Shielding influence evaluation method and system for radar station

Abstract

The invention provides a shielding influence evaluation method for a radar station. The method comprises the following steps: determining relative coordinates of a single longitude and latitude point of a building in a spherical coordinate system taking the radar station as an original point; taking the building as an obstacle, and judging whether the relative distance between the radar station and the obstacle is greater than a protection range threshold according to the relative coordinates; if yes, height limit calculation does not need to be carried out according to the requirement of the vertical shielding angle; otherwise, determining the altitude limit of the obstacle according to the relative distance; if the obstacle comprises a plurality of longitude and latitude points, repeating the steps for each longitude and latitude point to sequentially calculate all azimuth angles and determine a horizontal shielding angle according to the azimuth angles, otherwise, determining the obstacle width limit according to the relative distance; and determining the comprehensive altitude limit of each longitude and latitude point of the obstacle and the comprehensive horizontal shielding angle or the comprehensive limit width of the obstacle. The invention further provides a corresponding system. According to the shielding influence evaluation method, the labor cost can be reduced, and the calculation precision and accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the field of civil aviation air traffic control, and specifically relates to a method and system for evaluating the shielding effect of a radar station, which is applicable to evaluating the shielding effect of primary / secondary radars in civil aviation air traffic control. Background Art

[0002] Primary / secondary radar stations in civil aviation air traffic control (hereinafter referred to as inspection radar stations) are the main monitoring means for air traffic controllers to command and guide aircraft flights. The safe operation of the stations will directly affect flight safety. Radar equipment detects and exchanges information with air / ground targets through electromagnetic waves. Inevitably, the detection performance is vulnerable to changes in the surrounding electromagnetic environment, which in turn affects the coverage of radar signals. In response to the above situation, the Civil Aviation Administration of China has revised and issued MH / T 4003 "Specification for the Site Setting of Civil Aviation Communication, Navigation and Surveillance Stations", which has detailed regulations and restrictions on the topography and buildings within the site protection area of the radar station. According to the regulations of the "Measures for the Clearance Review and Management of Construction Projects within the Clearance Protection Area of Civil Airports", the regional administration of civil aviation is responsible for the review of construction projects within the clearance protection area of the airports under its jurisdiction. Before the project construction, the construction party needs to report the location information and elevation information of the project construction to the civil aviation department for consultation.

[0003] The calculation of the shielding limit of the site protection area of the radar station mainly involves the calculation of the vertical shielding angle and the horizontal shielding angle of the single (or dense) obstacle for the station. An obstacle refers to an object that may cause occlusion, reflection and interference to radio signals within the radio signal transceiver area of the monitoring equipment, specifically including buildings, high-voltage transmission lines, roads, railways, metal fences, iron towers, dams, trees, hills, etc. The horizontal shielding angle and the vertical shielding angle refer to the horizontal and vertical opening angles formed by the occlusion of obstacles within the radio signal transceiver area of the monitoring equipment, with the center point of the monitoring equipment antenna and the horizontal plane where the point is located as the reference. Due to the large amount of calculation work, it is usually completed manually, resulting in huge labor costs. At the same time, due to the limitations of human subjective factors and objective conditions, there are also certain uncertainties in the calculation accuracy and the accuracy of data entry.

[0004] In 2022, the Second Research Institute of the Civil Aviation Administration of China developed and released the "Software for Calculating the Electromagnetic Environment Protection of Air Traffic Control Stations" (Software Copyright Registration No.: 2022SR1619126). The "Site Protection Analysis" function in the "Primary / Secondary Surveillance Radar" module covers the calculation of the vertical shielding angle under the condition of the single longitude and latitude coordinates of a single obstacle, but does not involve the calculation of the vertical shielding angle and the horizontal shielding angle under the condition of multiple longitude and latitude coordinates of single / dense obstacles. However, in the actual calculation process, we found that the vast majority of cases involve multiple longitude and latitude coordinates of single / dense obstacles.

[0005] On the other hand, considering that a region usually contains more than one radar to achieve multiple coverage of surveillance sources in the airspace, it is necessary to consider the comprehensive impact of obstacles on multiple radars in order to determine the final restricted height and / or restricted width. Considering the above factors comprehensively, it is not difficult to find that the existing technologies still have the following deficiencies: 1. The human calculation cost of this tool is still very high; 2. There is a certain deviation between the calculation results of this tool and the actual functional requirements of "building restricted height"; 3. It is also impossible to detect and effectively suppress possible errors in data entry and calculation processes in a timely manner.

[0006] The existing known radar shadowing impact calculation methods and / or systems similar to or related to the present invention mainly include: a method and system for calculating radar shadowing angle based on DEM (patent number 20201016881.1), a method for calculating and visualizing radar shadowing angle based on the earth ellipsoid model (patent number 202310283295.7), a method for automatically generating and spatially discriminating the three-dimensional standard site protection area of an air traffic control station (patent number 202311454311.0), and "Electromagnetic Environment Protection Calculation Software for Air Traffic Control Stations" (software copyright registration number: 2022SR1619126).

[0007] Although the first two involve the calculation of radar shadowing angle, they are not aimed at primary and secondary radars for civil aviation air traffic control, and fail to reflect the particularity of air traffic control surveillance radars in terms of performance and use and do not consider the regulations of industry standards. At the same time, their systems mainly focus on constructing a radar shadowing map based on terrain elevation data, rather than being able to calculate based on industry standard regulations and evaluate the shadowing restrictions on construction planning schemes.

[0008] The method for automatically generating and spatially discriminating the three-dimensional standard site protection area of an air traffic control station (patent number 202311454311.0) considers the regulations of industry standards, but the definition of its site protection area is mainly applicable to navigation stations rather than radar stations.

