Antenna test method and system of 4D millimeter wave radar

Abstract

The invention provides an antenna test method and system for a 4D millimeter wave radar, and the method comprises the steps: generating a simulation target with a preset distance and a preset non-zero speed through a radar echo simulator, collecting the point cloud data of a to-be-tested radar at a plurality of rotation angles, and carrying out the screening of the data in two dimensions, namely the distance and the speed, so as to achieve the test of the antenna of the to-be-tested radar. The simulation target point is accurately identified from static environment clutters, complex frequency spectrum data of each channel corresponding to the target point are extracted, and the gain and phase characteristics of the antenna are determined according to the change of the complex frequency spectrum data along with the rotation angle. A traditional microwave darkroom is not needed, environmental clutter interference is effectively restrained through a signal processing means, and therefore the cost and the space requirement of a calibration system are remarkably reduced, portability and test flexibility are improved, and meanwhile the accuracy of a calibration result is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of radar testing technology, and in particular to an antenna testing method and system for 4D millimeter-wave radar. Background Technology

[0002] 4D millimeter-wave radar, capable of simultaneously providing target range, velocity, horizontal angle, and elevation angle information, has been widely used in fields such as autonomous driving, intelligent transportation, and security monitoring. The performance of the radar antenna, particularly its gain pattern and phase consistency between channels, directly determines the radar's detection accuracy and reliability. Therefore, precise antenna calibration is a crucial step in the research and development and production of radar systems.

[0003] Traditional 4D millimeter-wave radar antenna calibration methods are typically performed in a microwave anechoic chamber. This approach mainly relies on the following equipment: a microwave anechoic chamber to shield against external electromagnetic interference and absorb radar signal reflections, thus simulating a near-free-space environment; a corner reflector as an ideal point target source; a high-precision turntable to support the radar under test and precisely change its orientation; and a host computer to control the turntable's rotation and collect and process radar data. During testing, the corner reflector is placed deep within the anechoic chamber, and the radar under test is fixed on the turntable with its antenna normal aligned with the corner reflector. By rotating the turntable, the echo signals received by the radar from the corner reflector at different angles can be measured, thereby plotting the antenna pattern and calibrating the phase.

[0004] However, this traditional technique based on microwave anechoic chambers has many inherent drawbacks:

[0005] 1. High space and cost requirements: In order to meet the far-field testing conditions of the antenna, the length of the microwave anechoic chamber usually needs to be several times that of the radar range resolution, resulting in a huge footprint and high construction and maintenance costs.

[0006] 2. Environmental and health issues: The microwave-absorbing materials (such as cone sponge) lining the walls of the dark room may release odors during long-term use, posing a potential threat to the health of test personnel.

[0007] 3. Poor portability: Microwave anechoic chambers are large, fixed facilities that cannot be moved, which limits the testing location and flexibility, making it inconvenient to conduct on-site or field tests.

[0008] These shortcomings limit the efficiency and accessibility of radar antenna calibration work, and increase the research and development and production costs of radar products. Summary of the Invention

[0009] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an antenna testing method and system for 4D millimeter-wave radar, which solves the problem of relying on large, expensive and inconvenient microwave anechoic chambers for antenna testing in the prior art.

[0010] To achieve the above and other related objectives, this invention provides an antenna testing method for 4D millimeter-wave radar, comprising the following steps:

[0011] S1. Set the preset parameters for the radar echo simulator, including the preset target distance and the preset simulated target with non-zero target velocity;

[0012] S2. Transmit signal: The radar echo simulator transmits a signal to the antenna of the radar under test.

[0013] S3. Acquire point cloud data by rotating the radar under test at a specified rotation angle and acquiring point cloud data at multiple rotation angles. The point cloud data includes the measured distance, measured speed, and complex spectrum data of each channel for each detection point.

