Method for receive channel calibration of an integrated digital array radar

Abstract

The method for calibrating the receiving channel of the integrated digital array radar comprises the following steps: S101, determining the phase error and correcting it; S102, preparing the radar calibration test; S103, outputting the maximum value of the amplitude of all the one-dimensional complex data; S104, determining the calibration coefficient and storing it in the upper computer; S105, calculating the fixed amplitude-phase error of the receiving channel, comprising: determining the calibration coefficient through the closed-loop receiving and open-loop receiving, and performing the ratio to determine the fixed error; the upper computer transmits the fixed error to the radar for storage; S106, the fixed error C i is loaded into the system processing module of the radar, and the calibration coefficient is obtained through the power-off and power-on test of the radar; and S107, the calibration coefficient test of the open-loop receiving channel is performed to determine the final calibration performance parameter. The calibration coupling path and the amplitude-phase consistency of each link channel are lowed, and the overall complexity of the calibration is reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of radar, and particularly relates to a method for calibrating the receiving channel of an integrated digital array radar. Background Technology

[0002] Each element or subarray of a digital array radar is connected to a transmit / receive channel, and radar beamforming and scanning are achieved in the digital domain using digital beamforming technology. Due to the inherent differences in the components within each channel, the amplitude and phase characteristics exhibited by each channel under different frequencies and digitally controlled attenuation states are inconsistent. Without calibration, this will affect the quality of the radiation pattern after digital beamforming, particularly the beamwidth and sidelobe level, thus impacting radar detection performance. To mitigate the impact of channel inconsistencies on digital array radars, measures need to be taken to eliminate all errors from the antenna array to the digital channels, ensuring that the amplitude and phase characteristics of each subarray channel are consistent.

[0003] Currently, existing methods employ conventional digital array radar. Multi-channel calibration of conventional digital array radar does not include the antenna array. The calibration signal input uses a uniform calibration signal, which is fed into each channel through a coupling line with extremely high channel consistency design. The amplitude and phase difference of the received digital signal in each channel is calculated, and the error is compensated in the digital domain to achieve inter-channel calibration. Furthermore, channel calibration does not include the individual sub-array channels of the antenna array. Each sub-array channel of the antenna array is determined to have a certain error range of amplitude and phase of the signal through independent testing in a design-guaranteed manner.

[0004] It is evident that current calibration methods require designing to ensure the consistency of signal amplitude and phase at the input of the coupling port, as well as the consistency of signal amplitude during the calibration of the antenna array subarray RF / digital channels. Therefore, the performance of the radar digital beamforming pattern requires two sets of test errors to guarantee, introducing a degree of uncertainty. This necessitates radar pattern calibration using external targets. Furthermore, the front-end antenna array and back-end RF and digital processing of integrated digital array radars are physically inseparable; that is, when the antenna array becomes large, it cannot be tested independently, leading to reduced radar calibration efficiency.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for calibrating the receiving channel of an integrated digital array radar, solving the technical problem of reduced radar calibration efficiency in existing methods. The technical solution of this invention has many beneficial effects, as described below:

[0007] A method for calibrating the receiving channel of an integrated digital array radar is provided, the method comprising:

[0008] S101: When the test field does not meet the far-field test conditions, determine the phase error and correct it;

[0009] S102: Radar calibration test preparation, including: mounting the radar of the integrated digital array under test on the turntable support, connecting the radar's calibration signal output terminal to the radiation feed element for testing through an RF cable, and completing the connection between the radar and the host computer.

[0010] S103: Generate the calibration signal waveform of the radar, and receive the echo signal fed back by the radiation feed element and process the echo signal to output the maximum value of the amplitude in all the one-dimensional complex data.

