CN105759252A - Insect dimension measurement method based on multi-frequency scattering modeling - Google Patents

Abstract

The invention discloses an insect dimension measurement method based on multi-frequency scattering modeling. The method may simultaneously measure the length and the width of an insect and accordingly may further derive a ratio of the mass to the length and width of the insect in an inversion way. Compared with a conventional insect radar dimension measurement method, the insect dimension measurement method based on multi-frequency scattering modeling greatly expands the dimension range of covered insects so as to enhance a capability of identifying an insect category for an insect radar.

Description

A kind of insecticide dimension measurement method based on multifrequency scattering modeling

Technical field

The invention belongs to entomological radar technical field, be specifically related to a kind of insecticide dimension measurement method based on multifrequency scattering modeling.

Background technology

Radar is arising at the historic moment during the Second World War, is the electronic equipment utilizing electromagnetic wave target to be detected and finds range.Military and weather radar finds the echo point having a lot of both non-military objective also non-atmosphere elements in the air very early, confirms that these echoes were migrating property insecticides later.Owing to the water content in insect bodies is more than 80%, being good electromagnetic-wave reflector, this is also the important prerequisite that entomological radar is successfully developed and applied.Hereafter, entomologists all over the world utilize entomological radar that migrating property insecticide has been carried out a series of research.The current U.S., Australia and Britain have been owned by the entomological radar system of oneself, China also in Shandong, Henan, the many places such as Liaoning be configured with entomological radar system.

Tradition entomological radar is by the restriction of the factors such as working system, systemic-function, algorithm and index, it is impossible to accurately obtain insect biology parameter.Tradition entomological radar is usually operated at Rayleigh region, and only have single frequency band, therefore the entomological radar scattering resonance state that can only radar surveying be obtained is compared with the empirical value of Rayleigh region, thus extrapolating the quality of insecticide, and further according to quality inverting build or classify.More single, particularly that build is the bigger insecticide of quantity of information that this method obtains, its scattering can enter resonance region, and this can largely effect on the precision of tradition build inversion method.Therefore the insecticide dimension measurement method of tradition entomological radar often cannot cover wider insecticide size range, limits the effectiveness of entomological radar.Actually the shape parameter of insecticide also includes the long body width ratio of body, and this there is also notable difference between different types of insecticide, if the long body width ratio of the body that can record insecticide and quality simultaneously, then can be greatly improved the entomological radar precision to caste identification.

Summary of the invention

In view of this, it is an object of the invention to provide a kind of insecticide dimension measurement method based on multifrequency scattering modeling, can utilize rotationally symmetrical dielectric ellipsoid that insecticide carries out resonance region scattering modeling, and by biological parameters such as the body length of radar inverting insecticide and body width, entomological radar target recognition and classification is significant.

A kind of insecticide dimension measurement method based on multifrequency scattering modeling, comprises the steps:

Step one, multiband scattering resonance state RCS data acquisition:

Multiband radar system is adopted to detect insecticide to be measured, it is thus achieved that the scattered signal of N number of frequency altogether, wherein, the frequency number of each wave band is not less than 10；The log-frequency that each frequency is corresponding is dBf_n=10log₁₀(f_n), f_nIt is the frequency values of the n-th frequency, n=1～N；For the n-th frequency, it is thus achieved that the Complete polarimetry matrix that insecticide to be measured is corresponding:

Wherein,For horizontal polarized components,For perpendicular polarisation components,WithFor cross polar component；

By this radar Complete polarimetry matrix S_n, substitute in following formula:

Obtain the measurement data σ of the scattering resonance state RCS maximum of the n-th frequency_max(dBf_n)；Travel through N number of Frequency point, obtain the measurement data of scattering resonance state RCS maximum corresponding to each Frequency point；

Step 2, the search based on least square meaning obtains parameter dBf respectively₀Estimation with KWithParticularly as follows:

1), difference setup parameter dBf₀With the region of search of K and scouting interval；Wherein, dBf₀Representing log-frequency during scattering resonance state RCS maximum, K is the variable of the absolute intensity affecting scattering, represents that target is at dBf₀Time scattering resonance state RCS；Utilize electromagnetic simulation software simulating insects at the scattering properties of different-waveband, the σ obtained_maxAbout the fluctuation characteristic of log-frequency dBf by following piecewise function approximate expression:

