Evaluation and correction method for array element amplitude consistency of three-dimensional ground penetrating radar array antenna

Abstract

The invention discloses a method for evaluating and correcting amplitude consistency of array elements of a three-dimensional ground penetrating radar array antenna. The method comprises the following steps: step 1, simulating a total reflection scene in an air medium; step 2, acquiring data; step 3, recombining and intercepting the data; according to the method disclosed by the invention, a three-dimensional ground penetrating radar array antenna performance evaluation system is preliminarily established, and the method is a supplement for general ground penetrating radar performance evaluation. The method solves the problem that an existing evaluation method cannot accurately evaluate the matching degree of the array elements of the three-dimensional ground penetrating radar array antenna, the amplitude difference between the array elements and whether the quality and the display effect of various subsequent three-dimensional views are affected or not. Meanwhile, a correction coefficient calculation method which is not involved before is provided and can be used for reverse compensation.

Description

Technical Field

[0001] The invention belongs to the field of ground penetrating radar research, and particularly relates to an evaluation and correction method for amplitude consistency of array elements of a three-dimensional ground penetrating radar array antenna in the field. Background Art

[0002] Compared with the traditional two-dimensional ground penetrating radar that uses a single antenna to scan and can only obtain a single vertical profile data at a time, the three-dimensional ground penetrating radar uses array antenna scanning to collect multiple vertical profile data at a time. The array data are arranged in corresponding positions to generate a three-dimensional data body, showing horizontal profiles at different depths, longitudinal, transverse, and oblique profiles at any angle, and three-dimensional stereoscopic views. Three-dimensional ground penetrating radar has become a mainstream product in the industry due to its high efficiency and intuitiveness. Due to the manufacturing process of the three-dimensional ground penetrating radar array antenna, differences in electronic device performance, and crosstalk between array elements, the array data often have amplitude imbalance problems, resulting in striped or patchy interference or artifacts in the displayed image, affecting the detection and recognition results.

[0003] Therefore, it is necessary to establish a 3D GPR performance evaluation system, in which the amplitude consistency of the array antenna elements is an important evaluation indicator. The better the amplitude consistency of the 3D GPR array antenna elements, the higher the quality of the extracted and generated profiles and 3D stereoscopic views. Only by controlling or correcting the amplitude consistency of the 3D GPR array antenna elements within a certain range can subsequent target detection and recognition be guaranteed.

[0004] The patent "A general radar antenna amplitude jitter evaluation method (CN113126045B)" discloses collecting a certain length of ground-penetrating radar data, finding the amplitude corresponding to the direct-coupled wave or the reflected wave, calculating the amplitude extreme value and the mean value, and obtaining the amplitude jitter of the ground-penetrating radar antenna. The disadvantage is that it is based on amplitude stability and is only applicable to the evaluation of a single antenna of a two-dimensional ground-penetrating radar or the evaluation of multiple channels of a three-dimensional ground-penetrating radar array antenna. It cannot evaluate whether the amplitudes between the elements of a three-dimensional ground-penetrating radar array antenna can be coordinated and unified, and it cannot provide a quantitative correction coefficient. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array.

[0006] The present invention adopts the following technical solution:

[0007] A method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array is improved in that it comprises the following steps:

[0008] Step 1: Simulation of total reflection scene in air medium:

[0009] Copper foil is laid flat on the ground, a cubic foam is placed in the center of the copper foil, and a three-dimensional ground penetrating radar array antenna is horizontally placed on the top of the cubic foam, with the radiation surface of the array antenna facing downward, and the center point of the array antenna is aligned with the center point of the copper foil;

[0010] Step 2, data collection:

[0011] Turn on the 3D ground penetrating radar and save data of all elements of the array antenna for no less than 30 seconds;

[0012] Step 3, data reorganization and interception:

[0013] Arrange the data in the order of array antenna elements, and remove the data of the first 10 seconds and the last 10 seconds of each element, and only keep the middle data, so as to obtain the valid data set of each element: {S 1 , S 2 , …, S i , …, S N}, where S i S represents the valid data set of the ith array element, N is the total number of array antenna elements, and the valid data set of a single array element contains the received echo signals at several moments: i ={s i1 ,s i2 ,…,s ij ,…,s im}, where s ij represents the received echo signal of the i-th array element at the j-th moment;

[0014] Step 4: Array element amplitude consistency evaluation:

[0015] The valid data set S of the i-th array element is i The received echo signal s at a single moment in ij After analysis, the peak-to-peak amplitude of the sub-wave reflected by the ground copper foil of the array element at each moment is obtained: {mm i1 , mm i2 ,…,mm ij ,…,mm im}, where mm ij MeanMM represents the peak-to-peak value of the ground copper foil reflection amplitude in the echo signal received by the i-th array element at the j-th time. The peak-to-peak mean value of the amplitude of the ground copper foil reflection sub-wave of the array element is obtained after averaging: i =mean(mm i1 , mm i2 ,…,mm ij ,…,mm im );