[0009] "Electromagnetic Environment Protection Calculation Software for Air Traffic Control Stations" (software copyright registration number: 2022SR1619126) is the best existing technology known for calculating the radar shadowing angle of radar stations at present. The "site protection analysis" function in its "primary / secondary surveillance radar" module includes the calculation of the radar shadowing angle of primary and secondary radars for civil aviation air traffic control, but there are still the following disadvantages:

[0010] 1. It only involves the calculation of the vertical shadowing angle of the single longitude and latitude coordinates of obstacles. The calculation of the vertical shadowing angle of the multi-longitude and latitude coordinates of buildings needs to be calculated manually one by one and then obtained through comprehensive statistical analysis, and its human cost is still very high;

[0011] 2. It cannot calculate the horizontal shadowing angle of obstacles;

[0012] 3. Manual entry requires manually filling in the longitude, latitude, and elevation information, which is labor-intensive and error-prone.

[0013] 4. The occlusion angle calculation algorithm is not clearly given. Summary of the Invention

[0014] The purpose of the present invention is to provide a method and system for evaluating the occlusion effect of a radar station to reduce labor costs and improve calculation accuracy and precision.

[0015] To achieve the above purpose, the present invention provides a method for evaluating the occlusion effect of a radar station, which is used to evaluate the occlusion effect of a civil aviation air traffic control primary / secondary radar, including:

[0016] S1: According to the coordinates of a single radar station and the longitude and latitude coordinates of a building, determine the relative coordinates of the building's single longitude and latitude point in the spherical coordinate system with the radar station as the origin; the relative coordinates are used to represent the distance and azimuth of the obstacle's single longitude and latitude point relative to the radar station.

[0017] S2: Regarding the building as an obstacle, judge whether the relative distance between the radar station and the obstacle is greater than the protection range threshold according to the relative coordinates in step S1; if the relative distance is greater than the protection range threshold, there is no need to perform height limit calculation according to the requirements of the vertical occlusion angle; otherwise, determine the altitude height limit of the obstacle according to the relative distance; subsequently, continue to execute step S3.

[0018] S3: Judge whether the obstacle contains multiple longitude and latitude points.

[0019] If the obstacle contains multiple longitude and latitude points, repeat steps S1 and S2 for each longitude and latitude point to successively calculate the azimuth angle in the relative coordinates of each longitude and latitude point of the obstacle in the spherical coordinate system with the radar station as the origin, and determine the horizontal occlusion angle of the obstacle relative to the same radar station according to all azimuth angles; conversely, determine the width limit of the obstacle according to the relative distance between the radar station and the obstacle.

[0020] S4: According to the altitude height limit of the obstacle and the horizontal occlusion angle or the width limit of the obstacle, determine the comprehensive altitude height limit of each longitude and latitude point of the obstacle and the comprehensive horizontal occlusion angle or comprehensive width limit of the obstacle as the occlusion effect evaluation result.

[0021] The specific steps of step S1 include:

[0022] S11: Convert the coordinates of the radar station and the longitude and latitude coordinates of the building from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system to obtain the coordinates (X s , Y s , Z s ) of the radar station and the single longitude and latitude point of the building in the geocentric rectangular coordinate system, (X T , YT , Z T );

[0023] S12: Convert the coordinates of the radar station and the building's single longitude and latitude points in the geocentric rectangular coordinate system to the local rectangular coordinate system with the radar station as the origin, obtaining the relative coordinates (X r , Y r , Z r ) of the building's single longitude and latitude points in the local rectangular coordinate system;

[0024] S13: Convert the relative coordinates (X r , Y r , Z r ) of the building's single longitude and latitude points in the local rectangular coordinate system to the spherical coordinate system with the radar station as the origin, obtaining the relative coordinates (ro, Az, phi) of the building's single longitude and latitude points in the spherical coordinate system with the radar station as the origin.

[0025] The relational expression for converting from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system satisfies:

[0026]

[0027] In the formula, X, Y, and Z are the coordinates of the geocentric rectangular coordinate system, L, B, and H are the geodetic longitude coordinate, geodetic latitude coordinate, and height coordinate of the WGS84 geodetic coordinate system, a is the semi-major axis radius of the earth, and e is the eccentricity of the ellipse;

[0028] The relative coordinates (X r , Y r , Z r ) of the building's single longitude and latitude points in the local rectangular coordinate system are:

[0029]

[0030] Among them, L T , B T respectively represent the longitude and latitude coordinates of the building's single longitude and latitude points in the WGS84 geodetic coordinate system, (X s , Y s , Z s ) are the coordinates of the radar station in the geocentric rectangular coordinate system, and (X T , Y T , Z T ) are the coordinates of the building's single longitude and latitude points in the geocentric rectangular coordinate system;

[0031] The relative coordinates (ro, Az, phi) of the building's single longitude and latitude points in the spherical coordinate system with the radar station as the origin are:

[0032]

[0033] Among them, atan2(Y r , X r ) represents finding the arctangent value of Y r / X r . R is the radius of the earth at the single longitude and latitude point of the building, and h represents the altitude of the radar station.

[0034] For the radar station and the single longitude and latitude point of the building, the value of the height coordinate H in the WGS84 geodetic coordinate system is uniformly set to the altitude of the radar station.

[0035] In the step S2, the altitude limit B of the obstacle is:

[0036]

[0037] Among them, B represents the altitude limit of the obstacle, with the unit of m, T represents the altitude of the radar station, with the unit of m, and D represents the relative distance between the radar station and the obstacle, with the unit of km;

[0038] In the step S3, the width limit W of the obstacle satisfies the following formula:

[0039]

[0040] Among them, W represents the width limit of the obstacle, with the unit of m, and D represents the relative distance between the radar station and the obstacle, with the unit of km.

[0041] The step S4 specifically includes:

[0042] Judge whether there are multiple radar stations in the area where the obstacle is located; if there are multiple radar stations, repeat steps S1 to S3 to calculate the altitude limit B of the obstacle for each longitude and latitude point relative to each radar station and the horizontal shielding angle or width limit W of the obstacle in turn; subsequently, for each longitude and latitude point, take the minimum value from the altitude limits B of the obstacle for the single longitude and latitude point relative to all radar stations to obtain the comprehensive altitude limit of the single longitude and latitude point, and for each obstacle, take the minimum value from the horizontal shielding angles or width limits W of the obstacle relative to each radar station to obtain the comprehensive horizontal shielding angle or comprehensive width limit of the obstacle; otherwise, directly use the altitude limit B of the obstacle for each longitude and latitude point relative to the only radar station and the horizontal shielding angle or width limit W of the obstacle as the shielding impact evaluation result.

