler result directly using the coherent processing coefficients, and remove false frequency points in the coherent processing result according to the preset removal rules to obtain the direct coherent processing result;

[0106] Step 145: Determine the validity of the coherent accumulation based on the direct coherent processing result and the coherent result.

[0107] It is understood that, in the embodiments of this application, see Figure 5 The elimination rule can be to determine whether a frequency point is a peak value. The effectiveness of coherent accumulation can be determined by directly using coherent processing coefficients to coherently process each frequency point in the distance-Doppler result. During the coherent processing, the amplitude of the pulse repetition frequency signal is judged, and frequency points that do not meet the peak value condition are eliminated. This yields the direct coherent processing result. Subsequently, the effectiveness of coherent accumulation can be determined based on whether the Doppler frequency points of the direct coherent processing result and the Doppler frequency points of the coherent result coincide.

[0108] Step 150: Perform second-layer detection threshold detection on the coherent results, and perform target determination and parameter estimation based on the obtained second-layer detection results to obtain the accurate distance and velocity information of the target.

[0109] Understandably, referring to Figure 6 The second-layer detection threshold is higher than the first-layer detection threshold. Specifically, in this embodiment, the second detection threshold can be 13dB. When performing second-layer threshold detection on the coherent results, false alarms allowed by the first-layer detection threshold are eliminated through the second-layer detection threshold to obtain the second-layer detection result. Target determination and parameter estimation are then performed based on the obtained second-layer detection result to obtain the accurate distance and velocity information of the target.

[0110] The following comparison charts of detection results illustrate the superior performance of the detection method mentioned in this application:

[0111] Reference Figure 7 and Figure 8Under the condition of 20kHz repetition frequency and 256 pulses accumulated, the Doppler resolution of the traditional Multi-PRF detection method is 103Hz, while the Doppler resolution of the detection method of this application is less than 20Hz, which is about 5 times higher than that of the Multi-PRF detection method.

[0112] Reference Figure 9 and Figure 10 , Figure 9 The curve on the left is the target detection probability curve of the traditional Multi-PRF detection method. Figure 9 The curve on the right is the target detection probability curve of the detection method in this application; Figure 10 The relatively stable curve (generally close to the 0 mark on the ordinate) represents the velocity estimation accuracy curve of the detection method in this application, while the curve with larger fluctuations represents the velocity estimation accuracy curve of the traditional Multi-PRF detection method. Clearly, from... Figure 9 and Figure 10 It is evident that the signal-to-noise ratio of the detection method proposed in this application is improved by more than 8dB compared to the traditional Multi-PRF detection method. In target detection, under the same detection probability, the required echo signal-to-noise ratio is reduced by more than 8dB. Simultaneously, the longer latency leads to improved Doppler resolution, resulting in more accurate extraction of target velocity parameters.

[0113] The following describes in detail, with reference to the accompanying drawings, an airborne radar target detection system for clutter avoidance according to an embodiment of this application.

[0114] Reference Figure 11 The clutter-avoidance airborne radar target detection system proposed in this application includes:

[0115] Acquisition module 101 is used to acquire the echo signal of the airborne radar;

[0116] Grouping module 102 is used to group the echo signal according to the pulse repetition frequency to obtain pulse repetition frequency signal groups;

[0117] Processing module 103 is used to process all pulse repetition frequency signal groups using Keystone transform and Doppler ambiguity number compensation, and then perform discrete Fourier transform at slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group.

[0118] The detection module 104 is used to perform a first-level detection threshold detection on the distance Doppler result, and then perform deblurring and coherent processing to obtain a coherent result;

[0119] The determination module 105 is used to perform second-layer detection threshold detection on the coherent results, and to determine the target and estimate the parameters based on the obtained second-layer detection results, so as to obtain the accurate distance and speed information of the target.

[0120] It is understood that the content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0121] Reference Figure 12 This application also provides an airborne radar target detection device for clutter avoidance, comprising:

[0122] At least one processor 201;

[0123] At least one memory 202 is used to store at least one program;

[0124] When the at least one program is executed by the at least one processor 201, the at least one processor 201 implements the above-described embodiment of the airborne radar target detection method for clutter avoidance.

[0125] Similarly, it can be understood that the content of the above method embodiments is applicable to this device embodiment. The specific functions implemented by this device embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0126] This application also provides a computer-readable storage medium storing a program executable by a processor 201, which, when executed by the processor 201, is used to implement the above-described airborne radar target detection method embodiment for clutter avoidance.

[0127] Similarly, the content of the above method embodiments is applicable to the present computer-readable storage medium embodiments. The specific functions implemented by the present computer-readable storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0128] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this application are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and sub-operations described as part of a larger operation are executed independently.

