Multi-mode vortex wave radar target detection system and design method

Abstract

The invention relates to a multi-modal vortex wave radar target detection system and a design method, which have the target detection capability of simultaneous multi-modal generation, reduce the total weight of the system and improve the effective load ratio on one hand, and have more target information acquisition capability on the other hand. According to the multi-mode vortex wave radar target detection system, time-sharing work or simultaneous work of different modes can be realized under multiple working modes through corresponding control. The method is especially suitable for high-resolution detection of a static platform and other scenes with strict requirements on the resolution of the real aperture. The method can be popularized and applied to platforms such as approaching observation satellites and security inspection; the simultaneous multi-mode detection system can be conveniently changed into a multi-channel MIMO detection system by replacing emission signals and antenna phase configuration; therefore, more remote sensing detection functions are realized.

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 with traditional plane electromagnetic waves, electromagnetic vortex waves have the characteristics of spirally distributed wavefront phase, special ring antenna radiation pattern, unique vortex azimuth dimension information, etc. In recent years, thanks to its special physical properties, electromagnetic vortex waves have received widespread attention in the fields of wireless communication, radar remote sensing detection, terrain height measurement, etc. In the field of radar, electromagnetic vortex waves have been applied to the stare imaging and synthetic aperture imaging of targets. By transforming the mode number of orbital angular momentum, the radar can obtain the vortex azimuth resolution. Domestic scholars have analyzed the vortex azimuth imaging potential of electromagnetic vortex waves and given relevant imaging algorithms. They have given the vortex electromagnetic wave echo signal model under multi-transmitter and multi-receiver and multi-transmitter and single-receiver ring antennas and used the fast Fourier transform algorithm to achieve the target's range-vortex azimuth two-dimensional focusing. The vortex electromagnetic wave synthetic aperture imaging experiment shows that the electromagnetic vortex synthetic aperture radar has the characteristics of high short-range resolution.

[0003] Driven by the demand for real aperture high-resolution imaging, the materialization and engineering of electromagnetic vortex radar has become one of the hot areas of high-resolution imaging radar. However, electromagnetic vortex radar has the problem of high requirements for system integration and multiple requirements for working 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 device to generate N orthogonal baseband signals;

[0007] The N-channel transmitting group is used to up-convert and 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 radio frequency signals of N modes, and transmit the radio frequency signals of N modes;

[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-channel 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 ith 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 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.

[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 first-order Bessel function of the first kind, 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 number of modes 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] According to the required resolution of the vortex azimuth angle, the number of modes N of the radio frequency signal is determined;

[0022] According to the required angle of the beam pitch angle, the radius of the annular array corresponding to each mode is determined;

[0023] N circular arrays are arranged concentrically according to the radius of the circular array, and each circular array corresponds 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;

[0024] Calculate the phase of the modulation excitation of each antenna element for each circular 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 device are linear frequency modulation signals with random time width.

[0026] In one embodiment, the N-channel 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 ith 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 first-order Bessel function of the first kind, 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 number of modes 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 prior art, 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 target detection capability of simultaneous multi-modal generation, which reduces the total weight of the system and increases the payload ratio on the one hand; on the other hand, it has more target information acquisition capabilities. 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 given in conjunction with the accompanying drawings, which together with the following detailed description are included in this specification 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 The pitch angle θ under different modes is shown p =9° antenna radiation pattern and far-field phase distribution diagram;

[0040] Figure 4 The autocorrelation result diagram of 4-channel random time-width linear frequency modulation signals with a bandwidth of 600MHz and a pulse width of 2μs is shown;

[0041] Figure 5 The result diagram of the cross-correlation of 4-way signals is shown;

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

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

[0044] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure closely related to the scheme according to the present application is shown in the drawings, 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 implementation forms due to the following description with reference to the accompanying drawings. In this article, where feasible, the embodiments can be combined with each other, features between different embodiments can be replaced or borrowed, and one or more features can be omitted in one embodiment.

[0046] The present application provides a design method for a multi-modal vortex wave radar target detection system. Figure 1 A flowchart of 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 mode number N of the radio frequency signal according to the required size of the vortex azimuth angle resolution.

