Method and system for post-compensation calibration of near-field calibration volume echo based on frequency domain adjacent ratio

Abstract

The invention discloses a near-field calibration body echo post-compensation calibration method and system based on frequency domain adjacent ratio, which belongs to the field of signal processing, and comprises: acquiring the echo signal of the calibration body which is not placed at the rotation center; calculating the frequency domain adjacent ratio signal according to the echo signal of the calibration body, and calculating the correction phase corresponding to each rotation angle based on the frequency domain adjacent ratio signal; calculating the correction parameter corresponding to the rotation angle through the correction phase according to the least square method; calculating the phase correction factor according to the correction parameter, and performing phase correction on the echo signal of the calibration body through the phase correction factor to obtain the phase-corrected result; calculating the distance corresponding to the rotation angle for each rotation angle of the phase-corrected result; calculating the calibration distance difference according to the distance corresponding to the rotation angle; calculating the post-compensation factor according to the calibration distance difference; performing post-compensation on the phase-corrected result according to the post-compensation factor to obtain the calibration body echo signal after final calibration.

Description

Technical Field

[0001] The invention belongs to the field of signal processing, and in particular relates to a near-field calibration body echo post-compensation calibration method and system based on frequency domain adjacent ratio. Background Art

[0002] In the process of testing the RCS (Radar Cross Section) of the target, in the most ideal theoretical case, the center position of the calibration body should be at the center of rotation. However, in actual test scenarios, it is difficult to ensure that the calibration body can be placed in the ideal position under some circumstances. Therefore, if the position compensation is not performed on the input signal of the calibration body, the effective RCS of the target cannot be obtained. The traditional position compensation method is to first calculate the corresponding phase of the value at each scanning angle and frequency of the echo signal, and then subtract the phase group of the previous frequency from the phase group of the next frequency to obtain the phase difference group. The correction parameters of the phase difference group are calculated according to the least squares method, and the correction parameter groups calculated at different frequencies are averaged to obtain the average correction parameters. The compensation factor is calculated according to the average correction parameter, and the calibration body echo signal is phase compensated by the compensation factor to obtain the calibration body echo signal after recalibration. However, the traditional method has the following defects: first, the algorithm for extracting the correction parameters is too complicated because the correction parameters at multiple frequencies need to be calculated; second, in the near-field position, if there is a large distance deviation between the actual placement position of the calibration body and the rotation center, the algorithm cannot correct the calibration body to the rotation center, which will affect the RCS test accuracy. Summary of the invention

[0003] The purpose of the present invention is to provide a near-field calibration body echo post-compensation calibration method and system based on frequency domain adjacent ratio to overcome the problems existing in the prior art. The present invention adopts the method of calculating the phase compensation factor by frequency domain adjacent ratio to reduce the complexity of the algorithm. In addition, post-compensation is performed on the basis of the calibration body echo phase correction to improve the calibration accuracy of the calibration body.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] The method for post-compensation calibration of near-field calibration volume echo based on frequency domain adjacent ratio includes the following steps:

[0006] Acquire the echo signal of the calibration body which is not placed at the center of rotation;

[0007] Calculate a frequency domain adjacent ratio signal according to the echo signal of the calibration body, and calculate a correction phase corresponding to each rotation angle based on the frequency domain adjacent ratio signal;

[0008] According to the least square method, the correction parameter corresponding to the rotation angle is calculated by correcting the phase;

[0009] The phase correction factor is calculated according to the correction parameter, and the phase correction is performed on the echo signal of the calibration object by the phase correction factor to obtain a phase-corrected result;

[0010] For each rotation angle of the phase-corrected result, calculate the distance corresponding to the rotation angle;

[0011] Calculate the calibration distance difference according to the distance corresponding to the rotation angle;

[0012] Calculate the post-compensation factor based on the calibration distance difference;

[0013] The phase-corrected result is post-compensated according to the post-compensation factor to obtain the final calibrated volume echo signal.

