Vortex electromagnetic wave artifact suppression method, system and device
By constructing Bessel compensation coefficients and Fourier transform methods, the problem of artifact suppression in multi-target imaging scenarios of vortex electromagnetic wave radar is solved, improving imaging quality and artifact suppression effect. It is particularly suitable for vortex electromagnetic wave radar with uniform circular array.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-04-03
AI Technical Summary
Existing vortex electromagnetic wave radars suffer from the problem that artifact suppression methods are not applicable in multi-target imaging scenarios, especially in unidirectional modulation imaging mode. Windowing methods cannot effectively suppress artifacts, and existing Hilbert transform methods require determining whether the target's azimuth is in the positive or negative quadrant, making them unsuitable for multi-target distribution.
By employing the Bessel compensation coefficient and Fourier transform method, the compensation method is determined based on the waveform or center frequency of the vortex electromagnetic wave signal by constructing the Bessel compensation coefficient. The AD sampling data, pulse compression data, and down-conversion data of the vortex electromagnetic wave signal are compensated, and azimuth imaging is performed based on Fourier transform.
It effectively suppresses artifacts in unidirectional modulation imaging mode, improves imaging quality, and is particularly suitable for vortex electromagnetic wave radar based on uniform circular array, improving the accuracy of Bessel compensation coefficient construction and artifact suppression effect.
Smart Images
Figure CN121784731A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of orbital angular momentum technology, and in particular to a method, system and apparatus for suppressing vortex electromagnetic wave artifacts. Background Technology
[0002] Orbital angular momentum (OAM) provides a new dimension of electromagnetic waves, distinct from traditional information dimensions such as time, space, frequency, and polarization. Electromagnetic waves carrying OAM are called vortex electromagnetic waves. The amplitude characteristics of vortex electromagnetic waves exhibit a hollow circular shape, and their phase characteristics can be characterized as a phase gradient related to the mode values. Vortex electromagnetic waves can be used to achieve "staring" imaging under conditions where the target and platform are relatively stationary. Vortex electromagnetic wave radar imaging can employ bidirectional modulation imaging methods, where both transmission and reception use vortex electromagnetic waves, or unidirectional modulation imaging methods, where only one end of transmission or reception uses vortex electromagnetic waves, and the other end uses plane waves. For unidirectional modulation vortex electromagnetic wave radar imaging, artifacts symmetrical to the true image exist, which cannot be suppressed by windowing methods. Existing methods for suppressing artifacts using Hilbert transforms require first determining whether the target's azimuth is in the positive or negative quadrant before constructing the Hilbert transform pair, which is unsuitable for imaging scenarios with multiple targets. Therefore, there is an urgent need to study a method for suppressing vortex electromagnetic wave artifacts in imaging with multiple target distributions. Summary of the Invention
[0003] This invention provides a method, system, and apparatus for suppressing vortex electromagnetic wave artifacts, in order to solve the problem that existing artifact suppression methods are not suitable for multi-target imaging.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for suppressing vortex electromagnetic wave artifacts, comprising: The vortex electromagnetic wave signal can be a transmitted vortex electromagnetic wave signal or an echo vortex electromagnetic wave signal. Construct the Bessel compensation coefficient; Based on the waveform or center frequency of the vortex electromagnetic wave signal, the compensation method for the corresponding echo data of the vortex electromagnetic wave signal is determined. The compensation method includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal. The vortex electromagnetic wave signal is compensated based on the Bessel compensation coefficient and the compensation method. Azimuth-dimensional imaging is performed on the compensation results based on Fourier transform.
[0005] Optional, The constructed Béssel compensation coefficients include: The operating parameters of the vortex electromagnetic wave antenna array are obtained, including the mode value of the vortex electromagnetic wave, the wave number of the vortex electromagnetic wave, the imaging mode of the vortex electromagnetic wave, and the radius of the antenna array. Based on the imaging method of the vortex electromagnetic wave, determine the angle between the target and the direction of the vortex electromagnetic wave beam center; The Bessel compensation coefficients are constructed based on the modal values, the wavenumber, the included angle, the antenna array radius, and the first type of Bessel function.
[0006] Optional, Determining the angle between the target and the center direction of the vortex electromagnetic wave beam based on the imaging method of the vortex electromagnetic wave includes: If the imaging method is scanning imaging or non-scanning imaging, and the main lobe is aligned with the target, the included angle is the divergence angle of the vortex electromagnetic wave. If the imaging method is unscanning imaging and the non-main lobe is aligned with the target, the included angle is the target elevation angle of the vortex electromagnetic wave.
[0007] Optional, The Bessel compensation coefficient is specifically expressed as follows: in, For a Bessel function of the first kind, These are the modal values of the vortex electromagnetic wave. Let be the wave number of the vortex electromagnetic wave. The radius of the circular antenna array. The angle between the target and the center of the vortex electromagnetic wave beam.