[0043] The method for evaluating the shielding impact of the radar station further includes step S5: judging whether the building meets the requirements of the comprehensive altitude limit, and the comprehensive horizontal shielding angle or comprehensive width limit according to the shielding impact evaluation result.

[0044] On the other hand, the present invention provides a shielding impact assessment system for a radar station, which includes: an OCR recognition module configured to automatically extract the longitude and latitude coordinates of a building from a review material containing GIS information to obtain a coordinate file of the building; and a shielding angle calculation module for performing the shielding impact assessment method of the radar station described above according to the longitude and latitude coordinates extracted by the OCR recognition module and / or the manually input longitude and latitude coordinates to determine the shielding impact assessment result.

[0045] The shielding impact assessment system of the radar station further includes a visualization verification module, which is configured to mark the position and draw the contour according to the input longitude and latitude coordinates of the building to visually display the longitude and latitude coordinates of the building to be evaluated on an electronic map.

[0046] The visualization verification module is further configured to verify the distance and azimuth of the building target relative to the radar station.

[0047] The shielding impact assessment method of the radar station of the present invention mainly aims at the calculation of the shielding impact of the civil aviation primary and secondary radar stations. Under the condition of meeting the industry regulations of the shielding angle, it can realize the calculation of the vertical shielding angle of multiple longitude and latitude coordinates of single / dense buildings, and solve the problems of large manual calculation cost, the calculation accuracy and accuracy being affected by subjective factors and objective conditions, and being out of touch with the actual needs in the prior art, so as to provide data support and theoretical basis for the planning, design and review of surrounding buildings.

[0048] In addition, the system of the present invention has a user-friendly man-machine interface, is easy to operate and use, does not require manual filling of longitude and latitude and elevation information during use, realizes the automatic calculation of the shielding angle, can greatly reduce the manual calculation cost, and at the same time reduces the occurrence of errors. This tool and method can be widely used in production practice to provide shielding limit calculation services. Brief Description of the Drawings

[0049] Figure 1 is a flowchart of a shielding impact assessment method of a radar station according to an embodiment of the present invention.

[0050] Figure 2 is a data flow diagram of a shielding impact assessment system of a radar station according to an embodiment of the present invention.

[0051] Figure 3 is a schematic diagram of a visualization interface of the shielding angle calculation module.

[0052] Figures 4 to 6 is a schematic diagram of a visualization interface of the shielding angle calculation module at different working steps.

[0053] Figure 7It is a schematic diagram of the format of the imported coordinate file of the shielding angle calculation module.

[0054] Figure 8 It is a schematic diagram of the visualization interface when the shielding angle calculation module outputs the shielding effect evaluation result.

[0055] Figure 9 and Figure 10 It is a schematic diagram of the form generated by the shielding effect evaluation result of the shielding angle calculation module.

[0056] Figure 11 It is a schematic diagram of the visualization interface of the OCR recognition module.

[0057] Figures 12 to 15 It is a schematic diagram of the visualization interface of the OCR recognition module at different working steps.

[0058] Figure 16 It is a schematic diagram of the longitude and latitude coordinates saved by the OCR recognition module in an EXCEL file.

[0059] Figure 17 It is a schematic diagram of the web interface of the visualization verification module.

[0060] Figures 18 to 23 It is a schematic diagram of the interface of the visualization verification module at different working steps. Detailed implementation manners

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0062] The method for evaluating the shielding effect of the radar station of the present invention realizes the calculation of the shielding limit of the primary and secondary radars of civil aviation air traffic control according to the requirements of the 4003 site setting specification, and mainly involves two indicators: the calculation of the altitude limit of the obstacle and the calculation of the horizontal shielding angle.

[0063] As Figure 1 shown, the method for evaluating the shielding effect of the radar station of the present invention includes:

[0064] Step S1: Determine the relative coordinates of the single longitude and latitude point of the building in the spherical coordinate system with the radar station as the origin according to the coordinates of a single radar station and the single longitude and latitude coordinates of the building; the relative coordinates are used to represent the distance and azimuth (angle relative to the true north) of the single longitude and latitude point of the obstacle relative to the radar station.

[0065] The specific content of step S1 includes:

[0066] Step S11: Convert the coordinates of the radar station and the single longitude and latitude coordinates of the building from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system, and obtain the coordinates (X s , Y s , Z s ) and (X T , Y T , Z T ) of the radar station and the single longitude and latitude point of the building in the geocentric rectangular coordinate system:

[0067] Among them, the WGS84 geodetic coordinate system (World Geodetic System - 1984) is a standard ellipsoid with the centroid of the earth as the origin. In this coordinate system, the geographical coordinates of any point on the earth's surface can be represented by (L, B, H), where L is the geodetic longitude coordinate, representing the angle between the line connecting a point on the earth's surface to the two poles and the plane of the prime meridian, with a range of [-180°, 180°]; B is the geodetic latitude coordinate, representing the angle between the normal of the ground at a point on the earth's surface and the equatorial plane, with a range of [-90°, 90°]; H is the height coordinate, representing the height along the normal direction of the earth ellipsoid.

[0068] The conversion relationship from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system satisfies:

[0069]

[0070] In the formula, X, Y, and Z are the coordinates of the geocentric rectangular coordinate system, L, B, and H are the geodetic longitude coordinate, geodetic latitude coordinate, and height coordinate of the WGS84 geodetic coordinate system, a is the semi-major axis radius of the earth, a = 6378137m, and e is the eccentricity of the ellipse, e = 0.0818191908426.

[0071] For the radar station and the single longitude and latitude point of the building, the value of the height coordinate H of the WGS84 geodetic coordinate system is uniformly set to the altitude of the radar station.

[0072] Through the above formula, the coordinates (X s , Y s , Z s ) and (X T , Y T , Z T ) of the radar station and the single longitude and latitude point of the building in the geocentric rectangular coordinate system can be obtained respectively.

