Phased Array Radar Calibration Method Based on FFT

Abstract

The present invention discloses a phased array radar calibration method based on FFT, comprising: setting two different signal test points, testing the feedback echo signal according to the two different signal points, and calculating the frequency domain signal of the echo signal based on the FFT algorithm; each antenna unit is from the test point A , test point B Obtain frequency domain signals, calculate the error deviation coefficient of frequency domain signals, and then calculate the error coefficient of antenna units, evaluate whether antenna units are faulty, and replace or repair faulty antenna units; use the frequency domain signals of normal antenna units to calculate the internal and external field errors of phased array radars, and calculate the frequency domain signal errors of new antenna units after the faulty antenna units are replaced, and obtain the frequency domain signal errors of all antenna units in the phased array radar, and then obtain the phase and amplitude calibration values ​​of each antenna unit. The entire calibration process can calculate the calibration values ​​of the phase and amplitude of the antenna units to ensure the normal and accurate operation of the radar system.

Description

Technical Field

[0001] The invention relates to the field of phased array radar data processing, and in particular to a phased array radar calibration method based on FFT. Background Art

[0002] Phased array radar is a phase-controlled electronic scanning array radar. Its ability to quickly and accurately switch beams enables the radar to complete the scanning of the entire airspace within 1 minute. The so-called phased array radar is a radar array composed of a large number of identical antenna units. The antenna units include radiating units and receiving units. Each radiating unit is independently controlled by wave control and phase shifters in phase and amplitude, and can obtain accurate and predictable radiation patterns and beam pointing. Phased array radars produce amplitude and phase errors due to the influence of mutual coupling between units, device manufacturing, assembly errors, aging, thermal deformation and component replacement. These errors seriously affect the performance and accuracy of the radar. Traditional calibration methods often perform in-field calibration based on the overall phased array radar. The process is complicated and the accuracy is not high. It is difficult to meet the needs of modern radar systems. During the component replacement process, there will also be errors when replacing new antenna units. Existing calibration methods rarely take new antenna units into consideration during the calibration process, resulting in poor overall calibration results. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a phased array radar calibration method based on FFT, which realizes calibration of phased array radar components before and after replacement through a calculation process based on Fast Fourier Transform (FFT).

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] A phased array radar calibration method based on FFT is provided, comprising:

[0006] Step S1: according to the antenna unit layout of the phased array radar, two different signal test points are set, and the echo signal fed back according to the two different signal tests and the frequency domain signal of the echo signal is calculated based on the FFT algorithm;

[0007] Step S2: Each antenna element is connected from the test point A , test point B Obtain frequency domain signals, calculate the error deviation coefficient of the frequency domain signals, and then calculate the error coefficient of the antenna unit, evaluate whether the antenna unit is faulty, and replace or repair the faulty antenna unit;

[0008] Step S3: Calculate the internal and external field errors of the phased array radar using the frequency domain signals of the normal antenna units, and calculate the frequency domain signal errors of the new antenna units after the faulty antenna units are replaced, so as to obtain the frequency domain signal errors of all antenna units in the phased array radar, and then obtain the calibration values ​​of the phase and amplitude of each antenna unit.

[0009] Further, step S1 includes:

[0010] Step S11: determining a signal receiving plane according to the constructed phased array radar, establishing a signal test axis on the signal receiving plane, and the vertical point where the signal test axis intersects the signal receiving plane is located at the center of the signal receiving plane;

[0011] Step S12: construct a three-dimensional coordinate system 0-xyz, where the x0y plane of the three-dimensional coordinate system 0-xyz coincides with the signal receiving plane, and the z axis is parallel to the signal test axis; select any two points on the signal test axis as test points A , test point B ;

[0012] Step S13: At the test point A , test point B Two test units are installed respectively, and the antenna unit of the phased array radar sends radar test signals to the two test units respectively, and the FFT algorithm is used to calculate the frequency domain signals of the echo signals of the two test units.

[0013] ;

[0014] in, K is the frequency domain index of the frequency domain signal, n is the time domain signal sampling point of the echo signal, is the time domain signal, N is the number of sampling points of the time domain signal, i is the frequency domain range of the frequency domain signal, k is the spectrum sampling point of the frequency domain signal.

