Radar target simulator calibration system and method

Abstract

The application discloses a radar target simulator calibration system and method, and relates to the technical field of radars.The calibration system comprises a radar target simulator, an intermediate frequency signal output end of a radio frequency front end module, an input end of a simulator host computer, a radio frequency signal input end of the radio frequency front end module, a radio frequency signal output end of the radio frequency front end module, a first port of a vector network analyzer, a second port of the vector network analyzer, an output end of the simulator host computer, and a computer device.The computer device is in communication connection with the simulator host computer and the vector network analyzer.The radar target simulator calibration system based on the intermediate frequency method realizes accurate measurement of simulated distance, has low calibration equipment cost, and is simple to operate.

Description

Technical Field

[0001] This invention relates to the field of radar technology, specifically to a radar target simulator calibration system and method. Background Technology

[0002] Radar target simulators are primarily used for radar testing. During radar testing, they can simulate parameters such as target speed, distance, and radar cross-section, significantly improving the safety and speed of radar testing while reducing costs. With the development of the intelligent vehicle industry, the market demand for radar is gradually increasing, leading to a corresponding surge in the demand for radar target simulators.

[0003] Calibration of radar target simulators is a crucial step in ensuring their effectiveness as testing tools, and is of great significance for the research, development, testing, maintenance, and performance evaluation of radar systems.

[0004] In related technologies, the calibration method for radar target simulators involves calibrating the radar target simulator according to... Figure 1 The connection is made in the manner shown, and then the simulated distance calibration is performed based on the method of measuring the delay in the radio frequency band using a vector network analyzer.

[0005] However, the inventors discovered that because the vector network analyzer (as a calibration device) used in this calibration method needs to cover the radio frequency band, a more expensive vector network analyzer is required. For example, if the radio frequency band of an automotive millimeter-wave radar target simulator is (76~81) GHz, then this calibration method requires the vector network analyzer to also cover the 76~81 GHz band.

[0006] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the Invention

[0007] This invention provides a radar target simulator calibration system to address the problem of high cost of calibration equipment used in the prior art.

[0008] To address the aforementioned technical problems, embodiments of the present invention provide a radar target simulator calibration system, comprising:

[0009] A radar target simulator, comprising a simulator host and a radio frequency front-end module, wherein the input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the radio frequency front-end module, and the radio frequency signal input terminal of the radio frequency front-end module is connected to the radio frequency signal output terminal of the radio frequency front-end module.

[0010] The vector network analyzer has a first port connected to the intermediate frequency signal input terminal of the RF front-end module, and a second port connected to the output terminal of the simulator host.

[0011] The computer equipment is communicatively connected to both the simulator host and the vector network analyzer.

[0012] In calibration mode, the vector network analyzer generates and outputs an excitation signal, which serves as the input signal for the radar target simulator.

[0013] The radar target simulator performs delay processing on the input signal to generate an echo signal, and the echo signal has a time delay characteristic corresponding to a preset simulated distance.

[0014] The vector network analyzer measures the transmission delay of the echo signal relative to the excitation signal;

[0015] The computer device calculates the measured value of the simulated distance based on the measured transmission delay.

[0016] Optionally, the input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the radio frequency front-end module via an intermediate frequency cable.

[0017] Optionally, the RF signal input terminal and the RF signal output terminal of the RF front-end module are connected via an RF cable.

[0018] Optionally, the first port of the vector network analyzer is connected to the intermediate frequency signal input terminal of the RF front-end module via an intermediate frequency cable.

[0019] Optionally, the second port of the vector network analyzer is connected to the output of the simulator host via an intermediate frequency cable.

[0020] Optionally, the computer device is connected to the simulator host via a LAN cable.

[0021] Optionally, the computer device is connected to the vector network analyzer via a LAN cable or a GPIB cable.

[0022] This application also provides a radar target simulator calibration system, including:

[0023] A radar target simulator includes a simulator host and an RF front-end module. The input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the RF front-end module, and the RF signal input terminal of the RF front-end module is connected to the RF signal output terminal of the RF front-end module.

[0024] The vector network analyzer has a first port connected to the intermediate frequency signal input terminal of the RF front-end module, and a second port connected to the output terminal of the simulator host.

[0025] In calibration mode, the vector network analyzer generates and outputs an excitation signal, which serves as the input signal for the radar target simulator.

[0026] The radar target simulator performs delay processing on the input signal to generate an echo signal, and the echo signal has a time delay characteristic corresponding to a preset simulated distance.

[0027] The vector network analyzer measures the transmission delay of the echo signal relative to the excitation signal.

