Calibration method and device of anisotropic linear array radar, radar and storage medium

Abstract

The application provides a calibration method and device of a special-shaped linear array radar, a radar and a storage medium. The method comprises: performing discrete-time Fourier transform on echo intermediate frequency signals obtained by each antenna channel of the special-shaped linear array radar detecting a metal column, to determine actual phases of the echo intermediate frequency signals; based on the actual phases of the echo intermediate frequency signals received by each antenna channel, searching for actual position coordinates of the metal column in a position search range of the metal column by using an optimization problem; based on the actual position coordinates of the metal column, calculating theoretical phases of the metal column detected by each antenna channel; based on the actual phases and the theoretical phases of the echo intermediate frequency signals, determining channel calibration factors of each antenna channel; and using the channel calibration factors to calibrate target echo intermediate frequency signals received by the corresponding antenna channel. The application can avoid the problem of unfocused images caused by different gains and phases of different antenna channels in the special-shaped linear array radar, and improve the radar detection effect.

Description

Technical Field

[0001] This application relates to the field of radar technology, and in particular to a calibration method, apparatus, radar, and storage medium for an irregularly shaped linear array radar. Background Technology

[0002] Millimeter-wave body scanners are security inspection devices that use millimeter waves to image and detect dangerous items hidden under clothing. They feature high resolution, no radiation hazard to the human body, and the ability to perform holographic imaging of both metals and non-metals. In terms of antenna distribution, millimeter-wave body scanners are mainly divided into linear arrays and area arrays, with linear array scanning being the most widely developed both domestically and internationally. While linear array scanning structures cannot achieve real-time scanning due to limitations of mechanical scanning structures, they offer the advantage of low cost; therefore, linear array scanning millimeter-wave body scanners are currently the most prevalent in applications.

[0003] Current linear array security scanners all use a linear structure, meaning multiple antennas are arranged in a straight line to form a linear array. This linear array moves along different curves to form different scanning trajectories, such as... Figure 2 As shown, it illustrates a schematic diagram of a planar trajectory distribution. Figure 2 The solid triangles represent the transmitting and receiving antennas of the linear array, while the dashed triangles represent the scanning points formed by each antenna channel along the scanning direction; for example... Figure 3 As shown, it illustrates a schematic diagram of a cylindrical trajectory distribution. Figure 3 The solid triangles represent the transmitting and receiving antennas of the linear array, while the dashed triangles represent the scanning points formed by each antenna channel along the scanning direction. For cylindrical trajectory distributions, to cover the entire height of a human body, the linear array height is typically high, increasing system cost and impacting product competitiveness. Conversely, planar trajectory distributions have poor imaging of the human body's sides, easily leading to missed detections of hazardous materials. Therefore, to reduce costs and the rate of missed detections of hazardous materials, irregularly shaped linear array structures are typically considered. In this structure, antennas are distributed along a curve to form a curved linear array, which then moves horizontally in a certain direction to form the scanning trajectory.

[0004] For linear array scanning structures, during imaging processing, the equivalent phase center is used to approximate the transmit / receive separated antenna structure as a monostatic imaging method. Then, a traditional near-field imaging algorithm is used to obtain millimeter-wave holographic imaging results. Because the gain and phase of different channels in the linear array are different, directly using the acquired data for imaging cannot obtain well-focused images. Summary of the Invention

[0005] This application provides a calibration method, apparatus, radar, and storage medium for an irregularly shaped linear array radar, to solve the problem that directly acquired data cannot produce well-focused images due to differences in gain and phase between different channels of the irregularly shaped linear array.

[0006] In a first aspect, the application provides a calibration method of a special linear array radar, the special linear array being a linear array other than a straight linear array; the calibration method of the special linear array radar comprising:

[0007] obtaining a return intermediate frequency signal obtained by each antenna channel of a special linear array of a radar detecting a metal column, the metal column being vertically placed on an axis of the special linear array radar;

[0008] performing discrete time Fourier transform on the return intermediate frequency signal corresponding to each antenna channel to determine an actual phase of the return intermediate frequency signal corresponding to each antenna channel;

[0009] based on the actual phase of the return intermediate frequency signal received by each antenna channel, searching for actual position coordinates of the metal column in a radar coordinate system within a position search range of the metal column by using an optimization problem;

[0010] based on the actual position coordinates of the metal column in the radar coordinate system, calculating a theoretical phase of the metal column detected by each antenna channel;

[0011] based on the actual phase of the return intermediate frequency signal received by each antenna channel and the theoretical phase of the metal column detected by the corresponding antenna channel, determining a channel calibration factor of each antenna channel; the channel calibration factor is used for calibrating a target return intermediate frequency signal received by the corresponding antenna channel.