2), for each Frequency point corresponding log-frequency dBf, Selecting All Parameters dBf₀With the K one group of parameter in the respective region of search, from formula (5), find σ under current logarithmic frequency_maxCorresponding function expression, by current logarithmic frequency, the parameter dBf that chooses₀The σ found is substituted into K value_maxIn function expression, obtain the σ under current logarithmic frequency_maxValue of calculation, by the σ of the respective frequencies point that this value of calculation and step one obtain_maxMeasured value subtracts each other, and obtains error amount, then error amount is squared；Travel through all log-frequency point, obtain error amount corresponding to each Frequency point square, finally, to all error amounts square summation；

3), adopt 2) method, according to set scouting interval, in the respective region of search, constantly change dBf₀And K, obtain correspondence error amount square and value, choose and make corresponding with when being worth minimum group parameter dBf₀Estimation with KWith

Step 3, insecticide Size calculation:

By estimated resultSubstitute in following formula:

Obtain the length 2a of insecticide；

WillIt is updated in following formula:

Obtain insecticide volume V；

Calculate according to the cubature formula of ellipsoid simultaneously and obtain insecticide width 2b:

Described multiband radar system covers X-band, Ku wave band and Ka wave band, and each band is not less than 2GHz.

There is advantages that

A kind of insecticide dimension measurement method based on multifrequency scattering modeling of the present invention, the method can record body length and the body width of insecticide simultaneously, can the quality of inverting insecticide and the long body width ratio of body further based on this, the insecticide size range that the method can cover is greatly increased compared with traditional entomological radar dimension measurement method, therefore also enhances the entomological radar ability to caste identification.

Accompanying drawing explanation

Fig. 1 is list portion entomological radar Vertical Observation geometric representation.

Fig. 2 is insecticide resonance region scattering fluctuation characteristic and matching.

Fig. 3 is the long-pending emulation of different size insecticide broadband radar signal and matched curve.

Detailed description of the invention

Develop simultaneously embodiment below in conjunction with accompanying drawing, describe the present invention.

For the insecticide that build is bigger, such as loxostege sticticalis (body length 1～1.2cm), at X, Ku, Ka wave band, it is normally at resonance region, cannot be carried out Analytic modeling, therefore to insecticide with rotationally symmetrical dielectric ellipsoid model modeling, and dimensional measurement is carried out based on the rotationally symmetrical dielectric ellipsoid actual scattering properties in resonance region.

List portion radar is used to observe insecticide vertically upward, as shown in Figure 1.Generally it is believed that Migrating Insects is all flat fly motion doing, namely velocity is parallel to the ground, if insect bodies axle is in radar antenna polarization reception planeInterior projection and radar horizon polarised direction vectorAngle be α, radar vertical polarization directions vector representation is

Generally, polarization radar observes that the Complete polarimetry matrix of insecticide can be expressed as:

Wherein S_hhFor horizontal polarized components, S_vvFor perpendicular polarisation components, S_hvAnd S_vhFor cross polar component.

Assuming that polarization response matrix that radar Polarimetry obtains is such as (1) formula, rotationally symmetrical body insecticide has S_hv=S_vh, then the maximum reception polarization intensity of radar can be calculated as:

Maximum σ because of the Radar Cross Section (RCS) of insecticide_maxIt is expressed as:

σ_max=| S_max|²(3)

Emulate based on to the WB-RCS of rotationally symmetrical dielectric ellipsoid target, it is possible to approximate with power function piecewise fitting σ_maxAt the fluctuation characteristic of resonance region, represent in order to convenient, first definition decibel frequency dBf:

DBf=10 × log₁₀(f/10⁹)(4)

Wherein f is frequency, and unit is Hz.As shown in Figure 2.Utilize electromagnetic simulation software simulating insects in the scattering properties of different-waveband, find based on a large amount of emulation data analysiss, σ_maxFluctuation characteristic about dBf can be similar to by following piecewise function expression formula:

σ in above formula_maxUnit be dBsm, dBf₀Representing decibel frequency during RCS maximum, its relation with ellipsoid semi-major axis a can approximate representation be:

In other words, when body shaft length changes, σ_maxThere is the translation along frequency axis in the fluctuation characteristic in resonance region.K is the variable of the absolute intensity affecting scattering, and unit is dBsm, and it represents that target is at dBf₀Time RCS.When insecticide relative dielectric constant is determined, K and insecticide volume V (unit mm³) between relation can approximate representation be:

V=(58510 × 10^K/10-2.89)^4/3(7)

In other words, when insecticide volume changes, σ_maxThere is the translation along RCS axle in the fluctuation characteristic in resonance region.