[0028] This application also provides a radar target simulator calibration method, applied to a computer device in a radar target simulator calibration system, the method comprising:

[0029] Send configuration commands to the vector network analyzer to adapt its operating parameters to those required for calibration mode;

[0030] Obtain a list of calibration tasks containing multiple preset simulated distance parameters;

[0031] Select the current preset simulation distance parameter to be calibrated from the calibration task list and set it in the radar target simulator;

[0032] A measurement command is sent to the vector network analyzer to cause the vector network analyzer to generate and output an excitation signal to the radar target simulator, and to receive the echo signal returned after being delayed by the radar target simulator;

[0033] The transmission delay of the echo signal relative to the excitation signal is obtained from the vector network analyzer;

[0034] Based on the transmission delay, calculate the measured value of the simulated distance corresponding to the current preset simulated distance parameter to be calibrated;

[0035] Determine whether the calibration task list has been traversed completely;

[0036] If not completed, return to the step of selecting the current preset simulated distance parameter to be calibrated from the calibration task list and setting it in the radar target simulator, so as to select the next preset simulated distance parameter to continue execution;

[0037] If completed, the distance parameter calibration result of the radar target simulator is generated based on each preset simulated distance parameter and its corresponding measured simulated distance value.

[0038] The radar target simulator calibration system in this embodiment uses a vector network analyzer covering the intermediate frequency (IF) band of an automotive millimeter-wave radar target simulator, connected to its IF link. Simultaneously, an RF cable directly connects the two RF ports of the RF front-end module, forming a closed-loop signal link. The simulated distance parameters are calibrated based on the echo delay measured by the vector network analyzer on the IF link. This method achieves accurate measurement of simulated distance based on the IF band, requiring only that the vector network analyzer cover the IF band (e.g., 4.725 GHz). The measurement results and uncertainties are similar to conventional RF-based methods, significantly reducing the cost of calibration equipment. Furthermore, calibration using this system reduces the difficulty of setting up and operating the test system. During RF (67 GHz ~ 81 GHz) testing, connecting the two ports of the high-frequency vector network analyzer to the RF front-end is complex, requiring a rigid rectangular waveguide (for angle conversion) and a dedicated fine-tuning platform for fixation, demanding high operational skill and being time-consuming and labor-intensive. In contrast, this calibration system allows for automated control of the calibration process via computer equipment, improving calibration efficiency. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a schematic diagram of the architecture of a radar target simulator calibration system in related technologies;

[0041] Figure 2 This is a schematic diagram of the architecture of a radar target simulator calibration system according to an embodiment of this application;

[0042] Figure 3 This is a schematic diagram of the architecture of a radar target simulator calibration system according to another embodiment of this application;

[0043] Figure 4 This is a flowchart illustrating the steps of a radar target simulator calibration method in one embodiment of this application. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0045] It should be noted that the descriptions involving "first," "second," etc., in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0046] To facilitate understanding of the technical solutions provided in the embodiments of this application by those skilled in the art, the relevant technologies are described below:

[0047] In related technologies, the calibration method for radar target simulators involves calibrating the radar target simulator according to... Figure 1 The connection is made as shown, and then the simulated distance calibration is performed based on the time delay measured by a vector network analyzer in the radio frequency band. However, the inventors found that because the frequency band of the vector network analyzer used in this calibration method needs to cover the radio frequency band, a more expensive vector network analyzer is required (the radio frequency band is mainly 76-81 GHz, and the corresponding intermediate frequency band is mainly 0.6-5.6 GHz). For example, the radio frequency band of an automotive millimeter-wave radar target simulator is (76~81) GHz, so the calibration method requires the vector network analyzer to also cover the 76~81 GHz band.

[0048] Therefore, this application provides a radar target simulator calibration system. In this technical solution, a vector network analyzer (RF band mainly 24G-24.25G, corresponding to an IF band mainly 4.5G-4.75G) covering the intermediate frequency band of an automotive millimeter-wave radar target simulator is connected to its IF link. Simultaneously, an RF cable directly connects the two RF ports of the RF front-end module, forming a closed-loop signal link. The simulated distance parameters are calibrated based on the echo delay measured by the vector network analyzer on the IF link. This method achieves accurate measurement of simulated distance based on the IF band. The frequency requirement for the vector network analyzer is only that it covers the IF band (e.g., 4.725GHz). The measurement results and uncertainties are similar to conventional RF-based methods, significantly reducing the cost of calibration equipment. Details are provided below.

[0049] like Figure 2 As shown, this embodiment of the invention provides a radar target simulator calibration system, which includes a radar target simulator 1 (taking a car millimeter-wave radar target simulator as an example), a vector network analyzer 2, and a computer device 3.

[0050] The radar target simulator 1 includes a simulator host 11 and an RF front-end module 12. The simulator host 11 mainly consists of filters, an A / D conversion module, a signal processing module, and a D / A conversion module, generating information such as target velocity, range, and radar cross section (RCS) value. The RF front-end module 12 mainly consists of an up-conversion module and a down-conversion module, realizing signal up-conversion and down-conversion.

[0051] In this embodiment, the input terminal (RX) of the simulator host 11 is connected to the intermediate frequency signal output terminal (IF Out) of the RF front-end module 12 to receive the intermediate frequency signal. The RF signal input terminal (RF In) is connected to the RF signal output terminal (RF Out) of the RF front-end module 12 to achieve closed-loop configuration of the RF signal.

[0052] In an optional implementation, the input terminal (RX) of the simulator host 11 and the intermediate frequency signal output terminal (IF Out) of the radio frequency front-end module 12 can be connected via an intermediate frequency cable. This intermediate frequency cable can be provided with the target radar simulator 1 or can be selected by the user. When using a selected intermediate frequency cable, its length can be customized according to the optimal matching requirements of the internal signal transmission of the system.

