Polarimetric radar range-Doppler image enhancement method, device, equipment and medium

Abstract

The present invention belongs to the field of radar detection technology, and proposes a polarization radar range-Doppler image enhancement method, device, equipment and medium, including obtaining the dimensional range-Doppler data of the polarization radar echo data under the set scene of the polarization radar, where is the number of distance units; is the number of Doppler units, is the number of polarization channels; constructs the polarization control spectrum of each distance unit in the range-Doppler data; based on the polarization control spectrum of each distance unit, calculates the complex amplitude of the spectrum peak position under each polarization channel of each distance unit, and constructs the enhancement result of each distance unit by combining the complex amplitude and the spectrum peak position; combines the enhancement results of each distance unit to obtain the enhanced range-Doppler map. The present invention can effectively realize the range-Doppler image enhancement, improve the target clutter ratio, and is conducive to the detection and identification of radar.

Description

Technical Field

[0001] The present invention mainly relates to the field of radar detection technology, in particular to a polarization radar range-Doppler image enhancement method, device, equipment and medium. Background Art

[0002] Range-Doppler image is an important product in radar signal processing, which can accurately provide the distance and speed information of the target. Range-Doppler image enhancement technology can highlight the target signal in target detection and recognition, improve radar resolution, improve range and Doppler resolution, and help to distinguish the internal structure of the target; enhance anti-interference ability, highlight the real target signal in a complex electromagnetic environment, and reduce clutter interference, which has great research significance.

[0003] In traditional grayscale transformation methods, linear grayscale transformation is difficult to adapt to complex grayscale distribution, and nonlinear grayscale transformation parameters rely on experience, which can easily lead to image distortion. In spatial domain filtering methods, mean filtering will blur image edges and details, median filtering has poor processing effect on certain noises, and improper window size will destroy details. In frequency domain filtering methods, low-pass filtering will lose high-frequency details, and high-pass filtering will enhance edges but amplify noise. The polarization scattering matrix obtained by polarimetric radar contains more target characteristic information and can describe the target from a higher dimension. Using the difference in polarization characteristics between the target and clutter to enhance the target signal can improve image quality and interpretability, and is used to improve contrast. It is related to the physical characteristics of the target, and the enhancement results are easy to understand. How to make full use of the information provided by the polarization dimension to achieve range-Doppler image enhancement is an unresolved problem. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention proposes a polarization radar range-Doppler image enhancement method, device, equipment and medium.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In one aspect, the present invention provides a polarization radar range-Doppler image enhancement method, comprising:

[0007] Get polarization radar echo data for a given scenario dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels;

[0008] Construct the polarization control spectrum of each range unit in the range-Doppler data;

[0009] Based on the polarization control spectrum of each distance unit, the complex amplitude of the spectrum peak position under each polarization channel of each distance unit is calculated, and the enhancement result of each distance unit is constructed by combining the complex amplitude and the spectrum peak position;

[0010] The enhanced results of each range unit are combined to obtain the enhanced range-Doppler map.

[0011] Furthermore, for the distance units, , construct The polarization control spectrum of the distance unit is as follows: Distance unit Doppler data of the polarization channel To a single Doppler frequency The projection process is expressed as:

[0012] ;

[0013] ;

[0014] in, is an imaginary unit, is the Doppler frequency, is the number of pulses used to generate the range-Doppler data, is the two-norm operator, represents the polarization control weight vector, and the above formula represents the polarization control weight vector The solution satisfies the criterion of minimum norm part;

[0015] Polarization control weight vector There is an analytical solution:

[0016] ;

[0017] in, is the conjugate transpose operator, To find the inverse operator;

[0018] right and Perform Doppler Fourier transform and transform the polarization control weight vector Rewritten as:

[0019] ;

[0020] in, and They are and The Fourier transform result of

[0021] based on and The Fourier transform result of and Construct the first The polarization control spectrum of a distance unit is:

[0022] ;

[0023] Furthermore, based on The polarization control spectrum of the distance unit is extracted The peak position of the distance unit , Respectively represent The first, second, ...th distance unit The Doppler frequency corresponding to the target; calculate the The distance unit The complex amplitude of each spectral peak position under each polarization channel:

[0024] ;

[0025] in, Substitute the peak position The steering matrix after is the Fourier transform operator, ,express For one A complex vector of .