[0011] S104: The maximum value is used to perform a fixed amplitude phase difference test in the open-loop receiving channel to determine the calibration coefficient C. i_open The data is stored in the host computer, and the fixed amplitude and phase difference of the closed-loop receiving channel are tested to determine the calibration coefficient. And store it in the host computer;

[0012] S105: Fixed amplitude and phase difference calculation for the receiving channel, including: the calibration coefficients determined by closed-loop and open-loop reception, and the ratio to determine the fixed error C. i The host computer will fix the error C. i The data is transmitted to the radar for storage.

[0013] S106: The fixed error C i The calibration coefficient C is obtained by loading it into the system processing module of the radar and performing a power-down and power-on test. i_close2 ;

[0014] S107: Open-loop receiving channel calibration coefficient test to determine final calibration performance parameter C. i_correct .

[0015] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0016] By utilizing the characteristics of plane wave reception provided by far-field conditions, and through open-loop and closed-loop reception channel error tests, the fixed error of the calibration branch between different channels is calculated using the radar's own processing resources. This error is then stored inside the radar and compensated for. In the laboratory, the problem of imbalance in the calibration coupling branch can be made up, achieving the goal of multi-channel equalization of the entire signal link. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the connection relationships for test field calibration;

[0019] Figure 2 Schematic diagram of open-loop calibration of the receiving channel;

[0020] Figure 3 This is a schematic diagram of closed-loop calibration of the receiving channel. Detailed Implementation

[0021] The following specific examples 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. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Traditionally, error testing is performed on two separate segments of both the antenna and RF channels. This two-segment error testing serves as a design guarantee, but the amplitude-phase consistency of the interconnection between the two segments cannot be determined, leading to uncertainty and reduced radar performance. However, this invention, through the design of open-loop and closed-loop receiving methods, obtains a fixed error between the receiving channels. By correcting this fixed error, it achieves end-to-end channel calibration of the integrated digital array radar, spanning from the antenna array subarray channels to the subarray RF / digital conversion channels, providing support for efficient indoor testing of radar digital synthetic patterns. This method reduces the extremely high design requirements of the calibration coupling path and lowers the overall calibration complexity. The present invention provides a receiving channel calibration method for an integrated digital array radar, characterized in that the method includes:

[0023] S101: When the test field does not meet the far-field test conditions, the phase error is determined and corrected. The purpose is to correct the error of the test field measurement system. Specifically:

[0024] When the test field does not meet the far-field test conditions, the phase error between the test radar array and the test field radiating feed element is corrected; this error is used as a measurement system error correction. The integrated digital array radar under test is mounted on a turntable support, and the turntable is rotated to its mechanical zero position. The output of the vector network analysis (VNA) is connected to the radiating feed element of the test field, and the input of the VNA is sequentially connected to the RF port Ant of each array subarray. i (i = 1..N) (where N is the number of radar array subarrays), such as Figure 1 As shown, the radar is mounted on a turntable, which is connected to the control device. The radar's output is connected to the test radiating feed element via an amplifier. The test is completed by receiving the echo signal from the radiating feed element using the radar. The vector network reading C is recorded for each test. Ant_i (i = 1..16), calculate the plane wave error Plane wave errors are corrected using CAM software.

[0025] S102: Radar calibration test preparation, including: mounting the radar of the integrated digital array under test on the turntable bracket, connecting the radar's calibration signal output terminal to the radiation feed element for testing through an RF cable, and completing the connection between the radar and the host computer. During the test, the turntable bracket drives the radar to rotate to complete the radar test.

[0026] S103: Generate the calibration signal waveform of the radar, and receive the echo signal fed back from the radiating feed element and process the echo signal, outputting the maximum amplitude of all the one-dimensional complex data, exporting data from the radar recorder, and connecting the recorder to the debugging software of the host computer. Specifically:

[0027] Processing the echo signal includes: the radar generating N Pulse The calibration signal consists of pulses, each of which is a modulated continuous wave signal with zero initial phase. The baseband frequency of the continuous wave signal is set to a preset ratio of the sampling rate. For example, the baseband frequency of the continuous wave signal is 1 / 4 or 3 / 4 of the sampling rate or other ratios.