[0008] Optional, When the vortex electromagnetic wave signal is the transmitted vortex electromagnetic wave signal, the compensation method for the echo data corresponding to the transmitted vortex electromagnetic wave signal is determined according to the waveform of the transmitted vortex electromagnetic wave signal. When the vortex electromagnetic wave signal is an echo vortex electromagnetic wave signal, the compensation method for the echo data corresponding to the echo vortex electromagnetic wave signal is determined according to the center frequency of the echo vortex electromagnetic wave signal.
[0009] Optional, When the vortex electromagnetic wave signal is a transmitted vortex electromagnetic wave signal, the compensation method for determining the echo data corresponding to the transmitted vortex electromagnetic wave signal based on the waveform of the transmitted vortex electromagnetic wave signal includes: If the waveform of the transmitted vortex electromagnetic wave signal is a point frequency signal or a continuous wave signal, then the AD sampling data of the echo data is compensated. If the waveform of the transmitted vortex electromagnetic wave signal is a linear frequency modulated signal, then the AD sampling data of the echo data is compensated or the pulse compression data of the echo data is compensated.
[0010] Optional, When the vortex electromagnetic wave signal is an echo vortex electromagnetic wave signal, the compensation method for determining the echo data corresponding to the echo vortex electromagnetic wave signal based on the center frequency of the echo vortex electromagnetic wave signal includes: If the center frequency of the echo vortex electromagnetic wave signal is zero, then the AD sampling data of the echo data is compensated. If the center frequency of the echo vortex electromagnetic wave signal is not zero, then the AD sampling data of the echo data is compensated or the down-conversion data of the echo data is compensated.
[0011] Optional, The compensation of the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method includes: The compensation data is determined according to the compensation method, and the compensation data includes AD sampling data, pulse compression data, and downconversion data; The compensation data for different modes are multiplied by the Bessel compensation coefficient.
[0012] This invention provides a vortex electromagnetic wave artifact suppression system, comprising: The model is used to acquire vortex electromagnetic wave signals, which can be transmitted vortex electromagnetic wave signals or echo vortex electromagnetic wave signals. The building block is used to construct the Bessel compensation coefficients; The compensation method determination module is used to determine the compensation method of the echo data corresponding to the vortex electromagnetic wave signal based on the waveform or center frequency of the vortex electromagnetic wave signal. The compensation method includes compensating the AD sampling data of the vortex electromagnetic wave signal, compensating the pulse compression data of the vortex electromagnetic wave signal, and compensating the down-conversion data of the vortex electromagnetic wave signal. The compensation module is used to compensate the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method. The imaging module is used to perform azimuth-dimensional imaging based on the compensation results using Fourier transform.
[0013] This invention provides a device for suppressing vortex electromagnetic wave artifacts, comprising: processor, and A memory configured to store computer-executable instructions, which, when executed, cause the processor to perform the steps of the method described in any of the preceding claims.
[0014] At least one of the above-mentioned technical solutions adopted in this specification can achieve the following beneficial effects: This invention discloses a method, system, and apparatus for suppressing vortex electromagnetic wave artifacts. First, the vortex electromagnetic waves generated by a uniform circular array exhibit Bessel modulation in their radiation pattern amplitude. By setting Bessel compensation coefficients, imaging compensation can be achieved, improving imaging quality. Second, the Bessel compensation coefficients are composed of a first-type Bessel function, the mode value of the vortex electromagnetic wave, the wave number, and the target elevation angle. These parameters are readily available, enabling rapid construction of the Bessel compensation coefficients. Third, the target elevation angle is determined based on the vortex electromagnetic wave imaging method and the main lobe alignment, improving the accuracy of the Bessel compensation coefficient construction. Finally, the compensation position of the Bessel compensation coefficients is selected based on the waveform of the transmitted vortex electromagnetic wave, enhancing the vortex electromagnetic wave artifact suppression effect. This invention provides a vortex electromagnetic wave artifact suppression method that effectively solves the artifact problem caused by unidirectional modulation imaging modes, and is particularly suitable for vortex electromagnetic wave radars based on uniform circular arrays. Attached Figure Description
[0015] Figure 1 A flowchart of a vortex electromagnetic wave artifact suppression method provided in one embodiment of this specification; Figure 2 A schematic diagram of the geometric relationship of vortex electromagnetic waves generated based on a uniform circular array, provided as an embodiment of this specification. Figure 3 This is a schematic diagram of an embodiment of the present specification showing a case where the beam pointing to a vortex electromagnetic wave target is not scanned. Figure 4 A schematic diagram of beam scanning for the target orientation of a vortex electromagnetic wave, provided in one embodiment of this specification. Figure 5 This is a schematic diagram showing the result of suppressing vortex electromagnetic wave artifacts before suppression, provided in an embodiment of this specification. Figure 6 This is a schematic diagram showing the result of suppressing vortex electromagnetic wave artifacts according to an embodiment of this specification. Figure 7 A schematic diagram of a vortex electromagnetic wave artifact suppression system provided in one embodiment of this specification; Figure 8 This is a schematic diagram of a vortex electromagnetic wave artifact suppression device provided in one embodiment of this specification. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of this specification clearer, the technical solutions of this specification are described clearly and completely below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this specification.
