CN115932760A - Calibration method and device for special-shaped linear array radar, radar and storage medium - Google Patents
Calibration method and device for special-shaped linear array radar, radar and storage medium Download PDFInfo
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Abstract
The application provides a calibration method and device for a special-shaped linear array radar, a radar and a storage medium. The method comprises the following steps: performing discrete time Fourier transform on an echo intermediate frequency signal obtained by detecting the metal column by each antenna channel in the special-shaped linear array of the radar, and determining the actual phase of the echo intermediate frequency signal; based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in the position searching range of the metal column by utilizing an optimization problem; calculating the theoretical phase of the metal column detected by each antenna channel based on the actual position coordinates of the metal column; determining a channel calibration factor of each antenna channel based on the actual phase and the theoretical phase of the echo intermediate frequency signal; and calibrating the target echo intermediate frequency signal received by the corresponding antenna channel by adopting the channel calibration factor. The method and the device can avoid the problem that images are not focused due to different antenna channel gains and phases in the special-shaped linear array, and improve the radar detection effect.
Description
Technical Field
The application relates to the technical field of radars, in particular to a calibration method and device of a special-shaped linear array radar, a radar and a storage medium.
Background
The millimeter wave human body security inspection instrument is security inspection equipment for realizing imaging detection of dangerous goods hidden under human clothes by utilizing millimeter waves, and has the characteristics of high resolution, no radiation hazard to human bodies, capability of performing holographic imaging on metals and non-metals and the like. The millimeter wave human body security inspection instrument is mainly divided into a linear array and an area array in terms of antenna distribution, and the linear array scanning is developed at home and abroad currently. The linear array scanning structure is limited by a mechanical scanning structure which cannot scan in real time, but the structure has the advantage of low cost, so that the linear array scanning millimeter wave human body security check instrument product is mainly used in the existing application.
The current linear array scanning security inspection instrument adopts a linear structure, namely a plurality of antennas are arranged on a straight line to form a linear array, the linear array moves along different curves to form different scanning tracks, as shown in fig. 2, a plane track distribution schematic diagram is shown, a triangle of a solid line in fig. 2 is a receiving and transmitting antenna of the linear array, and a triangle of a dotted line is a scanning point formed by each antenna channel along the scanning direction; as shown in fig. 3, which shows a schematic diagram of a cylindrical track distribution, in fig. 3, a solid line triangle is a linear array of transceiver antennas, and a dashed line triangle is a scanning point formed by each antenna channel along the scanning direction. For the distribution of the cylindrical tracks, in order to cover the whole height of a human body, the linear array is generally higher in height, so that the system cost is increased to influence the product competitiveness; for plane track distribution, the imaging effect on the side face of a human body is poor, and the dangerous goods are easy to miss detection. Therefore, in terms of reducing the cost and the rate of missing detection of dangerous goods, the special-shaped linear array structure is usually considered to be used, in which the antennas are distributed on a curve to form a curved linear array, and then the curved linear array horizontally moves along a certain direction to form a scanning track.
For a linear array scanning structure, an equivalent phase center is used for approximating a receiving and transmitting separated antenna structure to a single-station imaging mode during imaging processing, and then a traditional near-field imaging algorithm is adopted to obtain a millimeter wave holographic imaging result. Due to the fact that gains and phases of different channels of the linear array are different, images with good focusing cannot be obtained by directly using acquired data for imaging.
Disclosure of Invention
The application provides a calibration method and device of a special-shaped linear array radar, the radar and a storage medium, and aims to solve the problem that data directly acquired cannot obtain well-focused images due to different channel gains and phases of the special-shaped linear array.
In a first aspect, the application provides a calibration method for a special-shaped linear array radar, wherein the special-shaped linear array is a linear array except for a linear array; the calibration method of the special-shaped linear array radar comprises the following steps:
acquiring an echo intermediate frequency signal obtained by detecting a metal column by each antenna channel in a special-shaped linear array of the radar, wherein the metal column is vertically placed on the axis of the special-shaped linear array radar;
performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel;
based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in a radar coordinate system in the position searching range of the metal column by utilizing an optimization problem;
calculating the theoretical phase of the metal column detected by each antenna channel based on the actual position coordinate of the metal column in the radar coordinate system;
determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.
