A multi-modal vortex wave radar target detection system and design method

Abstract

The present application relates to a multi-modal vortex wave radar target detection system and design method, which has the ability to detect targets with simultaneous multi-modal generation. On the one hand, it reduces the total weight of the system and increases the proportion of effective load. On the other hand, it has the ability to obtain more target information. The multi-modal vortex wave radar target detection system can realize multiple working modes through corresponding control, and different modes can work in time-sharing or simultaneously. It is particularly suitable for use in scenarios such as high-resolution detection of stationary platforms that require strict requirements on real aperture resolution; it can be extended and applied to platforms such as close-range observation satellites and security inspections; it can be relatively convenient to change the simultaneous multi-modal to a multi-channel MIMO detection system by changing the transmission signal and antenna phase configuration; thereby realizing more remote sensing detection functions.

Description

Technical Field

[0001] The present application relates to the field of remote sensing detection, and in particular to a multi-modal vortex wave radar target detection system and a design method. Background Art

[0002] Compared to traditional plane electromagnetic waves, electromagnetic vortex waves (EVWs) possess a spirally distributed wavefront phase, a unique loop antenna pattern, and unique vortex azimuth information. In recent years, thanks to their unique physical properties, EVWs have garnered widespread attention in fields such as wireless communications, radar remote sensing, and terrain altimetry. In radar, EVWs have been applied to target staring imaging and synthetic aperture imaging. By transforming the mode number of orbital angular momentum, radar can achieve vortex azimuth resolution. Domestic researchers have analyzed the vortex azimuth imaging potential of EVWs and proposed related imaging algorithms. They have also developed vortex electromagnetic wave echo signal models for multi-transmitter multi-receiver and multi-transmitter single-receiver loop antennas and achieved two-dimensional focusing of the target based on range and vortex azimuth using a fast Fourier transform algorithm. Experiments with vortex electromagnetic wave synthetic aperture imaging have demonstrated that EVW synthetic aperture radars possess high short-range resolution.

[0003] Driven by the demand for real-aperture high-resolution imaging, the implementation and engineering of electromagnetic vortex radar has become a hot area in the field of high-resolution imaging radar. However, electromagnetic vortex radar has the problem of high requirements for system integration and multiple operating modes and functions. Summary of the Invention

[0004] In order to overcome at least one deficiency in the prior art, the present application provides a multi-modal vortex wave radar target detection system and a design method.

[0005] In a first aspect, a multi-modal vortex wave radar target detection system is provided, comprising: a control computer, a signal device, a microwave channel device, and an antenna device; the microwave channel device comprises an N-channel transmitting group and an N-channel receiving group;

[0006] The control computer controls the signal equipment to generate N-channel orthogonal baseband signals;

[0007] The N-channel transmitting group is used to up-convert, filter and amplify N-channel orthogonal baseband signals to obtain N-channel RF signals;

[0008] The antenna device is used to perform power division processing, power amplification, and phase weighting on N radio frequency signals to obtain N modal radio frequency signals and transmit the N modal radio frequency signals.

[0009] The antenna device receives the echo signal of the detected object. The echo signal is stored in the signal device after passing through the N-channel receiving group and transmitted to the control computer for signal processing to obtain the target detection result.

[0010] In one embodiment, the N orthogonal baseband signals are:

[0011]

[0012] Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

[0013] In one embodiment, the antenna device includes N concentrically arranged annular arrays, each annular array corresponding to transmitting a radio frequency signal of a mode; each annular array includes multiple antenna units, and the multiple antenna units are distributed at half-wavelength intervals.

[0014] In one embodiment, the array radius of each annular array is:

[0015]

[0016] Among them, a l is the radius of the lth annular array, J l (x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle is the required angle.

[0017] In one embodiment, the modal number N of the radio frequency signal is determined using the following formula:

[0018]

[0019] in, is the required size of the vortex azimuth angle resolution.

[0020] In a second aspect, a design method for a multi-modal vortex wave radar target detection system is provided, comprising:

[0021] Determine the number of modes N of the RF signal according to the required resolution of the vortex azimuth angle;

[0022] Determine the radius of the annular array corresponding to each mode based on the required beam pitch angle;

[0023] N circular arrays are concentrically arranged according to the radius of the circular array, and each circular array transmits a radio frequency signal of a mode; each circular array includes multiple antenna units, and the multiple antenna units are distributed at half-wavelength intervals;

[0024] Calculate the phase of the modulated excitation of each antenna element for each ring array and input the phase into the TR module corresponding to the antenna element;

[0025] It is determined that the N-channel orthogonal baseband signals generated by the signal equipment are linear frequency modulation signals with random time widths.