[0026] Furthermore, The distance unit The complex amplitude of each spectral peak position under the polarization channel is projected onto the The distance unit The corresponding peak position under the polarization channel is obtained The enhanced result of the distance unit.

[0027] On the one hand, a polarization radar range-Doppler image enhancement device is provided, comprising:

[0028] The first module is used to obtain the polarization radar echo data of the polarization radar under the set scene. dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels;

[0029] The second module is used to construct the polarization control spectrum of each range unit in the range-Doppler data;

[0030] The third module is used to calculate the complex amplitude of the spectrum peak position of each distance unit under each polarization channel based on the polarization control spectrum of each distance unit, and construct the enhancement result of each distance unit by combining the complex amplitude and the spectrum peak position;

[0031] The fourth module is used to combine the enhancement results of each range unit to obtain an enhanced range-Doppler map.

[0032] On the other hand, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned polarization radar range-Doppler image enhancement method when executing the computer program.

[0033] On the other hand, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the above-mentioned polarization radar range-Doppler image enhancement method are implemented.

[0034] On the other hand, the present invention provides a computer program product, which is stored on a computer-readable storage medium and includes computer instructions, which, when executed by a processor, enable a computer device to implement the steps of the above-mentioned polarization radar range-Doppler image enhancement method.

[0035] Compared with the prior art, the technical effects of the present invention are:

[0036] The present invention obtains range-Doppler data of polarization radar echo data under a set scenario of a polarization radar, first constructs a polarization control spectrum of each range unit, calculates the complex amplitude of the spectrum peak position under each polarization channel of each range unit based on the polarization control spectrum of each range unit, and constructs the enhancement result of each range unit by combining the complex amplitude and the spectrum peak position; and obtains the enhanced range-Doppler map by combining the enhancement results of each range unit, which can effectively realize range-Doppler image enhancement, improve the target clutter ratio, and facilitate radar detection and recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0038] Figure 1 is a flow chart of a polarization radar range-Doppler image enhancement method provided by an embodiment;

[0039] Figure 2 A schematic diagram of the structure of a polarization control spectrum in one embodiment;

[0040] Figure 3 A comparison between the coherent accumulation result of the target distance unit and the polarization control spectrum in one embodiment;

[0041] Figure 4 The coherent processing results of two sets of 16 pulse data are shown. Figure 4 (a) is the result of the coherent processing of the first group of 16 pulse data. Figure 4 (b) is the result of the coherent processing of the second group of 16 pulse data;

[0042] Figure 5 The coherent processing results of two sets of 256 pulse data are shown. Figure 5 (a) is the result of the coherent processing of the first group of 256 pulse data. Figure 5 (b) is the result of the coherent processing of the second group of 256 pulse data;

[0043] Figure 6 The image enhancement results of two sets of 16 pulse data are shown. Figure 6 (a) is the image enhancement result of the first group of 16 pulse data. Figure 6 (b) is the image enhancement result of the second group of 16 pulse data;

[0044] Figure 7 Shown Figure 4 , Figure 5 , Figure 6 Doppler cross-section comparison of the target distance unit in the processing results, where Figure 7 (a) Figure 4 (a) Figure 5 (a) Figure 6 (a) Comparison of Doppler cross sections of target distance units in the processing results, Figure 7 (b) Figure 4 (b) Figure 5 (b) Figure 6 (b) Comparison of Doppler cross sections of target distance units in the processing results. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In one embodiment of the present invention, referring to Figure 1The present invention provides a polarization radar range-Doppler image enhancement method, comprising:

[0047] Get the range-Doppler data of the polarization radar echo data of the polarization radar pair under the set scene, where the range-Doppler data is dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels.

[0048] Construct the polarization control spectrum of each range unit in the range-Doppler data;

[0049] Based on the polarization control spectrum of each distance unit, the complex amplitude of the spectrum peak position under each polarization channel of each distance unit is calculated, and the enhancement result of each distance unit is constructed by combining the complex amplitude and the spectrum peak position;

[0050] The enhanced results of each range unit are combined to obtain the enhanced range Doppler map.