[0015] Further, step S2 includes:

[0016] Step S21: Get each antenna element from the test point A , test point B The acquired frequency domain signal , according to the antenna unit and test point A , test point B The coordinates of the antenna unit in the three-dimensional coordinate system 0-xyz are calculated respectively with respect to the test point A , test point B The distance between ;

[0017] ;

[0018] in, j is the number of the antenna unit in the phased array radar, are the coordinates of the antenna unit, For test point A The coordinates of For test point A The coordinates of

[0019] Step S22: Filter out distance values The frequency domain signals corresponding to the same antenna units form a frequency domain signal data set , , For the J The antenna element is from the test point B The obtained frequency domain signal, J is the number of frequency domain signals in the frequency domain signal data group, For the J The antenna element is from the test point A The acquired frequency domain signal;

[0020] Step S23: Calculate the first j The error deviation coefficient of the frequency domain signal obtained by the antenna unit , ;

[0021] ;

[0022] in, For the j The antenna element is from the test point A The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The obtained frequency domain signal, For the j The antenna element is from the test point A The obtained frequency domain signal, For the j The antenna element is from the test point A The error deviation coefficient of the obtained frequency domain signal, For the j The antenna element is from the test point B The error deviation coefficient of the acquired frequency domain signal;

[0023] Step S24: According to the error deviation coefficient , Calculate the j The error coefficient of the antenna element ;

[0024] ;

[0025] Step S25: Setting the antenna unit error tolerance threshold ,like , then determine the j If an antenna unit fails, the faulty antenna unit is located on the signal receiving plane according to the three-dimensional coordinates of the antenna unit, and the staff replaces or repairs the faulty antenna unit; , then determine the j The antenna unit is normal.

[0026] Further, step S3 includes:

[0027] Step S31: Screen out all faulty antenna units in the phased array radar and replace the faulty antenna units. , The frequency domain signal received by the faulty antenna unit is deleted, and the error of the frequency domain signal received by the normal antenna unit is calculated. ;

[0028] ;

[0029] in, u is the number of the normal antenna unit;

[0030] Step S32: Obtain the error data set of the frequency domain signal received by the normal antenna unit , filter error data set Minimum value within , get the minimum value Corresponding antenna unit usage cycle t , U is the number of normal antenna units;

[0031] Step S33: In the error data set The frequency domain signal error is greater than the minimum value. , and the service life is less than t Normal antenna unit w， Calculating In-Field Errors of Phased Array Radar , minimum As a reference for error;

[0032] ;

[0033] in,W The frequency domain signal error is greater than the minimum value , and the service life is less than t The normal number of antenna elements, Normal antenna unit w The frequency domain signal error of

[0034] Step S34: Calculate the external field error of the phased array radar , and field error Relationship coefficient with the use cycle;

[0035] ;

[0036] Step S35: According to the minimum value Calculate the frequency domain signal error of the new antenna unit after the faulty antenna unit is replaced ;

[0037] ;

[0038] Step S36: z The initial frequency domain signal error of each faulty antenna unit is defined as , and insert it into the error data set The frequency domain signal error of all antenna units in the phased array radar is obtained , S is the number of antenna units in the phased array radar;

[0039] Step S37: Based on the frequency domain signal error of each antenna unit Calculates phase and amplitude calibration values ​​for each antenna element in a phased array radar ;

[0040] ;

[0041] in, It is the relationship function between frequency domain signal, phase and amplitude.

[0042] The beneficial effects of the present invention are as follows: the present invention detects the errors of the antenna units in the phased array radar at the same time by using two test points, and screens the faulty antenna units, so as to avoid the accidental errors affecting the accuracy of the antenna unit fault assessment. At the same time, the frequency domain signal of the echo signal is calculated based on the FFT algorithm to calculate the internal and external field errors of the phased array radar antenna unit, and then the error of the replaced faulty antenna unit is corrected to further improve the accuracy of the phased array radar. The entire calibration process can calculate the calibration values ​​of the phase and amplitude of the antenna unit to ensure the normal and accurate operation of the radar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1The figure is a flow chart of the FFT-based phased array radar calibration method. DETAILED DESCRIPTION

[0044] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0045] like Figure 1 As shown, a phased array radar calibration method based on FFT includes:

[0046] A signal receiving plane is determined according to the constructed phased array radar, a signal test axis is established on the signal receiving plane, and a vertical point where the signal test axis intersects the signal receiving plane is located at the center of the signal receiving plane;

[0047] Construct a three-dimensional coordinate system 0-xyz, where the x0y plane of the three-dimensional coordinate system 0-xyz coincides with the signal receiving plane, and the z axis is parallel to the signal test axis; select any two points on the signal test axis as test points A , test point B ;

[0048] At the test point A , test point B Two test units are installed on each of the two test units, and the antenna unit of the phased array radar sends radar test signals to the two test units respectively, and the frequency domain signals of the echo signals of the two test units are calculated by using the FFT algorithm;

[0049] ;

[0050] in, K is the frequency domain index of the frequency domain signal, n is the time domain signal sampling point of the echo signal, is the time domain signal, N is the number of sampling points of the time domain signal, i is the frequency domain range of the frequency domain signal, k is the spectrum sampling point of the frequency domain signal;