[0017] Where there is no conflict, the embodiments of the present invention and the features thereof can be combined with each other.
[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of the embodiments of the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein.
[0019] In this article, "multiple or several" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Furthermore, the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.
[0021] Figure 2 This is a schematic diagram illustrating the geometric relationship of a vortex electromagnetic wave generated based on a uniform circular array in this embodiment. OXYZ is the antenna array coordinate system, with the origin coinciding with the center of the circular array. The antenna normal direction is the positive direction of the OZ axis. The antenna array is located on the XOY plane, with each antenna element uniformly distributed on the circumference. The coordinates of the target point P are... ,in, Let P be the location. The angle between the target and the center of the vortex electromagnetic wave beam is defined as follows: In this embodiment of the invention, it is the angle between the line connecting the target to point O and the antenna normal. It should be noted that in this embodiment, the antenna normal coincides with the center of the vortex electromagnetic wave beam. The target azimuth angle, in this embodiment of the invention, is the angle between the projection of the target onto the XOY plane and the positive direction of the OX axis.
[0022] Since the amplitude characteristics of vortex electromagnetic waves are characterized by a ring-shaped energy distribution, in this embodiment of the invention, the vortex wave beam center refers to the center of the ring-shaped energy distribution of the vortex electromagnetic wave, and the vortex electromagnetic wave beam center direction refers to the direction of the center of the ring-shaped energy distribution of the vortex electromagnetic wave.
[0023] By assigning a phase related to the mode value of a vortex electromagnetic wave to each antenna element on a uniform circular array, a vortex electromagnetic wave with the corresponding mode value can be generated. The specific generation method is not described in the embodiments of the present invention.
[0024] In this embodiment of the invention, the vortex electromagnetic waves generated by the uniform circular array exhibit Bessel modulation in their radiation pattern amplitude, meaning that the array factor contains a Bessel modulation term. Artifacts will occur during imaging and need to be compensated for. Among them, For a Bessel function of the first kind, These are the modal values of the vortex electromagnetic wave. Let be the wave number of the vortex electromagnetic wave. The angle between the target and the direction of the vortex electromagnetic wave beam center. The radius of the antenna array is given.
[0025] In this embodiment of the invention, vortex electromagnetic waves are generated based on the UCA method. The radius of the circular antenna array.
[0026] Figure 1 This specification provides a flowchart of a method for calculating the beam pointing angle based on an electromagnetic wave trajectory, as provided in one embodiment. The method may specifically include: Step 102: Obtain vortex electromagnetic wave signal, which can be transmitted vortex electromagnetic wave signal or echo vortex electromagnetic wave signal. Step 104: Construct the Bessel compensation coefficients; In one embodiment, step 104 is implemented as follows: The operating parameters of the vortex electromagnetic wave antenna array are obtained, including the mode value of the vortex electromagnetic wave, the wave number of the vortex electromagnetic wave, the imaging mode of the vortex electromagnetic wave, and the radius of the antenna array. Based on the imaging method of the vortex electromagnetic wave, determine the angle between the target and the direction of the vortex electromagnetic wave beam center; The Bessel compensation coefficients are constructed based on the modal values, the wavenumber, the included angle, the antenna array radius, and the first type of Bessel function.
[0027] Determining the angle between the target and the center direction of the vortex electromagnetic wave beam based on the imaging method of the vortex electromagnetic wave includes: If the imaging method is scanning imaging or non-scanning imaging, and the main lobe is aligned with the target, the included angle is the divergence angle of the vortex electromagnetic wave. If the imaging method is unscanning imaging and the non-main lobe is aligned with the target, the included angle is the target elevation angle of the vortex electromagnetic wave.
[0028] The construction of Bessel compensation coefficients based on the modal values, wavenumbers, included angles, antenna array radius, and the first type of Bessel function includes: The Bessel compensation coefficient is specifically expressed as follows: in, For a Bessel function of the first kind, These are the modal values of the vortex electromagnetic wave. Let be the wave number of the vortex electromagnetic wave. The radius of the circular antenna array. The angle between the target and the center of the vortex electromagnetic wave beam.
[0029] In one embodiment, step 104 is implemented as follows: Figure 3 This is a schematic diagram illustrating the case where the beam pointing to the target of a vortex electromagnetic wave is not scanned. Figure 4 This is a schematic diagram illustrating the beam scanning situation of a vortex electromagnetic wave target. This embodiment is applicable to both vortex electromagnetic wave beam scanning and unscanned imaging methods.