[0026] In one embodiment, the N orthogonal baseband signals are:

[0027]

[0028] Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

[0029] In one embodiment, the array radius of each annular array is:

[0030]

[0031] Among them, a l is the radius of the lth annular array, J l (x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle is the required angle.

[0032] In one embodiment, the modal number N of the radio frequency signal is determined using the following formula:

[0033]

[0034] in, is the required size of the vortex azimuth angle resolution.

[0035] Compared with the existing technology, the present application has the following beneficial effects: the multi-modal vortex wave radar target detection system and design method of the present application have the ability to detect targets with simultaneous multi-modal generation. On the one hand, it reduces the total weight of the system and increases the proportion of effective load; on the other hand, it has the ability to obtain more target information. The multi-modal vortex wave radar target detection system can realize multiple working modes through corresponding control, and different modes can work in time-sharing or simultaneously. It is particularly suitable for use in scenarios such as high-resolution detection of stationary platforms that require strict requirements on real aperture resolution; it can be extended to platforms such as close-range observation satellites and security inspections; it can be relatively convenient to change the simultaneous multi-modal to a multi-channel MIMO detection system by changing the transmission signal and antenna phase configuration; thereby realizing more remote sensing detection functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present application may be better understood by referring to the following description in conjunction with the accompanying drawings, which together with the following detailed description are incorporated into and form a part of this specification. In the drawings:

[0037] Figure 1 A flowchart of a design method for a multi-modal vortex wave radar target detection system is shown;

[0038] Figure 2 The structural block diagram of the multi-modal vortex wave radar target detection system is shown;

[0039] Figure 3 Shows the pitch angle pointing to θ under different modes p =9° antenna radiation pattern and far-field phase distribution diagram;

[0040] Figure 4 The figure shows the autocorrelation results of 4-channel random time-width linear frequency modulation signals with a bandwidth of 600MHz and a pulse width of 2μs.

[0041] Figure 5 The figure shows the result of the cross-correlation of 4 signals;

[0042] Figure 6 The normalized vortex azimuthal image results under different modes are shown. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present application are described below with reference to the accompanying drawings. For the sake of clarity and conciseness, not all features of actual embodiments are described in this specification. However, it should be understood that in the process of developing any such actual embodiment, many implementation-specific decisions may be made to achieve the developer's specific goals, and these decisions may vary from one implementation to another.

[0044] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, the accompanying drawings only show the device structure closely related to the solution according to the present application, while other details that are not closely related to the present application are omitted.

[0045] It should be understood that the present application is not limited to the described embodiments due to the following description with reference to the accompanying drawings. In this document, where feasible, the embodiments may be combined with each other, features between different embodiments may be replaced or borrowed, and one or more features may be omitted in one embodiment.

[0046] The present invention provides a method for designing a multi-modal vortex wave radar target detection system. Figure 1 A flowchart showing a design method for a multi-modal vortex wave radar target detection system is shown in FIG. Figure 1 , methods include:

[0047] Step S1: determining the number N of modes of the radio frequency signal according to the required resolution of the vortex azimuth angle.

[0048] Specifically, the number N of modes of the RF signal is determined using the following formula:

[0049]

[0050] in, is the required size of the vortex azimuth angle resolution.

[0051] Step S2: determining the radius of the annular array corresponding to each mode according to the beam pitch angle pointing to the required angle.

[0052] Specifically, the array radius of each annular array is:

[0053]

[0054] Among them, a l is the radius of the lth annular array, J l (x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p is the required angle of the beam pitch angle, and max() is the maximum value operation.

[0055] Step S3: Arrange N circular arrays concentrically according to the radius of the circular array, and each circular array transmits a radio frequency signal of a mode; each circular array includes multiple antenna units, and the multiple antenna units are distributed at half-wavelength intervals.

[0056] Step S4: Calculate the phase of the modulated excitation for each antenna element in each annular array and input the phase into the corresponding TR module to achieve complete phase weighting of the excitations for each antenna in different modes. The TR module performs phase weighting based on the input phase as the weight.