[0051] Get each antenna element from the test point A , test point B The acquired frequency domain signal , according to the antenna unit and test point A , test point B The coordinates of the antenna unit in the three-dimensional coordinate system 0-xyz are calculated respectively with respect to the test point A , test pointB The distance between ;

[0052] ;

[0053] in, j is the number of the antenna unit in the phased array radar, are the coordinates of the antenna unit, For test point A The coordinates of For test point A The coordinates of

[0054] Filter out distance values The frequency domain signals corresponding to the same antenna units form a frequency domain signal data set , , For the J The antenna element is from the test point B The obtained frequency domain signal, J is the number of frequency domain signals in the frequency domain signal data group, For the J The antenna element is from the test point A The acquired frequency domain signal;

[0055] The present invention uses antenna units with the same distance from the test point as a fault assessment group, which can effectively avoid the influence of signal delay errors caused by different distances and improve the accuracy of fault assessment. During the entire fault assessment process, multiple antenna units in the phased array radar will form multiple frequency domain signal data groups. During the data processing and calculation process, each frequency domain signal data group is used in turn to screen and eliminate the faults of the antenna unit.

[0056] Calculate the first j The error deviation coefficient of the frequency domain signal obtained by the antenna unit , ;

[0057] ;

[0058] in, For the j The antenna element is from the test point A The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The obtained frequency domain signal, For thej The antenna element is from the test point A The obtained frequency domain signal, For the j The antenna element is from the test point A The error deviation coefficient of the obtained frequency domain signal, For the j The antenna element is from the test point B The error deviation coefficient of the acquired frequency domain signal;

[0059] According to the error deviation coefficient , Calculate the j The error coefficient of the antenna element ;

[0060] ;

[0061] Set the error tolerance threshold of the antenna unit ,like , then determine the j If an antenna unit fails, the faulty antenna unit is located on the signal receiving plane according to the three-dimensional coordinates of the antenna unit, and the staff replaces or repairs the faulty antenna unit; , then determine the j The antenna units are normal;

[0062] The present invention sets two test points to comprehensively evaluate and screen the faults of the antenna unit of the phased array radar, and calculates the errors of the frequency domain signals obtained from the two test points respectively to comprehensively evaluate the fault conditions of the antenna unit. When the error coefficients of the frequency domain signals obtained from the two test points are too large, it can be determined that both signal tests are abnormal, or that the abnormal deviation of at least one signal test is too large, and it is determined that the antenna unit has failed. This method can effectively avoid the influence of accidental small fluctuation errors in the antenna unit, and misjudge the fault conditions of the antenna unit.

[0063] Phased array radar contains multiple antenna units, including radiating units and receiving units. The radiating unit sends the received echo signal to the host to complete the radar's search, tracking and measurement of the target. In addition to the antenna vibrator, each antenna unit also has necessary components such as phase shifters. Therefore, when troubleshooting a faulty antenna unit, in addition to replacing the radiating unit and the receiving unit, it is also necessary to replace or repair the remaining supporting components if necessary.

[0064] Screen out all faulty antenna units in the phased array radar and replace them. , The frequency domain signal received by the faulty antenna unit is deleted, and the error of the frequency domain signal received by the normal antenna unit is calculated. ;

[0065] ;

[0066] in, u is the number of the normal antenna unit;

[0067] Get the error data set of the frequency domain signal received by the normal antenna unit , filter error data set Minimum value within , get the minimum value Corresponding antenna unit usage cycle t , U is the number of normal antenna units;

[0068] In the error data set The frequency domain signal error is greater than the minimum value. , and the service life is less than t Normal antenna unit w， Calculating In-Field Errors of Phased Array Radar , minimum As a reference for error;

[0069] ;

[0070] in, W The frequency domain signal error is greater than the minimum value , and the service life is less than t The normal number of antenna elements, Normal antenna unit w The frequency domain signal error of

[0071] Calculating the Field Error of Phased Array Radar , and field error Relationship coefficient with the use cycle;

[0072] ;

[0073] According to the minimum Calculate the frequency domain signal error of the new antenna unit after the faulty antenna unit is replaced ;

[0074] ;

[0075] Will z The initial frequency domain signal error of each faulty antenna unit is defined as , and insert it into the error data set The frequency domain signal error of all antenna units in the phased array radar is obtained , S is the number of antenna units in the phased array radar;

[0076] According to the frequency domain signal error of each antenna element Calculates phase and amplitude calibration values ​​for each antenna element in a phased array radar ;

[0077] ;

[0078] in, It is the relationship function between frequency domain signal, phase and amplitude.