[0051] The setting scene is not limited. For example, in the sea surface detection scene, the polarization radar detects the sea surface target. The polarization radar uses a set of dual-polarization antennas with orthogonal polarization states to detect and obtain the scattered echo of the sea surface target. After matching filtering, coherent accumulation and other processing, the size of dimensional range-Doppler data, is the number of polarization channels, in the dual-polarization system , in the fully polarized system .

[0052] Assume that the transmission signal of the polarization radar is:

[0053] (1)

[0054] in, is the carrier center frequency, is the duration of the pulse, is the pulse sequence number, is the FM slope.

[0055] The polarization radar echo data received by the polarization radar is:

[0056] (2)

[0057] in, and Respectively The time delay and Doppler shift of a target, , is the bandwidth, It refers to The relative radial velocity between the target and the radar, is the speed of light, , is the distance between the target and the radar, .

[0058] Take the waveform of the transmitted signal as the reference signal , the intermediate frequency signal of the polarization radar after Stretch processing is:

[0059] (3)

[0060] Considering compensating the target's velocity before stretch processing, the intermediate frequency signal of the polarization radar can be obtained:

[0061] (4)

[0062] Assume that there are goals, consider The target can be distinguished in both the range dimension and the Doppler dimension. By performing a two-dimensional Fourier transform on the intermediate frequency signal of the polarimetric radar, the range-Doppler data of the polarimetric radar echo data is obtained, and the peak position points to frequency point positions, among which The peak position is , then The distance and Doppler frequency shift corresponding to the peak position are:

[0063] (5)

[0064] in, and Respectively The distance-dimensional frequency and Doppler-dimensional frequency corresponding to the peak position need to be converted into a specific distance through numerical calculation. With Doppler shift , The speed of light.

[0065] For distance units, , No. Distance unit Doppler data of the polarization channel It is expressed as:

[0066] ;

[0067] in, , For the The target complex amplitude in the transmit and receive polarization states, , Indicates The Doppler data vector under the transmit and receive polarization states, is the Doppler frequency matrix, For the The number of targets in each distance unit and the total number of targets The relationship is , Respectively represent The first, second, ...th distance unit The Doppler frequency corresponding to the target, for the Doppler frequency matrix, the first Vector It can be expressed as:

[0068] ;

[0069] Use the Distance unit Polarization signal of polarization channel To a single Doppler frequency The projection process is expressed as:

[0070] ;

[0071] ;

[0072] in, is an imaginary unit, is the Doppler frequency, is the number of pulses used to generate the range-Doppler data, is the two-norm operator, represents the polarization control weight vector, and the above formula represents the polarization control weight vector The solution satisfies the criterion of minimum norm part;

[0073] Polarization control weight vector There is an analytical solution:

[0074] ;

[0075] in, is the conjugate transpose operator, To find the inverse operator;

[0076] right and Perform Doppler Fourier transform and transform the polarization control weight vector Rewritten as:

[0077] ;

[0078] in, and They are and The Fourier transform result of That is the one-hot vector;

[0079] based on and The Fourier transform result of and The polarization control spectrum of the distance unit constructed for image enhancement is:

[0080] .

[0081] Reference Figure 2 , Figure 2 A schematic diagram of the construction of the polarization control spectrum is shown, indicating that the polarization control spectrum can be directly obtained from the coherent accumulation results of multiple polarization channels.

[0082] Based on The polarization control spectrum of the distance unit is extracted The peak position of the distance unit , calculate the The distance unit The complex amplitude of each spectral peak position under each polarization channel:

[0083] ;

[0084] in, Substitute the peak position The steering matrix after is the Fourier transform operator, ,express For one A complex vector of .

[0085] The first The distance unit The complex amplitude of each spectral peak position under the polarization channel is projected onto the The distance unit The corresponding peak position under the polarization channel is obtained The enhanced result of the distance unit.

[0086] The enhancement results of all range units are obtained through the above steps, and the enhanced range Doppler map is obtained by combining the enhancement results of each range unit.

[0087] In order to verify the effectiveness of the method of the present invention, the proposed method is used to enhance the range-Doppler map of the Ice Multiparameter Imaging X-Band Radar (IPIX radar) data published by McMaster University in Canada.

