Radar signal transmission environment modeling method

Abstract

The invention belongs to the field of computer application, and discloses a radar signal transmission environment modeling method, which comprises the following steps: (10) transmission environment data service including atmospheric environment data and terrain environment data, describing environment static attributes, and providing data query and calculation service; and (20) atmospheric environment transmission modeling: modeling the transmission process of the radar signal in the atmospheric environment. And (30) topographic environment transmission modeling: modeling the transmission process of the radar signal in the topographic environment. And (40) constructing a comprehensive transmission environment: comprehensively considering various transmission effects and mutual influence thereof, and constructing the comprehensive transmission environment. According to the method, various transmission effect mechanisms of radar signals are modeled and analyzed, a comprehensive and universal simulation radar signal transmission environment can be provided for radar electronic warfare simulation, and the reliability of radar electronic warfare simulation is improved.

Description

Technical Field

[0001] The invention belongs to the field of computer application and discloses a radar signal transmission environment modeling method. Background Art

[0002] The battlefield environment of future information warfare is very complex. Modern electronic warfare systems have developed from single electronic warfare equipment to multi-platform, multi-means, and multi-functional integrated systems. Radar electronic warfare has also developed from one-on-one equipment confrontation to system-to-system and system-to-system confrontation. Due to the complex structure and numerous functions of the electronic warfare system, and its close integration with the main combat weapons, it is difficult to comprehensively evaluate the actual effectiveness of the radar electronic warfare system in combat by relying on limited exercises and training. Exercises and training have the defects of being time-consuming, expensive, poorly confidential, easily restricted by the environment, and non-repeatable test results. Therefore, using computer simulation technology to simulate and evaluate the effectiveness of radar electronic warfare systems is a practical, flexible and convenient way.

[0003] The radar system works in a specific environment. The use of simulation technology for the development, testing and evaluation of radar electronic warfare systems must also provide a corresponding simulated radar signal transmission environment. Therefore, the radar electronic warfare simulation system includes not only the modeling and simulation of the radar system itself, but also the modeling and simulation of the radar signal transmission environment. Transmission environment modeling includes two parts. One part is the description of the physical state of the environment, such as atmospheric pressure, terrain height, etc.; the other part is the impact of the environment on radar signal transmission, such as atmospheric absorption, multipath, etc., which is called the transmission effect. Whether a realistic radar signal transmission environment can be constructed directly affects the confidence of the entire radar electronic warfare simulation system. Summary of the invention

[0004] In view of the above background, the present invention proposes a radar signal transmission environment modeling method. This method aims to provide a comprehensive and universal simulated radar signal transmission environment for radar electronic warfare simulation by modeling and analyzing various transmission effect mechanisms of radar signals, so that the influence of environmental factors on radar signal transmission can be reflected and the reliability of radar electronic warfare simulation can be improved.

[0005] The present invention implements a radar signal transmission environment modeling method through the following technical scheme, comprising the following steps:

[0006] (10) Transmission of environmental data services: including atmospheric environmental data and terrain environmental data, describing the static properties of the environment through atmospheric models and digital terrain elevation data (DTED), and providing data query and calculation services.

[0007] (20) Atmospheric environment transmission modeling: Modeling the transmission process of radar signals in the atmospheric environment, including the calculation of free space propagation loss, atmospheric absorption loss, and atmospheric refraction effect.

[0008] (30) Terrain environment transmission modeling: Modeling the transmission process of radar signals in terrain environment, including the calculation of multipath effect and diffraction effect.

[0009] (40) Construction of comprehensive transmission environment: Taking into account the above transmission effects and their mutual influence, a comprehensive transmission environment is constructed.

[0010] The beneficial effect of the present invention is that, by constructing a transmission environment data service, the attributes and behaviors of the environment object itself are separated and modeled separately, and the centralized processing of signal transmission is realized, thereby ensuring the consistency of the transmission effect. At the same time, by modeling the transmission effect based on the principle, a comprehensive and universal radar signal transmission environment model is constructed, which can more accurately simulate the propagation path of the radar signal under real atmospheric conditions, as well as the influence of atmospheric refraction, scattering, reflection and shielding of the signal by the terrain, and improve the reliability of the radar electronic warfare simulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The steps of the method of the present invention are shown in FIG.

[0012] Figure 2 Flowchart for 2D terrain profile analysis of propagation path

[0013] Figure 3 SEKE algorithm flow chart

[0014] Figure 4 Constructing a flow chart for an integrated transport environment DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] like Figure 1 As shown, the present invention proposes a radar signal transmission environment modeling method, and its specific steps are as follows:

[0017] (10) Transmission of environmental data services: including atmospheric environmental data and terrain environmental data, describing the static properties of the environment through atmospheric models and digital terrain elevation data (DTED), and providing data query and calculation services.