[0028] After digital preprocessing of the received signals of each subarray of the radar (preprocessing refers to the baseband signal or I / Q signal obtained by digital down-conversion processing), Fourier transform (FFT) is performed along the range dimension, and then summed along the pulse dimension to obtain one-dimensional complex data.

[0029] Output the maximum amplitude among all the aforementioned one-dimensional complex data, denoted as Data. i (i = 1..N).

[0030] S104: The maximum value is used to perform a fixed amplitude phase difference test in the open-loop receiving channel to determine the calibration coefficient C. i_open The data is stored in the host computer, and the fixed amplitude and phase difference of the closed-loop receiving channel are tested to determine the calibration coefficient. And it is stored in the host computer, specifically:

[0031] Open-loop receiving channel fixed amplitude phase difference test, including:

[0032] 1. During the test, the pointing azimuth and elevation angles of the radar under the radar system control pattern are 0°;

[0033] 2. Traverse the frequency points (radar frequency points), set the AGC of each subarray RF frequency conversion channel module of the radar to 0dB; record the processing results of each channel module at each frequency point (the processing method adopts the "method of processing echo signals" in S103), and record the processing results as Data. i_open (i = 1..N), and process the result Data i_open (i = 1..N) are forwarded to the host computer debugging software, which generates calibration coefficients for each frequency point. And save it on the host computer, C i_open The result of the initial calculation can also be represented as C. i-open1 ;

[0034] Closed-loop receiving channel fixed amplitude and phase difference test, including:

[0035] 1. During the test, the pointing azimuth and elevation angles of the radar under the radar system control pattern are 0°;

[0036] 2. Traverse the frequency points, set the digital gain control (AGC) of each subarray RF channel module to 0dB (using the "method for processing echo signals" in S103), and record the processing results of each channel as Data. i_close (i = 1..N), and forwarded to the host computer debugging software, which generates calibration coefficients for each frequency point. And save it on the host computer, C i_close The result of the initial calculation can also be represented as Ci-close1.

[0037] S105: Fixed amplitude and phase difference calculation for the receiving channel, including: the calibration coefficients determined by closed-loop and open-loop reception, and the ratio to determine the fixed error C. i The host computer will fix the error C. i The data is transmitted to the radar for storage, such as:

[0038] The fixed error C is determined by comparing the calibration coefficients determined by closed-loop and open-loop reception. i ;

[0039] Fixed error C i According to the formula Calculate the fixed error C at each frequency point i The host computer will fix the error C. iIt is transmitted to the radar for storage.

[0040] S106: The fixed error C i The calibration coefficient C is obtained by loading it into the system processing module of the radar and performing a power-down and power-on test. i_close2 Specifically,

[0041] 1. Power off and then power on the radar;

[0042] 2. Press Figure 3 The connection in the middle is tested again for closed-loop error. According to the closed-loop receiving channel fixed amplitude and phase difference test method in S104, the radar frequency points and AGC are traversed, and the processing results under each frequency point and AGC of each channel are recorded. i_close2 (i=1..N), then, the radar calculates the calibration coefficients under different frequencies and AGC. And it is stored in the radar.

[0043] S107: Open-loop receiving channel calibration coefficient test to determine final calibration performance parameter C. i_correct Specifically:

[0044] according to Figure 2 The way ( Figure 2 The radar's own module configuration method is the existing method, which will not be described in detail here. The open-loop receiving channel is loaded again, including:

[0045] Adjust the beam control to azimuth and pitch to 0°;

[0046] The radar frequency points and digital gain control (AGC) are traversed, and the echo signals are processed to obtain the processing result, Data. i_open2 (i = 1..N) and perform calibration. The calibration method is as follows:

[0047] Based on the radar frequency and AGC, find the corresponding calibration coefficient C. i ×C i_close2 and the data i_open2 (i = 1..N) are calibrated to obtain the calibrated result Data. i_correct The expression is:

[0048] Data i_correct =Data i_open2 ×C i ×C i_close2 ;

[0049] Data after calibration i_correct The data is transmitted to the host computer for analysis, and the final calibration performance parameters are calculated using a ratio method.