[0053] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0054] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the simulator host 11 and the radio frequency front-end module 12.

[0055] In other embodiments, the RF front-end module 12 and the simulator host 11 can be integrated on the same hardware circuit board, and the intermediate frequency signal output terminal (IF Out) and the simulator host input terminal (RX) can be directly electrically connected through microstrip lines or striplines on the circuit board. In this connection method, the RF front-end module 12 and the simulator host 11 share the same power supply module and grounding system, eliminating the need for additional external cable interfaces.

[0056] In an optional implementation, the RF signal input (RF In) and RF signal output (RF Out) of the RF front-end module 12 are connected via an RF cable. This RF cable can be a low VSWR (high voltage standing wave ratio) RF coaxial cable. This connection forms an internal loop for the RF signal, allowing the RF front-end module 12 to function as an independent RF unit.

[0057] In other embodiments, the RF signal input terminal (RF In) and the RF signal output terminal (RF Out) of the RF front-end module 12 can be integrated on the same RF circuit board, and the electrical connection between the RF signal input terminal (RF In) and the RF signal output terminal (RF Out) can be directly achieved through microstrip lines, striplines, or coplanar waveguides on the circuit board. By using an onboard integrated RF link connection, the connection nodes between cables and interfaces can be eliminated, reducing RF signal transmission loss.

[0058] The vector network analyzer 2 has a first port (Port1) and a second port (Port2). Its first port is connected to the intermediate frequency signal input (IF In) of the radio frequency front-end module 12 and is used to input the excitation signal to the radar target simulator 1; its second port is connected to the output (TX) of the simulator host 11 and is used to receive the echo signal.

[0059] In an optional implementation, the first port of the vector network analyzer 2 is connected to the intermediate frequency (IF In) signal input terminal of the radio frequency front-end module 12 via an intermediate frequency cable. This intermediate frequency cable can be provided with the target radar simulator 1 or be optional. When using an optional intermediate frequency cable, its length can be customized according to the optimal matching requirements of the system's internal signal transmission.

[0060] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0061] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the vector network analyzer 2 and the radio frequency front-end module 12.

[0062] In an optional implementation, the second port of the vector network analyzer 2 is connected to the output (TX) of the simulator host 11 via an intermediate frequency (IF) cable. This IF cable can be either built into the target radar simulator 1 or optional. When using an optional IF cable, its length can be customized to meet the optimal matching requirements of signal transmission within the system.

[0063] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0064] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the vector network analyzer 2 and the simulator host 11.

[0065] Computer device 3 establishes communication connections with simulator host 11 and vector network analyzer 2 respectively.

[0066] In an optional implementation, the computer device 3 and the simulator host 11 can be connected via a LAN cable to achieve high-speed data transmission and precise command control.

[0067] In an optional implementation, the computer device 3 and the vector network analyzer 2 can be connected via a LAN cable or a GPIB cable to achieve high-speed data transmission and precise command control.

[0068] The working principle of this system is as follows:

[0069] After the system enters calibration mode, computer device 3 sends control commands to vector network analyzer 2. Vector network analyzer 2 generates and outputs an excitation signal with preset parameters, which serves as the input signal for radar target simulator 1 and is input to the intermediate frequency signal input terminal of radio frequency front-end module 12.

[0070] The simulator host 11 of the radar target simulator 1 receives the input signal and controls the internal circuit to perform delay processing on the input signal according to the preset simulation distance parameters. The time delay characteristics of this delay processing correspond to the preset simulation distance. The processed signal generates an echo signal, which is fed back to the second port of the vector network analyzer 2 via the output terminal of the simulator host 11.

[0071] The Vector Network Analyzer 2 measures parameters such as phase and amplitude of the input excitation signal (as a reference signal) and the received echo signal, and accurately calculates the transmission delay of the echo signal relative to the excitation signal.

[0072] Computer device 3 acquires the transmission delay data measured by vector network analyzer 2 through the communication interface, and calculates the actual measured value of the distance simulated by radar target simulator 1 based on the mathematical relationship between signal propagation speed (such as the speed of light) and transmission delay. This measured value can be compared with the preset simulated distance to complete the calibration of radar target simulator 1.

[0073] The radar target simulator calibration system in this embodiment uses a vector network analyzer covering the intermediate frequency (IF) band of an automotive millimeter-wave radar target simulator, connected to its IF link. Simultaneously, an RF cable directly connects the two RF ports of the RF front-end module, forming a closed-loop signal link. The simulated distance parameters are calibrated based on the echo delay measured by the vector network analyzer on the IF link. This method achieves accurate measurement of simulated distance based on the IF band, requiring only that the vector network analyzer cover the IF band (e.g., 4.725 GHz). The measurement results and uncertainties are similar to conventional RF-based methods, significantly reducing the cost of calibration equipment. Furthermore, calibration using this system reduces the difficulty of setting up and operating the test system. During RF (67 GHz ~ 81 GHz) testing, connecting the two ports of the high-frequency vector network analyzer to the RF front-end is complex, requiring a rigid rectangular waveguide (for angle conversion) and a dedicated fine-tuning platform for fixation, demanding high operational skill and being time-consuming and labor-intensive. In contrast, this calibration system allows for automated control of the calibration process via computer equipment, improving calibration efficiency.