In a second aspect, the application provides a calibration device for a special-shaped linear array radar, wherein the special-shaped linear array is a linear array except a linear array; the device comprises:
the medium-frequency signal acquisition module is used for acquiring an echo medium-frequency signal obtained by detecting a metal column by each antenna channel in the special-shaped linear array of the radar, and the metal column is vertically placed on the axis of the special-shaped linear array radar;
the metal column actual phase calculation module is used for performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel;
the metal column position calculation module is used for searching the actual position coordinates of the metal column in a radar coordinate system in the position search range of the metal column by utilizing an optimization problem based on the actual phase of the echo intermediate frequency signal received by each antenna channel;
the metal column theoretical phase calculation module is used for calculating the theoretical phase of the metal column detected by each antenna channel based on the position coordinate of the metal column in the radar coordinate system;
the calibration module is used for determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.
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, wherein the processor implements the steps of the method according to any one of the possible implementations of the first aspect when executing the computer program.
In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program implements the steps of the method according to any one of the possible implementation manners of the first aspect.
The embodiment of the application provides a calibration method and device of a special-shaped linear array radar, the radar and a storage medium, wherein the method comprises the steps of firstly obtaining echo intermediate-frequency signals obtained by detecting metal columns through each antenna channel in the special-shaped linear array of the radar; then, performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel; based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in a radar coordinate system in the position searching range of the metal column by utilizing an optimization problem; calculating theoretical phases of the metal columns detected by each antenna channel based on actual position coordinates of the metal columns in the radar coordinate system; finally, determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel. According to the method and the device, the metal columns are used as calibration devices, so that each antenna channel can acquire the same intermediate frequency signal theoretically, parameter calibration is carried out on each channel based on the intermediate frequency signal, the problem that generated images are not focused due to different antenna channel gains and phases of the special-shaped linear array is avoided, and the radar detection effect is improved.
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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 the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a flowchart of an implementation of a method for calibrating a special-shaped linear array radar according to an embodiment of the present application;
fig. 2 is a schematic diagram of a linear scanning manner (planar track distribution) of a linear array provided in an embodiment of the present application;
fig. 3 is a schematic diagram of a cylindrical scanning manner of a linear array provided in an embodiment of the present application;
fig. 4 is an application scenario diagram of a calibration method for an irregular linear array radar provided in the embodiment of the present application;
fig. 5 is a schematic structural diagram of a calibration device of an irregular linear array radar provided in an embodiment of the present application;
FIG. 6 is a schematic structural diagram of a radar provided in an embodiment of the present application;
fig. 7 is a schematic diagram of a dog-leg-shaped special-shaped linear array provided in the embodiment of the present application;
fig. 8 is a schematic diagram of an arc-shaped special-shaped linear array provided in the embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
To make the objects, technical solutions and advantages of the present application more clear, the following description is made by way of specific embodiments with reference to the accompanying drawings.
The calibration method for the special-shaped linear array radar provided by the embodiment is detailed below by taking the security inspection instrument as an example:
in this embodiment, fig. 4 shows a schematic structure of a shaped line array security check instrument and a schematic position diagram of a metal column, an xy coordinate system in fig. 4 is a radar coordinate system of the security check instrument, and a y-axis direction of the radar coordinate system is the same as an axis direction of the security check instrument. The special-shaped linear array is a linear array except for a linear array; the plurality of transceiving antennas of the irregular-shaped linear array are arranged in the shape of the irregular-shaped linear array on the same horizontal plane, for example, the broken-line linear array shown in fig. 7 and the curved linear array shown in fig. 8, and the triangle in fig. 7 and 8 represents the transceiving antennas in the linear array.
Specifically, B in fig. 4 represents an irregular linear array, and in this embodiment, taking the irregular linear array as a broken line linear array as an example, C represents one of the transmitting and receiving antennas, whose corresponding coordinates under the radar coordinate system are (x, y), the metal column a is vertically placed on the axis of the irregular linear array security check instrument, and whose coordinates under the radar coordinate system are (x, y) 0 ,y 0 ) And x is 0 ＝0。
Specifically, because a plurality of receiving and transmitting antennas of the special-shaped linear array are all located on the same horizontal plane, and the different gains and phases of different receiving and transmitting antennas are all caused by different positions on the xy plane, only the information of the x axis and the y axis is considered in the embodiment, the information of the z axis is not introduced, and the calculation process is simplified.
Referring to fig. 1, it shows an implementation flowchart of the calibration method for a special-shaped linear array radar provided in the embodiment of the present application, and details are as follows:
s101: and acquiring an echo intermediate frequency signal obtained by detecting the metal column by each antenna channel in the special-shaped linear array of the radar.