[0012] In a second aspect, the application provides a calibration device of a special linear array radar, the special linear array being a linear array other than a straight linear array; the device comprising:

[0013] an intermediate frequency signal acquisition module, configured to obtain a return intermediate frequency signal obtained by each antenna channel of a special linear array of a radar detecting a metal column, the metal column being vertically placed on an axis of the special linear array radar;

[0014] a metal column actual phase calculation module, configured to perform discrete time Fourier transform on the return intermediate frequency signal corresponding to each antenna channel to determine an actual phase of the return intermediate frequency signal corresponding to each antenna channel;

[0015] a metal column position calculation module, configured to search for actual position coordinates of the metal column in a radar coordinate system within a position search range of the metal column by using an optimization problem based on the actual phase of the return intermediate frequency signal received by each antenna channel;

[0016] a metal column theoretical phase calculation module, configured to calculate a theoretical phase of the metal column detected by each antenna channel based on the position coordinates of the metal column in the radar coordinate system;

[0017] The calibration module is configured to determine a channel calibration factor of each antenna channel based on an actual phase of the echo intermediate frequency signal received by each antenna channel and a theoretical phase of the metal column detected by the corresponding antenna channel; and the channel calibration factor is used to calibrate a target echo intermediate frequency signal received by the corresponding antenna channel.

[0018] In a third aspect, the present application provides a radar, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method according to any possible implementation manner of the first aspect.

[0019] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executable by a processor to implement the steps of the method according to any possible implementation manner of the first aspect.

[0020] The method provided by the present application comprises the following steps: first, obtaining echo intermediate frequency signals of a metal column detected by each antenna channel in a special-shaped linear array of a radar; then, performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel to determine actual phases of the echo intermediate frequency signals corresponding to each antenna channel; based on the actual phases of the echo intermediate frequency signals received by each antenna channel, searching for actual position coordinates of the metal column in a radar coordinate system within a position search range of the metal column by using an optimization problem; based on the actual position coordinates of the metal column in the radar coordinate system, calculating theoretical phases of the metal column detected by each antenna channel; finally, determining a channel calibration factor of each antenna channel based on the actual phases of the echo intermediate frequency signals received by each antenna channel and the theoretical phases of the metal column detected by the corresponding antenna channel; and the channel calibration factor is used to calibrate a target echo intermediate frequency signal received by the corresponding antenna channel. The present application uses a metal column as a calibration device to enable each antenna channel to theoretically obtain the same intermediate frequency signal, and then calibrate parameters of each channel based on the intermediate frequency signal, thereby avoiding the problem that images generated due to different gains and phases of different antenna channels of the special-shaped linear array are not focused, and improving the radar detection effect. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0022] Figure 1is an implementation flowchart of a calibration method of a special-shaped linear array radar provided in an embodiment of the present application.

[0023] Figure 2 is a schematic diagram of a straight-line scanning mode (planar trajectory distribution) of a straight-line array provided in an embodiment of the present application.

[0024] Figure 3 is a schematic diagram of a cylindrical scanning mode of a straight-line array provided in an embodiment of the present application.

[0025] Figure 4 is an application scenario diagram of a calibration method of a special-shaped linear array radar provided in an embodiment of the present application.

[0026] Figure 5 is a structural schematic diagram of a calibration device of a special-shaped linear array radar provided in an embodiment of the present application.

[0027] Figure 6 is a structural schematic diagram of a radar provided in an embodiment of the present application.

[0028] Figure 7 is a schematic diagram of a zigzag-shaped special-shaped linear array provided in an embodiment of the present application.

[0029] Figure 8 is a schematic diagram of a circular arc-shaped special-shaped linear array provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In the following description, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the present embodiments. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known structures, devices, circuits, and methods have not been described in detail in order to avoid obscuring the present application.

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will be described with reference to the accompanying drawings through specific embodiments.

[0032] The calibration method of the special-shaped linear array radar provided in the present embodiment is described in detail below taking a security inspection instrument as an example.