[0073] Step S12: Convert the coordinates of the radar station and the single longitude and latitude point of the building in the geocentric rectangular coordinate system to the local rectangular coordinate system with the radar station as the origin, and obtain the relative coordinates (X r , Yr , Z r );

[0074] That is to say, step S12 is the coordinate transformation (including translation and rotation) between two rectangular coordinate systems, which transforms the absolute coordinates (i.e., the coordinates (X s , Y s , Z s ), (X T , Y T , Z T )) obtained by solving in step S11 into the relative coordinates (X r , Y r , Z r ) of the building position in the rectangular coordinate system with the radar station as the origin.

[0075] Among them, the relative coordinates (X r , Y r , Z r ) of a single longitude and latitude point of the building in the local rectangular coordinate system are:

[0076]

[0077] Among them, L T , B T respectively represent the longitude and latitude coordinates of a single longitude and latitude point of the building in the WGS84 geodetic coordinate system, (X s , Y s , Z s ) is the coordinate of the radar station in the geocentric rectangular coordinate system, and (X T , Y T , Z T ) is the coordinate of a single longitude and latitude point of the building in the geocentric rectangular coordinate system.

[0078] Step S13: Transform the relative coordinates (X r , Y r , z r ) of a single longitude and latitude point of the building in the local rectangular coordinate system into the spherical coordinate system with the radar station as the origin, and obtain the relative coordinates (ro, Az, phi) of a single longitude and latitude point of the building in the spherical coordinate system with the radar station as the origin.

[0079] Finally, it is necessary to further transform the rectangular coordinate system into the spherical coordinate system to obtain the required distance and the azimuth angle with respect to the due north (finally convert the radian into an angle).

[0080] The relative coordinates (ro, Az, phi) of a single longitude and latitude point of the building in the spherical coordinate system with the radar station as the origin are:

[0081]

[0082] Among them, X r , Y r , Z r is the relative coordinate of a single latitude and longitude point of a building in the local rectangular coordinate system, atan2(Y r , X r ) means to find Y r / X r The arc tangent value of, R is the radius of the earth at a single longitude and latitude point of the building, L T represents the longitude coordinate of a single latitude and longitude point of a building in the WGS84 geodetic coordinate system, h represents the altitude of the radar station (the sum of the radar station elevation and the radar station tower height), and H is the height coordinate of the WGS84 geodetic coordinate system, and its value is the altitude of the radar station. That is, in the present invention, Hh=0.

[0083] Among them, the radar station tower height is a relative height, and its value is equal to the radar station tower platform height + antenna base height + antenna height / 2, which represents the height of the radar antenna relative to the ground where the radar station is located. The radar station elevation (i.e. the radar station ground elevation) is an absolute height, which refers to the ground elevation height of the radar station. The altitude of the radar station is an absolute height, and its value is equal to the sum of the radar station elevation and the radar station tower height.

[0084] It should be noted that in the calculation of the shielding angle, only the distance ro and azimuth Az of the relative coordinates of a single latitude and longitude point of the building in the spherical coordinate system with the radar station as the origin are used. Phi represents the pitch angle. In the calculation process, H=h is set. That is, in the calculation process, we first assume that the radar station and the obstacle are roughly located on the same horizontal plane, so as to calculate the distance ro and azimuth Az. There are two reasons for doing this. First, the altitude limit of the obstacle is what we need to calculate later, and it is an unknown quantity at this time; secondly, assuming H=h, we can try to avoid the influence caused by the hypotenuse distance, which will lead to calculation errors of the distance ro. If the height is different, the final distance calculated by the distance ro is different from the distance value we need (what we want is the base distance of the right triangle, not the hypotenuse distance). If the height difference is large, the difference in distance between the two will be very obvious.

[0085] Therefore, by converting to the spherical coordinate system, the distance and azimuth (relative to due north) of each single longitude and latitude point of the obstacle relative to the radar station can be easily calculated, which is helpful to obtain the altitude limit and horizontal shielding angle required in the shielding calculation.

[0086] Step S2: Using the building as an obstacle, determine whether the relative distance D between the radar station and the obstacle is greater than the protection range threshold (i.e., 30 km) according to the relative coordinates in Step S1; if the relative distance D is greater than the protection range threshold, there is no need to calculate the height limit according to the requirement of the vertical shielding angle; otherwise, determine the altitude height limit B of the obstacle according to the relative distance D; subsequently, continue to execute Step S3;

[0087] Among them, the altitude height limit B of the obstacle is the altitude height limit of the longitude and latitude points of the obstacle relative to the radar station, which is calculated and determined according to the industry standard MH / T 4003.1 "Code for the Installation Site of Civil Aviation Communication, Navigation and Surveillance Stations".

[0088] The altitude height limit B of the obstacle is:

[0089]

[0090] Among them, B represents the altitude height limit of the obstacle, with the unit of m, T represents the altitude height of the radar station, with the unit of m, and D represents the relative distance between the radar station and the obstacle, with the unit of km.

[0091] Step S3: Determine whether the obstacle contains multiple longitude and latitude points;

[0092] If the obstacle contains multiple longitude and latitude points, then repeat Step S1 and Step S2 for each longitude and latitude point to sequentially calculate the azimuth angle in the relative coordinates in the spherical coordinate system with the radar station as the origin for each longitude and latitude point of the obstacle, and determine the horizontal shielding angle of the obstacle relative to the same radar station according to all the azimuth angles;

[0093] On the contrary, that is, the obstacle only contains a single longitude and latitude point, and determine the width limit W of the obstacle according to the relative distance between the radar station and the obstacle.

[0094] Generally, a building cannot be simply regarded as an ideal single longitude and latitude point in practical applications, but should be a polyhedron composed of multiple longitude and latitude points. Under normal circumstances. In order to calculate the shielding situation of the obstacle more scientifically, theoretically, multiple coordinate points that can reflect the contour of the obstacle should be given. However, in actual situations, there are still a few cases where only a single longitude and latitude coordinate is included in the review materials (that is, regarding the obstacle as a single longitude and latitude point, such as some used to erect antenna poles, etc.). For this situation, according to the formula of the horizontal shielding angle provided by the 4003 site setting specification, only its width limit can be calculated (see Step S5 below for details).