In a possible embodiment, the specific implementation flow of S101 includes:
and acquiring echo signals obtained by detecting the metal column by each antenna channel in the special-shaped linear array.
And performing deskew processing on the echo signal corresponding to each antenna channel to obtain a corresponding echo intermediate frequency signal.
In this embodiment, for any antenna channel of the special-shaped linear array, the specific implementation process of S101 includes:
assuming that an FMCW (Frequency Modulated Continuous Wave) signal is transmitted to the metal pillar through the special-shaped linear array of the security inspection instrument without considering the phase error introduced by the antenna channel, the transmitted signal can be expressed as:
the transmitting signal is reflected back after being incident to the metal column and is received by the special-shaped linear array, and then the received echo signal is expressed as:
wherein f0 represents the center frequency of the transmitted signal, K represents the chirp rate, A represents the echo amplitude, τ (x, y) represents the target echo delay, and
r represents the distance from the radar to the metal column, and c represents the propagation speed of the electromagnetic wave in free space.
After the antenna channel receives the metal column echo, obtaining an echo intermediate frequency signal through deskew operation as follows:
in the application scenario of the security check instrument, because the distance between the security check instrument and the detection target is short, and 1/2K τ (x, y) 2 is approximately zero and can be ignored, the 3 rd term of the exponential term in the formula (3) can be ignored, and the final echo intermediate frequency signal is obtained:
in the formula (3), the reaction mixture is,
(x, y) represents the position coordinates of the antenna channel in the radar coordinate system, (x) 0 ,y 0 ) Representing the position coordinates of the metal column in the radar coordinate system, f b (x, y) = K tau (x, y) represents the intermediate frequency signal corresponding to the metal column, phi (x, y) =2 pi f when the phase error introduced by the antenna channel is not considered 0 τ (x, y) represents the actual phase corresponding to the metal pillar.
The actual phase corresponding to the metal column given in the formula (4) and the position correlation system where the metal column is located indicate that the actual position coordinate of the metal column needs to be obtained during calibration, so the actual position coordinate of the metal column needs to be solved by using the actual phase given in the formula (4).
S102: and performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel.
In a possible embodiment, the specific implementation flow of S102 includes:
sampling an echo intermediate frequency signal corresponding to a first antenna channel in a time domain to obtain a first time sequence; the first antenna channel is any one antenna channel of the special-shaped linear array;
performing discrete time Fourier transform on the first time sequence to obtain a frequency spectrum corresponding to the first antenna channel;
and taking the phase corresponding to the maximum amplitude value in the frequency spectrum as the actual phase of the echo intermediate frequency signal of the first antenna channel.
Specifically, the echo intermediate frequency signal in the formula (4) is sampled in the time domain to obtain a time sequence:
wherein Ts is the intermediate frequency signal sampling interval.
The time sequence is subjected to N-point DTFT (Discrete-time Fourier Transform) to obtain a frequency spectrum as follows:
in the formula (6), ω b (x,y)＝2πf b (x, y) is the angular frequency of the echo intermediate frequency signal.
Since the echo intermediate frequency signal is sampled at equal intervals in the time domain, the calculation of equation (6) can be directly calculated quickly using the FFT.
When the frequency ω of the frequency spectrum is equal to the angular frequency of the echo intermediate frequency signal, that is, ω = ω b When (x, y) is carried out, it is determined that the formula (6) at the moment only has a term ej phi (x, y), the exponential term is the actual phase of the metal pillar, namely the phase in the formula (4), and the calculation error of the phase can be reduced by improving the FFT calculation precision in a zero filling mode in practice.
S103: and based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in a radar coordinate system in the position searching range of the metal column by utilizing an optimization problem.
In a possible embodiment, the specific implementation flow of S103 includes:
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 under a radar coordinate system;
wherein (x) i ,y i ) Representing the position coordinates of the ith antenna channel; phi (x) i ,y i ) Representing the actual phase, 2 π f, of the echo intermediate-frequency signal received by the ith antenna channel 0 τ j (x i ,y i ) Representing the theoretical phase of the echo intermediate frequency signal received by the i-th antenna channel,
representing the position coordinates of any alternative metal column in the position search range; { x 0 ,y 0 And H represents the position coordinate number set of the alternative metal columns in the position search range.
