Rapid calculation method of radar detection power map based on GIS

Abstract

The application discloses a GIS-based radar detection power diagram fast calculation method and belongs to the technical field of radars. Firstly, for a radar to be analyzed, the maximum detection distance of the radar is calculated according to design parameters of the radar in a free space environment, and meanwhile, corresponding DEM data are selected according to a region where the radar is to be deployed, so that the detection range of the radar to be analyzed in the free space environment is obtained. Then, all visible vector points of the radar are extracted by using GIS based on the detection range of the radar to be analyzed and all DEM data in the range, and a shielding angle formed by a terrain obstruction represented by all the visible vector points is calculated. Finally, a radar detection power diagram is calculated according to parameters of a detection target and the shielding angle. The application effectively reduces the calculation data amount, compensates for errors caused by the earth curvature, improves the timeliness and accuracy of simulation analysis, and improves the applicability of a radar power diagram calculation method.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to a method for rapid calculation of radar detection power maps based on GIS. Background Technology

[0002] Ground-based radar plays a crucial role as a key piece of equipment for situational awareness on the modern battlefield. Therefore, mastering radar detection capabilities is of great significance for maximizing the combat effectiveness of radar equipment. At the same time, mastering radar airspace detection capabilities is also necessary in radar deployment, operational planning, and operational capability analysis and simulation.

[0003] Radar detection capability is a key tactical performance indicator, reflecting performance metrics such as maximum effective range and elevation range. The working principle of radar detection primarily involves directional transmission of electromagnetic waves into space. Based on the reflection of these waves by targets within space, signal processing is used to obtain the target's azimuth, elevation, and velocity. Radar detection capability is not only related to the radar's own parameters, transmission power, electromagnetic wave propagation path attenuation, the Earth's curvature, and the nature and altitude of the observed target, but is also affected by the terrain surrounding the radar location. The angle between the radar's line of sight and the horizon formed by the continuous line of sight of terrain obstacles is called the obstruction angle. When the elevation angle of the radar antenna beam is smaller than this angle, the radar will be unable to detect the target due to the obstruction of terrain obstacles; this terrain-blocked radar signal propagation creates a detection blind zone.

[0004] In radar simulation analysis and research, radar detection capabilities can be calculated using the radar's performance parameters based on the radar equations. Furthermore, terrain data obtained using a Digital Elevation Model (DEM) can be used to calculate the radar obscuration angle, thereby obtaining a radar detection power map to analyze radar operational capabilities. Currently, publicly available global DEM data includes SRTM-90m, SRTM-30m, ASTER GDEM30m, TanDEM 90m, and ALOS-DEM terrain data. Among these, ALOS-DEM is the highest resolution terrain data publicly available globally, with a resolution of 12.5 meters, meaning each cell in this data is 12.5 meters long. According to relevant tests and verifications, the average elevation error of this data is approximately 2-4 meters, which basically meets the requirements for radar detection terrain analysis. The original ALOS-DEM data was imaged between 2008 and 2011, and the latest product data update was in 2019.

[0005] Currently, radar power map calculations face several major problems. First, traditional calculation methods are primarily based on the principle of rectilinear propagation of light, utilizing line-of-sight calculations to determine visibility by connecting the radar to the obstacle. These methods are suitable for short-range analysis, but considering radar detection ranges of hundreds of kilometers, the effects of atmospheric refraction and the Earth's spherical surface must also be taken into account. Second, when analyzing terrain obstruction, the ground elevation values ​​over a range of hundreds of kilometers need to be acquired and calculated based on the radar detection range. Especially for large areas and when using high-resolution DEM data, this involves millions of points, making existing calculation methods extremely time-consuming and inefficient. Summary of the Invention

[0006] To address the shortcomings of existing methods, this invention provides a rapid calculation method for radar detection power maps based on GIS. This method is applicable to radars with different detection ranges and can quickly complete the calculation when using DEM data of different resolutions.

[0007] A GIS-based method for rapid calculation of radar detection power maps includes the following steps:

[0008] Step 1: For the radar to be analyzed, calculate the maximum detection range of the radar in a free space environment;

[0009] The radar's maximum detection range R max The calculation formula is:

[0010]

[0011] Among them, P t Where is the radar transmit power, G is the antenna power gain, σ is the cross-sectional area of ​​the target detected by the radar, λ is the radar wavelength at the station, and F is the radar transmit power. t The pattern propagation factor from the transmitting antenna to the target, F r The target-to-receiving antenna pattern propagation factor (S / N) min The minimum detectable signal-to-noise ratio for the station radar is k = 1.38 × 10⁻⁶. -23 Boltzmann constant, T s The noise temperature of the receiving system is typically taken as 290K, B is the noise bandwidth of the pre-detector filter of the receiver, and L is the loss factor of the system.