[0014] S4. Point cloud data filtering and processing: Based on preset target distance and preset non-zero target velocity data, the point cloud data is filtered to identify the target point corresponding to the simulated target;

[0015] S5. Determine the antenna characteristics, extract the complex spectrum data of each channel corresponding to the target point, and determine the antenna characteristics based on the complex spectrum data extracted under multiple rotation angles.

[0016] By adopting the above technical solution, a radar echo simulator replaces the traditional combination of microwave anechoic chamber and corner reflector. The simulated target generated by the radar echo simulator is significantly distinguishable from surrounding stationary clutter (such as walls, furniture, etc.) in the Doppler dimension. Then, by testing point cloud data at multiple different rotation angles and filtering the point cloud data collected at each angle, the unique target point generated by the echo simulator is accurately separated and identified from the background environment containing a large amount of stationary clutter. Finally, the complex spectrum data of each channel corresponding to the target point is extracted, and based on the changes of these data at all rotation angles, the key characteristics such as the gain and phase of the radar antenna are calculated and determined. This series of steps cleverly achieves the suppression of environmental clutter through signal processing, thereby achieving the effect of accurate calibration in ordinary environments instead of microwave anechoic chambers.

[0017] In one embodiment of the present invention, the filtering step in step S4 includes: defining a distance window and a velocity window, and filtering out detection points whose measured distance and measured velocity both fall within the corresponding windows, wherein the distance window is: [ , The speed window is: [ , ],in, It is a constant. For the range resolution of the radar, This represents the radar's velocity resolution.

[0018] By employing the above technical solution, the filtering process utilizes a distance window (representing the distance the target travels around it) and a velocity window (representing the velocity of the target). A detection point is considered a valid candidate only when both its measured distance and velocity fall within these two windows. This dual-dimensional filtering mechanism significantly improves the accuracy and robustness of target identification, effectively avoiding potential misjudgments that might result from relying solely on distance or velocity as a single dimension for filtering.

[0019] In one embodiment of the present invention, the step of identifying the target point in step S4 further includes selecting the point with the largest signal strength among the screened detection points as the target point, wherein the signal strength is determined by the sum of the moduli of the complex spectral data of each channel.

[0020] By adopting the above technical solution, the target point can be more accurately locked from the few candidate points after filtering. The signal strength is usually characterized by the sum of the complex spectrum data of all receiving channels corresponding to the point, which ensures that the selected point is the clearest and most reliable echo point of the signal.

[0021] In one embodiment of the present invention, in step S3, the 4D millimeter-wave radar is mounted on a turntable, and the switching of the multiple rotation angles is achieved by controlling the rotation of the turntable.

[0022] In one embodiment of the present invention, the step of determining antenna characteristics includes generating an antenna gain diagram by plotting the modulus of the complex spectrum data as a function of the rotation angle.

[0023] By adopting the above technical solution, the antenna gain diagram is obtained by plotting the curve of the magnitude of the complex spectrum data as a function of the rotation angle, which can be used to evaluate indicators such as main lobe width and peak-to-side lobe ratio.

[0024] In one embodiment of the present invention, the step of determining antenna characteristics includes generating a spatial phase diagram by plotting the phase of the complex spectrum data as a function of the rotation angle.

[0025] By adopting the above technical solution, the spatial phase diagram is obtained by plotting the phase change curve of complex spectrum data with rotation angle, which can be used to check the consistency of phase of each channel.

[0026] In one embodiment of the present invention, the accuracy of antenna calibration is verified by analyzing the spatial phase diagram to check whether there is a linear relationship between the phase of the complex spectrum data and the sine value of the rotation angle.

[0027] An antenna testing system for a 4D millimeter-wave radar includes: a radar under test; a turntable for placing the radar under test and rotating it; a radar echo simulator for transmitting simulated signals to the antenna of the radar under test; and a main controller connected to the radar under test, the turntable, and the radar echo simulator, wherein the main controller is capable of executing the method as described in any one of claims 1 to 7.

