Insect radar parameter inversion method based on relative polarization information

Abstract

This invention discloses an insect radar parameter inversion method based on relative polarization information. By analyzing the impact of insect targets deviating from the beam on radar measurement results, the obtained radar scattering matrix is ​​decomposed and expressed as the product of the true target scattering matrix and the impact of the target's deviation from the beam center on the measurement results. To eliminate this impact, the ratio of any two channels is taken as the parameters for inverting the insect's body length and weight. That is, by canceling the ratio, the influence of the measurement results is eliminated, thereby obtaining a more accurate discrimination capability. This provides an effective means for accurately identifying insect species and accurately measuring the body length and weight of insects of all sizes.

Description

Technical Field

[0001] This invention belongs to the field of insect radar technology, specifically relating to a method for inverting insect radar parameters based on relative polarization information. Background Technology

[0002] Insect radar is an important tool for monitoring insect migration. It can acquire parameters such as mass, body length, and body axis orientation of insects flying past its beam by analyzing echoes. Based on these parameters, we can identify the insect species and issue early warnings. This is of great significance for preventing outbreaks of pests and diseases and for studying the theory of insect migration.

[0003] Polarization is one of the important characteristics of radar targets. Most existing methods for inverting insect body length and weight using radar are based on polarization information.

[0004] Traditional insect parameter inversion methods rely on absolute polarization information to derive insect body length and weight. However, when the insect target deviates from the beam, the target echo acquired by the fully polarimetric insect radar weakens, as shown in Figure 2. This causes the inversion results to deviate from the true insect parameters. Summary of the Invention

[0005] In view of this, the present invention provides a method for inverting insect radar parameters based on relative polarization information, which can avoid large errors in the inversion parameters caused by insects deviating from the beam, thereby improving the accuracy of insect parameter measurements. This is helpful for studying insect species, analyzing the migration characteristics of different insects, and providing early warning of pest and disease outbreaks.

[0006] A method for inverting insect radar parameters based on relative polarization information is proposed. The orientation of the insect target is set as θ. The ratio of any two channels of the radar scattering matrix at orientation θ is used as parameters for inverting the insect's body length and weight. The parameters for each insect target at orientation θ are obtained using the above method, and the relationship between these parameters and the insect's body length and weight is fitted and inverted. During actual measurement, the insect's weight and body length are obtained based on these parameters and the inversion relationship.

[0007] Preferably, when θ = 0°, take S hh / S vv As parameters for retrieving insect body length and weight, S hh and S vv These represent the hh and vv channel elements of the scattering matrix of the measured target.

[0008] Preferably, when θ = 90°, take S vv / S hh As parameters for retrieving insect body length and weight, S hh and S vvThese represent the hh and vv channel elements of the scattering matrix of the measured target.

[0009] Preferably, when the angle θ is neither parallel to the H polarization direction nor the V polarization direction, the ratio of any two channels of the scattering matrix is ​​taken as the parameter for inverting the insect's body length and weight.

[0010] Preferably, the specific method for fitting and inverting the relationship between the parameters and the insect's body length and weight is as follows:

[0011] Based on the obtained parameters, the phase and amplitude corresponding to the parameters are obtained, and finally the relationship between the insect's weight and body length and the amplitude and phase of the parameters is fitted.

[0012] Preferably, the least squares method is used to fit the relationship between the insect's weight and body length and the amplitude and phase of the parameters.

[0013] Beneficial effects

[0014] 1. This invention analyzes the impact of insect targets deviating from the beam on radar measurement results, finding that the measurement results of each channel are affected. Therefore, the obtained radar scattering matrix is ​​decomposed and expressed as the product of the true target scattering matrix and the impact of the target's deviation from the beam center on the measurement results. Then, to eliminate this effect, the ratio of any two channels is used as a parameter for inverting the insect's body length and weight. This ratio cancellation method eliminates the influence of the measurement results, thereby obtaining more accurate discrimination capabilities. This provides an effective means for accurately identifying insect species and accurately measuring the body length and weight of insects of all sizes.

[0015] 2. According to the experiment, when θ = 0°, because the cross passage S vh and S hv The result is 0, and all information is focused on S. hh and S vv The information utilization rate is higher in the above cases, so we take S in this case. vv / S hh Using these parameters to invert insect body length and weight yields the best results and the most accurate values.

[0016] 3. According to the experiment, when θ = 90°, because the cross passage S vh and S hv The result is 0, and all information is focused on S. hh and S vv Above, information usage rate is higher. vv / S hh Meanwhile, since the h-polarization and v-polarization are perpendicular to each other in the radar polarization coordinate system, the two eigenvalues ​​at θ = 0° and θ = 90° are interchanged. Therefore, S is taken as... vv / S hh Using these parameters to invert insect body length and weight yields the best results and the most accurate values.

[0017] 4. When the angle θ is neither parallel to the H-polarization direction nor the V-polarization direction, since all scattering matrix channels have values, the ratio of any two channels can be calculated to eliminate the influence. In this way, the insect's weight and body length can be obtained through inversion fitting at any angle.