Specifically, M = {1,2,3, \8230; M }, and H = {1,2, \8230; H }, where M represents the total number of antenna channels and H represents the total number of candidate positions of the metal posts.
In order to obtain the position of the metal post used in the actual calibration, the present embodiment may calculate the actual position coordinates of the metal post by an optimization method by integrating data of a plurality of antenna channels.
Specifically, this embodiment may:
(1) When the metal column is placed on the axis of the security check instrument, the approximate position of the radar can be calibrated, the position searching range is determined and the radar is input, and the radar selects a plurality of alternative metal column position coordinates of the metal column according to a preset step length in the position searching range and respectively brings the position coordinates into a formula (7).
(2) In the formula (7), for any alternative position coordinate
And respectively subtracting the theoretical phase of the metal column obtained by adopting the alternative position coordinate calculation from the actual phase of the metal column obtained by calculating the echo intermediate frequency signal obtained based on each antenna channel, and summing a plurality of phase difference values corresponding to the alternative position coordinate to obtain the sum of the phase deviation corresponding to the alternative position coordinate. In the step, the actual phase of the metal column, which is obtained by calculating the echo intermediate frequency signals acquired by each antenna channel, is calculated by using a formula (6).
(3) Searching the maximum value of the sum of the phase deviations corresponding to all the candidate position coordinates, and taking the candidate position coordinate corresponding to the maximum value as the actual position coordinate { x) of the metal column 0 ,y 0 }。
Specifically, the optimization problem may be to find the actual position coordinates of the metal pillar by a least squares fitting method.
S104: and calculating the theoretical phase of the metal column detected by each antenna channel based on the actual position coordinates of the metal column in the radar coordinate system.
In the embodiment, after the position coordinates of the metal column in the radar coordinate system are obtained through calculation, the position coordinates are based on a formula
Calculating theoretical phase phi of metal column detected by each antenna channel tar (x i ,y i )。
S105: determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.
In a possible embodiment, the specific implementation flow of S105 includes:
calculating the theoretical phase of the metal column detected by the first antenna channel based on the actual position coordinate of the metal column in the radar coordinate system; the first antenna channel is any one antenna channel of the special-shaped linear array;
subtracting 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;
and multiplying the phase deviation value corresponding to the first antenna channel by the maximum amplitude value of the frequency spectrum of the echo intermediate frequency signal of the first antenna channel to obtain a channel calibration factor of the first antenna channel.
In this embodiment, since the difference between the theoretical phase and the actual phase in the formula (7) includes both an error caused by the calculation accuracy and an error introduced by the phase of the antenna channel, in order to eliminate the error introduced by the antenna channel, in this embodiment, for any antenna channel in the special-shaped linear array, in consideration of the error introduced by the antenna channel, the echo intermediate frequency signal in the formula (4) may be written as:
wherein phi tar (x, y) represents the theoretical phase of the metal column, φ chan (x, y) represents the phase error introduced by the antenna channel.
Then, the phase error introduced by the antenna channel can be represented by equation (9):
φ chan (x,y)＝φ(x,y)-φ tar (x,y) (9)
phi (x, y) represents the actual phase of the metal column calculated by the formula (6), and the theoretical phase is subtracted from the actual phase of the echo intermediate frequency signal received by the antenna channel to obtain the phase error introduced by the antenna channel.
After the phase error introduced by the antenna channel is obtained through calculation, the maximum amplitude value of the frequency spectrum of the echo intermediate frequency signal is multiplied by the phase error to obtain a channel calibration factor, namely
In a possible embodiment, after the calculation of the channel calibration factor is completed, when the radar performs subsequent target detection, the error of the intermediate frequency signal of the target echo can be eliminated by the following method, which is detailed as follows:
and dividing 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.
In this embodiment, when the security check device actually performs target detection, the position of the target is assumed to be (x) s ,y s ) Then, the corresponding echo intermediate frequency signal is:
wherein phi is s (x, y) denotes the phase of the object to be imaged, phi chan (x, y) is the phase introduced by the antenna channel.
Then, the amplitude and phase of the echo intermediate frequency signal corresponding to the antenna channel are calibrated by equation (11) using equation (10):
the equation (12) is the echo intermediate frequency signal after the antenna channel calibration, and can be directly used for imaging processing.
It should be noted that, in this embodiment, the method for calibrating the special-shaped linear array radar is described by taking the special-shaped linear array security check instrument as an example, and the method is applicable to all radars including special-shaped linear arrays in practical application.