[0033] In the present embodiment, Figure 4 a structure of a special-shaped linear array security inspection instrument and a position schematic diagram of the special-shaped linear array security inspection instrument and a metal column are shown, Figure 4 an xy coordinate system in the present embodiment is a radar coordinate system of the security inspection instrument, and a y-axis direction of the radar coordinate system is the same as an axis direction of the security inspection instrument. The special-shaped linear array is a linear array other than a straight-line array; a plurality of transceiving antennas of the special-shaped linear array are arranged on a same horizontal plane according to a shape of the special-shaped linear array, for example, Figure 7 a zigzag-shaped linear array shown in FIG. 2 andFigure 8 The curved line array shown, Figure 7 and Figure 8 The triangle in the figure represents a transceiving antenna in the line array.

[0034] Specifically, Figure 4 B in the figure represents a special-shaped line array, and in this embodiment, taking the special-shaped line array as an example of a broken line array, C represents one of the transceiving antennas, which corresponds to a coordinate (x, y) in the radar coordinate system, and the metal column A is vertically placed on the axis of the special-shaped line array security instrument, and the coordinate of the metal column A in the radar coordinate system is (x0, y0), and x0 = 0.

[0035] Specifically, since the multiple transceiving antennas of the special-shaped line array are located on the same horizontal plane, the differences in the gains and phases of different transceiving antennas are caused by the different positions in the xy plane, and therefore, the embodiment only considers the x-axis and y-axis information, without introducing the z-axis information, so as to simplify the calculation process.

[0036] Referring to Figure 1 which shows an implementation flowchart of the calibration method of the special-shaped line array radar provided in the embodiments of the present application, and the details are as follows:

[0037] S101: Obtain the intermediate frequency signal of the echo obtained by each antenna channel of the special-shaped line array of the radar when detecting the metal column.

[0038] In one possible implementation, the specific implementation process of S101 includes:

[0039] Obtain the echo signal obtained by each antenna channel of the special-shaped line array when detecting the metal column.

[0040] Perform desquaring processing on the echo signal corresponding to each antenna channel to obtain the corresponding intermediate frequency signal of the echo.

[0041] In this embodiment, for any antenna channel of the special-shaped line array, the specific implementation process of S101 includes:

[0042] Without considering the phase error introduced by the antenna channel, it is assumed that a FMCW (Frequency Modulated Continuous Wave) signal is transmitted to the metal column by the special-shaped line array of the security instrument, and the transmitted signal can be represented as:

[0043]

[0044] After the transmitted signal is incident on the metal column and reflected back, it is received by the special-shaped line array, and the received echo signal is represented as:

[0045]

[0046] wherein f0 represents a center frequency of a transmitted signal, K represents a frequency modulation slope, A represents an echo amplitude, τ(x, y) represents a target echo delay, and R represents a distance from the radar to the metal column, and c represents a propagation speed of an electromagnetic wave in free space.

[0047] After the antenna channel receives the metal column echo, a radar echo intermediate frequency signal is obtained through dechirp operation as follows:

[0048]

[0049] In the application scenario of the security inspection instrument, since the distance between the security inspection instrument and the detection target is relatively close, 1 / 2Kτ(x, y)2 is approximately zero and can be ignored, so the third term of the exponential term in formula (3) can be ignored, and the final radar echo intermediate frequency signal is obtained as follows:

[0050]

[0051] In formula (3), (x, y) represents a position coordinate of the antenna channel in the radar coordinate system, (x0, y0) represents a position coordinate of the metal column in the radar coordinate system, f b (x, y) = Kτ(x, y) represents a metal column corresponding intermediate frequency signal, and φ(x, y) = 2πf0τ(x, y) represents an actual phase of the metal column when the phase error introduced by the antenna channel is not considered.

[0052] The actual phase of the metal column given in formula (4) is related to the position of the metal column, so the actual position coordinate of the metal column needs to be obtained during calibration, and therefore the actual position coordinate of the metal column needs to be solved by using the actual phase given in formula (4).

[0053] S102: Discrete time Fourier transform is performed on the radar echo intermediate frequency signals corresponding to each antenna channel to determine the actual phase of the radar echo intermediate frequency signal corresponding to each antenna channel.

[0054] In one possible implementation, the specific implementation process of S102 includes:

[0055] The radar echo intermediate frequency signal corresponding to the first antenna channel is sampled in the time domain to obtain a first time sequence; the first antenna channel is any antenna channel of the special-shaped linear array;

[0056] Discrete time Fourier transform is performed on the first time sequence to obtain a frequency spectrum corresponding to the first antenna channel;

[0057] The phase corresponding to the maximum amplitude in the frequency spectrum is taken as the actual phase of the radar echo intermediate frequency signal of the first antenna channel.