[0018] 5. By fitting and inverting, the relationship between the parameters and the insect's body length and weight is obtained. In real-world measurements, the insect's weight and body length can be quickly obtained by using the ratio of any two channels of the radar scattering matrix at orientation θ, saving time and improving measurement accuracy. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of measuring insects using a fully polarized radar.

[0020] Figures 2(a) and 2(b) show the errors of existing a0 and v methods for inverting insect weight error based on absolute polarization information when the target passes through the radar from the edge of the 3dB beam.

[0021] Figures 3(a) and 3(b) show the relationship between the body length and weight distribution and relative scattering characteristics of insects in the 16.2 GHz band, respectively.

[0022] Figure 4 This is a flowchart of the present invention. Detailed Implementation

[0023] The implementation of the method of the present invention will be described below with reference to the accompanying drawings and embodiments.

[0024] This invention provides a method for inverting insect radar parameters based on relative polarization information, such as... Figure 4 As shown, the basic idea is to analyze the impact of insect target deviation from the beam on radar measurement results, finding that the measurement results of each channel are affected. Therefore, the obtained radar scattering matrix is ​​decomposed and expressed as the product of the true target scattering matrix and the impact of the target deviation from the beam center on the measurement results. To eliminate this effect, it is found that the ratio of any two channels is used as a parameter for retrieving the insect's body length and weight. This allows the influence of the measurement results to be eliminated through ratio cancellation. Specifically, the amplitude and phase of the ratio are calculated, and finally, the relationship between the insect's weight and body length and the amplitude and phase of the ratio is fitted.

[0025] Because the orientation of insect targets varies during actual radar measurements, it is necessary to standardize the orientation of all insect targets, defining the target orientation as θ. Experiments have shown that when θ = 0° or θ = 90°, due to the intersecting channels S... vh and S hv The result is 0, and all information is focused on S. hh and S vv The information utilization rate is higher in the above cases, so we take S in this case. hh / S vv (θ=0°) or S vv / S hh Using θ = 90° as the parameter for inverting insect body length and weight yields the best results and the most accurate values. Therefore, this example uses θ = 0° for illustration.

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The specific ideas are as follows:

[0027] Let the insect scattering matrix (SM) measured by radar be:

[0028]

[0029] s ij (i,j=h,v) represents the elements of each channel of the target scattering matrix. s' ij (i,j=h,v) represents the elements of each channel of the actual target scattering matrix after removing the influence of the target's deviation from the beam center. g represents the influence of the target's deviation from the beam center on the measured insect scattering matrix. The target's orientation is defined as θ. Many methods exist for solving θ; one definition is given here:

[0030]

[0031] Where Re[·] denotes taking the real part of the complex number, Based on the target orientation, the scattering matrix when the target orientation is 0 can be obtained by matrix rotation:

[0032]

[0033] Substituting (1) into equation (3) yields:

[0034]

[0035] Then, using formula (4), the ratio of any two channels is taken as the parameters for retrieving the insect's body length and weight. However, since this embodiment uses θ = 0° as an example, the result of the cross-channel is 0, and all information is concentrated in S. hh and S vv Above, and taking the two diagonal elements of the scattering matrix at 0 degrees. It can be seen that S hh and S vv Since both are affected by g, their influence can be eliminated by comparing them. In other words... It is independent of g and only related to the scattering characteristics of the target itself.

[0036] Therefore, based on the above ideas, the specific implementation of this invention is as follows:

[0037] Take S hh / S vv The parameters are used for inversion of insect body length and weight. S can be calculated. hh / S vv Phase and amplitude:

[0038] Δφ=phase(S hh / S vv ),Δφ∈(-π,π] (5)

[0039] Δamp=lg(S hh )-lg(S vv (6)

[0040] Because S hh / S vv Since Δφ and Δamp are independent of g, they are not affected by the target's deviation from the beam center. However, if existing technology is used to calculate this, directly taking elements from any channel in the scattering matrix as parameters for inverting the insect's body length and weight without eliminating influencing factors, then when the target deviates from the beam center, S... hh and S vv This will result in varying degrees of underestimation, leading to inaccurate measurement results.

[0041] Bundle Substituting into equations (5) and (6):

[0042]

[0043]

[0044] and These are quantities related to the target's scattering characteristics and depend on the target's physical shape. Therefore, Δφ and Δamp are also related to the target's physical shape.

[0045] Finally, the relationship between insect body length and weight and Δφ and Δamp can be fitted using publicly available insect datasets. The fitting form is as follows:

[0046] lg(M)=x 11 +x 12 Δφ+x13 Δφ 2 +x 14 Δamp+x 15 Δamp 2 +x 16 ΔampΔφ (9)

[0047] L = x 21 +x 22 Δφ+x 23 Δφ 2 +x 24 Δamp+x 25 Δamp 2 +x 26 ΔampΔφ (10)

[0048] Where lg(M) represents body weight and L represents body length, the parameters that need to be estimated are:

[0049] x 11 ,x 12 ,x 13 ,x 14 ,x 15 ,x 16 ,x 21 ,x 22 ,x 23 ,x 24 ,x 25 ,x 26 .

