A Radar Echo Simulation Method Based on Layered Chalcolith Cloud Simulation

Abstract

This invention discloses a radar echo simulation method based on layered chaff cloud simulation, constructing the chaff cloud as a layered mathematical model segmented according to vertical height. The relationship between the shape parameters of the chaff layers and the chaff scattering coefficient is studied, solving the problems of excessive chaff unit numbers and slow computation speed caused by traditional ellipsoidal modeling based on small cube equivalents. First, the chaff cloud is divided into chaff units at different heights according to its density; second, the relationship between the shape of the chaff unit and the radar scattering coefficient is considered; finally, the echo signal generated by the motion law corresponding to the chaff unit is modeled, and the signals of the overall chaff units are superimposed to obtain the final echo. This invention only requires estimating the shape and size of the chaff cloud, thus achieving fast and accurate simulation of radar echoes from chaff clouds.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar echo simulation, and particularly relates to a radar echo simulation method based on layered chaff cloud simulation. BACKGROUND

[0002] Radar is widely used in the field of people's livelihood such as weather prediction and air traffic control, and it perceives the target azimuth and distance by periodically transmitting and receiving electromagnetic waves. Radar is easily disturbed by flying birds and cloud clusters, and even balloons, which are artificial interference, affecting the detection performance. Chaff is a typical artificial jammer, which can be used for radar performance test. Chaff simulation modeling is often used in radar digital signal processing simulation environment because of the advantages of simple manufacturing, convenient use, fast production, mature technology, good interference effect and large range of action. After the chaff device is launched, it will form a chaff cloud with a radar cross section several times larger than the target. Therefore, how to construct the chaff cloud to quickly simulate the interference target has become an important research direction in radar signal processing. The existing chaff simulation echo simulation technology uses a large number of small cubes to simulate the superposition of the delay frequency shift and other echo signals of the chaff cloud in different distance units of the radar, resulting in great calculation consumption.

[0003] In order to solve the above problems, the layered calculation is combined with the shape characteristics of the chaff cloud and the wavelength characteristics of the radar signal, so that the interaction and dynamic change of the chaff cloud inside can be better considered, and the reflection coefficient of the chaff is simulated and calculated as a whole, thereby improving the accuracy of the calculation result and saving the calculation cost. SUMMARY

[0004] The application proposes a radar echo simulation method based on layered chaff cloud simulation, which simulates and calculates the reflection coefficient of the chaff as a whole, improves the accuracy of the calculation result and saves the calculation cost.

[0005] The technical solution of the application is as follows: a radar echo simulation method based on layered chaff cloud simulation, comprising the following steps:

[0006] Step 1, defining a plurality of chaffs as a chaff unit body, a plurality of chaff unit bodies as a chaff cloud layer, and a plurality of chaff cloud layers as a chaff cloud, determining the parameters of the chaff cloud, including length, width, height, and corresponding long axis, short axis, and height of the ellipsoid.

[0007] Step 2, according to the reflection characteristics of a single chaff in the chaff cloud and the position difference of each chaff in the chaff cloud, establishing a layered mathematical model of the chaff cloud, selecting a cluster of parallel horizontal planes as the cutting surface, and dividing the ellipsoid into a plurality of elliptical slices, each elliptical slice representing a chaff cloud layer.

[0008] Step 3, according to the single foil strip parameter, a mathematical relationship between the RCS of the single foil strip and the radar echo polarization mode, frequency is established.

[0009] Step 4, according to the density distribution of the cut foil cloud layer, the mathematical relationship between the number of foils in each foil unit body in the foil cloud layer and the length of the single foil and the echo wavelength is calculated, and the mathematical relationship between the RCS of each foil unit body and the single foil is calculated according to the influence of the surrounding foils on the center foil in the foil unit body and the mathematical relationship between the RCS of the single foil and the radar echo polarization mode, frequency established in step 3.

[0010] Step 5, according to the RCS of each foil unit body obtained in step 4, the RCS of each foil cloud layer is obtained.

[0011] Step 6, according to the echo signal and the RCS of each foil cloud layer, the total echo signal of the foil cloud is calculated.

[0012] Compared with the prior art, the present application has the following advantages: through layered calculation, the interaction and dynamic change inside the foil cloud can be better considered, thereby improving the accuracy of the calculation result. The calculation complexity can be effectively reduced, because each layer can be regarded as a relatively independent system, facilitating parallel processing and optimization, and having obvious advantages when the number of foils is large. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The flow chart of the echo generation simulation of the layered model of the foil cloud of the present application is shown.

[0014] Figure 2 The diagram of the ellipsoid layered model of the foil cloud of the present application is shown. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0016] For those skilled in the art, the specific meanings of the above-mentioned terms in the present application can be understood according to specific circumstances.