[0095] In the said Step S3, according to the azimuth angles in the relative coordinates in the spherical coordinate system with the radar station as the origin for each single longitude and latitude point, take out the maximum azimuth value and the minimum azimuth value among them, and subtract the two to obtain the horizontal shielding angle of the obstacle for the radar station.

[0096] If the obstacle only contains a single latitude and longitude coordinate, it is impossible to calculate the horizontal shielding angle of the obstacle relative to the radar station based on the azimuth angle. Instead, the width limit of the obstacle can only be determined based on the relative distance between the radar station and the obstacle. Specifically, when the horizontal shielding angle cannot be calculated or the latitude and longitude coordinates provided in the "construction planning plan" cannot fully reflect the contour of the obstacle, the width limit W of the obstacle can be used for restriction to replace the horizontal shielding angle.

[0097] The width limit W of the obstacle satisfies the following formula:

[0098]

[0099] Among them, W represents the width limit of the obstacle, with the unit of m, and D represents the relative distance between the radar station and the obstacle, with the unit of km.

[0100] Step S4: Determine the comprehensive altitude limit of each latitude and longitude point of the obstacle and the comprehensive horizontal shielding angle or comprehensive width limit of the obstacle based on the altitude limit B of the obstacle and the horizontal shielding angle or width limit W of the obstacle, as the shielding impact assessment result.

[0101] The specific steps of step S4 include:

[0102] Judge whether there are multiple radar stations in the area where the obstacle is located. If there are multiple radar stations, repeat steps S1 to S3 to calculate the altitude limit B of the obstacle for each latitude and longitude point relative to each radar station in turn, and the horizontal shielding angle or width limit W of the obstacle relative to each radar station. Subsequently, for each latitude and longitude point of the obstacle, take the minimum value from the altitude limits B of the obstacle for all radar stations corresponding to this latitude and longitude point to obtain the comprehensive altitude limit of this single latitude and longitude point. For each obstacle, take the minimum value from the horizontal shielding angles or width limits W of the obstacle relative to each radar station to obtain the comprehensive horizontal shielding angle or comprehensive width limit of the obstacle, as the shielding impact assessment result. On the contrary (that is, there is only one radar station), directly use the altitude limit B of the obstacle for each latitude and longitude point of the obstacle relative to the only radar station and the horizontal shielding angle or width limit W as the shielding impact assessment result.

[0103] That is to say, the comprehensive altitude limit is mainly for the case where multiple radars are involved in calculating the obstacle. For example, when reviewing the proposed height of a newly built obstacle on a certain airway in a certain area, the area where the building is located involves two radars. Therefore, it is necessary to calculate the altitude limits of the latitude and longitude points of the obstacle for the two radars and take the smaller value as the comprehensive altitude limit according to the calculation results, so as to ensure that the radar coverage of any one of the two radars is not affected.

[0104] It should be noted that if the relative distance D between all the radar stations corresponding to the longitude and latitude points of the obstacle and the obstacle is greater than the protection range threshold, there will be no results for the building altitude limit, horizontal shielding angle, and building width limit. Therefore, "beyond the protection range" is output as the shielding impact assessment result.

[0105] Step S5: Determine whether the building meets the requirements of the comprehensive altitude limit, comprehensive horizontal shielding angle, or comprehensive width limit according to the shielding impact assessment result.

[0106] In the prior art, the altitude limit can be calculated according to the 4003 site setting specification (i.e., the formula in step S2). However, 4003 does not give the calculation formula for the distance between the obstacle and the radar. The present invention uses the method in step S1 to calculate the relative distance between the obstacle and the radar. Among them, the longitude and latitude of the radar station, the longitude and latitude of the building, and the altitude of the radar antenna are known, and the altitude of the building is the content to be calculated. Considering the definition of the obstacle in the "4003 site setting specification": an obstacle with a distance from the radar station less than or equal to 30 km constitutes a shielding limit. Therefore, the influence of the earth's curvature on the distance calculation is relatively limited. Therefore, in actual calculation, we also set the obstacle height to the altitude of the radar antenna to calculate the distance between two points. This is an improvement of this method for the calculation of the altitude limit.

[0107] On the other hand, the "4003 site setting specification" in the prior art gives the limitation index of the horizontal shielding angle, but does not give the relevant calculation standard. The present invention uses the method of coordinate transformation to convert the wgs84 longitude and latitude coordinates into spherical coordinates with the radar station as the origin, calculates the angle between the radar station coordinate point and the obstacle coordinate point relative to the due north, and calculates the horizontal shielding angle through the difference between the maximum angle and the minimum angle.

[0108] Based on the above-mentioned shielding impact assessment method of the radar station, the implemented shielding impact assessment system of the radar station is applicable to the shielding limit assessment of civil aviation air traffic control primary / secondary radar stations, and includes: an OCR (Optical Character Recognition) recognition module 10, a shielding limit calculation module 20, and a visualization verification module 30.

[0109] As Figure 2 shown, the OCR recognition module 10 is used to automatically extract the longitude and latitude coordinates of the building from the review materials containing GIS information to obtain the coordinate file of the building.

[0110] The shielding angle calculation module 20 is configured to execute the shielding impact assessment method of the radar station described above based on the longitude and latitude coordinates extracted by the OCR recognition module 10 and / or the manually input longitude and latitude coordinates, so as to determine the shielding impact assessment result, and further determine whether the current building meets the shielding angle limit requirements of all radar stations in the area where the obstacle is located. The shielding impact assessment result is provided to civil aviation air traffic control radar experts as a scientific basis for project review and judgment.

[0111] The visualization verification module 30 is set to label the position and draw the outline according to the input longitude and latitude coordinates of the building, so as to visually display the longitude and latitude coordinates of the building to be evaluated on the electronic map. Optionally, it can also be set to verify the distance and azimuth of the building target relative to the radar station.