[0050] Depending on the specific application, the final calibration performance parameters can also be modified, for example, by determining the final calibration performance parameters. The calibration performance indicators of each corresponding channel at different frequencies and under AGC are measured for amplitude and phase differences, and it is determined whether they are within a preset range. If so, the calibration coefficient applied to the open-loop receiving channel is valid; otherwise, the calibration coefficient applied to the open-loop receiving channel is invalid. The calibrated data is then processed. i_correct Reassigned, Data i_correct =Data i_open2 ×C i ×C i_close2 Repeat steps S101-S106 sequentially until the condition is within the preset range.

[0051] Example

[0052] The present invention will be further described in detail below through specific embodiments.

[0053] Without loss of generality, the specific steps for channel calibration of a certain type of integrated 16-channel digital array radar are as follows:

[0054] Step 1: Test Field Error Coefficient Calibration

[0055] When the test field does not meet the far-field test conditions, the phase error between the test radar array and the test field radiating feed element is corrected; this error is used as a measurement system error correction. The integrated digital array radar under test is mounted on a turntable support, and the turntable is rotated to its mechanical zero position. The output of the vector network analysis (VNA) is connected to the radiating feed element of the test field, and the input of the VNA is sequentially connected to the RF port Ant of each array subarray. i (i = 1..N) (where N is the number of radar array subarrays), such as Figure 1 As shown. Record the vector network reading C for each iteration. Ant_i (i = 1..16), calculate the plane wave error

[0056] Step Two: Radar Calibration Test Preparation

[0057] Assemble the integrated digital array radar under test completely. Connect the radar calibration signal output to the test radiation feed element via an RF cable. Connect the integrated digital array radar to the host computer, as shown in the attached diagram. Figure 1 As shown.

[0058] Step 3: Radar calibration signal waveform generation and received signal processing

[0059] Integrated digital array radar generates N PulseThe calibration signal consists of 100 pulses, each of which is a pulse-modulated point-frequency continuous wave with an initial phase of 0, a PRI of 100µs, a pulse width of 20µs, a transmit pulse delay of 20µs, and a baseband frequency of 1MHz.

[0060] The radar processing subsystem receives I and Q digital signals from each subarray channel at a sampling frequency of 4MHz. Each pulse has 320 sampling points. Starting from the 84th sampling point, 64 points are truncated, an FFT is performed along the range dimension, and then the summation is performed along the pulse dimension to obtain 64 complex data points. The maximum value after removing the 1st, 2nd, 63rd, and 64th points is output and denoted as Data. i (i = 1..16).

[0061] Step 4: Fixed Amplitude and Phase Difference Test of Open-Loop Receiving Channel

[0062] 1. According to Figure 2 Connect the lines; the wave controller points to azimuth 0° and elevation 0°.

[0063] 2. Traverse the frequency points from 8 to 12 GHz at 0.01 GHz intervals, fix the AGC of each subarray RF module at 0 dB, and record the processing results of 16 channels as Data, following the operation in step two. i_open (i = 1..16), and forwarded to the host computer debugging software, which then generates the coefficients for each frequency point. And save it on the host computer.

[0064] Step 5: Fixed Amplitude and Phase Difference Test of Closed-Loop Receiving Channel

[0065] 1. According to Figure 3 Connect the dots;

[0066] 2. Traverse the frequency points from 8 to 12 GHz at 0.01 GHz intervals, fix the AGC of each subarray RF module at 0 dB, and record the processing results of each channel as Data, following the steps in step two. i_close (i = 1..16), and forwarded to the host computer debugging software, which then generates the coefficients for each frequency point. And save it on the host computer.