[0028] In one embodiment of the present invention, the main controller can send rotation commands to the turntable to control the rotation angle and receive point cloud data from the radar under test.

[0029] In one embodiment of the present invention, a preset spatial distance is maintained between the radar echo simulator and the radar under test mounted on the turntable.

[0030] As described above, the antenna testing method and system for the 4D millimeter-wave radar of the present invention have the following beneficial effects:

[0031] 1. No need for an anechoic chamber, reducing costs and space requirements: By using a radar echo simulator and innovative signal processing methods, the reliance on large microwave anechoic chambers is completely replaced, greatly reducing equipment costs and site requirements.

[0032] 2. Portable, flexible, and highly adaptable: The entire system consists of portable devices that can be easily and quickly deployed and used in ordinary laboratories, production workshops, and even outdoor environments, improving the flexibility of testing.

[0033] 3. Eliminate environmental hazards: By avoiding the use of wave-absorbing materials, potential odors and health risks are fundamentally eliminated.

[0034] 4. High calibration accuracy: By performing precise filtering in both distance and Doppler velocity dimensions, it can effectively suppress interference from static environmental clutter, ensuring the accuracy and reliability of the calibration results. Its effect is comparable to that of testing conducted in an anechoic chamber. Attached Figure Description

[0035] Figure 1 The diagram shows the overall structure disclosed in Embodiment 1 of the present invention.

[0036] Figure 2 The diagram shown is a schematic representation of the process disclosed in the second embodiment of the present invention;

[0037] Figure 3 The diagram shows the interface of the radar echo simulator disclosed in Embodiment 2 of the present invention.

[0038] Figure 4 The diagram shown is a schematic representation of the operating interface of the echo simulator disclosed in Embodiment 2 of the present invention.

[0039] Component designation explanation

[0040] 1. Radar under test; 2. Turntable; 3. Radar echo simulator; 4. Main control unit. Detailed Implementation

[0041] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0042] Please see Figures 1 to 4 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0043] Example 1:

[0044] like Figure 1 As shown, this embodiment provides an antenna detection system for a 4D millimeter-wave radar, including a radar under test 1, a turntable 2 for placing the radar under test 1 and rotating it, a radar echo simulator 3 for transmitting analog signals to the radar under test 1, and a main control unit 4.

[0045] In this embodiment, the main controller 4 is a computer or industrial control computer, which includes an internal processor and memory. The main controller 4 can be connected to the radar under test 1, the turntable 2 and the radar echo simulator 3 through data cables to form a closed control and data acquisition system. The main controller 4 can send rotation commands to the turntable 2 to control the rotation angle and receive point cloud data from the radar under test 1.

[0046] The radar under test 1 can be fixedly installed on the turntable 2, and the geometric center line of the radar is aligned with the rotation center line of the turntable 2. The radar echo simulator 3 is placed directly in front of the radar, and the radar echo simulator 3 is kept at an appropriate distance from the radar under test 1 to ensure that the radar under test 1 can clearly receive the signal emitted by the radar echo simulator 3. The entire system can be set up in a normal indoor environment without special electromagnetic shielding measures.

[0047] Example 2:

[0048] like Figures 2-4 As shown, this embodiment provides an antenna detection method for a 4D millimeter-wave radar antenna detection system as described in Embodiment 1, including the following steps:

[0049] S1. Set the preset parameters for the radar echo simulator, including the preset target distance. ) and preset non-zero target velocity ( The simulated target, in this embodiment, can be set as follows: =40m, =10m / s;

[0050] S2. Transmit signal, adjust the turntable so that the antenna of the radar under test is aligned with the radar echo simulator, and control the radar echo simulator to transmit signal to the antenna of the radar under test through the main control computer.