[0112] The shielding limit calculation module 20 is the core of the system, written in the Java language, and generates the GUI of the program based on the Java Swing framework. As described above, the shielding angle calculation module first converts the longitude and latitude coordinates into Rho / Theta (distance / angle) coordinates in the local spherical coordinate system (with the radar station as the origin) to calculate the distance and azimuth values of the building relative to the radar. Subsequently, according to the shielding angle formula in the industry standard "MH / T 4003.2 Civil Aviation Communication, Navigation and Surveillance Station (Station) Site Specification Part 2: Surveillance", it accurately calculates and evaluates whether the buildings under the project meet the shielding limit requirements of the en-route radar in this area. The EXCEL formatted form generated according to the shielding impact assessment result provides a basis for the review of the construction project.

[0113] In this embodiment, the review materials containing GIS information are the "Engineering Construction Project Design Plan Opinion Solicitation Form" submitted by the Shanghai Civil Aviation Supervision Bureau. The above-mentioned review materials list the GIS information of the newly built obstacles (i.e., buildings) that need to be calculated.

[0114] The OCR recognition module 10 is mainly responsible for the preliminary data preparation work for the calculation. Since data preparation is a boring and error-prone task, the present invention develops the OCR recognition module 10 using the Python language combined with the Paddle OCR framework to accurately extract the required GIS data.

[0115] In this embodiment, the OCR recognition module is a GUI program written in Python, aiming to extract the longitude and latitude information of the buildings included in the project according to the text of the "Engineering Construction Project Design Plan Opinion Solicitation Form". The OCR recognition module is named the "CoordHelper" tool.

[0116] The OCR recognition module 10 is set to:

[0117] Step A1: Read the PDF file of the review materials containing GIS information;

[0118] Step A2: Use Python language combined with the Paddle OCR framework to perform OCR recognition on the specified area of the specified page of the read PDF file to obtain the longitude and latitude information of the building;

[0119] Step A3: Export the longitude and latitude information of the building to a form for use in subsequent execution of the shielding impact assessment method of the radar station.

[0120] In this embodiment, processing is carried out in terms of the robustness of extraction. For example, Paddle OCR is mainly suitable for horizontal extraction. If there is an angle rotation problem in the pdf file, the recognition efficiency will be greatly reduced. Therefore, in Step A2, before performing OCR recognition on the specified area of the specified page of the read PDF file, check the specified page of the PDF file imported into the OCR recognition module, and perform manual rotation correction when its angle is incorrect, and then perform OCR recognition, thereby improving the effectiveness of discrimination.

[0121] The visualization verification module 30 is set to mark the position and draw the outline according to the input longitude and latitude coordinates of the building, so as to visually display the longitude and latitude coordinates of the building to be evaluated on the electronic map. Specifically, the visualization verification module 30 uses a self-written web scripting language to interact with the Baidu Map API, thereby realizing the visual display of the vector map and the satellite map, and intuitively displaying the position distribution of the building through the input longitude and latitude information (WGS84 geodetic coordinate system). Through the visual display, an intuitive feeling of the position of the obstacle and the building outline distribution on the Baidu Map can be obtained. At the same time, problems with incorrect input of the longitude and latitude information of the obstacle can also be discovered and corrected in a timely manner. In this embodiment, the main part of the visualization verification module 30 is written in HTML and JavaScript to implement the interactive function with an electronic map such as the Baidu Map API.

[0122] In addition, it can also be set to verify the distance and azimuth of the building target relative to the radar station. Specifically, Baidu Map has a built-in ranging algorithm, and the azimuth can be calculated through the map image pixel information. According to the results of ranging and angle measurement between two points, the calculation results can be roughly further confirmed. Therefore, the visualization verification module 30 can work independently as a separate module for daily troubleshooting and handling of abnormal radar targets.

[0123] Such as Figure 2As shown in the figure, there are three ways for the visualization verification module 30 to input the longitude and latitude coordinates of the building: 1. Manually input the longitude and latitude coordinates, that is, add the longitude and latitude coordinates one by one manually on the left side of the visualization interface of the visualization verification module 30; 2. Batch import the longitude and latitude coordinates. By writing the longitude and latitude coordinates of the building in a text file in advance and clicking the "Text Import" button, the batch import of longitude and latitude coordinate points can be realized; 3. Obtain the longitude and latitude coordinates from the shielding limit calculation module 20. Specifically, by clicking the "Map Verification" function button on the visualization interface of the shielding limit calculation module 20, the program will automatically open the Chrome browser and start the web version of the electronic map. In the web page, the longitude and latitude coordinates of the buildings in the shielding limit calculation module 20 will be automatically filled into the web version of the electronic map, and the electronic map will automatically import the longitude and latitude coordinates of the building to be evaluated and perform position marking and display.

[0124] It should be noted that the visualization verification module 30 itself does not have the function of calculating the shielding limit. It only hopes to provide a more intuitive display of the building location distribution and the potential impact on the radar line-of-sight coverage for subsequent expert review through visualization methods. The content of the verification includes data verification and algorithm verification of distance and azimuth. Data verification is mainly reflected in the ability to timely detect and correct the problem of incorrect input of obstacle longitude and latitude information. For example, if in the map, the position of a certain coordinate point deviates greatly from other points, this point is very likely to be a wrong coordinate point input by us. By observing the "abrupt" points in the figure, it helps us correct the errors; Algorithm verification mainly refers to the calculation verification of the distance and azimuth between the radar station and the building. By comparing the calculation results of the azimuth and distance algorithms adopted in this paper with the ranging algorithm built in Baidu Map (the azimuth can be calculated through the map image pixel information), the effectiveness of the method proposed in this paper is demonstrated.

[0125] Experimental results:

[0126] The following gives an experimental example of a radar station shielding impact assessment system.

[0127] In this experiment, the shielding angle calculation module 20 mainly realizes its functions through a visualization interface called "Shielding Angle Calculation Tool", and the visualization interface is as Figure 3 shown.