[0058] Specifically, the echo intermediate frequency signal in formula (4) is sampled in time domain to obtain a time sequence:

[0059]

[0060] wherein Ts is an intermediate frequency signal sampling interval.

[0061] An N-point DTFT (Discrete-time Fourier Transform) is performed on the time sequence to obtain a frequency spectrum thereof as follows:

[0062]

[0063] In formula (6), ω b (x,y) = 2πf b (x,y) is an angular frequency of the echo intermediate frequency signal.

[0064] Since the echo intermediate frequency signal is sampled at equal intervals in time domain, the calculation of formula (6) can be directly performed using FFT for fast calculation.

[0065] In addition, when the frequency ω of the frequency spectrum is equal to the angular frequency of the echo intermediate frequency signal, i.e., ω = ω b (x,y), it is determined that formula (6) at this time has only one term ejφ(x,y), and the exponential term is actually the phase of the metal column, i.e., the phase in formula (4). In practice, the calculation error of the phase can be reduced by increasing the calculation precision of FFT through zero padding.

[0066] S103: Based on the actual phase of the echo intermediate frequency signal received by each antenna channel, an optimal problem is used to search for the actual position coordinates of the metal column in the radar coordinate system within a position search range of the metal column.

[0067] In one possible implementation, the specific implementation process of S103 includes:

[0068] An optimal problem is determined:

[0069]

[0070] A least square fitting method is used to solve the optimal problem to obtain the actual position coordinates of the metal column in the radar coordinate system;

[0071] wherein (x i ,y i ) represents the position coordinates of the i-th antenna channel; φ(x i ,y i ) represents the actual phase of the echo intermediate frequency signal received by the i-th antenna channel, and 2πf0τ j (xi , y i ) represents the theoretical phase of the echo intermediate frequency signal received by the i-th antenna channel, represents the position coordinates of any alternative metal column in the position search range; {x0, y0} represents the actual position coordinates of the metal column in the radar coordinate system, M represents the set of antenna channel numbers, and H represents the set of position coordinates of the alternative metal columns in the position search range.

[0072] Specifically, M = {1, 2, 3, … m} and H = {1, 2, … h}, where m represents the total number of antenna channels, and h represents the total number of alternative positions of the metal column.

[0073] In order to obtain the position of the metal column used in actual calibration, the embodiment can integrate the data of multiple antenna channels to calculate the actual position coordinates of the metal column through an optimization method.

[0074] Specifically, the embodiment can:

[0075] (1) When the metal column is placed on the axis of the security instrument, the approximate position of the radar can be calibrated to determine the position search range and input the radar. The radar selects multiple alternative position coordinates of the metal column in the position search range according to a preset step length and respectively inputs the formula (7).

[0076] (2) In formula (7), for any alternative position coordinate The theoretical phase of the metal column calculated by using the alternative position coordinate is respectively subtracted from the actual phase of the metal column calculated based on the echo intermediate frequency signals obtained by each antenna channel, and the sum of the phase deviations corresponding to the alternative position coordinate is obtained by summing the multiple phase deviation values corresponding to the alternative position coordinate. In this step, the actual phase of the metal column calculated based on the echo intermediate frequency signals obtained by each antenna channel is calculated by using formula (6).

[0077] (3) Find the maximum value of the sum of the phase deviations corresponding to all alternative position coordinates, and take the alternative position coordinate corresponding to the maximum value as the actual position coordinates {x0, y0} of the metal column.

[0078] Specifically, the above optimization problem can be solved to obtain the actual position coordinates of the metal column by using the least square fitting method.

[0079] S104: Based on the actual position coordinates of the metal column in the radar coordinate system, calculate the theoretical phase of the metal column detected by each antenna channel.

[0080] In the embodiment, after the position coordinates of the metal column in the radar coordinate system are calculated, the theoretical phase of the metal column detected by each antenna channel is calculated based on formula φtar (x i ,y i )。

[0081] S105: determining a channel calibration factor of each antenna channel based on an actual phase of the echo intermediate frequency signal received by each antenna channel and a theoretical phase of the metal column detected by the corresponding antenna channel; the channel calibration factor is used for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.

