Radar echo simulation method based on layered chaff cloud simulation

Abstract

The invention discloses a radar echo simulation method based on layered chaff cloud simulation. A chaff cloud is constructed into a layered mathematical model segmented according to the vertical height. The relation between chaff layering shape parameters and chaff scattering coefficients is studied, and the problems that the number of chaff units is too large and the operation speed is low due to the fact that a traditional ellipsoid is modeled equivalently according to a small cube are solved. Firstly, chaff unit bodies with different heights are divided according to chaff cloud density; secondly, considering a mutual relation between the shape of the chaff unit body and a radar scattering coefficient; and finally, modeling echo signals generated by the motion rules corresponding to the chaff units, and performing signal superposition on the overall chaff units to obtain final echoes. According to the method, only the shape and the size of the chaff cloud need to be estimated, so that the radar echo of chaff cloud simulation can be quickly and accurately simulated.

Description

Technical Field

[0001] The invention belongs to the technical field of radar echo simulation, and in particular relates to a radar echo simulation method based on layered foil cloud simulation. Background Art

[0002] Radar is widely used in the fields of weather forecasting and air traffic control, etc. It senses the target's direction and distance by periodically transmitting and receiving electromagnetic waves. Radar is susceptible to natural interference from birds and clouds, and even artificial interference such as balloons, which affects detection performance. Chaff is a typical artificial jammer and can be used for radar performance testing. Chaff itself has the advantages of simple manufacturing, convenient use, fast production speed, mature technology, good jamming effect, and large range of action. Chaff simulation modeling is often used in radar digital signal processing simulation environment, which is an effective measure to improve radar performance and reduce development costs. After the chaff device is launched, a chaff cloud with a radar reflection cross-sectional area several times that of the target will be formed. Therefore, how to construct a chaff cloud to quickly simulate the jamming 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 echo signals such as delay and frequency shift of the chaff cloud at different distance units of the radar, resulting in great computational consumption.

[0003] In order to solve the above problems, the present invention uses hierarchical calculation, combines the shape characteristics of the foil cloud and the wavelength characteristics of the radar signal, can better consider the interaction and dynamic changes inside the foil cloud, and simulate and calculate the reflection coefficient of the foil as a whole, thereby improving the accuracy of the calculation results and saving calculation overhead. Summary of the invention

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

[0005] The technical solution to realize the present invention is: a radar echo simulation method based on layered foil cloud simulation, the steps are as follows:

[0006] Step 1, define that multiple foil strips constitute a foil strip unit body, multiple foil strip unit bodies constitute a foil strip cloud layer, and multiple foil strip cloud layers constitute a foil strip cloud, and determine the parameters of the foil strip cloud, including length, width, height, and the major axis, minor axis, and height of the corresponding ellipsoid.

[0007] Step 2, based on the reflection characteristics of a single foil strip in the foil strip cloud and the position differences of each foil strip in the foil strip cloud, a layered mathematical model of the foil strip cloud is established, a cluster of planes parallel to the horizontal plane are selected as cutting planes, and the ellipsoid is divided into multiple elliptical slices, each of which represents a foil strip cloud layer.

[0008] Step 3: Based on the parameters of a single foil strip, establish the mathematical relationship between the RCS of a single foil strip and the polarization mode and frequency of the radar echo.

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

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

[0011] Step 6, based on the echo signal and the RCS of each chaff cloud layer, the overall echo signal of the chaff cloud is calculated by superposition.

[0012] Compared with the prior art, the present invention has the following significant advantages: through layered calculation, the interaction and dynamic changes within the foil cloud can be better considered, thereby improving the accuracy of the calculation results. The calculation complexity can be effectively reduced because each layer can be regarded as a relatively independent system, which is convenient for parallel processing and optimization, especially when the number of foil strips is large. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a simulation flow chart for echo generation of the foil cloud layering model of the present invention.

[0014] Figure 2 This is a diagram of the ellipsoidal layering model of the foil cloud of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0017] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0018] The following will further introduce the specific implementation method, as well as the technical difficulties and inventive points of this invention in combination with this design example.