[0018] (20) Atmospheric environment transmission modeling: Modeling the transmission process of radar signals in the atmospheric environment, including the calculation of free space propagation loss, atmospheric absorption loss, and atmospheric refraction effect.

[0019] (30) Terrain environment transmission modeling: Modeling the transmission process of radar signals in terrain environment, including the calculation of multipath effect and diffraction effect.

[0020] (40) Construction of comprehensive transmission environment: Taking into account the above transmission effects and their mutual influence, a comprehensive transmission environment is constructed.

[0021] The specific steps of the above (10) transmission of environmental data service are as follows:

[0022] (11) Atmospheric environment data preprocessing: The tropospheric atmospheric model is used to describe the relationship between tropospheric atmospheric pressure P, temperature T, water vapor density ρ and altitude, as follows:

[0023]

[0024]

[0025] Where R0 is the radius of the earth, h is the height, T is the temperature (K), α = 52561222, β = 0.034164794. The water vapor density is

[0026]

[0027] Among them, c0 = 5.96846604178320, c1 = -2.01631818815704, c2 = 0.26216323902426, c3 = -0.01627098273146, c4 = 0.00047861265798, c5 = -0.00000528421124

[0028] According to the above model, the atmospheric environment data table of each altitude is generated in turn according to the specified sampling interval, such as 100m.

[0029] (12) Terrain environment preprocessing: DTED data is used to describe terrain height. DTED is a grid-type data that records ground height data at certain intervals. It is divided into three levels: 0, 1, and 2, with increasing accuracy. Level 0 data is open to the public, and its accuracy corresponds to 30 seconds in the longitude and latitude coordinate system. Two-dimensional bilinear interpolation is used to improve the accuracy of DTED data, and the height of any point can be calculated as follows:

[0030] For z(x, y), select the four nearest grid nodes {z(x k ,y k )|k=j,j+1,x j <x <x j +1,y j <y <y j+1},have

[0031]

[0032] (13) Coordinate system conversion: Provides coordinate system conversion methods, including geodetic coordinate system, station-centered horizontal coordinate system, and earth-centered earth-fixed coordinate system, and their mutual conversion. Specifically, it includes the conversion of geodetic coordinate system to earth-centered earth-fixed coordinate system and its inverse conversion, the conversion of station-centered horizontal coordinate system to earth-centered earth-fixed coordinate system and its inverse conversion, so as to realize the mutual conversion between any two coordinate systems, as described below:

[0033] Conversion from geodetic coordinate system to center-fixed coordinate system:

[0034] Let the coordinates of the point P(L, B, H) in the geodetic coordinate system be (X, Y, Z), then

[0035]

[0036]

[0037] Among them, a=6378137 is the semi-major axis of the earth, and e=0.0167 is the eccentricity of the earth.

[0038] Its inverse transformation is

[0039]

[0040] For B, an iterative method can be used to obtain it.

[0041] Earth-centered horizontal coordinate system and Earth-centered earth-fixed coordinate system

[0042] Let the geodetic coordinates of the station center be (L, B, H), and the corresponding earth-fixed coordinates of the center be (X P , Y P , Z P ), a point P(x, y, z) in the Earth-centered horizontal coordinate system, its coordinates in the Earth-centered Earth-fixed coordinate system are (X, Y, Z), and the transformation matrix M is defined as

[0043]

[0044] Among them, T is the translation matrix, R is the rotation matrix, and the vector is defined but

[0045]

[0046] Its inverse transformation is

[0047] K=M -1 L

[0048] (14) Analysis of two-dimensional terrain profile of propagation path: Analyze the two-dimensional terrain on the propagation path based on the propagation path and terrain environment data, and calculate the minimum clearance and the width of the first Fresnel zone, such as Figure 2 As shown, the specific steps are:

[0049] 1) Direct path generation: Calculate the longitude and latitude of each sampling point on the straight path from the radar to the target;

[0050] 2) Calculation of two-dimensional terrain: Calculate the elevation of each sampling point on the straight line path from the radar to the target to obtain the two-dimensional terrain;

[0051] 3) Minimum clearance analysis: Find the minimum clearance point M and the minimum clearance δ;

[0052] 4) Calculate the width of the first Fresnel zone: Calculate the distances r1 and r2 from point M to the radar and the target, and calculate the width of the first Fresnel zone λ is the wavelength.

[0053] The specific steps of the atmospheric environment transmission modeling mentioned above (20) are:

[0054] (21) Free space propagation model: It describes the loss caused by diffusion when the radar signal propagates in free space and is expressed by the following formula:

[0055]

[0056] Among them, d is the transmission distance, λ is the wavelength of the radar signal, and f is the frequency.