[0017] In addition, the technical solutions of the various embodiments of the present application can be combined with each other, but it must be based on the fact that those skilled in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0018] The technical difficulties and inventive points of the specific embodiments and the present application will be further described in combination with the design examples below.

[0019] In combination Figure 1 and Figure 2 A radar echo simulation method based on layered chaff cloud simulation includes the following steps:

[0020] Step 1, determine the parameters of the chaff cloud, including length, width, height, and the corresponding long axis, short axis, and height of the ellipsoid, as follows:

[0021] After the chaff cloud is spread out, it is simulated as a symmetric and uniform ellipsoidal chaff cloud, with a long axis a, a short axis b, and a height c, and a wind speed drift speed v.

[0022] Step 2, according to the reflection characteristics of a single chaff in the chaff cloud unit and the position difference between each chaff, a cluster of planes parallel to the horizontal plane is selected as the cutting plane, and the plane is divided according to the height of the chaff distribution, and the ellipsoid is divided into multiple elliptical slices, each of which represents a chaff cloud layer.

[0023] Step 3, according to the parameters of a single chaff, a mathematical relationship between the RCS of a single chaff and the radar echo polarization mode and frequency is established, as follows:

[0024] The average RCS of a single chaff under each polarization mode is obtained, and its expression is

[0025]

[0026] where σ hh is the RCS of a single chaff corresponding to the horizontal polarization scattering field generated by the horizontal polarization incident wave, σ vv is the RCS of a single chaff corresponding to the vertical polarization scattering field generated by the vertical polarization incident wave, σ hv is the RCS of a single chaff corresponding to the vertical polarization scattering field generated by the horizontal polarization incident wave, σ cc is the RCS of a single chaff corresponding to the circular polarization scattering field generated by the circular polarization incident wave, σ hc is the RCS of a single chaff corresponding to the circular polarization scattering field generated by the horizontal polarization incident wave, σ vc is the RCS of a single chaff corresponding to the circular polarization scattering field generated by the vertical polarization incident wave, and λ is the echo wavelength.

[0027] Step 4, according to the density distribution of the chaff cloud, the mathematical relationship between the number of chaffs in each chaff unit and the length of a single chaff and the echo wavelength is calculated, as follows:

[0028] The foil cloud layer density function is constructed. Since the height cutting plane is according to the foil distribution, the foil density distribution form presents Gaussian curve characteristics in the height axis direction, that is, the density gradually decreases from the middle to both sides in the ellipsoid, so that the number n of foils inside the corresponding slice foil unit body λ For

[0029] n λ = ρ·2λ 2 ·l (2)

[0030] Wherein, λ is the echo wavelength, l is the foil length, ρ is the number of foils in the unit area of the current foil unit body layer, which obeys the Gaussian density distribution function.

[0031] According to the influence of the surrounding foils in the foil unit body on the center foil, the RCS expression of the foil unit body, that is, the rcs of the foil unit body, is constructed.

[0032]

[0033] σ is the RCS of a single foil, λ is the echo wavelength, n λ is the number of foils in the foil unit body.

[0034] Step 5, according to the rcs of each foil unit body obtained in step 4, the RCS of each foil cloud layer is obtained, which is as follows:

[0035] The total foil cloud RCS value of the i-th layer is RCS i :

[0036] RCS i = rcs·f N (4)

[0037] Wherein, f N is the number of foil unit bodies contained by each layer of foils, which is the thickness value corresponding to each layer of foils.

[0038] Step 6, according to the echo signal and the RCS of each layer of foil cloud, the total echo signal is calculated by superposition:

[0039] According to the echo signal and the RCS of each foil cloud layer in step 5, the corresponding echo S i (t) caused by the wind speed of the i-th layer of foil cloud is obtained:

[0040]

[0041] Wherein, f c is the signal frequency, f d is the velocity Doppler shift, τ i is the time delay of the lightning to the i-th layer of foil cloud;

[0042] The final all-layer summation echo signal matrix S is obtained;

[0043]

[0044] where j denotes imaginary part and t denotes time.