[0128] As Figure 3 shown, the "Shielding Angle Calculation Tool" can be divided into five functional areas: menu bar, function bar, information bar, result bar, and diagram bar. The functions and roles of each functional area specifically cover:

[0129] Menu bar: It includes two sub-menus, namely Source and SMR. Among them, Source is used to select whether the building coordinates to be calculated are from a file or the information bar on the panel; the SMR sub-menu mainly contains some auxiliary functions added later, including calculating the distance and azimuth information of the building from the Shanghai Area Surface Surveillance Radar and automatically generating a formatted form; and functions such as calculating the convex hull of coordinate points.

[0130] Function bar: It mainly covers functions such as obstruction angle calculation, form generation, and map verification. Among them, the calculation function can be further divided into "one-key calculation for multiple radars" and "one-key calculation for a single radar"; the program has built-in GIS information of 6 en-route radars in the Shanghai area. The "one-key calculation for multiple radars" button can quickly calculate the vertical and horizontal obstruction angles of the building from multiple radars and list information such as the "comprehensive height limit" and "comprehensive width limit" of the building for multiple radars in the exported EXCEL table.

[0131] Information bar: The information bar is divided into two parts. On the left is the GIS information of the radar station, including WGS84 longitude and latitude coordinates, radar station name, radar station tower height, and ground elevation of the area where the radar station is located. If you use the "one-key calculation for a single radar" button in the function bar, you need to accurately fill in the GIS information of the radar station here as required. On the right side of the information bar is the GIS information of the building. Usually, a building / building group contains the coordinates of multiple longitude and latitude points (several or even hundreds). For the case of fewer longitude and latitude coordinates, you can choose the manual addition method. Click the "More longitude and latitude coordinates" button to add the coordinates of a single longitude and latitude point. The interface for adding a single longitude and latitude point is as Figure 4 shown.

[0132] If the number of longitude and latitude coordinates exceeds a certain amount, the system will pop up a prompt indicating that no more addition is allowed. At this time, you should use the "file mode" in the Source sub-menu of the "Menu bar", and then click "Input From File" to select the coordinate file of the building to import the coordinates. The coordinate file of the building is generated by the OCR recognition module 10. The option location of "file mode" is as Figure 5 shown.

[0133] The result bar is used to display the calculation results of "one-key calculation for multiple radars" and "one-key calculation for a single radar". If you use "one-key calculation for multiple radars", it will default to display the obstruction limit requirements of all built-in radars for the building. Combining with the drop-down dialog box in the function bar, you can separately display the obstruction limit requirements of a specified single radar for the building. The calculation results of "one-key calculation for multiple radars" and "one-key calculation for a single radar" are as Figure 6 shown.

[0134] Illustration column: It is mainly used to prompt the user about the relative azimuth and distance of the building from the radar station, presented in the form of spherical coordinate system coordinates. Similarly, by cooperating with the drop-down dialog box in the function column, the illustration information of the distance and azimuth of a specified radar relative to the building can be displayed separately.

[0135] In an experimental example, the working process of the occlusion angle calculation module 20 is as follows:

[0136] 1) Taking "file mode" and "one-key calculation for multiple radars" as examples, first select "file mode" in the Source sub-menu of the "Menu bar", and then click "Input From File" to select the coordinate file of the building and import the coordinates. The coordinate file is a text file, and its content meets the format requirements as Figure 7 shown.

[0137] 2) When the coordinate points are successfully imported, the program pops up a corresponding prompt dialog box listing the imported coordinate points.

[0138] 3) After clicking "OK" in the dialog box, the coordinates are successfully imported. Click the "one-key calculation for multiple radars" button to calculate the occlusion impact assessment result. The occlusion impact assessment result will be displayed in the result column on the right, and the interface is as Figure 8 shown. If the result column on the right is empty, please go back and check whether the coordinate format / content entered in the text file is correct. Among them, some of the above Figures 3 to 8 radar information is occluded to hide some sensitive information.

[0139] 4) Perform form output.

[0140] Click the "Generate EXCEL Form" button in the function column, and fill in the name of the form in the popped-up file dialog box. The occlusion impact assessment result in the result column on the right can be generated into an EXCEL form according to the specified requirements, which can be further used by radar professionals for analysis and decision-making. The generated form is as Figure 9 and Figure 10 shown.

[0141] 5) Invoke the map verification function of the visualization verification module 30.

[0142] By clicking the "Map Verification" function button in the visualization interface of the occlusion limit calculation module 20, the map verification function of the visualization verification module 30 can be invoked, that is, the Baidu Map web page of the browser can be automatically opened and the longitude and latitude coordinates of the building are filled in. This function requires the cooperation of the installed webdriver plugin and a specified version of the chrome browser.

[0143] The OCR recognition module 10 is named the "CoordHelper" tool. When the "CoordHelper" tool is opened, the visualization interface is as Figure 11 shown.

[0144] The working process of the OCR recognition module 10 is as follows:

[0145] 1) First, click the "OPEN" button. In the opened file dialog box, select the review file to be opened. After the file is opened, the content of the current page of the PDF will be displayed in the file location display area below, and the current page number will be shown at the "Current Page Number". Subsequently, click the "SAVE" button and select the path (Excel format) to save the recognition result file, as follows Figure 12 shown.

[0146] 2) As Figure 12 shown, if the given file page is upside down, this will have a great impact on OCR recognition and reduce the recognition efficiency. Therefore, the rotation value needs to be filled in at the "Rotation Angle", then click "APPLY" to apply, and view the rotated result in the PDF display area. The rotation result is as Figure 13 shown.

[0147] 3) After confirming that the picture meets the requirements, select the page number to be recognized (i.e., the current page 4) in the text box behind Page, and click "APPLY" on the right side to take effect after filling. After confirming that it is correct, click the "START" button to start recognition. During the recognition process, the progress bar dialog box will be displayed until the recognition is completed. The progress bar dialog box is as Figure 14 shown.

[0148] 4) After the recognition is completed, the corresponding recognition result will be displayed in the recognition result display area on the right side, and a corresponding EXCEL file will be generated. If the recognition result is incorrect, it can be modified in the recognition result area. The recognition result in the recognition result area is as Figure 15 shown. After the modification is completed, click "SAVE MODIF" to save the modification result to the EXCEL file. The longitude and latitude coordinates in the EXCEL file are as Figure 16 shown.