[0030] like Figure 3 OXYZ is the antenna array coordinate system, with the positive direction of the OZ axis being the antenna normal direction, and point P being the target position. This refers to the divergence angle of the vortex electromagnetic wave. When vortex electromagnetic waves are used for imaging in a beam-unscanned manner, it is required that the divergence angles of vortex electromagnetic waves with different modes be the same. This ensures that vortex electromagnetic waves with different modes can illuminate the same location on the same target, so that the echo data of the vortex electromagnetic waves contains the phase gradients of different modes. Target imaging can be achieved using these phase gradients. When the main beams of vortex electromagnetic waves with different modes all point towards the target, the angle between the target and the direction of the vortex electromagnetic wave beam center is the divergence angle corresponding to the different modes of the vortex electromagnetic wave, i.e., .
[0031] like Figure 4 OXYZ is the antenna array coordinate system, and point P is the target position. The divergence angle of the vortex electromagnetic wave. When vortex electromagnetic waves are imaged using beam scanning, the divergence angles of vortex electromagnetic waves with different mode values can be the same or different. When the divergence angles of vortex electromagnetic waves with different mode values are different, the direction of the main beam of the vortex electromagnetic waves can be changed to make the main beams of the vortex electromagnetic waves with different mode values point towards the target. By changing the direction of the main beam of the vortex electromagnetic waves so that the main beams of vortex electromagnetic waves with different mode values all point towards the target, the angle between the target and the direction of the vortex electromagnetic wave beam center is the divergence angle corresponding to the different mode values of the vortex electromagnetic waves, i.e. At this moment, the target's pitch angle is... .
[0032] Based on this, two vortex electromagnetic wave imaging methods are provided. Regardless of whether vortex electromagnetic wave imaging is performed using antenna beam scanning or non-scanning, when the main beam of the vortex electromagnetic wave is aligned with the target, the angle between the target and the center of the vortex electromagnetic wave beam is the divergence angle of the vortex electromagnetic wave. When imaging is performed using the non-scanning antenna method, the angle between the target and the center of the vortex electromagnetic wave beam is the target elevation angle.
[0033] Step 106: Based on the waveform or center frequency of the vortex electromagnetic wave signal, determine the compensation method for the echo data corresponding to the vortex electromagnetic wave signal. The compensation method includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal.
[0034] In one embodiment, one implementation of step 106 is as follows: Based on the waveform or center frequency of the vortex electromagnetic wave signal, a compensation method for the corresponding echo data of the vortex electromagnetic wave signal is determined. The compensation method includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal.
[0035] If the waveform of the transmitted vortex electromagnetic wave signal is a point frequency signal or a continuous wave signal, then the AD sampling data of the echo data is compensated. If the waveform of the transmitted vortex electromagnetic wave signal is a linear frequency modulated signal, then the AD sampling data of the echo data is compensated or the pulse compression data of the echo data is compensated.
[0036] If the center frequency of the echo vortex electromagnetic wave signal is zero, then the AD sampling data of the echo data is compensated. If the center frequency of the echo vortex electromagnetic wave signal is not zero, then the AD sampling data of the echo data is compensated or the down-conversion data of the echo data is compensated.
[0037] In one embodiment, step 106 is specifically implemented as follows: The compensation position of the Bessel compensation coefficient is selected based on the waveform of the emitted vortex electromagnetic wave.
[0038] The emitted vortex electromagnetic waves are either point frequency signals or continuous wave signals, and the echo data of vortex electromagnetic waves of different modes can be compensated after AD sampling.
[0039] The emitted vortex electromagnetic wave is a linear frequency modulated signal, which can be used to compensate for the echo data of vortex electromagnetic waves of different modes after AD sampling, or after pulse compression.
[0040] The compensation position of the Bessel compensation coefficient is selected based on the center frequency of the received vortex electromagnetic wave signal.
[0041] The center frequency of the received vortex electromagnetic wave signal is non-zero. Compensation can be performed on the vortex electromagnetic wave echo data of different modes after AD sampling, or after down-conversion.
[0042] For example, if the center frequency of the received vortex electromagnetic wave signal is non-zero and is a linear frequency modulated signal, then the vortex electromagnetic wave echo data of different modes can be compensated after AD sampling, or after down-conversion, or after pulse compression.
[0043] Step 108: Compensate the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method. In one embodiment, one implementation of step 108 is as follows: The compensation data is determined according to the compensation method, and the compensation data includes AD sampling data, pulse compression data, and downconversion data; The compensation data for different modes are multiplied by the Bessel compensation coefficient.
[0044] In one embodiment, step 108 is specifically implemented as follows: The emitted vortex electromagnetic wave is a point frequency signal or a continuous wave signal. The echo data of different modes of vortex electromagnetic waves can be multiplied by the Bessel compensation coefficient after AD sampling.