[0074] like Figure 3 As shown, another embodiment of the present invention also provides a radar target simulator calibration system, which includes: a radar target simulator 10 and a vector network analyzer 20.

[0075] The radar target simulator 10 includes a simulator host 110 and an RF front-end module 120. The simulator host 110 mainly consists of filters, an A / D conversion module, a signal processing module, and a D / A conversion module, generating information such as target velocity, range, and radar cross section (RCS) value. The RF front-end module 120 mainly consists of an up-conversion module and a down-conversion module, realizing signal up-conversion and down-conversion.

[0076] In this embodiment, the input terminal (RX) of the simulator host 110 is connected to the intermediate frequency signal output terminal (IF Out) of the RF front-end module 120 to receive the intermediate frequency signal. The RF signal input terminal (RF In) is connected to the RF signal output terminal (RF Out) of the RF front-end module 120 to achieve closed-loop configuration of the RF signal.

[0077] In an optional implementation, the input terminal (RX) of the simulator host 110 and the intermediate frequency signal output terminal (IF Out) of the radio frequency front-end module 120 can be connected via an intermediate frequency cable. This intermediate frequency cable can be provided with the target radar simulator 10 or be optional. When using an optional intermediate frequency cable, its length can be customized according to the optimal matching requirements of the internal signal transmission of the system.

[0078] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0079] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the simulator host 110 and the radio frequency front-end module 120.

[0080] In other embodiments, the RF front-end module 120 and the simulator host 110 can be integrated on the same hardware circuit board, and the intermediate frequency signal output terminal (IF Out) and the simulator host input terminal (RX) can be directly electrically connected through microstrip lines or striplines on the circuit board. In this connection method, the RF front-end module 120 and the simulator host 110 share the same power supply module and grounding system, eliminating the need for additional external cable interfaces.

[0081] In an optional implementation, the RF signal input (RF In) and RF signal output (RF Out) of the RF front-end module 120 are connected via an RF cable. This RF cable can be a low VSWR (high voltage standing wave ratio) RF coaxial cable. This connection forms an internal loop for the RF signal, allowing the RF front-end module 120 to function as a standalone RF unit.

[0082] In other embodiments, the RF signal input terminal (RF In) and the RF signal output terminal (RF Out) of the RF front-end module 120 can be integrated on the same RF circuit board, and the electrical connection between the RF signal input terminal (RF In) and the RF signal output terminal (RF Out) can be directly achieved through microstrip lines, striplines, or coplanar waveguides on the circuit board. By using an onboard integrated RF link connection, the connection nodes between cables and interfaces can be eliminated, reducing RF signal transmission loss.

[0083] The vector network analyzer 20 has a first port (Port1) and a second port (Port2). Its first port is connected to the intermediate frequency signal input (IF In) of the radio frequency front-end module 120 and is used to input the excitation signal to the radar target simulator 10; its second port is connected to the output (TX) of the simulator host 110 and is used to receive the echo signal.

[0084] In an optional implementation, the first port of the vector network analyzer 20 is connected to the intermediate frequency (IF In) signal input terminal of the radio frequency front-end module 120 via an intermediate frequency cable. This intermediate frequency cable can be provided with the target radar simulator 10 or be optional. When using an optional intermediate frequency cable, its length can be customized according to the optimal matching requirements of the system's internal signal transmission.

[0085] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0086] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the vector network analyzer 20 and the radio frequency front-end module 120.

[0087] In an optional implementation, the second port of the vector network analyzer 20 is connected to the output (TX) of the simulator host 110 via an intermediate frequency (IF) cable. This IF cable can be either built into the target radar simulator 10 or optional. When using an optional IF cable, its length can be customized to meet the optimal matching requirements of signal transmission within the system.

[0088] As an example, the intermediate frequency cable can be a 2.92mm SMA connector intermediate frequency cable.

[0089] In this embodiment, the intermediate frequency cable connection ensures low-loss and low-interference transmission of the intermediate frequency signal between the vector network analyzer 20 and the simulator host 110.

[0090] The working principle of this system is as follows:

[0091] After the system enters the calibration mode, the vector network analyzer 20 generates and outputs an excitation signal with preset parameters. This signal is used as the input signal of the radar target simulator 10 and is input to the intermediate frequency signal input terminal of the radio frequency front-end module 120.

[0092] The simulator host 110 of the radar target simulator 10 receives the input signal and controls the internal circuit to perform delay processing on the input signal according to the preset simulation range parameters. The delay characteristics of this delay processing correspond to the preset simulation range, and the processed signal generates an echo signal, which is fed back to the second port of the vector network analyzer 20 via the output terminal of the simulator host 110.

[0093] The Vector Network Analyzer 20 measures parameters such as phase and amplitude of the input excitation signal (as a reference signal) and the received echo signal, and accurately calculates the transmission delay of the echo signal relative to the excitation signal.

[0094] Subsequently, the user can manually or with the aid of a computer to calculate the actual measured value of the distance simulated by the radar target simulator 10 based on the transmission delay. This measured value can be compared with the preset simulated distance to complete the calibration of the radar target simulator 10.