[0048] Specifically, the modal number N 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 first-order Bessel function of the first kind, 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, concentrically arranging N circular arrays 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.

[0056] Step S4, for each annular array, calculate the phase of the modulation excitation of each antenna unit, input the phase into the TR module corresponding to the antenna unit, and realize the complete phase weighting of each antenna excitation of different modes. The TR module performs phase weighting based on the input phase as the weight value.

[0057] Step S5, determining that the N orthogonal baseband signals generated by the signal device are linear frequency modulation signals with random time width.

[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 ith 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-mode vortex wave radar target detection system. Figure 2 The structural block diagram of the multi-mode 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 device to generate N orthogonal baseband signals;

[0064] The N-channel transmitting group is used to up-convert and 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 radio frequency signals of N modes, and transmit the radio frequency signals of N modes;

[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 device 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 and sends them to the control board in the signal device. The signal device generates N orthogonal baseband signals. The microwave channel includes N channel radiation groups and N channel receiving groups. The N orthogonal baseband signals are up-converted and filtered and amplified in the corresponding transmission channels to obtain N radio frequency signals; the antenna device includes N power division networks, N groups of TR modules and N groups of antenna units, wherein the power division network is used for power division processing, and each group of TR modules is used to power amplify and phase weight one power division processed signal to obtain a modal radio frequency signal, and each group of antenna units is used to transmit a modal radio frequency signal.

[0068] In one embodiment, considering the Doppler tolerance of the system, a linear frequency modulation signal with a random time width is selected as an orthogonal baseband signal, and 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 ith 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 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.

[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 first-order Bessel function of the first kind, 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 number of modes 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 technical effect of the present application is further illustrated by simulation experiments below.

[0079] In the simulation experiment, the radar center frequency is set to 10 GHz. Figure 3 The pitch angle θ under different modes is shown 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 pitch angle of mode 4 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 autocorrelation result diagram of 4-channel random time-width linear frequency modulation signals with a bandwidth of 600MHz and a pulse width of 2μs is shown. It can be seen that the selection of this form of waveform can realize matched filtering of 4-channel signals. Figure 5 The result diagram of the cross-correlation of the 4-channel signals is shown. It can be seen that the spacing between the 4 channels is greater than 15dB, and signal isolation between the channels can be achieved.

[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, and the concentric ring MIMO working mode is the method proposed in the application. As shown in the figure, the vortex azimuth image is widened when the concentric ring is used compared to the ring array mode. This is because the radius of the low-mode ring array is small, 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 rings 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 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 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 are only various implementations of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A multi-modal vortex 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 perform up-conversion and filtering amplification on 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 of N modes, and transmit the radio frequency signals of 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.

2. The system according to claim 1, characterized in that 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 ith 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 .

3. The system according to claim 1, characterized in that The antenna device includes N concentrically arranged annular arrays, each of which emits a radio frequency signal of one mode; each annular array includes a plurality of antenna units, and the plurality of antenna units are distributed at half-wavelength intervals.

4. The system according to claim 1, characterized in that 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 first-order Bessel function of the first kind, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle points to the required angle.

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

6. A design method for a multi-modal vortex wave radar target detection system, characterized in that: include: According to the required resolution of the vortex azimuth angle, the number of modes N of the radio frequency signal is determined; According to the required angle of the beam pitch angle, the radius of the annular array corresponding to each mode is determined; Arrange 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 modulation excitation of each antenna unit for each annular array, and input the phase into the TR module corresponding to the antenna unit; It is determined that the N-channel orthogonal baseband signals generated by the signal device are linear frequency modulation signals with random time width.

7. The method according to claim 6, characterized in that 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 ith 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 .

8. The method according to claim 6, characterized in that 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 first-order Bessel function of the first kind, k is the wave multiplier, k = 2π / λ, λ is the carrier wavelength, θ p The beam elevation angle points to the required angle.

9. The method according to claim 6, characterized in that The modal number N of the radio frequency signal is determined by the following formula: in, is the required size of the vortex azimuth angle resolution.

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