[0014] Furthermore, the echo signal of the calibration body which is not placed at the rotation center is expressed as follows:

[0015]

[0016]

[0017]

[0018]

[0019] in, are rotation angle index and frequency index respectively, , , M is the number of scanning angles, N is the number of frequency points; Indicated in i The rotation angle and n The echo signal of the calibration body under the condition of frequency; exp represents the exponential function with the natural constant e as the base; j is an imaginary unit; Indicates the distance between the radar antenna and the center of rotation; is a constant greater than 0, indicating the signal transmission power value; represents the speed of light; Indicates the coordinates of the center position of the calibration body in the turntable coordinate system; Indicates n Frequency; Indicates i The distance between the radar antenna and the calibration object at the rotation angle; Indicates i rotation angle; Indicates the starting rotation angle; Indicates the step angle; Indicates the starting frequency; Indicates the step frequency.

[0020] Further, the calculation of the frequency domain adjacent ratio signal according to the echo signal of the calibration body and the calculation of the correction phase corresponding to each rotation angle specifically include:

[0021] 2a) Calculate the adjacent ratio signal in the frequency domain , specifically:

[0022]

[0023] in, Indicated in i The rotation angle and The echo signal of the calibration body under the condition of frequency; Indicated in i The rotation angle and The echo signal of the calibration body under the condition of frequency; is the frequency difference index, , N is the number of frequency points;

[0024] 2b) Calculate each rotation angle The corresponding phase , specifically:

[0025]

[0026] in, It means to find the inverse tangent of the four symbols; for The real part of for The imaginary part of It means that for every given i The row average of the adjacent ratio signals in the frequency domain under the condition, ;

[0027] 2c) Phase Correction is performed to obtain the correction phase , specifically:

[0028] set up ,from To begin with, there are three situations:

[0029] Scenario 1: ,but ;

[0030] Scenario 2: ,but ;

[0031] Scenario 3: In addition to the above two scenarios, ;

[0032] in, , M is the number of scanning angles.

[0033] Furthermore, the calculation of the correction parameter corresponding to the rotation angle by correcting the phase according to the least square method specifically includes:

[0034] 3a) Constructing an array and the phase matrix ;

[0035] in, Represents matrix transpose; Indicates the correction phase group to be calculated; P represents an array The length of , It means rounding up, M is the number of scanning angles; for The matrix is ​​represented as follows:

[0036]

[0037] In the formula, Indicates the step angle;

[0038] 3b) Calculate correction parameters a and b , specifically:

[0039]

[0040]

[0041]

[0042] in, It is recorded as the sweeping angle matrix, and its size is ; Denoted as the correction parameter array, the size is ; Indicates the first value of the correction parameter array; Indicates the second value of the correction parameter array.

[0043] Further, the phase correction factor is calculated according to the correction parameter, and the phase correction is performed on the echo signal of the calibration object by the phase correction factor to obtain the result after the phase correction, which specifically includes:

[0044] 4a) Calculate the phase correction factor based on the correction parameters , the process is as follows:

[0045] set up represents the rotation angle averaging, which is expressed as follows:

[0046]

[0047] set up is the initial value of frequency quantization, then It is expressed as follows:

[0048]

[0049] in, Indicates i rotation angle; i is the rotation angle index, , represents the starting frequency, Indicates the step frequency; is the frequency index, , N is the number of frequency points;

[0050] 4b) The echo signal of the calibration object is corrected by the phase correction factor Perform phase correction to obtain the phase-corrected result as follows:

[0051]

[0052] in, It represents the result after phase correction at the corresponding rotation angle and frequency.

[0053] Furthermore, for each rotation angle of the phase-corrected result, the distance corresponding to the rotation angle is calculated, specifically:

[0054] The result after phase correction Perform IDFT transformation to obtain the echo signal in the range domain , which is expressed as follows:

[0055]

[0056] in, They are rotation angle index and distance index respectively. , Indicates the number of IDFT transformation points;

[0057] The distance corresponding to the rotation angle It is expressed as follows:

[0058]

[0059] in, For the corresponding i Down The index corresponding to the maximum modulus value, represents the distance between the radar antenna and the center of rotation, Indicates the maximum unambiguous distance;

[0060]

[0061] in, represents the speed of light, Indicates the step frequency.

[0062] Furthermore, the calibration distance difference is calculated based on the distance corresponding to the rotation angle, specifically:

[0063]

[0064] in, Represents the calibration distance difference, and M is the number of scanning angles.