[0016] Then, the peak-to-peak mean of the amplitude of the sub-waves reflected by the ground copper foil of all array elements is obtained: [MeanMM 1 , MeanMM2 , ..., MeanMM i , ..., MeanMM N ], the maximum value of the peak-to-peak mean of the sub-wave amplitude reflected by the ground copper foil of all array elements is MeanMM max , the minimum value is MeanMM min , the average value is MeanMM mean ;

[0017] The amplitude consistency of each element of the three-dimensional ground penetrating radar array antenna is:

[0018]

[0019] Step 5: Calculate the amplitude correction coefficient of each array element:

[0020] The correction coefficient corresponding to the i-th element of the three-dimensional ground penetrating radar array antenna is: Amplitude correction is performed after reverse compensation.

[0021] Further, in step 1, the cross-section of the top of the cubic foam is larger than the bottom surface of the array antenna.

[0022] Further, in step 1, the height of the cubic foam is 2λ, where λ is the wavelength of the center frequency of the array antenna corresponding to the air medium.

[0023] Furthermore, in step 1, in the length and width directions, the paving range of the copper foil exceeds the bottom edge of the cubic foam by 4λ.

[0024] Furthermore, in step 2, the corresponding array antenna default parameters are selected, and the antenna is preheated for ten minutes to check and confirm that all array elements are in working state, time-triggered mode, and can send and receive signals normally.

[0025] The beneficial effects of the present invention are:

[0026] The method disclosed in the present invention preliminarily establishes a three-dimensional ground-penetrating radar array antenna performance evaluation system, which is a supplement to the general ground-penetrating radar performance evaluation. It makes up for the fact that the existing evaluation method cannot accurately evaluate the matching degree of each element of the three-dimensional ground-penetrating radar array antenna, the difference in amplitude between the elements, and whether it will affect the quality and display effect of various subsequent three-dimensional stereoscopic views. At the same time, it provides a correction coefficient calculation method that has not been involved before, which can be used for reverse compensation.

[0027] The method disclosed in the present invention provides a basis for three-dimensional ground penetrating radar manufacturers to self-test performance indicators, provides guidance for three-dimensional ground penetrating radar users to purchase equipment, and provides a reference for three-dimensional ground penetrating radar users to conduct secondary development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is the transverse profile of the 3D GPR array antenna element when the amplitude consistency is poor;

[0029] Figure 2 It is the horizontal profile of the 3D GPR array antenna element when the amplitude consistency is poor;

[0030] Figure 3 It is a schematic flow diagram of the method of the present invention;

[0031] Figure 4 It is a schematic diagram of the total reflection simulation scene in the air medium;

[0032] Figure 5 It is a data set of ten elements of a three-dimensional ground penetrating radar array antenna;

[0033] Figure 6 It is the received echo signal diagram of a certain array element at a single moment. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Figure 1 It is the transverse profile of the 3D GPR array antenna element when the amplitude consistency is poor; Figure 2 It is the horizontal profile of the 3D GPR array antenna element when the amplitude consistency is poor;

[0036] Embodiment 1, this embodiment discloses a method for evaluating and correcting the amplitude consistency of a three-dimensional ground-penetrating radar array antenna element. Under static conditions, the reflected waves of each element of the three-dimensional ground-penetrating radar array antenna to the same surface target are collected at the same time, and the amplitude of the reflected waves of each element is statistically analyzed, and its consistency is calculated, and the amplitude correction coefficient of each element of the array antenna is obtained. Figure 3 As shown, the specific steps are as follows:

[0037] Step 1: Simulation of total reflection scene in air medium:

[0038] like Figure 4 As shown, the 1500M array antenna of the three-dimensional ground penetrating radar is placed horizontally on a cubic foam with a cross-section larger than the bottom surface of the array antenna. The height of the foam is 40cm. The wavelength of the array antenna with a center frequency of 1500M corresponds to 20cm in the air medium. The radiation surface of the array antenna faces downward, and the ground is flat and paved with copper foil. In the length and width directions, the paving range of the copper foil exceeds the edge of the bottom surface of the antenna by 80cm. The center point of the array antenna is aligned with the center point of the paved copper foil;

[0039] Step 2, data collection:

[0040] Turn on the 3D ground penetrating radar, select the corresponding array antenna default parameters, preheat for ten minutes, check that all 10 array elements are in working condition, time trigger mode, and can send and receive signals normally. At the same time, save the data of 10 array elements for no less than 30 seconds;

[0041] Step 3, data reorganization and interception:

[0042] Arrange the data in the order of the array antenna elements, and remove the data of the first 10 seconds and the last 10 seconds of each element, and only keep the data of the middle 10 seconds, so as to obtain the following Figure 5 The 10-element valid data set is shown in Figure 1. Figure 6 As shown, the effective data set of a single array element includes the received echo signals at several moments;

[0043] Step 4: Array element amplitude consistency evaluation:

[0044] The effective data sets of each array element are counted in turn. For the effective data set of each array element, the received echo signal at a single moment is analyzed in turn. The peak-to-peak value of the ground copper foil reflection sub-wave amplitude of the array element at each moment is obtained, and the peak-to-peak mean value of the ground copper foil reflection sub-wave amplitude of the array element is obtained by averaging. Thus, the peak-to-peak mean values ​​of the ground copper foil reflection sub-wave amplitude of 10 array elements are obtained respectively [13161, 11528, 8212, 8718, 8256, 8339, 7440, 6718, 9209, 10147]. The maximum value of the peak-to-peak mean value of the ground copper foil reflection sub-wave amplitude of 10 array elements is 13161, the minimum value is 6718, and the average value is 9172.7. The amplitude consistency of the three-dimensional ground penetrating radar array antenna array element is about 5.84dB;

[0045] Step 5: Calculate the amplitude correction coefficient of each array element:

[0046] The amplitude correction coefficients corresponding to the 10 array elements of the three-dimensional ground penetrating radar array antenna are [-7.2203dB, -4.5716dB, 2.2128dB, 1.0179dB, 2.1051dB, 1.9068dB, 4.1873dB, 6.2301dB, -0.0789dB, -2.0186dB], and the amplitude correction can be performed by reverse compensation.

Claims

1. A method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array, characterized in that: The steps include: Step 1: Simulation of total reflection scene in air medium: Copper foil is laid flat on the ground, a cubic foam is placed in the center of the copper foil, and a three-dimensional ground penetrating radar array antenna is horizontally placed on the top of the cubic foam, with the radiation surface of the array antenna facing downward, and the center point of the array antenna is aligned with the center point of the copper foil; Step 2, data collection: Turn on the 3D ground penetrating radar and save data of all elements of the array antenna for no less than 30 seconds; Step 3, data reorganization and interception: Arrange the data in the order of array antenna elements, and remove the data of the first 10 seconds and the last 10 seconds of each element, and only keep the middle data, so as to obtain the valid data set of each element: {S1, S2, ..., S i , …, S N }, where S i S represents the valid data set of the ith array element, N is the total number of array antenna elements, and the valid data set of a single array element contains the received echo signals at several moments: i ={s i1 ,s i2 ,…,s ij ,…,s im }, where s ij represents the received echo signal of the i-th array element at the j-th moment; Step 4: Array element amplitude consistency evaluation: The effective data set S of the i-th array element is i The received echo signal s at a single moment in ij After analysis, the peak-to-peak amplitude of the sub-wave reflected by the ground copper foil of the array element at each moment is obtained: {mm i1 , mm i2 ,…,mm ij ,…,mm im }, where mm ij MeanMM represents the peak-to-peak value of the ground copper foil reflection amplitude in the echo signal received by the i-th array element at the j-th time. The peak-to-peak mean value of the amplitude of the ground copper foil reflection sub-wave of the array element is obtained after averaging: i =mean(mm i1 , mm i2 ,…,mm ij ,…,mm im ); Then, the peak-to-peak mean of the amplitude of the sub-waves reflected by the ground copper foil of all array elements is obtained: [MeanMM1, MeanMM2, …, MeanMM i , ..., MeanMM N ], the maximum value of the peak-to-peak mean of the sub-wave amplitude reflected by the ground copper foil of all array elements is MeanMM max , the minimum value is MeanMM min , the average value is MeanMM mean ; The amplitude consistency of each element of the three-dimensional ground penetrating radar array antenna is: Step 5: Calculate the amplitude correction coefficient of each array element: The correction coefficient corresponding to the i-th element of the three-dimensional ground penetrating radar array antenna is: Amplitude correction is performed after reverse compensation.

2. The method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array according to claim 1, characterized in that: In step 1, the top cross-section of the cubic foam is larger than the bottom surface of the array antenna.

3. The method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array according to claim 1, characterized in that: In step 1, the height of the cubic foam is 2λ, where λ is the wavelength of the center frequency of the array antenna corresponding to the air medium.

4. The method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array according to claim 3 is characterized by: In step 1, in the length and width directions, the paving range of the copper foil exceeds the bottom edge of the cubic foam by 4λ.

5. The method for evaluating and correcting the amplitude consistency of antenna elements of a three-dimensional ground penetrating radar array according to claim 1, characterized in that: In step 2, select the corresponding default parameters of the array antenna, preheat for ten minutes, check and confirm that all array elements are in working state, time-triggered mode, and can send and receive signals normally.

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