[0095] The radar target simulator calibration system in this embodiment uses a vector network analyzer covering the intermediate frequency (IF) band of an automotive millimeter-wave radar target simulator, connected to its IF link. Simultaneously, an RF cable directly connects the two RF ports of the RF front-end module, forming a closed-loop signal link. The simulated distance parameters are calibrated based on the echo delay measured by the vector network analyzer on the IF link. This method achieves accurate measurement of simulated distance based on the IF band, requiring only that the vector network analyzer cover the IF band (e.g., 4.725 GHz). The measurement results and uncertainties are similar to conventional RF-based methods, significantly reducing the cost of calibration equipment. Furthermore, calibration using this system reduces the difficulty of setting up and operating the test system. In RF (67 GHz ~ 81 GHz) setup and testing, connecting the two ports of the high-frequency vector network analyzer to the RF front-end is complex, requiring a rigid rectangular waveguide (angle conversion) and a dedicated fine-tuning platform for fixation, demanding high operational skill and being time-consuming and labor-intensive.

[0096] See Figure 4 This application also provides a radar target simulator calibration method, applied to the above-mentioned... Figure 2 In the radar target simulator calibration system shown, the method is performed by a computer device, and the method includes:

[0097] Step S1: Send a configuration command to the vector network analyzer to adapt its operating parameters to those required for calibration mode.

[0098] Specifically, the computer equipment establishes a connection with the vector network analyzer through a preset communication link (LAN line or GPIB line), and generates configuration instructions corresponding to the calibration mode based on the core parameters such as the operating frequency band and signal bandwidth of the radar target simulator, and sends them to the vector network analyzer.

[0099] The configuration instructions include a first setting instruction for setting the measurement mode of the vector network analyzer, a second setting instruction for setting the output frequency and sweep range of the vector network analyzer, a third setting instruction for setting the number of scan points and intermediate frequency bandwidth of the vector network analyzer, and a fourth instruction for performing dual-port self-calibration on the vector network analyzer.

[0100] The measurement mode can be selected as S21 mode (measuring signal transmission from port 1 to port 2). The output frequency and sweep range of the vector network analyzer can be set based on the RF input power and frequency range of the radar target simulator. The number of scan points and intermediate frequency bandwidth of the vector network analyzer can be set based on the simulated range of the radar target simulator.

[0101] In this embodiment, after receiving the above configuration command, the vector network analyzer can first set the corresponding parameters based on the configuration command, and then perform dual-port self-calibration to facilitate subsequent measurement operations.

[0102] Step S2: Obtain a list of calibration tasks containing multiple preset simulated distance parameters.

[0103] Specifically, the computer device obtains a pre-compiled calibration task list by reading from local storage or importing from external storage. The calibration task list contains multiple preset simulated distance parameters, with parameter values ​​covering the effective working range of the radar target simulator, for example, from 1m to 400m, set in gradients of 1m, 5m, 10m, 20m, 50m, 100m, etc. This includes both short-range, small-step parameters to verify the simulator's range resolution and long-range parameters to verify the simulator's time delay stability. Each preset simulated distance parameter can correspond to a unique identifier, facilitating the matching and traceability of subsequent calibration results.

[0104] The preset simulated distance parameters may include simulated distance, simulated velocity, radar carrier frequency f, radar cross section (RCS) parameters, etc.

[0105] Step S3: Select the preset simulation distance parameter to be calibrated from the calibration task list and set it in the radar target simulator.

[0106] Specifically, the computer device selects the first uncalibrated preset simulated distance parameter from the calibration task list as the current parameter to be calibrated, following a preset traversal order (e.g., from smallest to largest distance gradient). Subsequently, the computer device sends a parameter setting command, containing the value of the currently calibrated preset simulated distance parameter, to the radar target simulator's host computer via a LAN cable. Upon receiving the command, the simulator host computer calculates the parameter setting based on the electromagnetic wave propagation speed (speed of light c ≈ 3 × 10⁻⁶). 8 The system calculates the target delay value (delay t = 2 × distance d / c, where coefficient 2 is the path compensation for the signal round trip) corresponding to the preset simulated distance by establishing the correspondence between m / s and distance. The target delay value is then loaded into the internal delay processing module to complete the parameter configuration of the radar target simulator. At the same time, a confirmation signal indicating successful parameter setting is sent back to the computer device.

[0107] Step S4: Send a measurement command to the vector network analyzer so that the vector network analyzer generates and outputs an excitation signal to the radar target simulator, and receives the echo signal returned after being delayed by the radar target simulator.

[0108] Specifically, after receiving the parameter setting confirmation signal from the radar target simulator, the computer equipment sends a start measurement command to the vector network analyzer. Upon responding to the command, the vector network analyzer outputs an intermediate frequency (IF) excitation signal in a preset frequency band through its first port. This excitation signal is transmitted via an IF cable to the IF signal input terminal of the radar target simulator's radio frequency (RF) front-end module, and then sequentially passes through the RF front-end module and the simulator host's internal link for processing. The simulator host's delay processing module performs precise delay compensation processing on the input excitation signal according to the loaded target delay value, generating an echo signal carrying preset simulated range delay characteristics. This echo signal is transmitted via the simulator host's output terminal to the second port of the vector network analyzer, completing one excitation-echo signal transmission process.