[0065] Furthermore, the post-compensation factor calculated according to the calibration distance difference is specifically:

[0066]

[0067] in, represents the post-compensation factor, exp represents the exponential function with the natural constant e as the base, Indicates n frequency, j Represents an imaginary unit.

[0068] Furthermore, the phase-corrected result is post-compensated according to the post-compensation factor to obtain the final calibrated volume echo signal, specifically:

[0069]

[0070] in, It is the calibration volume echo signal after final calibration.

[0071] The near-field calibration volume echo post-compensation calibration system based on frequency domain adjacent ratio includes:

[0072] Echo signal acquisition module: used to acquire the echo signal of the calibration body which is not placed at the rotation center;

[0073] Correction phase calculation module: used to calculate the frequency domain adjacent ratio signal according to the echo signal of the calibration body, and calculate the correction phase corresponding to each rotation angle based on the frequency domain adjacent ratio signal;

[0074] Correction parameter calculation module: used to calculate the correction parameter corresponding to the rotation angle by correcting the phase according to the least square method;

[0075] Phase correction module: used to calculate the phase correction factor according to the correction parameter, and perform phase correction on the echo signal of the calibration object through the phase correction factor to obtain the phase-corrected result;

[0076] Distance calculation module: used to calculate the distance corresponding to each rotation angle of the result after phase correction;

[0077] Calibration distance difference calculation module: used to calculate the calibration distance difference according to the distance corresponding to the rotation angle;

[0078] Post-compensation factor calculation module: used to calculate the post-compensation factor according to the calibration distance difference;

[0079] Post-compensation module: used to perform post-compensation on the result after phase correction according to the post-compensation factor to obtain the final calibrated calibration volume echo signal.

[0080] Compared with the prior art, the present invention has the following beneficial technical effects:

[0081] The present invention is based on the traditional calibration technology of the calibration body, and adopts the method of the adjacent ratio signal in the frequency domain to obtain the corresponding correction phase under each rotation angle, and then calculates the correction parameter by comparing the phase, and performs phase correction on the echo signal of the calibration body to obtain the result after phase correction, and combines the result after phase correction with the distance of the radar antenna in the rotation center domain to calculate the calibration distance difference, and obtains the post-compensation factor by combining the calibration distance difference, and performs post-compensation on the result after phase correction to obtain the calibration body echo signal after the final calibration. The present invention adopts the method of obtaining the phase compensation factor by the adjacent ratio in the frequency domain, which reduces the complexity of the algorithm, performs post-compensation on the basis of the calibration of the calibration body echo phase, and improves the calibration accuracy of the calibration body. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0083] Figure 1 It is a flow chart of a near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio in embodiment 1 of the present invention;

[0084] Figure 2 The figure is a schematic diagram of the calibration body placement, where 1 represents the rotation center, 2 represents the calibration body, and 3 represents the radar antenna. R 0 is the distance between the radar antenna 3 and the rotation center 1;

[0085] FIG3 (a) is a stereogram of a range image of an echo signal of a calibration body;

[0086] FIG3( b ) is a plan view of the range image of the echo signal of the calibration body;

[0087] Figure 4 (a) is a stereogram of the range image corresponding to the traditional method;

[0088] Figure 4 (b) is a plan view of the range image corresponding to the traditional method;

[0089] FIG5 (a) is a stereogram of the range image corresponding to the calibration volume echo signal after the final calibration of the method of the present invention;

[0090] FIG5( b ) is a plan view of the range image corresponding to the calibration volume echo signal after the final calibration of the method of the present invention;

[0091] Figure 6 This is a structural diagram of a near-field calibration volume echo post-compensation calibration system based on frequency domain adjacent ratio according to embodiment 3 of the present invention. DETAILED DESCRIPTION

[0092] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0093] It should be understood that the numbers used in this way are interchangeable where appropriate, so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein. In addition, the terms "comprises" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products, or apparatus.