[0088] Figure 3 The coherent integration results of the target distance unit are compared with the polarization control spectrum. It can be seen that the sidelobes of the target in the Doppler dimension are suppressed to a great extent, and the polarization control spectrum has the effect of image enhancement.

[0089] Figure 4 The coherent processing results of two sets of 16 pulse data are shown. Figure 4 (a) is the result of the coherent processing of the first group of 16 pulse data. Figure 4 (b) is the coherent processing result of the second group of 16 pulse data, where the strong scattering points in the first group of 16 pulse data are located in the 9th distance unit, and the strong scattering points in the second group of 16 pulse data are located in the 3rd and 9th distance units. The two groups of data are coherently processed, and it can be seen that when the number of pulses is insufficient, the Doppler resolution and sidelobe level are significantly deteriorated, which is not conducive to target detection.

[0090] Figure 5 The coherent processing results of two sets of 256 pulse data are shown. Figure 5 (a) is the result of the coherent processing of the first group of 256 pulse data. Figure 5 (b) is the coherent processing result of the second group of 256 pulse data. The strong scattering points in the first group of 256 pulse data are located in the 9th distance unit, and the strong scattering points in the second group of 256 pulse data are located in the 3rd and 9th distance units. After coherent processing of the two groups of data, it can be seen that a sufficient number of pulses can effectively improve the quality of the range-Doppler image, but it is limited by observation conditions and cannot be guaranteed in some mobile platform detection tasks. A range-Doppler image enhancement method under the condition of a small number of pulses is required to ensure the detection effect.

[0091] Figure 6 The image enhancement results of two sets of 16 pulse data are shown. Figure 6 (a) is the image enhancement result of the first group of 16 pulse data. Figure 6 (b) is the image enhancement result of the second group of 16 pulse data. The strong scattering points in the first group of 16 pulse data are located in the 9th distance unit, and the strong scattering points in the second group of 16 pulse data are located in the 3rd and 9th distance units. The two groups of data are processed using the proposed method. It can be seen that after the image enhancement using the proposed method, the range-Doppler map is significantly sharpened and the sidelobe level is significantly reduced, which is beneficial to target detection.

[0092] Figure 7 Shown Figure 4 , Figure 5 , Figure 6 Doppler cross-section comparison of the target distance unit in the processing results, where Figure 7 (a) Figure 4 (a) Figure 5 (a) Figure 6 (a) Comparison of Doppler cross sections of target distance units in the processing results, Figure 7 (b) Figure 4 (b) Figure 5 (b) Figure 6 (b) The comparison diagram of the Doppler cross-section of the target distance unit in the processing result is intended to further intuitively demonstrate the performance gain provided by the present invention. It can be seen that after image enhancement, the image quality of 16-pulse data can reach the processing level of 256-pulse data, which greatly improves the radar detection performance under few-pulse conditions.

[0093] In summary, the method of the present invention can effectively realize range-Doppler image enhancement, improve the target clutter ratio, and facilitate radar detection and recognition.

[0094] In one embodiment of the present invention, a polarization radar range-Doppler image enhancement device is provided, comprising:

[0095] The first module is used to obtain the polarization radar echo data of the polarization radar under the set scene. dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels;

[0096] The second module is used to construct the polarization control spectrum of each range unit in the range-Doppler data;

[0097] The third module is used to calculate the complex amplitude of the spectrum peak position of each distance unit under each polarization channel based on the polarization control spectrum of each distance unit, and construct the enhancement result of each distance unit by combining the complex amplitude and the spectrum peak position;

[0098] The fourth module is used to combine the enhancement results of each range unit to obtain an enhanced range-Doppler map.

[0099] On the other hand, the present invention provides a computer device, including a memory and a processor, the memory storing a computer program, and the processor implementing the steps of the polarization radar range-Doppler image enhancement method provided in any of the above embodiments when executing the computer program. The computer device may be a server. The computer device includes a processor, a memory, a network interface and a database connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store sample data. The network interface of the computer device is used to communicate with an external terminal via a network connection.

[0100] On the other hand, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the polarization radar range-Doppler image enhancement method provided in any of the above embodiments.

[0101] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0102] Matters not covered by the present invention are known technologies.