[0051] S3. Acquire point cloud data, and send commands to the turntable via the main control unit. The turntable then adjusts the angle (...). Rotate, so that the radar under test on the turntable rotates according to a specified rotation angle. The rotation is recorded by the main controller, and the rotation angle is obtained by the main controller. Point cloud data under ( );

[0052] S4. Point cloud data filtering and processing, based on a preset target distance ( ) and preset non-zero target velocity ( The point cloud data is filtered to identify the target points corresponding to the simulated target.

[0053] S5. Determine the antenna characteristics, extract the complex spectrum data of each channel corresponding to the target point, and determine the antenna characteristics based on the complex spectrum data extracted under multiple rotation angles.

[0054] In step S2, the turntable can be manually or electrically adjusted to ensure that the direction of the radar antenna under test is precisely aligned with the radar echo simulator, and the alignment position is set at 0 degrees. Then, the main control unit can control the turntable to rotate at the required angle.

[0055] In step S3, when the turntable angle is At that time, a frame of point cloud data is a collection of data from multiple detection points. Each point includes the target's distance R, velocity V, and complex spectrum of each channel. ;

[0056] Point cloud data includes the measured distance for each detection point. , measuring speed and complex spectrum data for each channel ;

[0057] If the point cloud read by the main controller includes There are 1 point, and the m-th point is represented by ( ). , , , , , ) indicates that among them It measures distance. It measures speed. It is the complex spectrum data of the nth receiving channel at this point, where N refers to the total receiving channels of the radar under test.

[0058] In step S4, the main control unit performs filtering processing on the acquired point cloud data. This filtering process includes:

[0059] By setting in step S1 and and the radar's own range resolution and speed resolution Distance and velocity windows are defined separately, and detection points whose measured distance and velocity both fall within the corresponding windows are selected. A rectangular filtering window is formed by connecting the distance and velocity serial ports, and the boundaries of this filtering window are determined by the following conditions:

[0060] ;

[0061] ;

[0062] ;

[0063] ;

[0064] Distance window is: [ , The speed window is: [ , ];

[0065] in, It is a constant, in this example Set as tolerance factor, set This is to account for errors generated by radar measurements and simulators.

[0066] The master controller will screen all detection points and remove any point that does not meet any of the above four conditions. Since most clutter points in the environment are stationary (i.e., their velocity is close to 0), they will be easily filtered out because they do not meet the velocity window condition. At the same time, the range window condition filters out interference at other distances. This dual constraint of distance and velocity constitutes a highly selective AND gate logic that can reliably separate the simulated target point from the complex background environment.

[0067] The step of identifying target points in step S4 further includes, among the selected detection points, having remaining Calculate these points. The strength of each of the m points is given, and the strength of the m points is set as follows: The calculation formula is:

[0068]

[0069] At this time, for ,set up If the maximum value is , then:

[0070]

[0071] The point with the strongest signal strength is selected as the target point, wherein the signal strength is determined by the sum of the complex spectral data of each channel.

[0072] In step S5, the main control unit repeats steps S3 and S4, causing the turntable to complete all angle scans from -90 degrees to +90 degrees. After the scan is completed, the main control unit obtains a series of data corresponding to each angle. Corresponding complex spectrum data Based on this data, the main control unit automatically generates antenna characteristic charts.

[0073] The following antenna test results were finally obtained:

[0074] 1. By plotting the modulus of the complex spectrum data as a function of the rotation angle, an antenna gain map is generated, i.e., the angle. and The curve;

[0075] 2. By plotting the phase of the complex spectral data as a function of the rotation angle, a spatial phase diagram is generated, i.e., the angle. and The curve;

[0076] On the antenna gain diagram, the main lobe width and peak sidelobe ratio can be obtained, and then compare whether the measured value of the main lobe width is consistent with the design target, and compare whether the measured value of the peak sidelobe ratio is consistent with the design target. If they are consistent, it is determined to be qualified.

[0077] On the spatial phase diagram, the complex spectrum of each channel can be obtained At each turntable angle of the phase, check with whether there is a significant linear relationship. If the linear relationship is obvious, it is determined to be qualified.