[0045] The transmitted vortex electromagnetic wave is a linear frequency modulated signal. The echo data of different modes of the vortex electromagnetic wave can be multiplied by the Bessel compensation coefficient after AD sampling, or after pulse compression. When multiplying the echo data of different modes of the vortex electromagnetic wave by the Bessel compensation coefficient after pulse compression, both the real and imaginary parts must be multiplied by the Bessel compensation coefficient.
[0046] The compensation position of the Bessel compensation coefficient is selected based on the center frequency of the received vortex electromagnetic wave signal.
[0047] The center frequency of the received vortex electromagnetic wave signal is non-zero. The Bessel compensation coefficient can be applied to the vortex electromagnetic wave echo data of different modes after AD sampling, or it can be applied to the vortex electromagnetic wave echo data of different modes after down-conversion. When applying the Bessel compensation coefficient to the vortex electromagnetic wave echo data of different modes after down-conversion, both the real and imaginary parts need to be multiplied by the Bessel compensation coefficient.
[0048] For example, if the center frequency of the received vortex electromagnetic wave signal is non-zero and is a linear frequency modulated signal, then the vortex electromagnetic wave echo data of different modes can be multiplied by the Bessel compensation coefficient after AD sampling, or after down-conversion, or after pulse compression.
[0049] Step 110: Perform azimuth imaging on the compensation results based on Fourier transform.
[0050] In one embodiment, one implementation of step 110 is as follows: First, the vortex electromagnetic wave echo data of each compensated mode value are arranged in rows to form a two-dimensional array, with echo data of the same mode value in one row. Then, Fourier transform is performed on the two-dimensional array column by column to obtain the azimuth imaging result.
[0051] When performing azimuth imaging based on Fourier transform, the difference between the modal values of vortex electromagnetic waves in adjacent rows is a fixed value, that is, the modal value intervals are equal in adjacent vortex electromagnetic wave echo data.
[0052] In one embodiment, a comparison of results before and after vortex electromagnetic wave artifact suppression is provided.
[0053] Figure 5 This is a schematic diagram showing the results of vortex electromagnetic wave artifact suppression before suppression. Figure 6 Schematic diagram of the results of vortex electromagnetic wave artifact suppression. Figure 5The left figure shows the two-dimensional imaging results in the range and azimuth dimensions. The range dimension uses pulse compression and the azimuth dimension uses Fourier transform imaging. The horizontal axis represents the number of range dimension units and the vertical axis represents the number of azimuth dimension units. Figure 5 The right figure shows the azimuth imaging result, with the horizontal axis representing the number of azimuth units and the vertical axis representing the amplitude. Figure 6 The left image shows the adoption of Figures 1-3 The two-dimensional imaging results obtained by the vortex electromagnetic wave artifact suppression method in any embodiment are in the range dimension and the azimuth dimension. The range dimension adopts pulse compression and the azimuth dimension adopts Fourier transform imaging. The horizontal axis is the number of range dimension units and the vertical axis is the number of azimuth dimension units. Figure 6 The right figure shows the azimuth imaging result, with the horizontal axis representing the number of azimuth units and the vertical axis representing the amplitude.
[0054] contrast Figure 5 and Figure 6 It can be seen that by using the present invention Figure 3 and Figure 4 The vortex electromagnetic wave artifact suppression method of any embodiment can effectively suppress artifacts generated during imaging of unidirectionally modulated vortex electromagnetic waves.
[0055] Therefore, the vortex electromagnetic wave artifact suppression method of this invention firstly, generates Bessel modulation in the radiation pattern amplitude of the vortex electromagnetic wave generated by a uniform circular array. By setting Bessel compensation coefficients, imaging compensation can be achieved, improving imaging quality. Secondly, the Bessel compensation coefficients are composed of a first-type Bessel function, the mode value of the vortex electromagnetic wave, the wave number, and the target elevation angle. These parameters are easily obtained, enabling rapid construction of the Bessel compensation coefficients. Thirdly, the target elevation angle is determined based on the vortex electromagnetic wave imaging method and the main lobe alignment, which improves the construction accuracy of the Bessel compensation coefficients. Finally, the compensation position of the Bessel compensation coefficients is selected according to the waveform of the transmitted vortex electromagnetic wave, which improves the vortex electromagnetic wave artifact suppression effect. This invention provides a vortex electromagnetic wave artifact suppression method that can effectively solve the artifact problem caused by unidirectional modulation imaging mode, and is particularly suitable for vortex electromagnetic wave radars based on uniform circular arrays.