[0094] Embodiment 1

[0095] See also Figure 1 and Figure 2 The present invention provides a near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio, comprising the following steps:

[0096] Acquire the echo signal of the calibration body 2 which is not placed at the rotation center 1;

[0097] Calculate the frequency domain adjacent ratio signal according to the echo signal of the calibration body 2, and calculate the correction phase corresponding to each rotation angle;

[0098] According to the least square method, the correction parameters are calculated by correcting the phase;

[0099] Calculate the phase correction factor according to the correction parameter, and perform phase correction on the echo signal of the calibration body 2 by using the phase correction factor to obtain a phase-corrected result;

[0100] For each rotation angle of the phase-corrected result, calculate the distance corresponding to the rotation angle;

[0101] Calculate the calibration distance difference according to the distance corresponding to the rotation angle;

[0102] Calculate the post-compensation factor based on the calibration distance difference;

[0103] The phase-corrected result is post-compensated according to the post-compensation factor to obtain the final calibrated volume echo signal.

[0104] The present invention is based on the traditional calibration technology of the calibration body, and adopts the method of the frequency domain adjacent ratio signal to obtain the corresponding correction phase under each rotation angle, and then calculates the correction parameter by correcting the phase, and performs phase correction on the echo signal of the calibration body 2 to obtain the result after phase correction, and combines the result after phase correction with the distance between the rotation center 1 and the radar antenna 3 to calculate the calibration distance difference, and obtains the post-compensation factor in combination with the calibration distance difference, and performs post-compensation on the result after phase correction to obtain the final calibration of the calibration body echo signal. The present invention adopts the method of obtaining the phase compensation factor by the frequency domain adjacent ratio, which reduces the complexity of the algorithm, and performs post-compensation on the basis of the calibration body echo phase correction, thereby improving the calibration accuracy of the calibration body 2.

[0105] Embodiment 2

[0106] The present invention provides a near-field calibration body echo post-compensation calibration method based on frequency domain adjacent ratio. For the echo signal of the calibration body 2 at the same rotation angle, the value at the latter frequency is compared with the value at the previous frequency to obtain the frequency domain adjacent ratio signal, and the correction phase corresponding to each rotation angle is obtained according to the frequency domain adjacent ratio signal. According to the correction phase at different rotation angles, the least square method is used to calculate the correction parameter, the phase correction factor is calculated according to the correction parameter, and the phase correction of the echo signal of the calibration body 2 based on the phase correction factor is completed. Then, the result after phase correction is transformed by IDFT (Inverse Discrete Fourier Transform) to obtain the echo signal in the distance domain, and at the same time, the position corresponding to the maximum value of the echo signal modulus value in the distance domain is found, and the post-compensation factor is calculated in combination with the distance from the radar antenna 3 to the rotation center 1, and then the result after phase correction is post-compensated in combination with the post-compensation factor to obtain the calibration body echo signal after the final correction.

[0107] The specific steps include:

[0108] Step 1: Obtain the echo signal of the calibration body 2 which is not placed at the rotation center 1 .

[0109] in, are rotation angle index and frequency index respectively, , , M is the number of scanning angles, N is the number of frequency points.

[0110] The analytical formula is as follows:

[0111]

[0112]

[0113] like Figure 2 As shown: Among them, , , Indicates i Rotation angle (when i =1, the radar antenna 3 is located at the initial position B. i =M, the radar antenna 3 is located at the end position C, is the line connecting the position O of the rotation center 1 and the position of the radar antenna 3 and y The angle between the negative half axis of the axis), Indicates n frequency, is the starting rotation angle, Indicates the step angle; Indicates the step frequency; Indicates the starting frequency; is a constant greater than 0, indicating the signal transmission power value; j is an imaginary unit; Indicated in i The rotation angle and n The echo signal of the calibration body 2 under the condition of frequency; exp represents the exponential function with the natural constant e as the base; Indicates i The distance between the radar antenna 3 and the calibration body 2 at the rotation angle; represents the distance between the radar antenna 3 and the rotation center 1; assuming that in the turntable coordinate system, the coordinate of the center position of the calibration body 2 is .

[0114] Step 2: Calculate the frequency domain adjacent ratio signal ( , is the frequency difference index), and calculates each rotation angle The corresponding correction phase .