[0012] Step 2: Select the corresponding DEM data based on the proposed deployment area of ​​the radar to be analyzed, and combine it with the maximum detection range of the radar to obtain the detection range of the radar to be analyzed in free space environment.

[0013] Specifically:

[0014] First, let the coordinates of the deployment location O of the radar to be analyzed be (x0, y0, y0).o ),

[0015] Then, the three-dimensional coordinates O(x0, y0) of the deployment location point are obtained based on the DEM data. o ,z0);

[0016] Finally, in free space, with point O as the center and radius R... max The range is the detection range of the radar to be analyzed.

[0017] Step 3: Based on the detection range of the radar to be analyzed and all DEM data within that range, use GIS to extract all visible vector points of the radar;

[0018] Specifically:

[0019] Step 301: Extract all DEM data within the radar detection range to be analyzed;

[0020] Step 302: Set the radar antenna's offset height relative to the ground, Observer_offset, which is the antenna's height above the ground.

[0021] Step 303: Call the field of view analysis module of the GIS software, input the radar deployment location, DEM data, antenna offset height, maximum detection distance and line of sight elevation angle respectively, and calculate to obtain the field of view vector of the radar deployment point.

[0022] The overhead viewing angle is set to 0°-90°.

[0023] Step 304: Extract all visible vector points P(x) from the DEM data based on the field of view vector. i ,y i ,z i ), i = 1...N, including coordinate position and terrain height value.

[0024] Step 4: Calculate the obstruction angles caused by terrain obstacles, representing all visible vector points of the radar to be analyzed;

[0025] Specifically:

[0026] Step 401, with the radar deployment location O(x0, y) o With z0 as the origin, starting from 0° north as the azimuth angle, we traverse 360° clockwise at 1° intervals.

[0027] Step 402, take the total distance as R in each azimuth angle θ direction. max Obtain all visible vector points P in this direction. k ,k=1...M.

[0028] Step 403, taking into account standard atmospheric refraction and the equivalent Earth radius R, for a visible vector point P at a certain azimuth angle k The formula for calculating the occlusion angle is as follows:

[0029]

[0030] Among them, h a =z0 + Observer_offset is the vertical distance (m) of the radar antenna height (above sea level), h = z k It is a surface obstacle P k The height value of the point (m). It is a surface obstacle P k The horizontal distance (m) from the radar. Furthermore, the horizontal distance can also be calculated based on the radar's deployment location in the row and column numbers of the DEM data and surface obstacles P. k Calculate the row and column numbers. Where i0,i k ,j0,j k These are the row and column numbers of the radar deployment point and the surface obstacle in the elevation data, respectively.

[0031] Step 404, obtain all visible vector points P at this azimuth angle from formula (2). k The maximum value α is selected from the occlusion angles of k = 1...M. max That is, the shielding angle α in that direction. θ The corresponding point is P. θ .

[0032] Step 405: Repeat steps 402 to 404 to obtain all the shielding angles in the 360° direction of the radar to be analyzed.

[0033] Step 5: Calculate the radar detection power map based on the parameters of the target and the obscuring angle.

[0034] Step 501, with the radar deployment location O(x0, y o With z0 as the origin, starting from 0° north as the azimuth angle, we traverse 360° clockwise at 1° intervals.

[0035] Step 502: For a specific target, calculate the maximum distance at which the radar beam center axis can reach the target's altitude under standard atmospheric refraction conditions in each azimuth angle θ direction. The calculation formula is as follows:

[0036]

[0037] Where H is the height of the target (KM), Observer_offset is the height of the radar antenna itself above the ground (KM), and α is the shielding angle in that direction.

[0038] Step 503, compare R in each azimuth angle θ direction. max and r θ The smaller value is taken as the detection capability for this azimuth angle.

[0039] Step 504: Traverse the 360° azimuth to obtain the detection capabilities of all azimuth angles, and finally connect them to form a detection power map of the radar to be analyzed.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] (1) The method of the present invention is based on the GIS module to quickly extract the terrain information of the obstruction obstacle, which effectively reduces the amount of computational data. Furthermore, it corrects the linear propagation model of light in geometric optics, compensates for the error caused by the curvature of the earth, improves the timeliness and accuracy of simulation analysis, and improves the applicability of the radar power map calculation method.