[0129] Furthermore, although this application is described in the context of functional modules, it should be understood that, unless otherwise stated to the contrary, one or more of the functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding this application. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional technology for an engineer. Therefore, those skilled in the art can implement the application set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of this application, which is determined by the full scope of the appended claims and their equivalents.

[0130] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods in the embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0131] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0132] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0133] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0134] In the foregoing description of this specification, the references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0135] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

[0136] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A clutter-avoidance airborne radar target detection method, characterized in that, include: Collect the echo signal of the airborne radar; The echo signals are grouped according to the pulse repetition frequency to obtain pulse repetition frequency signal groups; the Doppler sampling intervals of the pulse repetition frequency signal groups are the same. For all pulse repetition frequency signal groups, Keystone transform and Doppler ambiguity number compensation processing are applied, and then discrete Fourier transform is performed at the slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group; The distance Doppler results are subjected to a first-level detection threshold, followed by deblurring and coherent processing to obtain coherent results. The coherent results are subjected to a second-layer detection threshold detection. Based on the obtained second-layer detection results, target determination and parameter estimation are performed to obtain the accurate distance and velocity information of the target. The process of defuzzifying and coherently processing to obtain coherent results includes: Coherent processing coefficients are constructed using the target's true Doppler frequencies; Based on the true Doppler frequency, determine the fuzzy post-Doppler unit in the distance Doppler result that corresponds to the true Doppler frequency; The blurred post-Doppler unit is subjected to coherent processing based on the coherent processing coefficients to determine the coherent result.

2. The airborne radar target detection method for clutter avoidance according to claim 1, characterized in that, The airborne radar is used to generate a transmission signal, which includes pulses corresponding to the pulse repetition frequency group. The first pulse between each of the transmitted signals is transmitted according to the first pulse interval corresponding to the pulse repetition frequency group, and the subsequent pulses of each of the transmitted signals are transmitted sequentially according to the pulse repetition frequency corresponding to the pulse repetition frequency in the pulse repetition frequency group, wherein the different transmitted signals are orthogonal to each other.

3. The airborne radar target detection method for clutter avoidance according to claim 2, characterized in that, After grouping the echo signals according to the pulse repetition frequency to obtain pulse repetition frequency signal groups, the method further includes: The pulse repetition frequency signal group is subjected to pulse compression processing.

4. The airborne radar target detection method for clutter avoidance according to claim 1, characterized in that, After performing Keystone transform and Doppler ambiguity number compensation processing on all pulse repetition frequency signal groups, and then performing slow-time discrete Fourier transform to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group, the method further includes: Based on the distance Doppler results, a matching calculation is performed to obtain the correct Doppler information corresponding to the pulse repetition frequency signal group.

5. The airborne radar target detection method for clutter avoidance according to claim 1, characterized in that, The process of performing a first-level detection threshold detection on the distance Doppler results, followed by deblurring and coherent processing to obtain coherent results, also includes determining the validity of coherent accumulation. The determination of the effectiveness of coherent accumulation includes: The coherent processing coefficients are used to directly coherently process each frequency point in the range Doppler result, and false frequency points in the coherent processing result are removed according to the preset removal rules to obtain the direct coherent processing result. The validity of the coherent accumulation is determined based on the direct coherent processing results and the coherent results.

6. A clutter-avoiding airborne radar target detection system, characterized in that, include: The acquisition module is used to acquire the echo signal of the airborne radar; A grouping module is used to group the echo signals according to the pulse repetition frequency to obtain pulse repetition frequency signal groups; the Doppler sampling intervals of the pulse repetition frequency signal groups are the same; The processing module is used to process all pulse repetition frequency signal groups using Keystone transform and Doppler ambiguity number compensation, and then perform discrete Fourier transform at the slow time sampling time to obtain the distance Doppler result corresponding to the pulse repetition frequency signal group. The detection module is used to perform a first-level detection threshold detection on the distance Doppler results, and then perform deblurring and coherent processing to obtain coherent results; The determination module is used to perform second-layer detection threshold detection on the coherent results, and to determine the target and estimate parameters based on the obtained second-layer detection results, so as to obtain the accurate distance and velocity information of the target. The process of defuzzifying and coherently processing to obtain coherent results includes: Coherent processing coefficients are constructed using the target's true Doppler frequencies; Based on the true Doppler frequency, determine the fuzzy post-Doppler unit in the distance Doppler result that corresponds to the true Doppler frequency; The blurred post-Doppler unit is subjected to coherent processing based on the coherent processing coefficients to determine the coherent result.

7. An airborne radar target detection device for clutter avoidance, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the airborne radar target detection method for clutter avoidance as described in any one of claims 1-5.

8. A computer-readable storage medium storing a processor-executable program, characterized in that, The program executable by the processor, when executed by the processor, is used to implement the airborne radar target detection method for clutter avoidance as described in any one of claims 1-5.

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