[0115] 2a) Calculate the adjacent ratio signal in the frequency domain , as shown below:

[0116]

[0117] in, Indicated in i The rotation angle and The echo signal of calibration body 2 under the condition of frequency; Indicated in i The rotation angle and The echo signal of calibration body 2 under the condition of frequency;

[0118] 2b) Calculate each rotation angle The corresponding phase , as shown below:

[0119]

[0120] It means that for every given i The row average of the adjacent ratio signals in the frequency domain under the condition is for The real part of for The imaginary part of It is expressed as follows:

[0121]

[0122] in, It means to find the inverse tangent of the four symbols.

[0123] 2c) Phase Correction is performed to obtain the correction phase , the method is as follows:

[0124] set up ,from To begin with, there are three situations:

[0125] Scenario 1: ,but .

[0126] Scenario 2: ,but .

[0127] Scenario 3: Excluding the above two scenarios, .

[0128] in, .

[0129] Step 3: According to the least squares algorithm, Calculate correction parameters a, b , the method is as follows:

[0130] 3a) Constructing an array , Represented as matrix transpose, Indicates the correction phase group to be calculated.

[0131] Constructing the Phase Matrix ( for matrix), P represents an array The length of , Indicates rounding up. It is expressed as follows:

[0132]

[0133] 3b) Calculate correction parameters a, b , the method is as follows:

[0134]

[0135] in, It is recorded as the sweeping angle matrix, and its size is , Denoted as the correction parameter array, the size is , then:

[0136]

[0137]

[0138] in, Indicates the first value of the correction parameter array; Indicates the second value of the correction parameter array.

[0139] Step 4: Calculate the phase correction factor , and at the same time the echo signal of calibration body 2 Perform phase correction as follows:

[0140] 4a) Phase correction factor The calculation method is as follows:

[0141] set up represents the rotation angle averaging, which is expressed as follows:

[0142]

[0143] set up is the initial value of frequency quantization, then It is expressed as follows:

[0144]

[0145] in, Indicates i rotation angle; i is the rotation angle index, , represents the starting frequency, Indicates the step frequency; is the frequency index, , N is the number of frequency points;

[0146] 4b) Echo signal of calibration body 2 Perform phase correction as follows:

[0147]

[0148] in, It represents the result after phase correction at the corresponding rotation angle and frequency.

[0149] Step 5: Results after phase correction For each rotation angle, calculate the corresponding distance as follows:

[0150] right Perform IDFT transformation to obtain the echo signal in the range domain , which is expressed as follows:

[0151]

[0152] in, , Indicates the number of IDFT transformation points, Values ​​are usually N Large, preferably an integer power of 2, so that the fast Fourier transform can be used.

[0153] Represents the maximum unambiguous distance, and the calculation formula is as follows:

[0154]

[0155] represents the speed of light, For the corresponding i Down The index corresponding to the maximum modulus value. The corresponding distance It is expressed as follows:

[0156]

[0157] Step 6: Calculate the calibration distance difference , the method is as follows:

[0158]

[0159] Step 7: According to the calibration distance difference , calculate the compensation factor , and the phase-corrected result Post-compensation, the specific process is:

[0160] 6a) Post-compensation factor The calculation formula is as follows:

[0161]

[0162] 6b) Results after phase correction After compensation, it is expressed as follows:

[0163]

[0164] is the final calibrated volume echo signal obtained.

[0165] The effect of the present invention can be further illustrated by the following simulation:

[0166] 1. Simulation environment

[0167] The simulation was carried out under Matlab2007.

[0168] set up , the horizontal coordinate of calibration body 2 , vertical coordinate .

[0169] Follow step 1: Set , , , , , , .

[0170] 2. Simulation content

[0171] Follow steps 1 to 7, where step 5 sets .

[0172] The echo signal of the calibration body 2 generated in step 1 is calibrated and compared with the traditional method.

[0173] 3. Simulation results

[0174] If the center of the calibration body 2 is at the rotation center 1, then no matter how the rotation angle changes, the distance between the radar antenna 3 and the calibration body 2 is always equal to From the perspective of the distance image plane, it is a line perpendicular to the distance coordinate axis, and the coordinates of the intersection point with the distance coordinate axis are As can be seen from FIG3 (a) and FIG3 (b), since the calibration body 2 is not located at the rotation center 1, a curve is presented from the range image plane, that is, the distance between the radar antenna 3 and the calibration body 2 changes as the rotation angle changes.