[0056] Figure 7 This specification provides a schematic diagram of a vortex electromagnetic wave artifact suppression system according to an embodiment. The system may specifically include: Step 202: Acquisition module, used to acquire vortex electromagnetic wave signal, which can be transmitted vortex electromagnetic wave signal or echo vortex electromagnetic wave signal. Step 204: Construct a module to build the Bessel compensation coefficients; Step 206: The compensation method determination module is used to determine the compensation method of the echo data corresponding to the vortex electromagnetic wave signal based on the waveform or center frequency of the vortex electromagnetic wave signal. The compensation method includes compensating the AD sampling data of the vortex electromagnetic wave signal, compensating the pulse compression data of the vortex electromagnetic wave signal, and compensating the down-conversion data of the vortex electromagnetic wave signal. Step 208: Compensation module, used to compensate the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method; Step 210: Imaging module, used to perform azimuth imaging on the compensation results based on Fourier transform. In one embodiment, the construction module is specifically implemented as follows: Figure 3 This is a schematic diagram illustrating the case where the beam pointing to the target of a vortex electromagnetic wave is not scanned. Figure 4 This is a schematic diagram illustrating the beam scanning situation of a vortex electromagnetic wave target. This embodiment is applicable to both vortex electromagnetic wave beam scanning and unscanned imaging methods.
[0057] like Figure 3 OXYZ is the antenna array coordinate system, with the positive direction of the OZ axis being the antenna normal direction, and point P being the target position. This refers to the divergence angle of the vortex electromagnetic wave. When vortex electromagnetic waves are used for imaging in a beam-unscanned manner, it is required that the divergence angles of vortex electromagnetic waves with different modes be the same. This ensures that vortex electromagnetic waves with different modes can illuminate the same location on the same target, so that the echo data of the vortex electromagnetic waves contains the phase gradients of different modes. Target imaging can be achieved using these phase gradients. When the main beams of vortex electromagnetic waves with different modes all point towards the target, the angle between the target and the direction of the vortex electromagnetic wave beam center is the divergence angle corresponding to the different modes of the vortex electromagnetic wave, i.e., .
[0058] like Figure 4 OXYZ is the antenna array coordinate system, and point P is the target position. The divergence angle of the vortex electromagnetic wave. When vortex electromagnetic waves are imaged using beam scanning, the divergence angles of vortex electromagnetic waves with different mode values can be the same or different. When the divergence angles of vortex electromagnetic waves with different mode values are different, the direction of the main beam of the vortex electromagnetic waves can be changed to make the main beams of the vortex electromagnetic waves with different mode values point towards the target. By changing the direction of the main beam of the vortex electromagnetic waves so that the main beams of vortex electromagnetic waves with different mode values all point towards the target, the angle between the target and the direction of the vortex electromagnetic wave beam center is the divergence angle corresponding to the different mode values of the vortex electromagnetic waves, i.e. At this moment, the target's pitch angle is... .
[0059] Based on this, two vortex electromagnetic wave imaging methods are provided. Regardless of whether vortex electromagnetic wave imaging is performed using antenna beam scanning or non-scanning, when the main beam of the vortex electromagnetic wave is aligned with the target, the angle between the target and the center of the vortex electromagnetic wave beam is the divergence angle of the vortex electromagnetic wave. When imaging is performed using the non-scanning antenna method, the angle between the target and the center of the vortex electromagnetic wave beam is the target elevation angle.
[0060] In one embodiment, the compensation method determination module is specifically implemented as follows: The compensation position of the Bessel compensation coefficient is selected based on the waveform of the emitted vortex electromagnetic wave.
[0061] The emitted vortex electromagnetic waves are either point frequency signals or continuous wave signals, and the echo data of vortex electromagnetic waves of different modes can be compensated after AD sampling.
[0062] The emitted vortex electromagnetic wave is a linear frequency modulated signal, which can be used to compensate for the echo data of vortex electromagnetic waves of different modes after AD sampling, or after pulse compression.
[0063] The compensation position of the Bessel compensation coefficient is selected based on the center frequency of the received vortex electromagnetic wave signal.
[0064] The center frequency of the received vortex electromagnetic wave signal is non-zero. Compensation can be performed on the vortex electromagnetic wave echo data of different modes after AD sampling, or after down-conversion.
[0065] For example, if the center frequency of the received vortex electromagnetic wave signal is non-zero and is a linear frequency modulated signal, then the vortex electromagnetic wave echo data of different modes can be compensated after AD sampling, or after down-conversion, or after pulse compression.
[0066] In one embodiment, the compensation method determination module is implemented as follows: The emitted vortex electromagnetic wave is a point frequency signal or a continuous wave signal. The echo data of different modes of vortex electromagnetic waves can be multiplied by the Bessel compensation coefficient after AD sampling.
[0067] The transmitted vortex electromagnetic wave is a linear frequency modulated signal. The echo data of different modes of the vortex electromagnetic wave can be multiplied by the Bessel compensation coefficient after AD sampling, or after pulse compression. When multiplying the echo data of different modes of the vortex electromagnetic wave by the Bessel compensation coefficient after pulse compression, both the real and imaginary parts must be multiplied by the Bessel compensation coefficient.