Therefore, the invention provides a kind of insecticide dimension measurement method based on multifrequency scattering modeling, comprise the steps.

Step one, multifrequency RCS data acquisition:

Assume that multiband radar system launches the signal of N number of frequency simultaneously, it is desirable to frequency covers three wave bands of X, Ku and Ka, and each band is not less than 2G, and each wave band frequency number is not less than 10.Corresponding decibel frequency is dBf_j, j=1～N.To each frequency, we can obtain single Complete polarimetry matrix corresponding to insecticide:

Utilize polarization radar collision matrix measured value S_n, substitution (2) formula and (3) formula can obtain the rcs measurement data σ of N number of frequency_max(dBf_j), j=1～N.

Step 2, utilizes (5) formula, and the search based on least square meaning can obtain parameter dBf₀Estimation with KWith

1), dBf is set₀With the traversal of K interval and traversal interval, dBf₀Traversal interval can be determined according to the frequency range and amplitude range that obtain data respectively with K；

2), for log-frequency dBf corresponding to each Frequency point, it is chosen at one group of parameter dBf in interval range_0,pAnd K_q, from formula (5), find σ under current logarithmic frequency_maxCorresponding function expression, by current logarithmic frequency, the parameter dBf that chooses₀The σ found is substituted into K value_maxIn function expression, obtain the σ under current logarithmic frequency_maxValue of calculation, the measured value of the respective frequencies point this value of calculation and step one obtained subtracts each other, and obtains error amount, then error amount is squared；Travel through all log-frequency point, obtain error amount corresponding to each Frequency point square, finally, to all error amounts square summation:

3), adopt 2) method, according to set scouting interval, in the respective region of search, constantly change dBf₀And K, obtain correspondence error amount square and value, choose and make corresponding with when being worth minimum group parameter dBf₀Estimation with KWith

Step 3, insecticide Size calculation:

By estimated resultSubstitute in following formula:

Obtain the length 2a of insecticide；

WillIt is updated in following formula:

Obtain insecticide volume V；

Calculate according to the cubature formula of ellipsoid simultaneously and obtain insecticide width 2b:

Embodiment:

For checking aforementioned dimensions measuring method, rotationally symmetrical dielectric ellipsoid is utilized to be modeled four kinds of typical Migrating Insects (loxostege sticticalis, bollworm, mythimna separata and oryza chinensis), if being sized respectively 12mm × 2mm, 20mm × 4mm, 24mm × 4mm and 30mm × 6mm (major axis × short axle).CST is utilized to emulate the WB-RCS of four different size dielectric ellipsoids.And provide corresponding piecewise function fitting result, as shown in Figure 3.Can be seen that and can meet, to the piecewise function of definite form, the matching that different size insecticide WB-RCS is emulated data.

Point frequency RCS based on three wave bands of X, Ku and Ka emulates data, adopts a kind of insecticide dimension measurement method based on multifrequency scattering modeling of the present invention, completes the insecticide dimensional measurement emulation under this parameter, and idiographic flow is as follows:

1. assume that insect bodies direction of principal axis is parallel with horizontal polarization directions, according to (2) formula and (3) formula, it is possible to try to achieve insecticide RCS and polarize maximum (unit is dBsm) as shown in table 1.

Table 1 insecticide multifrequency RCS data

2. the RCS data given by table 1, substitute into formula (5) formula and carry out two-dimensional search, it is possible to obtain parameterEstimated result, as shown in table 2:

Table 2 parameter of curve estimated result

3. the parameter estimation result in table 2 is substituted into (6) (7) (11) formula, it is possible to try to achieve the shape parameter of insecticide, as shown in table 3.

Table 3 insecticide dimension measurement result

Can be concluded that based on above-mentioned simulation result

To various sizes of big insecticide, utilizing resonance region multifrequency point RCS data to do curve matching can effective inverting insect bodies shape parameter.

Be can be seen that by simulation result and utilize this high efficiency based on multifrequency scattering modeling method and effectiveness.Utilize this method can realize the target size measurement of entomological radar.

In sum, these are only presently preferred embodiments of the present invention, be not intended to limit protection scope of the present invention.All within the spirit and principles in the present invention, any amendment of making, equivalent replacement, improvement etc., should be included within protection scope of the present invention.