[0067] Step Six: Calculation of Fixed Error in Receiver Channel

[0068] The host computer follows the formula Calculate the fixed error C at each frequency point i The host computer will fix the error C. i It is transmitted to the radar for storage.

[0069] Step 7: Calibration Coefficient Loading Test 1: Closed-Loop Receiving Channel Amplitude and Phase Difference Test

[0070] 1. Wait at least 10 minutes after powering down the radar before powering it back on;

[0071] 2. Press Figure 3 The closed-loop error test was performed again, traversing the frequency points from 8 to 12 GHz at 0.01 GHz intervals and traversing the AGC from 0 to 56 dB at 2 dB intervals. All subarrays were controlled by the same AGC. Following the operation in step two, the processing results under each frequency point and AGC of each channel were recorded as Data. i_close2 (i = 1..16), coefficients generated by radar at different frequencies and under AGC. And it is stored in the radar processing subsystem memory;

[0072] Step 8: Calibration Coefficient Loading Test Part 2: Open-Loop Receiving Channel Calibration Coefficient Loading Test

[0073] 1. According to Figure 2 The open-loop calibration coefficient loading test was performed with the wave controller pointing at 0° azimuth and elevation.

[0074] 2. Traverse the frequency points from 8 to 12 GHz at 0.01 GHz intervals, and traverse the AGC from 0 to 56 dB at 2 dB intervals. All subarrays are controlled by the same AGC. Following the operation in step two, the radar processes the data for each channel. i_open2 (i = 1..16) are calibrated, and the corresponding calibration coefficient C is found based on the frequency point and AGC. i ×C i_close2 Data i_open2 Process (i = 1..16) to obtain Data i_correct =Data i_open2 ×C i ×C i_close2 Data i_correct The data is transmitted to the host computer for analysis, and the calibration performance indicators are obtained through formulas.

[0075] After calibration, the amplitude difference between channels is within 0.5 dB, and the phase difference is within 6°, meeting the system requirements. This method uses the radar as both the test device and the device under test, achieving self-transmitting and self-receiving calibration. It can realize the full-link channel calibration of an integrated digital array radar, reducing the stringent performance requirements for amplitude and phase consistency of the calibration coupling path and each level of the link channel, and reducing the overall complexity of calibration.

[0076] The product provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention claims.

Claims

1. A method for calibrating the receiving channel of an integrated digital array radar, characterized in that, The methods include: S101: When the test field does not meet the far-field test conditions, determine the phase error and correct it; S102: Radar calibration test preparation, including: mounting the radar of the integrated digital array under test on the turntable support, connecting the radar's calibration signal output terminal to the radiation feed element for testing through an RF cable, and completing the connection between the radar and the host computer. S103: Generate the calibration signal waveform of the radar, and receive the echo signal fed back by the radiation feed element and process the echo signal to output the maximum value of the amplitude in all one-dimensional complex data. S104: The maximum value is used for open-loop receiving channel fixed amplitude phase difference testing to determine the calibration coefficient. The data is stored in the host computer, and the fixed amplitude and phase difference of the closed-loop receiving channel are tested to determine the calibration coefficient. And store it in the host computer; S105: Fixed amplitude and phase difference calculation for the receiving channel, including: the calibration coefficients determined by closed-loop and open-loop reception, and the ratio to determine the fixed error. The host computer will fix the error. The data is transmitted to the radar for storage. S106: The fixed error The calibration coefficients are loaded into the radar's system processing module and tested by powering the radar down and then powering it back on. ; S107: Open-loop receiver channel calibration coefficient test to determine final calibration performance parameters. This includes adjusting the beam control pointing azimuth and elevation to 0°, traversing the radar's frequency points and digital gain control (AGC), and processing the echo signal to obtain the processing result. And perform calibration. The calibration method is as follows: Find the corresponding calibration coefficients based on the radar frequency and AGC. and the data The calibration process is performed to obtain the calibrated result. The expression is: ; The calibrated processing results The data is transmitted to the host computer for analysis, and the final calibration performance parameters are calculated using a ratio method. ; Depending on the specific usage scenario, the final calibration performance parameters are adjusted. Specifically, the final calibration performance parameters are determined. The calibration performance indicators of each corresponding channel at different frequencies and under AGC are measured for amplitude and phase differences, and it is determined whether they are within a preset range. If so, the calibration coefficient applied to the open-loop receiving channel is valid; otherwise, the calibration coefficient applied to the open-loop receiving channel is invalid. The calibration results are then processed accordingly. Reassign value, Repeat steps S101-S106 sequentially until the condition is within the preset range.