As can be seen from the above embodiments, in the embodiments of the present application, first, an echo intermediate frequency signal obtained by detecting a metal column by each antenna channel in a special-shaped linear array of a radar is obtained; then, performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel; based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in a radar coordinate system in the position searching range of the metal column by utilizing an optimization problem; calculating the theoretical phase of the metal column detected by each antenna channel based on the actual position coordinate of the metal column in the radar coordinate system; finally, determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel. This application adopts the metal column to acquire the same intermediate frequency signal as calibrating device in theory for each antenna channel, and then carries out parameter calibration to each passageway based on intermediate frequency signal, avoids not focusing the problem because of the different antenna channel gain of special-shaped linear array and the different image that cause the generation of phase place, improves radar detection effect.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The following are apparatus embodiments of the present application, and for details not described in detail therein, reference may be made to the corresponding method embodiments described above.
Fig. 5 shows a schematic structural diagram of a calibration apparatus for an irregular linear array radar provided in the embodiment of the present application, and for convenience of description, only a part related to the embodiment of the present application is shown, which is detailed as follows:
as shown in fig. 5, the calibration apparatus 5 for the shaped line radar includes:
the intermediate frequency signal acquisition module 110 is configured to acquire an echo intermediate frequency signal obtained by detecting a metal column by each antenna channel in a special-shaped linear array of the radar, where the metal column is vertically placed on an axis of the special-shaped linear array radar;
the metal column actual phase calculation module 120 is configured to perform discrete time fourier transform on the echo intermediate-frequency signal corresponding to each antenna channel, and determine an actual phase of the echo intermediate-frequency signal corresponding to each antenna channel;
a metal pillar position calculating module 130, configured to search, based on an actual phase of an echo intermediate-frequency signal received by each antenna channel, an actual position coordinate of the metal pillar in a radar coordinate system within a position search range of the metal pillar by using an optimization problem;
the metal column theoretical phase calculation module 140 is 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;
the calibration module 150 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 pillar 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.
In one possible implementation, the intermediate frequency signal obtaining module 110 includes:
the echo signal acquisition unit is used for acquiring echo signals obtained by detecting the metal column by each antenna channel in the special-shaped linear array of the radar;
and the intermediate frequency signal acquisition unit is used for performing deskew processing on the echo signal corresponding to each antenna channel to obtain the echo intermediate frequency signal.
In one possible implementation, the metal pillar actual phase calculation module 120 is specifically configured to:
sampling an echo intermediate frequency signal corresponding to a first antenna channel in a time domain to obtain a first time sequence; the first antenna channel is any one antenna channel of the special-shaped linear array;
performing discrete time Fourier transform on the first time sequence to obtain a frequency spectrum corresponding to the first antenna channel;
and taking the phase corresponding to the maximum amplitude value in the frequency spectrum as the actual phase of the echo intermediate frequency signal of the first antenna channel.
In one possible implementation, the metal post position calculation module 130 includes:
determining an optimization problem：
Solving the optimization problem by using a least square fitting method to obtain the actual position coordinates of the metal column under a radar coordinate system;
wherein (x) i ,y i ) Representing the position coordinates of the ith antenna channel; phi (x) i ,y i ) Representing the actual phase, 2 π f, of the echo intermediate-frequency signal received by the ith antenna channel 0 τ j (x i ,y i ) Representing the theoretical phase of the echo intermediate frequency signal received by the i-th antenna channel,
representing the position coordinates of any alternative metal column in the position search range; { x 0 ,y 0 And (4) representing the actual position coordinates of the metal column in a radar coordinate system, M representing an antenna channel number set, and H representing a position coordinate number set of the alternative metal column in the position search range.
In one possible embodiment, the calibration module 150 comprises a calibration factor calculation unit for:
calculating a theoretical phase of the metal column detected by the first antenna channel based on the actual position coordinate of the metal column in the radar coordinate system; the first antenna channel is any one antenna channel of the special-shaped linear array;
subtracting 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;
and multiplying the phase deviation value corresponding to the first antenna channel by the maximum amplitude value of the frequency spectrum of the echo intermediate frequency signal of the first antenna channel to obtain a channel calibration factor of the first antenna channel.
In one possible embodiment, the calibration apparatus for the anomalous line radar further comprises:
and the echo signal calibration module is used for dividing 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.