[0057] Step S5: Determine whether the N orthogonal baseband signals generated by the signal device are linear frequency modulation signals with random time widths.

[0058] Specifically, when the bandwidth of the orthogonal baseband signal is B and the pulse width is τ, the N-channel orthogonal baseband signal is:

[0059]

[0060] Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

[0061] Through the design method of the above embodiment, a multi-modal vortex wave radar target detection system is obtained.

[0062] The present application also provides a multi-modal vortex wave radar target detection system. Figure 2 The structural block diagram of the multi-modal vortex wave radar target detection system is shown in FIG. Figure 2 , the system includes: a control computer, a signal device, a microwave channel device and an antenna device; the microwave channel device includes an N-channel transmitting group and an N-channel receiving group;

[0063] The control computer controls the signal equipment to generate N-channel orthogonal baseband signals;

[0064] The N-channel transmit group is used to up-convert, filter and amplify N-channel orthogonal baseband signals to obtain N-channel RF signals;

[0065] The antenna device is used to perform power division processing, power amplification, and phase weighting on N radio frequency signals to obtain N modal radio frequency signals and transmit the N modal radio frequency signals.

[0066] The antenna device receives the echo signal of the detected object. The echo signal is stored in the signal device after passing through the N-channel receiving group and transmitted to the control computer for signal processing to obtain the target detection result.

[0067] In this embodiment, the signal equipment includes a signal board, a control board, a data board, and a power supply. The control computer is used for human-computer interaction and generates initial system control instructions, which are then sent to the control board in the signal equipment. The signal equipment generates N orthogonal baseband signals. The microwave channel includes N-channel radiation groups and N-channel reception groups. The N orthogonal baseband signals are up-converted and filtered and amplified in the corresponding transmission channels to obtain N RF signals. The antenna equipment includes N power splitter networks, N groups of TR modules, and N groups of antenna units. The power splitter network is used for power splitting processing. Each group of TR modules is used to power amplify and phase-weight one power splitter-processed signal to obtain a modal RF signal. Each group of antenna units is used to transmit a modal RF signal.

[0068] In one embodiment, considering the Doppler tolerance of the system, a linear frequency modulation signal with random time width is selected as the orthogonal baseband signal. The N-channel orthogonal baseband signals are:

[0069]

[0070] Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

[0071] In one embodiment, the antenna device includes N concentrically arranged annular arrays, each annular array corresponding to transmitting a radio frequency signal of a mode; each annular array includes multiple antenna units, and the multiple antenna units are distributed at half-wavelength intervals.

[0072] In one embodiment, the array radius of each annular array is:

[0073]

[0074] Among them, a l is the radius of the lth annular array, J l(x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle is the required angle.

[0075] In one embodiment, the modal number N of the radio frequency signal is determined using the following formula:

[0076]

[0077] in, is the required size of the vortex azimuth angle resolution.

[0078] The following simulation experiments further illustrate the technical effects of this application.

[0079] In the simulation experiment, the radar center frequency is set to 10GHz. Figure 3 Shows the pitch angle pointing to θ under different modes p = 9° antenna radiation pattern and far-field phase distribution diagram, where (a) is the radiation pattern and far-field phase distribution diagram corresponding to mode 1, (b) is the radiation pattern and far-field phase distribution diagram corresponding to mode 2, (c) is the radiation pattern and far-field phase distribution diagram corresponding to mode 3, and (d) is the radiation pattern and far-field phase distribution diagram corresponding to mode 4. Figure 3 As shown, when the mode 4 pitch angle is pointed to θ p When =9°, it can be seen that the directivity patterns of each mode are relatively consistent, and the pointing error in each mode is less than 1.5 degrees.

[0080] Figure 4 The figure shows the autocorrelation results of four random-width linear frequency modulation signals with a bandwidth of 600MHz and a pulse width of 2μs. It can be seen that the selection of this waveform can realize matched filtering of the four signals. Figure 5 The cross-correlation result diagram of the four-channel signals is shown. It can be seen that the spacing between the four channels is greater than 15dB, which can achieve signal isolation between channels.