Claims (2)

1. the insecticide dimension measurement method based on multifrequency scattering modeling, it is characterised in that comprise the steps:

Step one, multiband scattering resonance state RCS data acquisition:

Multiband radar system is adopted to detect insecticide to be measured, it is thus achieved that the scattered signal of N number of frequency altogether, wherein, the frequency number of each wave band is not less than 10；The log-frequency that each frequency is corresponding is dBf_n=10log₁₀(f_n), f_nIt is the frequency values of the n-th frequency, n=1～N；For the n-th frequency, it is thus achieved that the Complete polarimetry matrix that insecticide to be measured is corresponding:

Wherein,For horizontal polarized components,For perpendicular polarisation components,WithFor cross polar component；

By this radar Complete polarimetry matrix S_n, substitute in following formula:

${\mathrm{\σ}}_{max}\left({\mathrm{dBf}}_n\right)={\left|\frac{1}{2}\left(\right|S_{hh}^n+S_{vv}^n|+\sqrt{{\left|S_{hh}^n-S_{vv}^n\right|}^2+4\left|S_{vh}^n\right|})\right|}^2$

Obtain the measurement data σ of the scattering resonance state RCS maximum of the n-th frequency_max(dBf_n)；Travel through N number of Frequency point, obtain the measurement data of scattering resonance state RCS maximum corresponding to each Frequency point；

Step 2, the search based on least square meaning obtains parameter dBf respectively₀Estimation with KWithParticularly as follows:

1), difference setup parameter dBf₀With the region of search of K and scouting interval；Wherein, dBf₀Representing log-frequency during scattering resonance state RCS maximum, K is the variable of the absolute intensity affecting scattering, represents that target is at dBf₀Time scattering resonance state RCS；Utilize electromagnetic simulation software simulating insects at the scattering properties of different-waveband, the σ obtained_maxAbout the fluctuation characteristic of log-frequency dBf by following piecewise function approximate expression:

$\begin{array}{c}{\mathrm{\&sigma;}}_{\max }=F\left(dBf\right){|}_{{\mathrm{dBf}}_0,K}\\ =\left\{\begin{array}{cc}-3.3\&times;{(dBf-{\mathrm{dBf}}_0)}^{1.5}+K& dBf\&le;{\mathrm{dBf}}_0\\ \frac{{\left|dBf-{\mathrm{dBf}}_0-3.3\right|}^{1.6}}{0.9623}+K-3.3& {\mathrm{dBf}}_0<dBf\&le;({\mathrm{dBf}}_0+3.3)\\ \frac{{\left|dBf-{\mathrm{dBf}}_0-3.3\right|}^{1.2}}{1.5513}+K-3.3& ({\mathrm{dBf}}_0+3.3)<dBf\&le;({\mathrm{dBf}}_0+4.4)\\ \begin{array}{c}-0.35\&times;dBf+K-4.7607\\ +0.35\&times;({\mathrm{dBf}}_0+4.4)\end{array}& ({\mathrm{dBf}}_0+4.4)<dBf\end{array}\right.\end{array}---\left(5\right)$

2), for each Frequency point corresponding log-frequency dBf, Selecting All Parameters dBf₀With the K one group of parameter in the respective region of search, from formula (5), find σ under current logarithmic frequency_maxCorresponding function expression, by current logarithmic frequency, the parameter dBf that chooses₀The σ found is substituted into K value_maxIn function expression, obtain the σ under current logarithmic frequency_maxValue of calculation, by the σ of the respective frequencies point that this value of calculation and step one obtain_maxMeasured value subtracts each other, and obtains error amount, then error amount is squared；Travel through all log-frequency point, obtain error amount corresponding to each Frequency point square, finally, to all error amounts square summation；

3), adopt 2) method, according to set scouting interval, in the respective region of search, constantly change dBf₀And K, obtain correspondence error amount square and value, choose and make corresponding with when being worth minimum group parameter dBf₀Estimation with KWith

Step 3, insecticide Size calculation:

By estimated resultSubstitute in following formula:

$a=70.246\&times;{10}^{-d\hat{B}{f}_0/10}+0.482---\left(6\right)$

Obtain the length 2a of insecticide；

WillIt is updated in following formula:

$V={(58510\&times;{10}^{\hat{K}/10}-2.89)}^{4/3}---\left(7\right)$

Obtain insecticide volume V；

Calculate according to the cubature formula of ellipsoid simultaneously and obtain insecticide width 2b:

$b=\sqrt{\frac{3V}{4\mathrm{\&pi;}a}}---\left(11\right).$

2. a kind of insecticide dimension measurement method based on multifrequency scattering modeling as claimed in claim 1, it is characterised in that described multiband radar system covers X-band, Ku wave band and Ka wave band, and each band is not less than 2GHz.