[0078] In summary, the present invention generates a virtual moving target with non-zero speed by using a radar echo simulator, and combines data filtering techniques in the dual dimensions of distance and speed, and successfully realizes effective suppression of stationary clutter in an unshielded ordinary environment. This enables high-precision gain and phase calibration of the antenna of a 4D millimeter-wave radar even without a microwave anechoic chamber.

[0079] Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0080] The above embodiments are only illustrative of the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for testing the antenna of a 4D millimeter-wave radar, characterized in that, Includes the following steps: S1. Set the preset parameters for the radar echo simulator, including the preset target distance (R). target ) and preset non-zero target velocity (V) target The simulated target; S2. Transmit signal: The radar echo simulator transmits a signal to the antenna of the radar under test. S3. Acquire point cloud data by rotating the radar under test at a specified rotation angle and acquiring its point cloud data at the rotation angle. The point cloud data includes the measurement distance, measurement speed, and complex spectrum data of each channel for each detection point. S4. Point cloud data filtering and processing: Based on preset target distance and preset non-zero target velocity data, the point cloud data is filtered to identify the target point corresponding to the simulated target; S5. Determine the antenna characteristics, repeat steps S3 and S4 to obtain point cloud data at multiple rotation angles, extract complex spectrum data of each channel corresponding to the target point, and determine the antenna characteristics based on the complex spectrum data extracted at multiple rotation angles.

2. The antenna testing method for 4D millimeter-wave radar according to claim 1, characterized in that: The filtering step in step S4 includes: Define a distance window and a velocity window, and filter out detection points whose measured distance and velocity both fall within the corresponding windows. The distance window is: [R target -kδ R R target +kδ R The velocity window is: [V] target -kδ v V target +kδ v ], where k is a constant, δ R For the range resolution of the radar, δ v This represents the radar's velocity resolution.

3. The antenna testing method for 4D millimeter-wave radar according to claim 2, characterized in that: The step of identifying the target point in step S4 further includes selecting the point with the strongest signal strength from the selected detection points as the target point, wherein the signal strength is determined by the sum of the moduli of the complex spectral data of each channel.

4. The antenna testing method for 4D millimeter-wave radar according to claim 1, characterized in that: In step S3, the 4D millimeter-wave radar is installed on a turntable, and the switching of the multiple rotation angles is achieved by controlling the rotation of the turntable.

5. The antenna testing method for 4D millimeter-wave radar according to claim 1, characterized in that: The step of determining antenna characteristics includes generating an antenna gain diagram by plotting the modulus of the complex spectrum data as a function of the rotation angle.

6. The antenna testing method for 4D millimeter-wave radar according to claim 1, characterized in that: The step of determining antenna characteristics includes generating a spatial phase diagram by plotting the phase of the complex spectrum data as a function of the rotation angle.

7. The antenna testing method for 4D millimeter-wave radar according to claim 6, characterized in that: By analyzing the spatial phase diagram, the accuracy of the antenna calibration is verified by examining whether there is a linear relationship between the phase of the complex spectrum data and the sine value of the rotation angle.

8. An antenna detection system for a 4D millimeter-wave radar, characterized in that, include: Radar under test; A turntable is used to place the radar under test and rotate it. A radar echo simulator is used to transmit simulated signals to the antenna of the radar under test. The main control unit is connected to the radar under test, the turntable, and the radar echo simulator, and the main control unit is capable of executing the method as described in any one of claims 1 to 7.

9. The antenna testing method for 4D millimeter-wave radar according to claim 8, characterized in that: The main control unit can send rotation commands to the turntable to control the rotation angle and receive point cloud data from the radar under test.

10. The antenna testing method for 4D millimeter-wave radar according to claim 8, characterized in that: The radar echo simulator maintains a preset spatial distance from the radar under test mounted on the turntable.

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