[0057] (22) Atmospheric absorption model: It describes the loss caused by the absorption of electromagnetic waves by oxygen molecules (O2) and water vapor molecules (H2O) in the atmosphere, and is expressed by the following formula:

[0058]

[0059] in, is the oxygen molecule absorption factor, unit is dB / m, Water vapor molecular absorption factor, unit is dB / m.

[0060] (23) Atmospheric refraction effect model: describes the propagation trajectory of radar signals under the influence of atmospheric refraction effect. Since the refractive index of the atmosphere changes with altitude, the propagation path of the radar signal bends.

[0061] According to the geometric relationship, the geocentric angle between the radar and the target is

[0062]

[0063] Where a is the radius of the earth, h O is the radar altitude, hT is the target altitude, R d is the straight-line distance between the radar and the target.

[0064] According to the radio wave propagation theory,

[0065]

[0066] Where n(h) is the atmospheric refractive index at h. Combining the above two equations, we can find θ0.

[0067] make

[0068]

[0069] By dividing the geocentric angle m into equal parts, the propagation trajectory is discretized, and then we have

[0070]

[0071] h can be obtained i , combined with the spherical longitude and latitude calculation method, the longitude and latitude p of the discrete points of the propagation trajectory can be obtained i , so the radar signal propagation trajectory is {(p i ,h i )|i=1,2,...,m}.

[0072] The specific steps of the terrain environment modeling (30) above are:

[0073] (31) Multipath effect model: describes the process in which radar signals travel through multiple paths to the target due to reflections from the ground or sea surface and interference occurs during the propagation of radar signals. It is characterized by the pattern propagation factor, as follows:

[0074]

[0075] Among them, G D is the antenna gain in the target direction, f j is the voltage at the jth reflection point, and N is the number of reflection points.

[0076] (32) Diffraction effect model: describes the process of radar signals bypassing obstacles and propagating to the shielded area when encountering obstacles. Depending on the obstacles, the diffraction effect model includes spherical earth diffraction and edge diffraction, which are characterized by the directional pattern propagation factor, as follows:

[0077] Spherical Earth Diffraction:

[0078]

[0079] If the target is not obscured, is the antenna gain in the target direction, otherwise it is the antenna gain in the direction of the highest shielding point, F(x, y, z) is the Fock's series, x, y, z are the normalized ground distance from the radar to the target, the radar effective height, and the target effective height, respectively.

[0080] Edge diffraction:

[0081]

[0082] If the target is not obscured, is the antenna gain in the target direction, otherwise it is the antenna gain in the direction of the highest shielding point, F L is the left edge peak propagation factor, F M is the main edge propagation factor, F R is the right edge peak propagation factor.

[0083] (33) Comprehensive effect model: In actual practice, the multipath effect and diffraction effect are mutually exclusive. The comprehensive effect model takes these two effects into consideration and uses the SEKE algorithm to construct the comprehensive effect model. Figure 3 As shown, the details are as follows:

[0084]

[0085]

[0086] Among them, a M =4p-2, F M , F K , F S They come from the multipath model, the blade peak diffraction model and the spherical earth diffraction model respectively.

[0087] The above (40) comprehensive transmission environment is constructed as follows Figure 4 As shown, the specific steps are:

[0088] (41) Pre-generation of atmospheric absorption factor data: Start the transmission environment data service and generate oxygen molecule absorption factor and water vapor absorption factor data at different altitudes and frequencies based on the atmospheric environment data;

[0089] (42) Propagation path calculation: Calculate the propagation path from the radar to the target by using the transmission environment data service and the atmospheric refraction effect model;

[0090] (43) Calculation of terrain environment effects: Based on the propagation path, the reflection path and minimum clearance are analyzed through the transmission environment data service, and the comprehensive effect model is called to calculate the comprehensive effect of the terrain environment;

[0091] (44) Calculation of atmospheric environmental effects: Based on the propagation path, the oxygen molecule absorption factor and water vapor absorption factor data of each discrete trajectory point are obtained through the transmission environment data service, and the atmospheric absorption loss is calculated through discrete integration; the propagation distance is obtained based on the propagation trajectory, and the free space propagation loss is calculated.

[0092] The above is only a preferred embodiment of the present invention, and the invention is not limited to the above embodiment. Anyone should know that any technical solution that is the same or similar to the present invention made under the inspiration of the present invention shall fall within the protection scope of the present invention.