Claims

1. A phased array radar calibration method based on FFT, characterized in that: include: Step S1: according to the antenna unit layout of the phased array radar, two different signal test points are set, and the echo signal fed back according to the two different signal tests and the frequency domain signal of the echo signal is calculated based on the FFT algorithm; Step S2: Each antenna element is connected from the test point A , test point B Obtain frequency domain signals, calculate the error deviation coefficient of the frequency domain signals, and then calculate the error coefficient of the antenna unit, evaluate whether the antenna unit is faulty, and replace or repair the faulty antenna unit; Step S3: Calculate the internal field error and external field error of the phased array radar using the frequency domain signal of the normal antenna unit, and calculate the frequency domain signal error of the new antenna unit after the faulty antenna unit is replaced, so as to obtain the frequency domain signal error of all antenna units in the phased array radar, and then obtain the calibration value of the phase and amplitude of each antenna unit; The step S1 comprises: Step S11: determining a signal receiving plane according to the constructed phased array radar, establishing a signal test axis on the signal receiving plane, and the vertical point where the signal test axis intersects the signal receiving plane is located at the center of the signal receiving plane; Step S12: construct a three-dimensional coordinate system 0-xyz, where the x0y plane of the three-dimensional coordinate system 0-xyz coincides with the signal receiving plane, and the z axis is parallel to the signal test axis; select any two points on the signal test axis as test points A , test point B ; Step S13: At the test point A , test point B Two test units are installed on each of them. The antenna unit of the phased array radar sends radar test signals to the two test units respectively. The frequency domain signals of the echo signals of the two test units are calculated using the FFT algorithm: ； in, K is the frequency domain index of the frequency domain signal, n is the time domain signal sampling point of the echo signal, is the time domain signal, N is the number of sampling points of the time domain signal, i is the frequency domain range of the frequency domain signal, k is the spectrum sampling point of the frequency domain signal; The step S2 comprises: Step S21: Get each antenna element from the test point A , test point B The acquired frequency domain signal , according to the antenna unit and test point A , test point B The coordinates of the antenna unit in the three-dimensional coordinate system 0-xyz are calculated respectively with respect to the test point A , test point B The distance between ; ； in, j is the number of the antenna unit in the phased array radar, are the coordinates of the antenna unit, For test point A The coordinates of For test point A The coordinates of Step S22: Filter out distance values The frequency domain signals corresponding to the same antenna units form a frequency domain signal data set , , For the J The antenna element is from the test point B The obtained frequency domain signal, J is the number of frequency domain signals in the frequency domain signal data group, For the J The antenna element is from the test point A The acquired frequency domain signal; Step S23: Calculate the first j The error deviation coefficient of the frequency domain signal obtained by the antenna unit , ; ； in, For the j The antenna element is from the test point A The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The standard value of the frequency domain signal obtained, For the j The antenna element is from the test point B The obtained frequency domain signal, For the j The antenna element is from the test point A The obtained frequency domain signal, For the j The antenna element is from the test point A The error deviation coefficient of the obtained frequency domain signal, For the j The antenna element is from the test point B The error deviation coefficient of the acquired frequency domain signal; Step S24: According to the error deviation coefficient , Calculate the j The error coefficient of the antenna element ; ； Step S25: Setting the antenna unit error tolerance threshold ,like , then determine the j If an antenna unit fails, the faulty antenna unit is located on the signal receiving plane according to the three-dimensional coordinates of the antenna unit, and the staff replaces or repairs the faulty antenna unit; , then determine the j The antenna units are normal; The step S3 comprises: Step S31: Screen out all faulty antenna units in the phased array radar and replace the faulty antenna units. , The frequency domain signal received by the faulty antenna unit is deleted, and the error of the frequency domain signal received by the normal antenna unit is calculated. ; ； in, u is the number of the normal antenna unit; Step S32: Obtain the error data set of the frequency domain signal received by the normal antenna unit , filter error data set Minimum value within , get the minimum value Corresponding antenna unit usage cycle t , U is the number of normal antenna units; Step S33: In the error data set The frequency domain signal error is greater than the minimum value. , and the service life is less than t Normal antenna unit w， Calculating In-Field Errors of Phased Array Radar , minimum As a reference for errors; ； in, W The frequency domain signal error is greater than the minimum value , and the service life is less than t The normal number of antenna elements, Normal antenna unit w The frequency domain signal error; Step S34: Calculate the external field error of the phased array radar , and field error Relationship coefficient with the use cycle; ； Step S35: According to the minimum value Calculate the frequency domain signal error of the new antenna unit after the faulty antenna unit is replaced ; ； Step S36: z The initial frequency domain signal error of each faulty antenna unit is defined as , and insert it into the error data set The frequency domain signal error of all antenna units in the phased array radar is obtained , S is the number of antenna units in the phased array radar; Step S37: Based on the frequency domain signal error of each antenna unit Calculates phase and amplitude calibration values ​​for each antenna element in a phased array radar ; ； in, It is the relationship function between frequency domain signal, phase and amplitude.

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