An embodiment of the present application further provides a computer program product, which has a program code, and when the program code is run in a corresponding processor, controller, computing device or radar, the program code executes steps in any one of the above embodiments of the calibration method for a shaped line radar, for example, steps S101 to S105 shown in fig. 1. Those skilled in the art will appreciate that the methods presented in the embodiments of the present application and the associated apparatus may be implemented in various forms of hardware, software, firmware, special purpose processors, or a combination thereof. The special-purpose processor may include an Application Specific Integrated Circuit (ASIC), a Reduced Instruction Set Computer (RISC), and/or a Field Programmable Gate Array (FPGA). The proposed method and apparatus are preferably implemented as a combination of hardware and software. The software is preferably installed as an application program on the program storage device. It is typically a machine based computer platform having hardware such as one or more Central Processing Units (CPU), a Random Access Memory (RAM), 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 may either be part of an application program or part may be performed by an operating system.
Fig. 6 is a schematic diagram of a radar provided in an embodiment of the present application. As shown in fig. 6, the radar 6 of this embodiment includes: a processor 60, a memory 61 and a computer program 62 stored in said memory 61 and executable on said processor 60. The processor 60, when executing the computer program 62, implements the steps in the calibration method embodiments of the wire array radar described above, such as the steps S101 to S105 shown in fig. 1. Alternatively, the processor 60, when executing the computer program 62, implements the functions of the modules/units in the above-mentioned device embodiments, such as the functions of the modules 110 to 150 shown in fig. 5.
Illustratively, the computer program 62 may be divided into one or more modules/units, which are stored in the memory 61 and executed by the processor 60 to accomplish/implement the solution provided herein. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 62 in the radar 6. For example, the computer program 62 may be divided into the modules 110 to 150 shown in fig. 5.
The radar 6 may include, but is not limited to, a processor 60, a memory 61. Those skilled in the art will appreciate that fig. 6 is merely an example of a radar 6 and does not constitute a limitation of the radar 6, and may include more or fewer components than shown, or some components in combination, or different components, e.g., the radar may also include input-output devices, network access devices, buses, etc.
The Processor 60 may be a Central Processing Unit (CPU), other general purpose Processor, 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, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 61 may be an internal storage unit of the radar 6, such as a hard disk or a memory of the radar 6. The memory 61 may 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 memory Card (Flash Card), and the like, which are provided on the radar 6. Further, the memory 61 may also include both an internal storage unit of the radar 6 and an external storage device. The memory 61 is used for storing the computer program and other programs and data required by the radar. The memory 61 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed 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 perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus/radar and method may be implemented in other ways. For example, the above-described apparatus/radar embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the method of the embodiments may be implemented by a computer program instructing related hardware, where the computer program may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the embodiments of the calibration method for the anomalous line radar may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain suitable additions or subtractions depending on the requirements of legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media may not include electrical carrier signals or telecommunication signals in accordance with legislation and patent practice.
Furthermore, features of the embodiments shown in the drawings of the present application or of the various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of 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 to yield yet further embodiments described in text or with reference to the figures.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. A calibration method of a special-shaped linear array radar is characterized in that the special-shaped linear array is a linear array except a linear array; the calibration method of the special-shaped linear array radar comprises the following steps:
acquiring an echo intermediate frequency signal obtained by detecting a metal column by each antenna channel in a special-shaped linear array of the radar, wherein the metal column is vertically placed on the axis of the special-shaped linear array radar;
performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel, and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel;
based on the actual phase of the echo intermediate frequency signal received by each antenna channel, searching the actual position coordinate of the metal column in a radar coordinate system in the position searching range of the metal column by utilizing an optimization problem;
calculating the theoretical phase of the metal column detected by each antenna channel based on the actual position coordinate of the metal column in the radar coordinate system;
determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.
2. The method for calibrating a profiled bar radar according to claim 1, wherein the obtaining of the echo intermediate frequency signal obtained by detecting the metal column by each antenna channel in the profiled bar array of the radar comprises:
acquiring echo signals obtained by detecting the metal column by each antenna channel in the special-shaped linear array;
and performing deskew processing on the echo signal corresponding to each antenna channel to obtain a corresponding echo intermediate frequency signal.