[0082] In one possible implementation, the specific implementation process of S105 includes:

[0083] calculating a theoretical phase of the metal column detected by a first antenna channel based on actual position coordinates of the metal column in a radar coordinate system; the first antenna channel is any antenna channel of the shaped line array;

[0084] subtracting the theoretical phase of the metal column detected by the first antenna channel from an actual phase of the echo intermediate frequency signal received by the first antenna channel to obtain a phase deviation value corresponding to the first antenna channel;

[0085] multiplying the phase deviation value corresponding to the first antenna channel and a maximum amplitude value of a spectrum of the echo intermediate frequency signal of the first antenna channel to obtain a channel calibration factor of the first antenna channel.

[0086] In this embodiment, since the difference between the theoretical phase and the actual phase in formula (7) includes both the error caused by the calculation accuracy and the error introduced by the antenna channel, in order to eliminate the error introduced by the antenna channel, for any antenna channel in the shaped line array, the echo intermediate frequency signal in formula (4) can be written as:

[0087]

[0088] wherein, φ tar (x,y) represents the theoretical phase of the metal column, φ chan (x,y) represents the phase error introduced by the antenna channel.

[0089] Then, the phase error introduced by the antenna channel can be represented by formula (9):

[0090] φ chan (x,y)=φ(x,y)-φ tar (x,y) (9)

[0091] wherein, φ(x,y) represents the actual phase of the metal column calculated by formula (6), and the actual phase of the echo intermediate frequency signal received by the antenna channel is subtracted from the theoretical phase to obtain the phase error introduced by the antenna channel.

[0092] After the phase error introduced by the antenna channel is calculated, the amplitude maximum of the spectrum of the echo intermediate frequency signal is multiplied by the phase error to obtain the channel calibration factor, that is

[0093]

[0094] In one possible implementation, after the calculation of the channel calibration factor is completed, when the radar performs subsequent target detection, the error of the target echo intermediate frequency signal can be eliminated by the following method, which is described in detail as follows:

[0095] Divide the target echo intermediate frequency signal received by each antenna channel by the channel calibration factor corresponding to the corresponding antenna channel to obtain the calibrated target echo intermediate frequency signal.

[0096] In this embodiment, when the security instrument actually performs target detection, assuming that the position of the target is (x s ,y s ), the corresponding echo intermediate frequency signal is:

[0097]

[0098] Where, φ s (x,y) represents the phase of the target to be imaged, and φ chan (x,y) is the phase introduced by the antenna channel.

[0099] Then, the amplitude and phase of the echo intermediate frequency signal corresponding to the antenna channel are calibrated for formula (11) using formula (10):

[0100]

[0101] Formula (12) is the calibrated echo intermediate frequency signal of the antenna channel, which can be directly used for imaging processing.

[0102] It should be noted that this embodiment only takes the special-shaped linear array security instrument as an example to describe the calibration method of the special-shaped linear array radar, and in actual application, this method is applicable to all radars including special-shaped linear array.

[0103] It can be known from the above embodiment that the embodiment of the application first acquires the echo intermediate frequency signals obtained by each antenna channel of a special-shaped linear array of a radar detecting a metal column; then performs discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel to determine the actual phases of the echo intermediate frequency signals corresponding to each antenna channel; based on the actual phases of the echo intermediate frequency signals received by each antenna channel, the optimal problem is used to search for the actual position coordinates of the metal column in a radar coordinate system within a position search range of the metal column; based on the actual position coordinates of the metal column in the radar coordinate system, the theoretical phases of the metal column detected by each antenna channel are calculated; finally, based on the actual phases of the echo intermediate frequency signals received by each antenna channel and the theoretical phases of the metal column detected by the corresponding antenna channel, the channel calibration factor of each antenna channel is determined; the channel calibration factor is used to calibrate the target echo intermediate frequency signals received by the corresponding antenna channel. The metal column is used as a calibration device in the application, which can enable each antenna channel to theoretically acquire the same intermediate frequency signals, and then the parameters of each channel are calibrated based on the intermediate frequency signals, thereby avoiding the problem that the generated image is not focused due to different gains and phases of different antenna channels of the special-shaped linear array, and improving the radar detection effect.

[0104] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0105] The following is a device embodiment of the application. For details not described in detail, reference can be made to the corresponding method embodiments described above.