[0175] As can be seen from Figure 4 (a) and Figure 4 (b), although the conventional method makes the distance between the radar antenna 3 and the calibration body 2 close to , but there is still a large error.

[0176] As can be seen from FIG. 5 (a) and FIG. 5 (b), the calibration method of the present invention can make the distance between the radar antenna 3 and the calibration body 2 closer than the traditional method. .

[0177] Embodiment 3

[0178] See also Figure 6 The present invention provides a near-field calibration volume echo post-compensation calibration system based on frequency domain adjacent ratio, comprising:

[0179] Echo signal acquisition module: used to acquire the echo signal of the calibration body 2 which is not placed at the rotation center 1;

[0180] Correction phase calculation module: used to calculate the frequency domain adjacent ratio signal according to the echo signal of the calibration body 2, and calculate the correction phase corresponding to each rotation angle;

[0181] Correction parameter calculation module: used to calculate the correction parameter by correcting the phase according to the least square method;

[0182] Phase correction module: used to calculate the phase correction factor according to the correction parameter, and perform phase correction on the echo signal of the calibration body 2 by the phase correction factor to obtain the phase-corrected result;

[0183] Distance calculation module: used to calculate the distance corresponding to each rotation angle of the result after phase correction;

[0184] Calibration distance difference calculation module: used to calculate the calibration distance difference according to the distance corresponding to the rotation angle;

[0185] Post-compensation factor calculation module: used to calculate the post-compensation factor according to the calibration distance difference;

[0186] Post-compensation module: used to perform post-compensation on the result after phase correction according to the post-compensation factor to obtain the final calibrated calibration volume echo signal.

[0187] Embodiment 4

[0188] The present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio are implemented.

[0189] Embodiment 5

[0190] The present invention provides a computer storage medium, wherein the computer storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio are realized.

[0191] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program code.

[0192] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0193] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0194] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0195] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A near-field calibration method based on frequency domain adjacent ratio for post-compensation calibration of volume echo, characterized in that: The following steps are involved: Acquire the echo signal of the calibration body which is not placed at the rotation center; Calculate a frequency domain adjacent ratio signal according to the echo signal of the calibration body, and calculate a correction phase corresponding to each rotation angle based on the frequency domain adjacent ratio signal; According to the least square method, the correction parameter corresponding to the rotation angle is calculated by correcting the phase; The phase correction factor is calculated according to the correction parameter, and the phase correction is performed on the echo signal of the calibration object by the phase correction factor to obtain a phase-corrected result; For each rotation angle of the phase-corrected result, calculate the distance corresponding to the rotation angle; Calculate the calibration distance difference according to the distance corresponding to the rotation angle; Calculate the post-compensation factor based on the calibration distance difference; The phase-corrected result is post-compensated according to the post-compensation factor to obtain the final calibrated volume echo signal.

2. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 1 is characterized in that: The echo signal of the calibration body which is not placed at the rotation center is expressed as follows: in, are rotation angle index and frequency index respectively, , , M is the number of scanning angles, N is the number of frequency points; Indicated in i The rotation angle and n The echo signal of the calibration body under the condition of frequency; exp represents the exponential function with the natural constant e as the base; j is an imaginary unit; Indicates the distance between the radar antenna and the center of rotation; is a constant greater than 0, indicating the signal transmission power value; represents the speed of light; Indicates the coordinates of the center position of the calibration body in the turntable coordinate system; Indicates n Frequency; Indicates i The distance between the radar antenna and the calibration object at the rotation angle; Indicates i rotation angle; Indicates the starting rotation angle; Indicates the step angle; Indicates the starting frequency; Indicates the step frequency.

3. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 1 is characterized in that: The step of calculating the frequency domain adjacent ratio signal according to the echo signal of the calibration body and calculating the correction phase corresponding to each rotation angle specifically includes: 2a) Calculate the adjacent ratio signal in the frequency domain , specifically: in, Indicated in i The rotation angle and The echo signal of the calibration body under the condition of frequency; Indicated in i The rotation angle and The echo signal of the calibration body under the condition of frequency; is the frequency difference index, , N is the number of frequency points; 2b) Calculate each rotation angle The corresponding phase , specifically: in, It means to find the inverse tangent of the four symbols; for The real part of for The imaginary part of It means that for every given i The row average of the adjacent ratio signals in the frequency domain under the condition, ; 2c) Phase Correction is performed to obtain the correction phase , specifically: set up ,from To begin with, there are three scenarios: Scenario 1: ,but ; Scenario 2: ,but ; Scenario 3: In addition to the above two scenarios, ; in, , M is the number of scanning angles.

4. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 1 is characterized in that: The method of calculating the correction parameter corresponding to the rotation angle by correcting the phase according to the least squares method specifically includes: 3a) Constructing an array and the phase matrix ; in, Represents matrix transpose; Indicates the correction phase group to be calculated; P represents an array The length of , It means rounding up, M is the number of scanning angles; for The matrix is ​​represented as follows: In the formula, Indicates the step angle; 3b) Calculate correction parameters a and b , specifically: in, It is recorded as the sweeping angle matrix, and its size is ; Denoted as the correction parameter array, the size is ; Indicates the first value of the correction parameter array; Indicates the second value of the correction parameter array.

5. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 4 is characterized in that: The calculating of the phase correction factor according to the correction parameter and performing phase correction on the echo signal of the calibration object by the phase correction factor to obtain the phase-corrected result specifically includes: 4a) Calculate the phase correction factor based on the correction parameters , the process is as follows: set up represents the rotation angle averaging, which is expressed as follows: set up is the initial value of frequency quantization, then It is expressed as follows: in, Indicates i rotation angle; i is the rotation angle index, , represents the starting frequency, Indicates the step frequency; is the frequency index, , N is the number of frequency points; 4b) The echo signal of the calibration object is corrected by the phase correction factor Perform phase correction to obtain the phase-corrected result as follows: in, It represents the result after phase correction at the corresponding rotation angle and frequency.

6. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 1 is characterized in that: For each rotation angle of the phase-corrected result, the distance corresponding to the rotation angle is calculated, specifically: The result after phase correction Perform IDFT transformation to obtain the echo signal in the range domain , which is expressed as follows: in, They are rotation angle index and distance index respectively. , Indicates the number of IDFT transformation points; The distance corresponding to the rotation angle It is expressed as follows: in, For the corresponding i Down The index corresponding to the maximum modulus value, represents the distance between the radar antenna and the center of rotation, Indicates the maximum unambiguous distance; in, represents the speed of light, Indicates the step frequency.

7. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 6 is characterized in that: The calibration distance difference is calculated based on the distance corresponding to the rotation angle, specifically: in, Represents the calibration distance difference, and M is the number of scanning angles.

8. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 7 is characterized in that: The post-compensation factor calculated according to the calibration distance difference is specifically: in, represents the post-compensation factor, exp represents the exponential function with the natural constant e as the base, Indicates n frequency, j Represents an imaginary unit.

9. The near-field calibration volume echo post-compensation calibration method based on frequency domain adjacent ratio according to claim 8 is characterized in that: The post-compensation of the phase-corrected result is performed according to the post-compensation factor to obtain the final calibrated calibration volume echo signal, specifically: in, It is the calibration volume echo signal after final calibration.

10. A near-field calibration volume echo post-compensation calibration system based on frequency domain adjacent ratio, characterized in that: include: Echo signal acquisition module: used to acquire the echo signal of the calibration body which is not placed at the rotation center; Correction phase calculation module: used to calculate the frequency domain adjacent ratio signal according to the echo signal of the calibration body, and calculate the correction phase corresponding to each rotation angle based on the frequency domain adjacent ratio signal; Correction parameter calculation module: used to calculate the correction parameter corresponding to the rotation angle by correcting the phase according to the least square method; Phase correction module: used to calculate the phase correction factor according to the correction parameter, and perform phase correction on the echo signal of the calibration object through the phase correction factor to obtain the phase-corrected result; Distance calculation module: used to calculate the distance corresponding to each rotation angle of the result after phase correction; Calibration distance difference calculation module: used to calculate the calibration distance difference according to the distance corresponding to the rotation angle; Post-compensation factor calculation module: used to calculate the post-compensation factor according to the calibration distance difference; Post-compensation module: used to perform post-compensation on the result after phase correction according to the post-compensation factor to obtain the final calibrated calibration volume echo signal.

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