Claims

1. A method of radar return simulation based on layered cloud of dipoles simulation, characterized in that, The method comprises the following steps: Step 1, define a plurality of foil strips to constitute a foil strip unit, a plurality of foil strip units constitute a foil strip cloud layer, a plurality of foil strip cloud layers constitute a foil strip cloud, determine the parameters of the foil strip cloud, including length, width, height, and the corresponding long axis, short axis, height of the ellipsoid; Step 2, according to the reflection characteristics of the single foil strip in the foil strip cloud and the position difference of each foil strip in the foil strip cloud, a mathematical model of the foil strip cloud is established, a cluster of parallel horizontal planes is selected as the cutting surface, and the ellipsoid is divided into a plurality of elliptical slices, each elliptical slice represents a foil strip cloud layer; Step 3, according to the parameters of the single foil strip, a mathematical relationship between the RCS of the single foil strip and the radar echo polarization mode and frequency is established; Step 4, according to the density distribution of the cut foil strip cloud layer, the mathematical relationship between the number of foil strips in each foil strip unit and the length of the single foil strip and the echo wavelength is calculated, and according to the influence of the surrounding foil strips on the center foil strip in the foil strip unit and the mathematical relationship between the RCS of the single foil strip and the radar echo polarization mode, frequency and mathematical relationship established in step 3, the mathematical relationship between the RCS of each foil strip unit and the single foil strip is calculated; Step 5, according to the RCS of each foil strip unit obtained in step 4, the RCS of each foil strip cloud layer is obtained; Step 6, according to the echo signal and the RCS of each foil strip cloud layer, the total echo signal of the foil strip cloud is calculated.

2. The method according to claim 1, wherein, In step 1, the parameters of the foil strip cloud are determined, including length, width, height, and the corresponding long axis, short axis, height of the ellipsoid, which are as follows: After the foil strip cloud is spread out, it is simulated as a symmetric and uniform ellipsoidal foil strip cloud, the long axis is a, the short axis is b, the height is c, and the wind speed drift speed is v.

3. The method according to claim 2, characterized in that, In step 2, according to the reflection characteristics of the single foil strip in the foil strip cloud and the position difference of each foil strip in the foil strip cloud, a mathematical model of the foil strip cloud is established, a cluster of parallel horizontal planes is selected as the cutting surface, and the ellipsoid is divided into a plurality of elliptical slices, each elliptical slice represents a foil strip cloud layer.

4. The method according to claim 3, characterized in that, In step 3, according to the parameters of the single foil strip, a mathematical relationship between the RCS of the single foil strip and the radar echo polarization mode and frequency is established, which is as follows: The average RCS of the single foil strip under each polarization mode is obtained, and its expression is where σ hh is the RCS of a single strip corresponding to the horizontally polarized scattering field produced by a horizontally polarized incident wave, σ vv is the RCS of a single strip corresponding to the vertically polarized scattering field produced by a vertically polarized incident wave, σ hv is the RCS of a single strip corresponding to the vertically polarized scattering field produced by a horizontally polarized incident wave, σ cc is the RCS of a single strip corresponding to the circularly polarized scattering field produced by a circularly polarized incident wave, σ hc is the RCS of a single strip corresponding to the circularly polarized scattering field produced by a horizontally polarized incident wave, σ vc is the RCS of a single strip corresponding to the circularly polarized scattering field produced by a vertically polarized incident wave, and λ is the wavelength of the return.

5. The method according to claim 4, characterized in that, In step 4, the mathematical relationship between the number of foil strips in each foil strip unit and the length of the single foil strip and the echo wavelength is calculated according to the density distribution of the foil strip cloud, which is as follows: The layered density function of the foil cloud is constructed. Since the height cutting plane is according to the foil distribution, the foil density distribution shape presents Gaussian curve characteristics in the height axis direction, that is, the density gradually decreases from the middle to both sides in the ellipsoid, so that the number n of foils inside the foil unit body corresponding to the cutting plane λ is n λ = p - 2l 2 · l (2) Wherein, λ is the echo wavelength, l is the foil strip length, ρ is the number of foil strips in the unit area of the current foil strip unit, which obeys the Gaussian density distribution function; According to the influence of the surrounding foil strips on the center foil strip in the foil strip unit, the RCS expression of the foil strip unit is constructed, that is, the RCS of the foil strip unit rcs: σ is the RCS of a single foil strip, n λ is the number of foil strips within the foil unit.

6. The method according to claim 5, wherein, In step 5, according to the rcs of each foil strip unit obtained in step 4, the RCS of each foil strip cloud layer is obtained, which is as follows: Total foil cloud layer RCS value for the ith layer, RCS i : RCS i = rcs f N (4) wherein f N the number of foil units contained in each layer of foil strip, which is the thickness value corresponding to each layer of foil strip.

7. The method according to claim 1, wherein, In step 6, the corresponding echo S caused by the wind speed of the i-th chaff cloud layer is calculated according to the echo signal and the RCS of each chaff cloud layer in step 5 i (t): where f c is the signal frequency, f d is the velocity Doppler shift, τ i is the time delay for the lightning to reach the i-th layer of the foil cloud; All layers are obtained to add up the echo signal matrix S; Wherein, j represents the imaginary part, t represents time.

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