3. The method for calibrating a pseudo-linear array radar according to claim 1, wherein the performing discrete time fourier transform on the echo intermediate frequency signal corresponding to each antenna channel to determine the actual phase of the echo intermediate frequency signal corresponding to each antenna channel comprises:
sampling an echo intermediate frequency signal corresponding to a first antenna channel in a time domain to obtain a first time sequence; the first antenna channel is any one antenna channel of the special-shaped linear array;
performing discrete time Fourier transform on the first time sequence to obtain a frequency spectrum corresponding to the first antenna channel;
and taking the phase corresponding to the maximum amplitude value in the frequency spectrum as the actual phase of the echo intermediate frequency signal of the first antenna channel.
4. The method for calibrating a wire array radar according to claim 1, wherein the step of finding the actual position coordinates of the metal pillar in the radar coordinate system within the position search range of the metal pillar by using an optimization problem based on the actual phase of the intermediate frequency signal of the echo received by each antenna channel comprises:
determining an optimization problem:
solving the optimization problem by using a least square fitting method to obtain the actual position coordinates of the metal column under a radar coordinate system;
wherein (x) i ,y i ) Representing the position coordinates of the ith antenna channel; phi (x) i ,y i ) Representing the actual phase, 2 π f, of the echo intermediate-frequency signal received by the ith antenna channel 0 τ j (x i ,y i ) Representing the theoretical phase of the echo intermediate frequency signal received by the i-th antenna channel,
representing the position coordinates of any alternative metal column in the position search range; { x 0 ,y 0 And (4) representing the actual position coordinates of the metal column in a radar coordinate system, M representing an antenna channel number set, and H representing a position coordinate number set of the alternative metal column in the position search range. />
5. The method for calibrating a pseudo-linear array radar according to claim 1, wherein the determining a channel calibration factor for each antenna channel based on an actual phase of an echo intermediate-frequency signal received by each antenna channel and a theoretical phase of the metal pillar detected by the corresponding antenna channel comprises:
calculating a theoretical phase of the metal column detected by the first antenna channel based on the actual position coordinate of the metal column in the radar coordinate system; the first antenna channel is any one antenna channel of the special-shaped linear array;
subtracting 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;
and multiplying the phase deviation value corresponding to the first antenna channel by the maximum amplitude value of the frequency 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 wire array radar as recited in claim 1, further comprising:
and dividing 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.
7. The calibration device of the special-shaped linear array radar is characterized in that the special-shaped linear array is a linear array except a linear array; the device comprises:
the medium-frequency signal acquisition module is used for acquiring an echo medium-frequency signal obtained by detecting a metal column by each antenna channel in the special-shaped linear array of the radar, and the metal column is vertically placed on the axis of the special-shaped linear array radar;
the metal column actual phase calculation module is used for performing discrete time Fourier transform on the echo intermediate frequency signals corresponding to each antenna channel and determining the actual phase of the echo intermediate frequency signals corresponding to each antenna channel;
the metal column position calculation module is used for searching the actual position coordinates of the metal column in a radar coordinate system in the position search range of the metal column by utilizing an optimization problem based on the actual phase of the echo intermediate frequency signal received by each antenna channel;
the metal column theoretical phase calculation module is used for calculating the theoretical phase of the metal column detected by each antenna channel based on the position coordinate of the metal column in the radar coordinate system;
the calibration module is used for determining a channel calibration factor of 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 for calibrating the target echo intermediate frequency signal received by the corresponding antenna channel.
8. The apparatus for calibrating a pseudo-linear array radar according to claim 7, wherein the intermediate frequency signal acquisition module comprises:
the device comprises an echo signal acquisition unit, a data acquisition unit and a data processing unit, wherein the echo signal acquisition unit is used for acquiring an echo signal obtained by detecting a metal column through each antenna channel in a special-shaped linear array of the radar;
and the intermediate frequency signal acquisition unit is used for performing deskew processing on the echo signal corresponding to each antenna channel to obtain the echo intermediate frequency signal.
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, when executing the computer program, carries out the steps of the method for calibrating a wire radar as claimed in any one of the preceding claims 1 to 6.
10. A computer-readable storage medium, in which a computer program is stored, which, when being executed by a processor, carries out the steps of the method for calibrating a pseudowire radar as claimed in any one of claims 1 to 6.
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| CN117008071A (en) * | 2023-10-07 | 2023-11-07 | 广东大湾区空天信息研究院 | Linear frequency modulation MIMO radar channel calibration method and related equipment |
| CN117008071B (en) * | 2023-10-07 | 2023-12-12 | 广东大湾区空天信息研究院 | Linear frequency modulation MIMO radar channel calibration method and related equipment |
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