[0081] Figure 6 The normalized vortex azimuth image results under different modes are shown, where the target vortex azimuth angles are 0° and 35°. The ring array mode uses the outermost array of the concentric ring array to time-share the vortex electromagnetic waves of multiple modes. The concentric ring MIMO working mode is the method proposed in the application. As shown in the figure, the vortex azimuth image is wider when using the concentric ring than the ring array mode. This is because the radius of the low-mode ring array is smaller, and the corresponding vortex beam main lobe is wider, resulting in a decrease in resolution. However, there are more sidelobe pseudo-peaks in the ring array mode, and there are more noise points in the imaging. The sidelobe energy under the concentric ring is significantly reduced, and the overall imaging quality is significantly improved.

[0082] In summary, this application has the following technical effects:

[0083] The multi-modal vortex wave radar target detection system and design method of the present application have the ability to detect targets with simultaneous multi-modal generation. On the one hand, it reduces the total weight of the system and increases the proportion of effective payload; on the other hand, it has the ability to obtain more target information. The multi-modal vortex wave radar target detection system can realize multiple working modes through corresponding control, and different modes can work in time-sharing or simultaneously. It is particularly suitable for use in scenarios such as high-resolution detection of stationary platforms that require strict requirements on real aperture resolution; it can be extended to platforms such as close-range observation satellites and security inspections; it can be relatively convenient to change the simultaneous multi-modal to a multi-channel MIMO detection system by changing the transmission signal and antenna phase configuration; thereby realizing more remote sensing detection functions.

[0084] The above descriptions are merely examples of various embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A multi-modal eddy wave radar target detection system, characterized in that: include: control computers, signal equipment, microwave channel equipment, and antenna equipment; The microwave channel equipment includes an N-channel transmitting group and an N-channel receiving group; The control computer controls the signal device to generate N orthogonal baseband signals; The N-channel transmitting group is used to up-convert and filter and amplify the N-channel orthogonal baseband signals to obtain N-channel radio frequency signals; The antenna device is used to perform power division processing, power amplification and phase weighting on the N radio frequency signals to obtain radio frequency signals in N modes, and transmit the radio frequency signals in the N modes; The antenna device receives the echo signal of the detected object, the echo signal is stored in the signal device after passing through the N-channel receiving group, and is transmitted to the control computer for signal processing to obtain the target detection result; The N-channel orthogonal baseband signals are: Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

2. The system according to claim 1, wherein The antenna device includes N concentrically arranged annular arrays, each of which transmits a radio frequency signal of one mode; each annular array includes multiple antenna units, and the multiple antenna units are distributed at half-wavelength intervals.

3. The system according to claim 2, wherein: The array radius of each annular array is: Among them, a l is the radius of the lth annular array, J l (x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle is the required angle.

4. The system according to claim 1, wherein: The modal number N of the radio frequency signal is determined using the following formula: in, is the required size of the vortex azimuth angle resolution.

5. A design method for a multi-modal vortex wave radar target detection system, characterized in that: include: Determine the number of modes N of the RF signal according to the required resolution of the vortex azimuth angle; Determine the radius of the annular array corresponding to each mode based on the required beam pitch angle; Arranging N circular arrays concentrically according to the radius of the circular array, each circular array corresponding to transmitting a radio frequency signal of a mode; each circular array includes a plurality of antenna units, and the plurality of antenna units are distributed at half-wavelength intervals; Calculate the phase of the modulated excitation of each antenna element for each annular array, and input the phase into the TR module corresponding to the antenna element; Determine that the N-channel orthogonal baseband signals generated by the signal equipment are linear frequency modulation signals with random time width; The N-way orthogonal baseband signals are: Among them, s m (t) is the m-th orthogonal baseband signal, i is the sub-pulse number, N a is the number of sub-pulses, f i is the center frequency of the ith sub-pulse, f i is a random number between [-B / 2, B / 2], B is the bandwidth of the orthogonal baseband signal, t is the time, T i is the pulse width of the i-th sub-pulse, 0 <T i <τ, τ is the pulse width of the orthogonal baseband signal, k i is the modulation frequency of the ith sub-pulse, k i =B / T i .

6. The method according to claim 5, wherein The array radius of each annular array is: Among them, a l is the radius of the lth annular array, J l (x) is the lth-order first-kind Bessel function, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle is the required angle.

7. The method according to claim 5, wherein The modal number N of the radio frequency signal is determined using the following formula: in, is the required size of the vortex azimuth angle resolution.

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