Claims

1. A radar signal transmission environment modeling method, characterized in that: include: (10) Transmission of environmental data services: including atmospheric environmental data and terrain environmental data, describing environmental static properties through atmospheric models and digital terrain elevation data (DTED), and providing data query and calculation services; (20) Atmospheric environment transmission modeling: Modeling the transmission process of radar signals in the atmospheric environment, including the calculation of free space propagation loss, atmospheric absorption loss, and atmospheric refraction effect; (30) Terrain environment transmission modeling: Modeling the transmission process of radar signals in terrain environment, including calculation of multipath effect and diffraction effect; (40) Construction of comprehensive transmission environment: Taking into account the above transmission effects and their mutual influence, a comprehensive transmission environment is constructed.

2. A radar signal transmission environment modeling method according to claim 1, characterized in that: The (10) transmission environment data service includes: (11) Atmospheric environment data preprocessing: Use the tropospheric atmospheric model to describe the relationship between tropospheric atmospheric pressure, temperature, water vapor density and altitude; (12) Terrain environment data preprocessing: Use DTED data to describe terrain height, use two-dimensional bilinear interpolation to improve the accuracy of DTED data, and be able to calculate the height of any point; (13) Coordinate system conversion: Provides coordinate system conversion methods, including geodetic coordinate system, station-centered horizontal coordinate system, and Earth-centered Earth-fixed coordinate system, as well as their mutual conversion; (14) Two-dimensional terrain profile analysis of the propagation path: Analyze the two-dimensional terrain on the propagation path based on the propagation path and terrain environment data to obtain the minimum clearance and the width of the first Fresnel zone.

3. A radar signal transmission environment modeling method according to claim 1, characterized in that: The (20) atmospheric environment modeling includes: (21) Free space propagation model: It describes the loss caused by diffusion when the radar signal propagates in free space and is expressed by the following formula: Where d is the transmission distance, λ is the wavelength of the radar signal, and f is the frequency; (22) Atmospheric absorption model: It describes the loss caused by the absorption of electromagnetic waves by oxygen molecules (O2) and water vapor molecules (H2O) in the atmosphere, and is expressed by the following formula: in, is the oxygen molecule absorption factor, unit is dB / m, Water vapor molecule absorption factor, in dB / m; (23) Atmospheric refraction effect model: describes the propagation trajectory of radar signals under the influence of atmospheric refraction effect. Since the atmospheric refraction coefficient changes with altitude, the propagation path of radar signals becomes curved. According to the geometric relationship, the geocentric angle between the radar and the target is Where a is the radius of the earth, h O is the radar altitude, h T is the target altitude, R d is the straight-line distance between the radar and the target According to the radio wave propagation theory, Where n(h) is the atmospheric refractive index at h. Combining the above two equations, we can get θ0 make By dividing the geocentric angle m into equal parts, the propagation trajectory is discretized, and then we have h can be obtained i , combined with the spherical longitude and latitude calculation method, the longitude and latitude p of the discrete points of the propagation trajectory can be obtained i , so the radar signal propagation trajectory is {(p i ,h i )|i=1,2,...,m}.

4. The radar signal transmission environment modeling method according to claim 1, characterized in that: The (30) terrain environment modeling includes: (31) Multipath effect model: describes the process in which radar signals travel through multiple paths to the target due to reflections from the ground or sea surface and interference occurs during the propagation of radar signals. It is characterized by the pattern propagation factor. (32) Diffraction effect model: describes the process of radar signal bypassing obstacles and propagating to the shielded area when encountering obstacles. Depending on the obstacles, the diffraction effect model includes spherical earth diffraction and blade edge diffraction, which are characterized by the directional pattern propagation factor; (33) Comprehensive effect model: In practice, the multipath effect and diffraction effect are in a trade-off relationship. The comprehensive effect model takes the two into consideration and constructs the comprehensive effect model using the SEKE algorithm.

5. The radar signal transmission environment modeling method according to claim 1, characterized in that: The (40) integrated transmission environment construction comprises the following steps: (41) Pre-generation of atmospheric absorption factor data: Start the transmission environment data service and generate oxygen molecule absorption factor and water vapor absorption factor data at different altitudes and frequencies based on the atmospheric environment data; (42) Propagation path calculation: Calculate the propagation path from the radar to the target by using the transmission environment data service and the atmospheric refraction effect model; (43) Calculation of terrain environment effects: Based on the propagation path, the reflection path and minimum clearance are analyzed through the transmission environment data service, and the comprehensive effect model is called to calculate the comprehensive effect of the terrain environment; (44) Calculation of atmospheric environmental effects: Based on the propagation path, the oxygen molecule absorption factor and water vapor absorption factor data of each discrete trajectory point are obtained through the transmission environment data service, and the atmospheric absorption loss is calculated through discrete integration; the propagation distance is obtained based on the propagation trajectory, and the free space propagation loss is calculated.

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