[0109] The measurement command may include measurement mode commands for the vector network analyzer and aperture parameter commands. In this embodiment, the measurement mode can be a group delay measurement mode; the aperture is not less than 3%.

[0110] Step S5: Obtain the transmission delay of the measured echo signal relative to the excitation signal from the vector network analyzer.

[0111] In one embodiment, the vector network analyzer initiates the group delay measurement function, continuously scanning the group delay of the excitation signal and the echo signal to generate a group delay curve covering the calibration frequency band. This curve reflects the group delay value corresponding to different frequency points. Since the delay processing of the radar target simulator applies a uniform delay to the signal throughout the entire calibration frequency band, the group delay data of all effective frequency points in the group delay curve are read, and their arithmetic mean is calculated. t s , the average value t s This is the final measured transmission delay. After the measurement is completed, the vector network analyzer encapsulates the final transmission delay data and sends it to the computer device.

[0112] In another embodiment, after obtaining the echo signal, the echo signal can also be compared and analyzed with the excitation reference signal output from the first port, based on the conversion relationship between phase difference and time delay ( t s =Phase difference Δφ / (2πf), where f is the signal frequency), to calculate the actual transmission delay of the echo signal relative to the excitation signal. Simultaneously, the vector network analyzer performs mean filtering on multiple measurement data to eliminate random noise interference with the delay measurement results. After the measurement is completed, the vector network analyzer encapsulates the final transmission delay data and sends it to the computer.

[0113] Step S6: Calculate the measured value of the simulated distance corresponding to the current preset simulated distance parameter to be calibrated, based on the transmission delay.

[0114] After acquiring the transmission delay data, the computer device calculates the simulated distance R based on the distance calculation formula for electromagnetic wave round-trip propagation. The formula is as follows:

[0115] R= c t s

[0116] Where c is the speed of light. t s The transmission delay is measured by a vector network analyzer.

[0117] Step S7: Determine whether the calibration task list has been traversed completely.

[0118] If not completed, return to step S3 and select the next preset simulation distance parameter to continue execution;

[0119] If completed, proceed to step S8: Generate the distance parameter calibration result of the radar target simulator based on each preset simulated distance parameter and its corresponding measured simulated distance value.

[0120] The computer device compares the number of calibrated parameters with the total number of parameters in the calibration task list to determine whether the calibration of all preset simulated distance parameters has been completed. If there are uncalibrated parameters, the process returns to step S3, selects the next parameter to be calibrated, and repeats steps S3 to S6. If all parameters have been calibrated, the computer device generates the distance parameter calibration result of the radar target simulator based on each preset simulated distance parameter and its corresponding measured simulated distance value.

[0121] The distance parameter calibration result may include the error value between the preset simulated distance parameter and the corresponding measured value (error value = |preset value - measured value|).

[0122] Traditional radar target simulator calibration methods often rely on manual, one-time parameter settings and manual recording of measurement data. This approach suffers from low calibration efficiency, significant human error, and poor data traceability, and struggles to cover the simulator's full operating range. The calibration method in this embodiment automates the entire process using computer equipment. It achieves precise parameter adaptation for the vector network analyzer by sending configuration commands, avoiding the randomness of manual parameter adjustments. By loading a calibration task list with multiple preset simulation distances, it enables batch calibration across the simulator's full operating range, improving efficiency by more than three times compared to manual, one-time calibration. Furthermore, in this embodiment, operators only need to perform simple parameter settings and issue operation commands on the control software interface to complete the entire calibration process, eliminating the need for manual intervention and reducing the skill requirements for operators.

[0123] In an optional implementation, calculating the measured value of the simulated distance corresponding to the current preset simulated distance parameter to be calibrated, based on the transmission delay, includes: obtaining the cable introduction delay; calculating the simulated distance echo delay based on the transmission delay and the cable introduction delay; and calculating the measured value of the simulated distance based on the simulated distance echo delay and a preset simulated distance calculation formula.

[0124] Cable-induced delay This refers to the inherent time delay generated during the transmission of excitation and echo signals in all connecting cables of the system (including intermediate frequency cables between the vector network analyzer and the RF front-end module, and intermediate frequency cables between the RF front-end module and the simulator host, etc.). This time delay is unrelated to the delay processing of the radar target simulator and belongs to the system's fixed error term.

[0125] The cable introduction delay can be obtained in the following two ways:

[0126] 1. Offline calibration method: Before formal calibration, the delay processing module of the radar target simulator is set to zero-delay mode. At this time, the transmission delay measured by the vector network analyzer is the pure cable-introduced delay. The computer device stores the calibration value in a local database for use in subsequent calibration calculations.

[0127] 2. Real-time Measurement Method: The computer sends a cable delay measurement command to the vector network analyzer. The vector network analyzer, through its built-in cable delay analysis algorithm, calculates the cable-introduced delay in real time based on the signal propagation speed in the cable (the signal propagation speed of a coaxial intermediate frequency cable is approximately 0.6-0.8c, where c is the speed of light) and the cable length. .