[0103] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polarization radar range-Doppler image enhancement method, characterized in that: include: Get polarization radar echo data for a given scenario dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels; Construct the polarization control spectrum of each range unit in the range-Doppler data, where: distance units, , construct The polarization control spectrum of the distance unit is as follows: Distance unit Doppler data of the polarization channel To a single Doppler frequency The projection process is expressed as: ； ； in, is an imaginary unit, is the Doppler frequency, is the number of pulses used to generate the range-Doppler data, is the two-norm operator, represents the polarization control weight vector, and the above formula represents the polarization control weight vector The solution satisfies the criterion of minimum norm part; Polarization control weight vector There is an analytical solution: ； in, is the conjugate transpose operator, To find the inverse operator; right and Perform Doppler Fourier transform and transform the polarization control weight vector Rewritten as: ； in, and They are and The Fourier transform result of based on and The Fourier transform result of and Construct the first The polarization control spectrum of a distance unit is: ； Based on the polarization control spectrum of each distance unit, the complex amplitude of the spectrum peak position under each polarization channel of each distance unit is calculated, and the enhancement result of each distance unit is constructed by combining the complex amplitude and the spectrum peak position; The enhanced results of each range unit are combined to obtain the enhanced range-Doppler map.

2. The polarization radar range-Doppler image enhancement method according to claim 1, characterized in that: The polarization radar echo data is dual-polarization data or full-polarization data, respectively including 2 or 4 polarization channels. =2 or 4.

3. The polarization radar range-Doppler image enhancement method according to claim 1 or 2, characterized in that: Based on The polarization control spectrum of the distance unit is extracted The peak position of the distance unit , Respectively represent The first, second, ...th distance unit The Doppler frequency corresponding to the target; calculate the The distance unit The complex amplitude of each spectral peak position under each polarization channel: ； in, Substitute the peak position The steering matrix after is the Fourier transform operator, ,express For one A complex vector of .

4. The polarization radar range-Doppler image enhancement method according to claim 3, characterized in that: Combine the complex amplitude and the peak position to construct the enhancement result of each distance unit. The method is as follows: distance unit, The distance unit The complex amplitude of each spectral peak position under the polarization channel is projected onto the The distance unit The corresponding peak position under the polarization channel is obtained The enhancement result of the distance unit.

5. Polarimetric radar range-Doppler image enhancement device, characterized in that: include: The first module is used to obtain the polarization radar echo data of the polarization radar under the set scene. dimensional range-Doppler data, is the number of distance units; is the number of Doppler cells, is the number of polarization channels; The second module is used to construct the polarization control spectrum of each range unit in the range-Doppler data, where: distance units, , construct The polarization control spectrum of the distance unit is as follows: Distance unit Doppler data of the polarization channel To a single Doppler frequency The projection process is expressed as: ； ； in, is an imaginary unit, is the Doppler frequency, is the number of pulses used to generate the range-Doppler data, is the two-norm operator, represents the polarization control weight vector, and the above formula represents the polarization control weight vector The solution satisfies the criterion of minimum norm part; Polarization control weight vector There is an analytical solution: ； in, is the conjugate transpose operator, To find the inverse operator; right and Perform Doppler Fourier transform and transform the polarization control weight vector Rewritten as: ； in, and They are and The Fourier transform result of based on and The Fourier transform result of and Construct the first The polarization control spectrum of a distance unit is: ； The third module is used to calculate the complex amplitude of the spectrum peak position of each distance unit under each polarization channel based on the polarization control spectrum of each distance unit, and construct the enhancement result of each distance unit by combining the complex amplitude and the spectrum peak position; The fourth module is used to combine the enhancement results of each range unit to obtain an enhanced range-Doppler map.

6. The polarization radar range-Doppler image enhancement device according to claim 5, characterized in that: In the third module, based on The polarization control spectrum of the distance unit is extracted The peak position of the distance unit , Respectively represent The first, second, ...th distance unit The Doppler frequency corresponding to the target; calculate the The distance unit The complex amplitude of each spectral peak position under each polarization channel: ； in, Substitute the peak position The steering matrix after is the Fourier transform operator, ,express For one A complex vector of .

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the polarization radar range-Doppler image enhancement method as claimed in claim 1 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the polarization radar range-Doppler image enhancement method as claimed in claim 1 are implemented.

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