[0042] (2) This invention calculates the maximum detection range of radar in free space environment by radar equation, and obtains the radar wave action range under terrain obstruction by combining the shielding angle, thereby obtaining the simulation results of the radar's accurate detection capability in all directions. Attached Figure Description

[0043] Figure 1 This is a flowchart of the GIS-based rapid calculation method for radar detection power maps according to the present invention;

[0044] Figure 2 This is a radar detection capability diagram of a ground radar against a flying target at a specified altitude, according to an embodiment of the present invention. Detailed Implementation

[0045] This invention calculates the maximum propagation distance of radar waves in free space based on radar equations, and quickly extracts the height of terrain obstacles that affect radar wave propagation using GIS software, effectively reducing the amount of data that needs to be processed. It also corrects the rectilinear propagation model of light in geometric optics to calculate the shielding angle, and calculates the maximum distance that radar waves can reach at a certain height based on the radar height measurement formula.

[0046] To facilitate understanding and implementation of this invention by those skilled in the art, the following description is provided in conjunction with the appendix. Figure 1 The present invention will be further described in detail and in depth, including the following steps:

[0047] Step 1: Select the corresponding DEM data based on the proposed deployment area of ​​the radar to be analyzed.

[0048] In this embodiment of the invention, ALOS-DEM data with a resolution of 12.5 meters was selected. This terrain data was updated and released in 2019 and includes most of the land areas of the world. It uses the WGS84 coordinate system and UTM projection. The data is divided into sheets according to projection zones. To avoid distortion at the boundaries of UTM projection zones, the UTM projection coordinate system is transformed to the WGS84 geographic coordinate system using GIS software.

[0049] Step 2: For the radar to be analyzed, in a free space environment, without considering any environmental influences, calculate the maximum detection range of the radar based on the general radar equation according to the radar's design parameters.

[0050] The radar's maximum detection range R max The calculation formula is:

[0051]

[0052] Among them, P t Where is the radar transmit power, G is the antenna power gain, σ is the cross-sectional area of ​​the target detected by the radar, λ is the radar wavelength at the station, and F is the radar transmit power. t The pattern propagation factor from the transmitting antenna to the target, F r The target-to-receiving antenna pattern propagation factor (S / N) min The minimum detectable signal-to-noise ratio for the station radar is k = 1.38 × 10⁻⁶. -23 Boltzmann constant, T s The noise temperature of the receiving system is typically taken as 290K, B is the noise bandwidth of the pre-detector filter in the receiver, and L is the system loss factor. For free-space propagation, when the antenna's principal axis is aligned with the target, the corresponding F... t and F r The value is usually 1.

[0053] Step 3: Select the corresponding DEM data based on the proposed deployment area of ​​the radar to be analyzed, and combine it with the maximum detection range of the radar to obtain the detection range of the radar to be analyzed in free space environment.

[0054] Specifically:

[0055] First, let the coordinates of the deployment location O of the radar to be analyzed be (x0, y0, y0). o );

[0056] Then, the three-dimensional coordinates O(x0, y0) of the deployment location point are obtained based on the DEM data. o ,z0);

[0057] Finally, in free space, with point O as the center and radius R... max The range is the detection range of the radar to be analyzed.

[0058] Step 4: Based on the detection range of the radar to be analyzed and all DEM data within that range, use GIS to extract all visible vector points of the radar.

[0059] Specifically:

[0060] Step 401: Extract all DEM data within the radar detection range to be analyzed;

[0061] Step 402: Set the radar antenna's offset height relative to the ground, Observer_offset, which is the antenna's height above the ground.

[0062] Step 403: Call the field of view analysis module of the GIS software, input the radar deployment location, DEM data, antenna offset height, maximum detection range and line of sight elevation angle respectively, and calculate to obtain the field of view vector of the radar deployment point.

[0063] The overhead viewing angle is set to 0°-90°.

[0064] Step 404: Extract all visible vector points P(x) from the DEM data based on the field of view vector. i ,y i ,z i ), i = 1...N, including coordinate position and terrain height value.

[0065] Step 5: Calculate the shielding angle formed by terrain obstacles representing all visible vector points of the radar to be analyzed. That is, with the radar antenna center point and the horizontal plane where the visible vector point is located as the reference, the maximum vertical angle formed by the shielding of the ground surface obstacles within its range of action.