[0106] Figure 5 A structure diagram of a calibration device of a special-shaped linear array radar provided by an embodiment of the application is shown. For ease of illustration, only parts related to the embodiment of the application are shown, and the details are as follows:

[0107] As shown in Figure 5 The calibration device 5 of the special-shaped linear array radar includes:

[0108] The intermediate frequency signal acquisition module 110 is configured to acquire echo intermediate frequency signals obtained by each antenna channel of a special-shaped linear array of a radar detecting a metal column, and the metal column is vertically placed on an axis of the special-shaped linear array radar.

[0109] The metal column actual phase calculation module 120 is configured to perform discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel to determine the actual phases of the echo intermediate frequency signals corresponding to each antenna channel.

[0110] The metal pillar position calculation module 130 is used to find the actual position coordinates of the metal pillar in the radar coordinate system within the position search range of the metal pillar based on the actual phase of the echo intermediate frequency signal received by each antenna channel and by using an optimization problem.

[0111] The metal pillar theoretical phase calculation module 140 is used to calculate the theoretical phase of the metal pillar detected by each antenna channel based on the position coordinates of the metal pillar in the radar coordinate system.

[0112] The calibration module 150 is used to determine the channel calibration factor for each antenna channel based on the actual phase of the echo intermediate frequency signal received by each antenna channel and the theoretical phase of the metal column detected by the corresponding antenna channel; the channel calibration factor is used to calibrate the target echo intermediate frequency signal received by the corresponding antenna channel.

[0113] In one possible implementation, the intermediate frequency signal acquisition module 110 includes:

[0114] The echo signal acquisition unit is used to acquire the echo signal obtained by each antenna channel in the irregular linear array of the radar detecting the metal column;

[0115] The intermediate frequency signal acquisition unit is used to perform deskewing processing on the echo signal corresponding to each antenna channel to obtain the echo intermediate frequency signal.

[0116] In one possible implementation, the actual phase calculation module 120 of the metal pillar is specifically used for:

[0117] The echo intermediate frequency signal corresponding to the first antenna channel is sampled in the time domain to obtain a first time series; the first antenna channel is any antenna channel of the irregular linear array;

[0118] Perform a discrete-time Fourier transform on the first time series to obtain the spectrum corresponding to the first antenna channel;

[0119] The phase corresponding to the maximum amplitude in the spectrum is taken as the actual phase of the echo intermediate frequency signal of the first antenna channel.

[0120] In one possible implementation, the metal pillar position calculation module 130 includes:

[0121] Determine the optimization problem:

[0122] The optimization problem is solved using the least squares fitting method to obtain the actual position coordinates of the metal column in the radar coordinate system.

[0123] Among them, (x i ,y i ) represents the position coordinates of the i-th antenna channel; φ(x)i , y i represents the actual phase of the echo intermediate frequency signal received by the i th antenna channel, 2πf0τ j (x i , y i represents the theoretical phase of the echo intermediate frequency signal received by the i th antenna channel, represents the position coordinates of any candidate metal column in the position search range; {x0, y0} represents the actual position coordinates of the metal column in the radar coordinate system, M represents a set of antenna channels, and H represents a set of position coordinates of candidate metal columns in the position search range.

[0124] In one possible implementation, the calibration module 150 includes a calibration factor calculation unit configured to:

[0125] calculate a theoretical phase of the metal column detected by a first antenna channel based on the actual position coordinates of the metal column in the radar coordinate system; the first antenna channel is any antenna channel of the profiled linear array;

[0126] subtract the theoretical phase of the metal column detected by the first antenna channel from the actual phase of the echo intermediate frequency signal received by the first antenna channel to obtain a phase deviation value corresponding to the first antenna channel;

[0127] multiply the phase deviation value corresponding to the first antenna channel by the maximum amplitude of the spectrum of the echo intermediate frequency signal of the first antenna channel to obtain a channel calibration factor of the first antenna channel.

[0128] In one possible implementation, the calibration device of the profiled linear array radar further includes:

[0129] a echo signal calibration module configured to divide the target echo intermediate frequency signal received by each antenna channel by the channel calibration factor corresponding to the corresponding antenna channel to obtain a calibrated target echo intermediate frequency signal.

[0130] The embodiments of the present application also provide a computer program product having program codes, which perform the steps in any of the above-mentioned calibration method embodiments of the profiled linear array radar when running in a corresponding processor, controller, computing device or radar, for example Figure 1The steps S101-S105 shown above. Those skilled in the art should understand that the method and the device provided in the embodiments of the present application can be implemented in various forms of hardware, software, firmware, special-purpose processor or combination thereof. The special-purpose processor can include application-specific integrated circuit (ASIC), reduced instruction set computer (RISC) and / or field programmable gate array (FPGA). The method and the device provided in the embodiments are preferably implemented as a combination of hardware and software. The software is preferably installed as an application program on a program storage device. It is typically a machine based on a computer platform with hardware, such as one or more central processing units (CPUs), random access memories (RAMs) and one or more input / output (I / O) interfaces. An operating system is also typically installed on the computer platform. The various processes and functions described herein can be part of the application program or part thereof can be executed by the operating system.