[0050] The amplitude and phase differences of all insects can be calculated based on the insect scattering matrix in the public dataset, and the above parameters can be calculated by regression using the least squares method.

[0051] It should be noted that this embodiment only uses θ = 0° as an example. If the value of θ is not equal to 0 degrees or 90 degrees, or is parallel to the H polarization or V polarization direction, the ratio of any two scattering channels can be selected as a parameter for fitting and inversion.

[0052] When used in real-world measurements, the weight and length of an insect can be quickly obtained by using the ratio of any two channels of the radar scattering matrix when the orientation is θ. This not only saves time but also provides more accurate measurements.

[0053] Figure 1 A schematic diagram is given showing the target passing through the edge of the radar beam. When the target passes through the center of the beam, the size of the target's SM (Size of Target) matches the expectation, but when the target passes through the edge of the beam, the SM is smaller. Therefore, the insect size parameters estimated using the absolute SM will also have errors.

[0054] Figure 2 shows the magnitude of errors that may occur when using absolute SM inversion to retrieve insect body length and weight in the simulation. The simulation assumes that the target passes through the edge of the radar's 3dB beam.

[0055] Figures 2(a) and 2(b) show the a0 method and the v method, respectively. In Figure 2(a), the horizontal axis represents the value of a0, and the vertical axis represents the relative error of weight measurement corresponding to a0. In Figure 2(b), the horizontal axis represents the value of v, and the vertical axis represents the relative error of weight measurement corresponding to v.

[0056] Figures 3(a) and 3(b) show the relationship between the body weight, body length, amplitude difference, and phase difference of insect targets under 200 mg at 16.2 GHz. The plane in the figures is determined by the formula:

[0057] lg(M)=x11+x12Δφ+x13Δφ 2 +x14Δamp+x15Δamp 2 +x16ΔampΔφ

[0058] L=x21+x22Δφ+x23Δφ 2 +x24Δamp+x25Δamp 2 +x26ΔampΔφ

[0059] The plotted plane represents the corresponding weight, body length, amplitude difference, and phase difference of the insect target. The scatter points in the plot are the corresponding scatter points of the insect target's weight, body length, amplitude difference, and phase difference drawn from records in a public dataset.

[0060] It can be seen that there is a clear relative size relationship between them. The error of the insect radar parameter inversion method based on relative polarization information described in this invention is less than 15% for body weight and less than 10% for body length in the 16.2 GHz band.

[0061] This method is applicable to the inversion of body size parameters of insects weighing less than 200mg in the Ku band, and can solve the problem of the target not being in the beam.

[0062] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for inverting insect radar parameters based on relative polarization information, characterized in that: The orientation of the insect target is set to The ratio of any two channels of the obtained radar scattering matrix is taken as a parameter for inverting the body length and weight of the insect when the orientation is The parameters of each insect target when the orientation is are obtained according to the above method, and the relationship between the parameters and the body length and weight of the insect is fitted; in actual measurement, the body weight and length of the insect are obtained according to the parameters and the inversion relationship; the specific process is as follows: Let the scattering matrix of the insect measured by radar be: （1） denotes the elements of the measured target scattering matrix for each channel; denotes the elements of the actual target scattering matrix for each channel after removing the influence of the target deviation from the beam center; g represents the effect of the target offset from the beam center pair on the measured insect scattering matrix; the orientation of the target is defined as : （2） wherein denotes taking the real part of a complex number, ; according to the target orientation, the scattering matrix is obtained by matrix rotation when the target orientation is 0: （3） Substituting (1) into equation (3) yields: （4） when At that time, take As parameters for retrieving insect body length and weight, among which and Represents the target scattering matrix Channel elements and Channel elements; calculation Phase and amplitude: （5） （6） Bundle , Substituting into equations (5) and (6): （7） （8） Fitting insect body length and weight using publicly available insect datasets and The relationship is fitted in the following form: （9） （10） in, represents body weight, Represents body length.

2. The inversion method as described in claim 1, characterized in that: when At that time, take As parameters for retrieving insect body length and weight, among which and Represents the target scattering matrix Channel elements and Channel element.

3. The inversion method as described in claim 1, characterized in that: when If the angle is neither parallel to the H polarization direction nor the V polarization direction, then the ratio of any two channels of the scattering matrix is ​​taken as the parameter for inverting the insect's body length and weight.

4. The inversion method as described in claim 1, 2, or 3, characterized in that: The specific method for fitting and inverting the relationship between the parameters and the insect's body length and weight is as follows: Based on the obtained parameters, the phase and amplitude corresponding to the parameters are obtained, and finally the relationship between the insect's weight and body length and the amplitude and phase of the parameters is fitted.

5. The inversion method as described in claim 4, characterized in that: The relationship between the insect's weight and body length and the amplitude and phase of the parameters was fitted using the least squares method.

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