[0066] Specifically:

[0067] Step 501, with the radar deployment location O(x0, y o With z0 as the origin, starting from 0° north as the azimuth angle, we traverse 360° clockwise at 1° intervals.

[0068] Step 502, take the total distance as R in each azimuth angle θ direction. max Obtain all visible vector points P in this direction. k ,k=1...M.

[0069] Step 503, taking into account standard atmospheric refraction and the equivalent Earth radius R (8496 km), for a visible vector point P at a certain azimuth angle... k The formula for calculating the occlusion angle is as follows:

[0070]

[0071] Among them, h a=z0 + Observer_offset is the vertical distance (m) of the radar antenna height (above sea level), h = z k It is a surface obstacle P k The height value of the point (m). It is a surface obstacle P k The horizontal distance (m) from the radar. Furthermore, the horizontal distance can also be calculated based on the radar's deployment location in the row and column numbers of the DEM data and surface obstacles P. k Calculate the row and column numbers. Where i0,i k ,j0,j k These are the row and column numbers of the radar deployment point and the surface obstacle in the elevation data, respectively.

[0072] Step 504, obtain all visible vector points P at this azimuth angle from formula (2). k The maximum value α is selected from the occlusion angles of k = 1...M. max That is, the shielding angle α in that direction. θ The corresponding point is P. θ .

[0073] Step 505: Repeat steps 502 to 504 to obtain all the shielding angles in the 360° direction of the radar to be analyzed.

[0074] Step 6: Calculate the radar detection power map based on the parameters of the target and the obscuring angle.

[0075] Step 601, with the radar deployment location O(x0, y o With z0 as the origin, starting from 0° north as the azimuth angle, we traverse 360° clockwise at 1° intervals.

[0076] Step 602: For a specific target, calculate the maximum distance that the radar beam center axis can reach the target's altitude in each azimuth angle θ direction under the assumption of standard atmospheric refraction. The calculation formula is as follows:

[0077]

[0078] Where H is the target height (KM), which can usually be set to 1Km, 3Km or 5Km, Observer_offset is the radar antenna height above the ground (KM), and α is the shielding angle in that direction.

[0079] Step 603, compare R in each azimuth angle θ direction. max and r θ The smaller value is taken as the detection capability for this azimuth angle.

[0080] Step 604: Traverse the 360° azimuth to obtain the detection capabilities of all azimuth angles, and finally connect them to form a detection power map of the radar to be analyzed.

[0081] Example

[0082] Taking a location in Xiangshan, Ningbo, Zhejiang Province as an example, ALOS-DEM data for that location was selected and converted to the WGS84 geographic coordinate system. The latitude and longitude location of the radar station was set based on satellite imagery, and the elevation values ​​of the DEM data were read to determine the three-dimensional coordinates O(x0, y0) of the radar deployment location. o ,z0).

[0083] Calculate the maximum detection range R of the radar based on the radar parameters. max , where P t The radar transmit power is set to 21MW, the operating frequency to 5.6GHz, the antenna power gain to 45dB, and the minimum detectable signal-to-noise ratio (S / N) for the radar. min Set to 20dB, the cross-sectional area of ​​the aerial target is 0.1m. 2 The receiver's pre-detector filter has a noise bandwidth of 5MHz, and the system loss factor L is 3dB. The calculated maximum detection range R is... max It is 166 km.

[0084] Based on parameters such as the radar's three-dimensional coordinate position, antenna offset height, and maximum detection range, the field-of-view vector of the radar deployment point is calculated using the view analysis module of GIS software, i.e., the visible vector point P(x i ,y i ,z i ), i = 1...N.

[0085] With the radar deployment location O(x0,y) o Using z0 as the origin, and true north as the starting azimuth (0°), angles are taken clockwise at 1° intervals for a total of 360°. The maximum shielding angle in each direction is calculated based on standard atmospheric refraction and an equivalent Earth model. With target flight altitudes H set to 1km, 3km, and 6km, the maximum distance r that the radar beam centerline can reach the target flight altitude in each azimuth direction under the assumption of standard atmospheric refraction is calculated. θ Compared to R max and r θ The smaller value is taken as the detection capability at this azimuth angle. The detection range for all azimuth angles is obtained by traversing 360° of the azimuth axis, and finally connected to form a radar detection capability map, as shown below. Figure 2 As shown.

[0086] Except for the technical features described in the specification, all other technologies are known to those skilled in the art. Descriptions of publicly known technologies are omitted in this invention. The embodiments described above do not represent all embodiments consistent with this application. Various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this invention are still within the protection scope of this invention.