2. The receiving channel calibration method for an integrated digital array radar according to claim 1, characterized in that, The phase error determined in S101 includes: The radar is mounted on a turntable support. The turntable is rotated to the mechanical zero position. The radar's output is connected to the radiation feed element of the test field, and the radar vector network input is sequentially connected to the radio frequency port of each array subarray. ,in, Given the number of subarrays in the radar array, record the vector network readings for each operation. Calculate plane wave error ; The plane wave error is corrected.

3. The receiving channel calibration method for an integrated digital array radar according to claim 2, characterized in that, The radar recorder exports data, and the recorder is connected to the debugging software of the host computer. In step S103, the echo signal is processed, including: The radar generates The calibration signal consists of one pulse, each of which is a modulated continuous wave signal with zero initial phase. The baseband frequency of the continuous wave signal is set to a preset ratio of the sampling rate. After digital preprocessing of the received signals from each subarray of the radar, a Fourier transform (FFT) is performed along the range dimension, and then the signals are summed along the pulse dimension to obtain one-dimensional complex data. Output the maximum amplitude among all the given one-dimensional complex data, denoted as . .

4. The receiving channel calibration method for an integrated digital array radar according to claim 3, characterized in that, S104 includes performing an open-loop receiving channel fixed amplitude phase difference test on the maximum value, including: During testing, the radar's pointing azimuth and elevation angles in the radar system control pattern were set to 0°. The radar's frequency points were traversed, and the AGC of each subarray RF frequency conversion channel module of the radar was set to 0dB. Record the processing results of each channel module at each frequency point; the processing results are denoted as... and the processing results The debugging software is forwarded to the host computer, which then generates calibration coefficients for each frequency point. And store.

5. The receiving channel calibration method for an integrated digital array radar according to claim 4, characterized in that, The closed-loop receiving channel fixed amplitude phase difference test in S104 includes: During testing, the radar's pointing azimuth and elevation angles were set to 0° under the radar system control pattern. The radar's frequency points were traversed, and the digital gain control (AGC) of each subarray RF channel module was set to 0 dB. The processing results of each channel were recorded as follows: The data is then forwarded to the host computer's debugging software, which generates calibration coefficients for each frequency point. And store it in the host computer.

6. The receiving channel calibration method for an integrated digital array radar according to claim 5, characterized in that, Determining the fixed error in S105 ,include: Fixed error at each frequency point .

7. The receiving channel calibration method for an integrated digital array radar according to claim 6, characterized in that, S106: The fixed error The calibration coefficients are loaded into the radar's system processing module and tested by powering the radar down and then powering it back on. ,include: The amplitude and phase difference test of the closed-loop receiving channel was performed again, including: The radar is powered off and then powered on again after a preset time interval. The closed-loop error test was performed again, traversing the radar frequency points from 8-12GHz at 0.01GHz intervals and the AGC from 0-56dB at 2dB intervals, with all subarrays controlled by the same AGC. The processing results of each channel at each frequency point and under the AGC were recorded. Generate coefficients at different frequencies and under AGC. And it is stored in the radar's processing subsystem memory; S107: Open-loop receiver channel calibration coefficient test to determine final calibration performance parameters. .

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