[0131] Figure 6 is a schematic diagram of a radar provided by the embodiments of the present application. As shown in Figure 6 , the radar 6 of the embodiments includes a processor 60, a memory 61 and a computer program 62 stored in the memory 61 and executable on the processor 60. The processor 60 implements the steps in the calibration method embodiments of the various shaped line array radars described above when executing the computer program 62, for example Figure 1 the steps S101-S105 shown above. Alternatively, the processor 60 implements the functions of the modules / units in the various device embodiments described above when executing the computer program 62, for example Figure 5 the functions of the modules 110-150 shown above.

[0132] For example, the computer program 62 can be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to complete / implement the schemes provided in the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 62 in the radar 6. For example, the computer program 62 can be divided into Figure 5 the modules 110-150 shown above.

[0133] The radar 6 can include, but is not limited to, the processor 60, the memory 61. Those skilled in the art can understand that Figure 6 is only an example of the radar 6 and does not constitute a limitation on the radar 6, and can include more or fewer components than shown, or combine certain components, or different components, for example, the radar can also include an input / output device, a network access device, a bus, etc.

[0134] The processor 60 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0135] The memory 61 can be an internal storage unit of the radar 6, such as a hard disk or a memory of the radar 6. The memory 61 can also be an external storage device of the radar 6, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 61 can also include both the internal storage unit and the external storage device of the radar 6. The memory 61 is used to store the computer program and other programs and data required by the radar. The memory 61 can also be used to temporarily store data that has been output or will be output.

[0136] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to complete all or part of the above-described functions. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0137] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0138] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0139] In the embodiments provided in the present application, it should be understood that the disclosed apparatus / radar and method can be implemented by other ways. For example, the apparatus / radar embodiments described above are only schematic, for example, the division of the modules or units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different parts can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0140] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0141] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0142] The integrated module / unit, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiments can also be implemented by a computer program instructing related hardware to complete, and the computer program can be stored in a computer readable storage medium. The computer program can implement the steps of the above-mentioned each special-shaped linear array radar calibration method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The computer readable medium can include any entity or device, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), electric carrier wave signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code. It should be noted that the content included in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electric carrier wave signal and telecommunication signal.

[0143] In addition, the features of the embodiments shown in the drawings of the present application or mentioned in the specification of the present application are not necessarily understood as independent embodiments from each other. Rather, each feature described in one example of an embodiment can be combined with one or more other desired features from other embodiments, thereby generating other embodiments not described in words or with reference to the drawings.

[0144] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A calibration method for an irregularly shaped linear array radar, characterized in that, The shaped linear array is a linear array other than a straight linear array; and the calibration method of the shaped linear array radar comprises: obtaining a received signal of each antenna channel of the shaped linear array radar, the received signal being obtained by detecting a metal column, and the metal column being vertically placed on an axis of the shaped linear array radar; performing discrete-time Fourier transform on the received signal of each antenna channel to determine an actual phase of the received signal of each antenna channel; based on the actual phase of the received signal of each antenna channel, searching for an actual position coordinate of the metal column in a radar coordinate system within a position search range of the metal column by using an optimization problem; based on the actual position coordinate of the metal column in the radar coordinate system, calculating a theoretical phase of the metal column detected by each antenna channel; based on the actual phase of the received signal of each antenna channel and the theoretical phase of the metal column detected by the corresponding antenna channel, determining a channel calibration factor of each antenna channel; and the channel calibration factor is used for calibrating a target received signal of the corresponding antenna channel.