[0019] Combination Figure 1 and Figure 2 , a radar echo simulation method based on layered chaff cloud simulation, comprising the following steps:

[0020] Step 1, determine the parameters of the foil cloud, including length, width, height, and the corresponding major axis, minor axis, and height of the ellipsoid, as follows:

[0021] After the foil strip cloud is spread out, it is simulated as a symmetrical and uniform ellipsoid foil strip cloud with a major axis of a, a minor axis of b, a height of c, and a drift speed of v with the wind speed.

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

[0023] Step 3: Based on the parameters of a single foil strip, establish the mathematical relationship between the RCS of a single foil strip and the polarization mode and frequency of the radar echo, as follows:

[0024] Get the average RCS of a single foil strip in each polarization mode, and its expression is:

[0025]

[0026] Among them, σ hh The RCS of a single foil strip corresponding to the horizontally polarized scattered field generated by the horizontally polarized incident wave, σ vv The RCS of a single foil strip corresponding to the vertically polarized incident wave generating the vertically polarized scattered field is σ hv is the RCS value of a single foil strip corresponding to the vertically polarized scattering field generated by the horizontally polarized incident wave, σ cc The RCS of a single foil strip corresponding to the circularly polarized incident wave generating a circularly polarized scattered field, σ hc is the RCS of a single foil strip corresponding to the circularly polarized scattered field generated by the horizontally polarized incident wave, σ vc The RCS of a single foil strip corresponding to the circularly polarized scattering field generated by vertically polarized emission, λ is the echo wavelength.

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

[0028] Constructing the layered density function of the foil cloud, since the plane is divided according to the height of the foil distribution, the foil density distribution in the height axis direction presents a Gaussian curve characteristic, that is, the density gradually decreases from the middle to the sides of the ellipsoid, so the number of foil strips inside the corresponding sliced ​​foil strip unit body n λ for

[0029] n λ =ρ·2λ 2 ·l (2)

[0030] Among them, λ is the echo wavelength, l is the foil strip length, and ρ is the number of foil strips per unit area of ​​the layer where the current foil strip unit body is located, which obeys the Gaussian density distribution function.

[0031] According to the influence of surrounding foil strips on the central foil strip in the foil strip unit body, the RCS expression of the foil strip unit body is constructed, that is, the rcs of the foil strip unit body:

[0032]

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

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

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

[0036] RCS i = rcs·f N (4)

[0037] Among them, f N is the number of foil strip units contained in each layer of foil strip, and is the thickness value corresponding to each layer of foil strip.

[0038] Step 6, based on the echo signal and the RCS of each layer of foil cloud, the overall 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 caused by the wind speed of the i-th foil cloud layer is obtained. i (t):

[0040]

[0041] Among them, f c is the signal frequency, f d is the velocity Doppler shift, τ i is the time delay of the radar reaching the i-th layer of chaff cloud;

[0042] Finally, the superimposed echo signal matrix S of all layers is obtained;

[0043]

[0044] Wherein, j represents the imaginary part and t represents time.

Claims

1. A radar echo simulation method based on layered chaff cloud simulation, characterized in that: The following steps are involved: Step 1, defining that a plurality of foil strips constitute a foil strip unit body, a plurality of foil strip unit bodies constitute a foil strip cloud layer, a plurality of foil strip cloud layers constitute a foil strip cloud, and determining the parameters of the foil strip cloud, including length, width, height, and the major axis, minor axis, and height of the corresponding ellipsoid; Step 2, according to the reflection characteristics of a single foil strip in the foil strip cloud and the position difference of each foil strip in the foil strip cloud, a layered mathematical model of the foil strip cloud is established, a cluster of planes parallel to the horizontal plane is selected as a cutting plane, and the ellipsoid is divided into a plurality of elliptical slices, each of which represents a foil strip cloud layer; Step 3, based on the parameters of a single foil strip, establish a mathematical relationship between the RCS of a single foil strip and the polarization mode and frequency of the radar echo; Step 4, according to the density distribution of the cut foil cloud layer, calculate the mathematical relationship between the number of foil strips of each foil strip unit body in the foil strip cloud layer and the length of a single foil strip and the wavelength of the echo, and calculate the mathematical relationship between the RCS of each foil strip unit body and the single foil strip according to the influence of the surrounding foil strips in the foil strip unit body on the central foil strip and the RCS of the single foil strip established in step 3 and the polarization mode, frequency, and mathematical relationship of the radar echo; Step 5, obtaining the RCS of each foil cloud layer according to the RCS of each foil unit obtained in step 4; Step 6, based on the echo signal and the RCS of each chaff cloud layer, the overall echo signal of the chaff cloud is calculated by superposition.