[0068] The compensation position of the Bessel compensation coefficient is selected based on the center frequency of the received vortex electromagnetic wave signal.
[0069] The center frequency of the received vortex electromagnetic wave signal is non-zero. The Bessel compensation coefficient can be applied to the vortex electromagnetic wave echo data of different modes after AD sampling, or it can be applied to the vortex electromagnetic wave echo data of different modes after down-conversion. When applying the Bessel compensation coefficient to the vortex electromagnetic wave echo data of different modes after down-conversion, both the real and imaginary parts need to be multiplied by the Bessel compensation coefficient.
[0070] For example, if the center frequency of the received vortex electromagnetic wave signal is non-zero and is a linear frequency modulated signal, then the vortex electromagnetic wave echo data of different modes can be multiplied by the Bessel compensation coefficient after AD sampling, or after down-conversion, or after pulse compression.
[0071] In one embodiment, the imaging module is specifically implemented as follows: First, the vortex electromagnetic wave echo data of each compensated mode value are arranged in rows to form a two-dimensional array, with echo data of the same mode value in one row. Then, Fourier transform is performed on the two-dimensional array column by column to obtain the azimuth imaging result.
[0072] When performing azimuth imaging based on Fourier transform, the difference between the modal values of vortex electromagnetic waves in adjacent rows is a fixed value, that is, the modal value intervals are equal in adjacent vortex electromagnetic wave echo data.
[0073] Therefore, the vortex electromagnetic wave artifact suppression system of this invention firstly utilizes the Bessel modulation of the radiation pattern amplitude generated by the vortex electromagnetic wave produced by the uniform circular array. By setting the Bessel compensation coefficient, imaging compensation can be achieved, improving imaging quality. Secondly, the Bessel compensation coefficient is composed of the first-type Bessel function, the mode value of the vortex electromagnetic wave, the wave number, and the target elevation angle. These parameters are easily obtained, enabling rapid construction of the Bessel compensation coefficient. Thirdly, the target elevation angle is determined based on the vortex electromagnetic wave imaging method and the main lobe alignment, which improves the construction accuracy of the Bessel compensation coefficient. Finally, the compensation position of the Bessel compensation coefficient is selected according to the waveform of the transmitted vortex electromagnetic wave, which improves the vortex electromagnetic wave artifact suppression effect. This invention provides a vortex electromagnetic wave artifact suppression method that can effectively solve the artifact problem caused by unidirectional modulation imaging mode, and is particularly suitable for vortex electromagnetic wave radar based on uniform circular array.
[0074] Figure 8 A schematic diagram of a vortex electromagnetic wave artifact suppression device provided in one embodiment of this specification includes: processor, and A memory configured to store computer-executable instructions, which, when executed, cause the processor to perform the steps of the following method: Step 1: Obtain vortex electromagnetic wave signal, which can be either transmitted vortex electromagnetic wave signal or echo vortex electromagnetic wave signal. Step 2: Construct the Bessel compensation coefficients; Step 3: Based on the waveform or center frequency of the vortex electromagnetic wave signal, determine the compensation method for the echo data corresponding to the vortex electromagnetic wave signal. The compensation method includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal. Step 4: Compensate the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method; Step 5: Perform azimuth imaging on the compensation results based on Fourier transform.
[0075] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0076] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that specifies a function in one or more boxes.
[0077] These computer program instructions may also be stored in a computer-readable storage medium that directs a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0078] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps that specify the function are in one or more boxes.
[0079] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.
Claims
1. A method for suppressing vortex electromagnetic wave artifacts, characterized in that, include: Acquire vortex electromagnetic wave signals, wherein the vortex electromagnetic wave signals are transmitted vortex electromagnetic wave signals or echo vortex electromagnetic wave signals. Construct the Bessel compensation coefficient; Based on the waveform or center frequency of the vortex electromagnetic wave signal, the compensation method for the corresponding echo data of the vortex electromagnetic wave signal is determined. The compensation method includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal. The vortex electromagnetic wave signal is compensated based on the Bessel compensation coefficient and the compensation method. Azimuth-dimensional imaging is performed on the compensation results based on Fourier transform.
2. The method for suppressing vortex electromagnetic wave artifacts according to claim 1, characterized in that, The constructed Béssel compensation coefficients include: The operating parameters of the vortex electromagnetic wave antenna array are obtained, including the mode value of the vortex electromagnetic wave, the wave number of the vortex electromagnetic wave, the imaging mode of the vortex electromagnetic wave, and the radius of the antenna array. Based on the imaging method of the vortex electromagnetic wave, determine the angle between the target and the direction of the vortex electromagnetic wave beam center; The Bessel compensation coefficients are constructed based on the modal values, the wavenumber, the included angle, the antenna array radius, and the first type of Bessel function.