[0128] The computer equipment calculates the simulated distance echo delay using a difference formula based on the measured transmission delay and cable-introduced delay.t This delay is the actual processing time of the signal by the radar target simulator, and the calculation formula is as follows:

[0129] t = t s t 0.

[0130] The computer device calls a preset simulated distance calculation formula to calculate the measured simulated distance value R based on the simulated distance echo delay. The simulated distance calculation formula is as follows:

[0131] R= c t

[0132] Where c is the speed of light.

[0133] Traditional calibration methods directly substitute the total transmission delay measured by the vector network analyzer into the distance calculation formula without considering the impact of cable-introduced delay. Cable-introduced delay varies with cable length, material, and operating frequency, and is a non-negligible fixed system error. Direct calculation will lead to deviations in the actual measured value of the simulated distance, especially in close-range simulation scenarios where cable delay accounts for a high proportion and the error is more significant.

[0134] This implementation method obtains the cable-introduced delay in advance and removes the error term from the total transmission delay to obtain the effective echo delay generated only by the delay processing of the radar target simulator. Then, it substitutes the echo delay into the formula to calculate the measured distance, thus eliminating the system error caused by the hardware link at the algorithm level.

[0135] To verify that the calibration system in this application achieves similar measurement results and uncertainties when calibrated using the intermediate frequency method compared to the radio frequency method in related technologies, a comparative experimental test will be conducted on the two methods below.

[0136]

Example 1

[0137] In this embodiment, the connection line based on the simulated distance of the radio frequency calibration radar target simulator is as follows: Figure 1 As shown. The vector network analyzer is connected to the RF port of the automotive millimeter-wave radar target simulator. Specifically, the RF Out module of the RF front-end module is connected to Port2 of the vector network analyzer, and the Port1 of the vector network analyzer is connected to the RF In module of the radar target simulator, forming a closed loop. After completing the wiring, perform the following operations:

[0138] 1. Vector Network Analyzer Dual-Port Self-Calibration. Select S21 mode, set the output frequency and sweep range according to the RF input power and frequency range of the automotive millimeter-wave radar target simulator being calibrated, and set the appropriate number of scan points and intermediate frequency bandwidth according to the simulated distance range of the automotive millimeter-wave radar target simulator being calibrated. Connect the intermediate frequency connection cable to Port1, and perform dual-port (from the cable end of Port1 to the end of Port2) self-calibration of the vector network analyzer VNA including the cable.

[0139] 2. Set up the millimeter-wave radar simulator for the vehicle being calibrated. Set the simulation distance (minimum value for the first time), the simulation speed parameter to 0, the radar carrier frequency f, and the radar cross section (RCS) parameter to an appropriate value.

[0140] 3. Measure the simulated distance echo delay. Set the Vector Network Analyzer (VNA) measurement mode to group delay and the aperture to no less than 3%. Run the scan to obtain the group delay curve. Read and record the average value ts of the group delay curve. Subtract the delay t0 introduced by the RF direct connection cable to calculate the simulated distance echo delay t = ts - t0.

[0141] 4. Calculate the measured value of the simulated distance. According to the simulated distance calculation formula R=1 / 2ct (where R is the measured simulated distance (m), c is the speed of light (m / s)), and t is the measured time delay, the measured value of the simulated distance is obtained.

[0142] Change the simulated distance of the radar target simulator and repeat steps 2-4 to complete the measurement of all calibration points.

[0143]

Example 2

[0144] In this embodiment, the range connection is simulated based on the intermediate frequency calibration radar target simulator, as follows: Figure 3 The vector network analyzer is connected between the simulator host and the RF front-end module of the radar simulator. Specifically, the TX output signal from the simulator host enters the second port (Port2) of the vector network analyzer, and the output signal from the first port (Port1) of the vector network analyzer enters the RF front-end module (IFIn). The RF Out and RF In of the RF front-end module are directly connected using an RF cable or device. The IF Out intermediate frequency output signal of the RF front-end module is connected to the RX port of the simulator host, forming a closed-loop signal link. After completing the wiring, the following operations are performed:

[0145] 1. Vector Network Analyzer Dual-Port Self-Calibration. Select S21 mode, set the output frequency and sweep range according to the RF input power and frequency range of the automotive millimeter-wave radar target simulator being calibrated, and set the appropriate number of scan points and intermediate frequency bandwidth according to the simulated distance range of the automotive millimeter-wave radar target simulator being calibrated. Connect the intermediate frequency connection cable to Port1, and perform dual-port (from the cable end of Port1 to the end of Port2) self-calibration of the vector network analyzer VNA including the cable.

[0146] 2. Set up the millimeter-wave radar simulator for the vehicle being calibrated. Set the simulation distance (minimum value for the first time), the simulation speed parameter to 0, the radar carrier frequency f, and the radar cross section (RCS) parameter to an appropriate value.

[0147] 3. Measure the simulated distance echo delay. Set the Vector Network Analyzer (VNA) measurement mode to group delay and the aperture to no less than 3%. Run the scan to obtain the group delay curve. Read and record the average value ts of the group delay curve. Subtract the delay t0 introduced by the RF direct connection cable to calculate the simulated distance echo delay t = t_s - t_0.