Claims

1. A method for rapid calculation of radar detection power maps based on GIS, characterized in that, Includes the following steps: First, for the radar to be analyzed, the maximum detection range of the radar is calculated in free space. At the same time, the corresponding DEM data is selected according to the radar's proposed deployment area. Combined with the maximum detection range, the detection range of the radar to be analyzed in free space is obtained. Then, based on the detection range of the radar to be analyzed and all DEM data within that range, all visible vector points of the radar are extracted using GIS, and the occlusion angles formed by terrain obstacles represented by all visible vector points are calculated. The specific calculation method for the shading angle is as follows: Step 401, based on the radar deployment location Starting from the origin, with true north as the azimuth starting at 0°, and traversing 360° clockwise at 1° intervals; Step 402, at each azimuth angle Take the total distance in the direction as Obtain all visible vector points in this direction. ; Step 403, taking into account standard atmospheric refraction and the equivalent Earth radius R, for a visible vector point at a certain azimuth angle The formula for calculating the occlusion angle is as follows: （2） in, It is the vertical distance of the radar antenna from the sea level. Surface obstacles The height value of the point, Surface obstacles Horizontal distance from the radar; Step 404: Obtain all visible vector points at this azimuth angle from formula (2). Select the maximum value from the occlusion angles. That is, the shielding angle in that direction. The corresponding point is ; Step 405: Repeat steps 402 to 404 to obtain all the shielding angles in the 360° direction of the radar to be analyzed; Finally, the radar detection power map is calculated based on the parameters of the detected target and the obscuring angle; The specific calculation process for the radar detection power map is as follows: Step 501, based on the radar deployment location Starting from the origin, with true north as the azimuth starting at 0°, and traversing 360° clockwise at 1° intervals; Step 502: For a specific target, calculate the azimuth angles under the assumption of standard atmospheric refraction conditions. The maximum distance at which the radar beam's center axis can reach the target's altitude is calculated using the following formula: （3） in, To detect the target's altitude, It refers to the height of the radar antenna itself above the ground. This is the shielding angle in that direction; Step 503, at each azimuth angle Directional comparison and The smaller value is taken as the detection capability for this azimuth angle; Step 504: Traverse the 360° azimuth to obtain the detection capabilities of all azimuth angles, and finally connect them to form a detection power map of the radar to be analyzed.

2. The method for rapid calculation of radar detection power maps based on GIS according to claim 1, characterized in that, The maximum detection range of the radar to be analyzed The calculation formula is: （1） in, G is the radar transmit power, and G is the antenna power gain. For radar to detect the cross-sectional area of ​​the target, For the radar wavelength of the station, The propagation factor of the radiation pattern from the transmitting antenna to the target The propagation factor of the radiation pattern from the target to the receiving antenna, For the minimum detectable signal-to-noise ratio of the station radar, Boltzmann constant, For receiving system noise temperature, For the noise bandwidth of the receiver pre-detector filter, This is the system's loss factor.

3. The method for rapid calculation of radar detection power maps based on GIS according to claim 1, characterized in that, The detection range of the radar to be analyzed in the free space environment is specifically described as follows: First, determine the deployment location of the radar to be analyzed. coordinate position value ; Then, the three-dimensional coordinates of the deployment location points are obtained based on the DEM data. ; Finally, in a free space environment, using three-dimensional coordinates Centered on point, with radius The range is the detection range of the radar to be analyzed.

4. The method for rapid calculation of radar detection power maps based on GIS according to claim 1, characterized in that, The extraction of all visible vector points of the radar to be analyzed using GIS is specifically as follows: Step 301: Extract all DEM data within the radar detection range to be analyzed; Step 302: Set the radar antenna's offset height relative to the ground, Observer_offset, which is the height of the antenna itself above the ground; Step 303: Call the field of view analysis module of the GIS software, and input the radar deployment location, DEM data, antenna offset height, maximum detection range and line of sight elevation angle respectively to calculate and obtain the field of view vector of the radar deployment point; The downward angle is set to 0°-90°; Step 304: Extract all visible vector points from the DEM data based on the field of view vector. This includes coordinate location and terrain elevation value.

5. The method for rapid calculation of radar detection power maps based on GIS according to claim 1, characterized in that, Instead, the surface obstacles The horizontal distance to the radar is determined by the radar's deployment location in the row and column numbers of the DEM data and by surface obstacles. The row and column numbers are calculated, that is... in, These are the row and column numbers of the radar deployment point and the surface obstacle in the elevation data, respectively.

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