2. The method of calibrating a heterogenous linear array radar of claim 1, wherein, The obtaining a received signal of each antenna channel of the shaped linear array radar, the received signal being obtained by detecting a metal column, and the metal column being vertically placed on an axis of the shaped linear array radar, comprises: obtaining a received signal of each antenna channel of the shaped linear array radar, the received signal being obtained by detecting a metal column, and the metal column being vertically placed on an axis of the shaped linear array radar; performing discrete-time Fourier transform on the received signal of each antenna channel to determine an actual phase of the received signal of each antenna channel; 3. The method of calibrating a heterogenous linear array radar of claim 1, wherein, The performing discrete-time Fourier transform on the received signal of each antenna channel to determine an actual phase of the received signal of each antenna channel, comprises: sampling the received signal of a first antenna channel in a time domain to obtain a first time sequence; the first antenna channel is any antenna channel of the shaped linear array; performing discrete-time Fourier transform on the first time sequence to obtain a spectrum corresponding to the first antenna channel; taking a phase corresponding to a maximum value of an amplitude in the spectrum as the actual phase of the received signal of the first antenna channel.

4. The method of calibrating a heterogenous linear array radar of claim 1, wherein, The searching for an actual position coordinate of the metal column in a radar coordinate system within a position search range of the metal column by using an optimization problem based on the actual phase of the received signal of each antenna channel, comprises: determining an optimization problem: solving the optimization problem by using a least square fitting method to obtain the actual position coordinate of the metal column in the radar coordinate system; wherein (x i ,y i ) represents the position coordinates of the i-th antenna channel; φ(x i ,y i ) represents the actual phase of the echo intermediate frequency signal received by the i-th antenna channel, 2πf0τ j (x i ,y i ) represents the theoretical phase of the echo intermediate frequency signal received by the i-th antenna channel, represents the position coordinates of any alternative metal column within the position search range; {x0, y0} represents the actual position coordinates of the metal column in the radar coordinate system, M represents the set of antenna channels, and H represents the set of position coordinates of the alternative metal columns within the position search range.

5. The method of calibrating a heterogenous linear array radar of claim 1, wherein, The determining a channel calibration factor of each antenna channel based on the actual phase of the received signal of each antenna channel and the theoretical phase of the metal column detected by the corresponding antenna channel, comprises: calculating a theoretical phase of the metal column detected by a first antenna channel based on the actual position coordinate of the metal column in the radar coordinate system; the first antenna channel is any antenna channel of the shaped linear array; subtracting the theoretical phase of the metal column detected by the first antenna channel from the actual phase of the received signal of the first antenna channel to obtain a phase deviation value corresponding to the first antenna channel. The phase deviation value corresponding to the first antenna channel is multiplied by the amplitude maximum value of the spectrum of the echo intermediate frequency signal of the first antenna channel, to obtain a channel calibration factor of the first antenna channel.

6. The method of calibrating a heterogenous linear array radar of claim 1, wherein, The method further comprises: The target echo intermediate frequency signal received by each antenna channel is divided by the channel calibration factor corresponding to the corresponding antenna channel, to obtain a calibrated target echo intermediate frequency signal.

7. A calibration device for a heterogenous linear array radar, characterized in that The shaped line array is a line array other than a straight line array; the device comprises: An intermediate frequency signal acquisition module is configured to acquire echo intermediate frequency signals obtained by each antenna channel of a shaped line array of a radar when detecting a metal column, wherein the metal column is vertically placed on an axis of the shaped line array radar; A metal column actual phase calculation module is configured to perform discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, to determine actual phases of the echo intermediate frequency signals corresponding to each antenna channel; A metal column position calculation module is configured to search for actual position coordinates of the metal column in a radar coordinate system within a position search range of the metal column based on the actual phases of the echo intermediate frequency signals received by each antenna channel by using an optimization problem; A metal column theoretical phase calculation module is configured to calculate theoretical phases of the metal column detected by each antenna channel based on the position coordinates of the metal column in the radar coordinate system; A calibration module is configured to determine a channel calibration factor of each antenna channel based on the actual phases of the echo intermediate frequency signals received by each antenna channel and the theoretical phases of the metal column detected by the corresponding antenna channel; the channel calibration factor is used to calibrate target echo intermediate frequency signals received by the corresponding antenna channel.

8. The calibration device of the heterogeneous linear array radar according to claim 7, characterized in that, The intermediate frequency signal acquisition module comprises: An echo signal acquisition unit is configured to acquire echo signals obtained by each antenna channel of a shaped line array of a radar when detecting a metal column; An intermediate frequency signal acquisition unit is configured to perform desquaring processing on the echo signals corresponding to each antenna channel, to obtain the echo intermediate frequency signals.

9. A radar comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the steps of the calibration method of the shaped line array radar according to any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 9. The computer program is executed by the processor to implement the steps of the calibration method of the shaped line array radar according to any one of claims 1 to 6.

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