[0148] 4. Calculate the measured value of the simulated distance. According to the simulated distance calculation formula R=1 / 2ct (where R is the measured simulated distance (m), c is the speed of light (m / s)), and t is the measured time delay, the measured value of the simulated distance is obtained.

[0149] Change the simulated distance of the car millimeter-wave radar target simulator and repeat steps 2-4 to complete the measurement of all calibration points.

[0150] After conducting tests using the methods of Example 1 and Example 2 respectively, the test data shown in Table 1 below can be obtained.

[0151] Table 1: Test data obtained by conducting tests according to the methods of Example 1 and Example 2

[0152]

[0153] The test results of calibrating the same instrument using the two methods in Table 1 show that the difference in the simulated distance measurements is no more than 0.01m. Uncertainty assessment of the two test results yields U1=U2=0.02. Comparison with the calibration results... ,according to En The basis for judgment is... The results from the two methods are similar, which verifies the correctness of the calibration results based on the intermediate frequency method.

[0154] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A radar target simulator calibration system, characterized in that, include: A radar target simulator, comprising a simulator host and a radio frequency front-end module, wherein the input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the radio frequency front-end module, and the radio frequency signal input terminal of the radio frequency front-end module is connected to the radio frequency signal output terminal of the radio frequency front-end module. The vector network analyzer has a first port connected to the intermediate frequency signal input terminal of the RF front-end module, and a second port connected to the output terminal of the simulator host. The computer equipment is communicatively connected to both the simulator host and the vector network analyzer. In calibration mode, the vector network analyzer generates and outputs an excitation signal, which serves as the input signal for the radar target simulator. The radar target simulator performs delay processing on the input signal to generate an echo signal, and the echo signal has a time delay characteristic corresponding to a preset simulated distance. The vector network analyzer measures the transmission delay of the echo signal relative to the excitation signal; The computer device calculates the measured value of the simulated distance based on the measured transmission delay.

2. The radar target simulator calibration system according to claim 1, characterized in that, The input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the radio frequency front-end module via an intermediate frequency cable.

3. The radar target simulator calibration system according to claim 1, characterized in that, The RF signal input terminal and the RF signal output terminal of the RF front-end module are connected via an RF cable.

4. The radar target simulator calibration system according to claim 1, characterized in that, The first port of the vector network analyzer is connected to the intermediate frequency signal input port of the RF front-end module via an intermediate frequency cable.

5. The radar target simulator calibration system according to claim 1, characterized in that, The second port of the vector network analyzer is connected to the output of the simulator host via an intermediate frequency cable.

6. The radar target simulator calibration system according to claim 1, characterized in that, The computer device is connected to the simulator host via a LAN cable.

7. The radar target simulator calibration system according to claim 1, characterized in that, The computer device is connected to the vector network analyzer via a LAN cable or a GPIB cable.

8. A radar target simulator calibration system, characterized in that, include: A radar target simulator includes a simulator host and an RF front-end module. The input terminal of the simulator host is connected to the intermediate frequency signal output terminal of the RF front-end module, and the RF signal input terminal of the RF front-end module is connected to the RF signal output terminal of the RF front-end module. The vector network analyzer has a first port connected to the intermediate frequency signal input terminal of the RF front-end module, and a second port connected to the output terminal of the simulator host. In calibration mode, the vector network analyzer generates and outputs an excitation signal, which serves as the input signal for the radar target simulator. The radar target simulator performs delay processing on the input signal to generate an echo signal, and the echo signal has a time delay characteristic corresponding to a preset simulated distance. The vector network analyzer measures the transmission delay of the echo signal relative to the excitation signal.

9. A radar target simulator calibration method, applied to a computer device in the radar target simulator calibration system according to any one of claims 1 to 7, characterized in that, The method includes: Send configuration commands to the vector network analyzer to adapt its operating parameters to those required for calibration mode; Obtain a list of calibration tasks containing multiple preset simulated distance parameters; Select the current preset simulation distance parameter to be calibrated from the calibration task list and set it in the radar target simulator; A measurement command is sent to the vector network analyzer to cause the vector network analyzer to generate and output an excitation signal to the radar target simulator, and to receive the echo signal returned after being delayed by the radar target simulator; The transmission delay of the echo signal relative to the excitation signal is obtained from the vector network analyzer; Based on the transmission delay, calculate the measured value of the simulated distance corresponding to the current preset simulated distance parameter to be calibrated; Determine whether the calibration task list has been traversed completely; If not completed, return to the step of selecting the current preset simulated distance parameter to be calibrated from the calibration task list and setting it in the radar target simulator, so as to select the next preset simulated distance parameter to continue execution; If completed, the distance parameter calibration result of the radar target simulator is generated based on each preset simulated distance parameter and its corresponding measured simulated distance value.

10. The radar target simulator calibration method according to claim 9, characterized in that, Based on the transmission delay, the calculation of the measured simulated distance value corresponding to the current preset simulated distance parameter to be calibrated includes: Obtain the cable introduction delay; The simulated distance echo delay is calculated based on the transmission delay and the cable introduction delay. The measured value of the simulated distance is calculated based on the simulated distance echo delay and the preset simulated distance calculation formula.

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