3. The method for suppressing vortex electromagnetic wave artifacts according to claim 2, characterized in that, Determining the angle between the target and the center direction of the vortex electromagnetic wave beam based on the imaging method of the vortex electromagnetic wave includes: If the imaging method is scanning imaging or non-scanning imaging, and the main lobe is aligned with the target, the included angle is the divergence angle of the vortex electromagnetic wave. If the imaging method is unscanning imaging and the non-main lobe is aligned with the target, the included angle is the target elevation angle of the vortex electromagnetic wave.
4. The method for suppressing vortex electromagnetic wave artifacts according to claim 2, characterized in that, The construction of Bessel compensation coefficients based on the modal values, wavenumbers, included angles, antenna array radius, and the first type of Bessel function includes: The Bessel compensation coefficient is specifically expressed as follows: Among them, J l (·) represents the first-kind Bessel function, l represents the mode value of the vortex electromagnetic wave, x represents the wave number of the vortex electromagnetic wave, a represents the radius of the circular antenna array, and θ represents the angle between the target and the center of the vortex electromagnetic wave beam.
5. The method for suppressing vortex electromagnetic wave artifacts according to claim 1, characterized in that, The step of determining the compensation method for the echo data corresponding to the vortex electromagnetic wave signal based on the waveform or center frequency of the vortex electromagnetic wave signal includes compensating for the AD sampling data of the vortex electromagnetic wave signal, compensating for the pulse compression data of the vortex electromagnetic wave signal, and compensating for the down-conversion data of the vortex electromagnetic wave signal. When the vortex electromagnetic wave signal is the transmitted vortex electromagnetic wave signal, the compensation method for the echo data corresponding to the transmitted vortex electromagnetic wave signal is determined according to the waveform of the transmitted vortex electromagnetic wave signal. When the vortex electromagnetic wave signal is an echo vortex electromagnetic wave signal, the compensation method for the echo data corresponding to the echo vortex electromagnetic wave signal is determined according to the center frequency of the echo vortex electromagnetic wave signal.
6. The method for suppressing vortex electromagnetic wave artifacts according to claim 5, characterized in that, When the vortex electromagnetic wave signal is a transmitted vortex electromagnetic wave signal, the compensation method for determining the echo data corresponding to the transmitted vortex electromagnetic wave signal based on the waveform of the transmitted vortex electromagnetic wave signal includes: If the waveform of the transmitted vortex electromagnetic wave signal is a point frequency signal or a continuous wave signal, then the AD sampling data of the echo data is compensated. If the waveform of the transmitted vortex electromagnetic wave signal is a linear frequency modulated signal, then the AD sampling data of the echo data is compensated or the pulse compression data of the echo data is compensated.
7. The method for suppressing vortex electromagnetic wave artifacts according to claim 5, characterized in that, When the vortex electromagnetic wave signal is an echo vortex electromagnetic wave signal, the compensation method for determining the echo data corresponding to the echo vortex electromagnetic wave signal based on the center frequency of the echo vortex electromagnetic wave signal includes: If the center frequency of the echo vortex electromagnetic wave signal is zero, then the AD sampling data of the echo data is compensated. If the center frequency of the echo vortex electromagnetic wave signal is not zero, then the AD sampling data of the echo data is compensated or the down-conversion data of the echo data is compensated.
8. The method for suppressing vortex electromagnetic wave artifacts according to claim 1, characterized in that, The compensation of the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method includes: The compensation data is determined according to the compensation method, and the compensation data includes AD sampling data, pulse compression data, and downconversion data; The compensation data for different modes are multiplied by the Bessel compensation coefficient.
9. A vortex electromagnetic wave artifact suppression system, characterized in that, include: The acquisition module is used to acquire vortex electromagnetic wave signals, which can be transmitted vortex electromagnetic wave signals or echo vortex electromagnetic wave signals. The building block is used to construct the Bessel compensation coefficients; The compensation method determination module is used to determine the compensation method of the echo data corresponding to the vortex electromagnetic wave signal based on the waveform or center frequency of the vortex electromagnetic wave signal. The compensation method includes compensating the AD sampling data of the vortex electromagnetic wave signal, compensating the pulse compression data of the vortex electromagnetic wave signal, and compensating the down-conversion data of the vortex electromagnetic wave signal. The compensation module is used to compensate the vortex electromagnetic wave signal based on the Bessel compensation coefficient and the compensation method. The imaging module is used to perform azimuth-dimensional imaging based on the compensation results using Fourier transform.
10. A device for suppressing vortex electromagnetic wave artifacts, characterized in that, include: processor, and A memory configured to store computer-executable instructions, which, when executed, cause the processor to perform the steps of the method as described in any one of claims 1 to 8.