2. A radar echo simulation method based on layered chaff cloud simulation according to claim 1, characterized in that: In step 1, the parameters of the foil cloud are determined, including length, width, height, and the major axis, minor axis, and height of the corresponding ellipsoid, as follows: After the foil strip cloud is spread out, it is simulated as a symmetrical and uniform ellipsoid foil strip cloud with a major axis of a, a minor axis of b, a height of c, and a drift speed of v with the wind speed.

3. A radar echo simulation method based on layered chaff cloud simulation according to claim 2, characterized in that, In step 2, a layered mathematical model of the foil cloud is established based on the reflection characteristics of a single foil strip in the foil cloud and the position differences of each foil strip in the foil cloud. A cluster of planes parallel to the horizontal plane are selected as cutting planes, and the planes are divided according to the height of the foil strip distribution. The ellipsoid is divided into multiple elliptical slices, and each elliptical slice represents a foil cloud layer.

4. A radar echo simulation method based on layered chaff cloud simulation according to claim 3, characterized in that: In step 3, based on the parameters of a single foil strip, a mathematical relationship between the RCS of a single foil strip and the polarization mode and frequency of the radar echo is established, as follows: Get the average RCS of a single foil strip in each polarization mode, and its expression is: Among them, σ hh The RCS of a single foil strip corresponding to the horizontally polarized scattered field generated by the horizontally polarized incident wave, σ vv The RCS of a single foil strip corresponding to the vertically polarized incident wave generating the vertically polarized scattered field is σ hv is the RCS value of a single foil strip corresponding to the vertically polarized scattering field generated by the horizontally polarized incident wave, σ cc The RCS of a single foil strip corresponding to the circularly polarized incident wave generating a circularly polarized scattered field, σ hc is the RCS of a single foil strip corresponding to the circularly polarized scattered field generated by the horizontally polarized incident wave, σ vc The RCS of a single foil strip corresponding to the circularly polarized scattering field generated by vertically polarized emission, λ is the echo wavelength.

5. A radar echo simulation method based on layered chaff cloud simulation 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 a single foil strip and the echo wavelength is calculated according to the density distribution of the foil strip cloud, as follows: Constructing the layered density function of the foil cloud, since the plane is divided according to the height of the foil distribution, the foil density distribution in the height axis direction presents a Gaussian curve characteristic, that is, the density gradually decreases from the middle to the sides of the ellipsoid, so the number of foil strips inside the corresponding sliced ​​foil strip unit body n λ for n λ =p·2l 2 ·l (2) Among them, λ is the echo wavelength, l is the foil strip length, ρ is the number of foil strips per unit area of ​​the layer where the current foil strip unit body is located, which obeys the Gaussian density distribution function; According to the influence of surrounding foil strips on the central foil strip in the foil strip unit body, the RCS expression of the foil strip unit body is constructed, that is, the rcs of the foil strip unit body: σ is the RCS of a single foil strip, n λ is the number of foil strips in the foil strip unit.

6. A radar echo simulation method based on layered chaff cloud simulation according to claim 5, characterized in that: In step 5, the RCS of each foil strip cloud layer is obtained according to the RCS of each foil strip unit obtained in step 4, as follows: RCS value of the total foil cloud layer in the i-th layer i : RCS i =rcs·f N (4) Among them, f N is the number of foil strip units contained in each layer of foil strip, and is the thickness value corresponding to each layer of foil strip.

7. A radar echo simulation method based on layered chaff cloud simulation according to claim 1, characterized in that: In step 6, according to the echo signal and the RCS of each foil cloud layer in step 5, the corresponding echo S of the i-th foil cloud layer caused by the wind speed is obtained. i (t): Among them, f c is the signal frequency, f d is the velocity Doppler shift, τ i is the time delay of the radar reaching the i-th layer of chaff cloud; Obtain the stacked echo signal matrix S of all layers; Among them, j represents the imaginary part and t represents time.

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