[0149] The visualization verification module 30 is implemented by writing HTML and JavaScript code to call the Baidu Map API. Its web interface is as Figure 17 shown.

[0150] Figure 17 In it, the left area is the coordinate input area and function area, and the right part is the map area for map display. The left area realizes operations such as adding, deleting, clearing, and inverse selection of arbitrary coordinates.

[0151] The working process of the visualization verification module 30 is as follows:

[0152] 1) Taking the addition of a coordinate as an example, first click the "Add" button, and a dialog box will pop up as Figure 18 shown.

[0153] 2) After entering the coordinate to be added and clicking "OK", the added coordinate will first be displayed in the list below, and at the same time, the corresponding coordinate (named coordinate point 1) will also be added to the drop-down box above, as Figure 19 shown.

[0154] 3) The "Distance and Angle Measurement" section includes two parts: "Starting Coordinate" and "Ending Coordinate", which are used to measure the distance between two points. The WGS84 coordinates of all en-route radars and surface surveillance radars in the Shanghai area are built-in. After setting the "Starting Coordinate" and "Ending Coordinate", click the "Coordinate Distance Measurement" button to measure the distance and angle between the selected two points. The measurement results will be displayed on the Baidu Map on the right, as Figure 20 shown. Note: The coordinates in the figure have been converted from WGS84 to the BD09 coordinate system.

[0155] 4) By clicking the "Enable" button above, the coordinate selection function can be enabled. At that time, any point clicked on the Baidu Map, its longitude and latitude coordinates will be displayed in the longitude and latitude text boxes in front, as Figure 21 shown.

[0156] 5) Perform the map verification function.

[0157] To implement the map verification function, the coordinates of buildings need to be imported first. As mentioned above, the batch import and marked display of the longitude and latitude coordinates of buildings can be achieved through the occlusion limit calculation module 20, but a more common method is to click the "File Import" button on the web page. After clicking the "File Import" button and selecting the coordinate file, the batch import of coordinates can be achieved.

[0158] After the batch import of coordinates is completed, the "Mark" button can be clicked to display the imported coordinates on the map, or the outline of the building can be drawn by plotting coordinates. The display results of the imported coordinates are as Figure 22 and Figure 23 shown.

[0159] The significance of the building outline is that a convex polygon can be obtained. Based on some vertices of this convex polygon, the approximate information of the horizontal shielding angle of the obstacle for the radar station can be intuitively obtained. It should be noted that the visualization verification module itself does not have the function of calculating shielding limitations. It only hopes to provide a more intuitive display of the building location distribution and potential impacts on radar line-of-sight coverage for subsequent expert reviews through visualization methods.

[0160] The method for evaluating the shielding impact of the radar station of the present invention is mainly aimed at calculating the shielding impact of civil aviation air traffic control primary and secondary radar stations. It can calculate the vertical shielding angle of single / dense building multi-latitude and longitude coordinates under the industry regulations that meet the shielding angle, and solve the problems in the prior art such as high manual calculation cost, the calculation accuracy and accuracy being affected by subjective factors and objective conditions, and being out of touch with actual needs, so as to provide data support and theoretical basis for the planning, design, and review of surrounding buildings.

[0161] In addition, the system of the present invention has a user-friendly interface, is easy to operate and use. During use, it is not necessary to manually fill in latitude, longitude, and elevation information, and it can automatically calculate the shielding angle, which can greatly reduce the cost of manual calculation and also reduce the occurrence of errors. This tool and method can be widely used in production practice to provide shielding limitation calculation services.

[0162] The systems, devices, modules, or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0163] For the convenience of description, when describing the above devices, they are described as various units according to functions. Of course, when implementing this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0164] Those skilled in the art should understand that the embodiments of this specification can be provided as a method, a system, or a computer program product. Therefore, this specification can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, this specification can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0165] This specification is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the specification. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to produce a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices produce means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or multiple blocks.

[0166] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or multiple blocks.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are performed on the computer or other programmable device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or multiple blocks.

[0168] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0169] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0170] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0171] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0172] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems or computer program products. Therefore, this specification may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0173] This specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. This specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0174] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the method embodiment.

[0175] The above description is only for the embodiments of this specification and is not intended to limit this specification. For those skilled in the art, various modifications and changes can be made to this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included within the scope of the claims of this specification.

Claims

1. A method for evaluating the shielding effect of a radar station, which is used to evaluate the shielding effect of a primary / secondary radar of a civil air traffic control, characterized in that: include: Step S1: According to the coordinates of a single radar station and the single longitude and latitude coordinates of a building, the relative coordinates of the single longitude and latitude point of the building in the spherical coordinate system with the radar station as the origin are determined; Step S2: Taking the building as an obstacle, determine whether the relative distance between the radar station and the obstacle is greater than the protection range threshold according to the relative coordinates; if it is greater than the protection range threshold, there is no need to calculate the height limit according to the vertical shielding angle requirement; otherwise, determine the obstacle altitude limit according to the relative distance; Step S3: Determine whether the obstacle contains multiple longitude and latitude points; If the obstacle includes multiple longitude and latitude points, repeat steps S1 and S2 for each longitude and latitude point to sequentially calculate the azimuth in the relative coordinates of each longitude and latitude point of the obstacle, and determine the horizontal shielding angle of the obstacle relative to the same radar station based on all azimuths; On the contrary, the obstacle width limit is determined according to the relative distance between the radar station and the obstacle; Step S4: According to the altitude limit and horizontal shielding angle or width limit of the obstacle, determine the comprehensive altitude limit of each longitude and latitude point of the obstacle and the comprehensive horizontal shielding angle or comprehensive width limit of the obstacle as the shielding impact assessment result.

2. The method for evaluating the shielding impact of a radar station according to claim 1, characterized in that: The step S1 specifically includes: Step S11: Convert the coordinates of the radar station and the single longitude and latitude coordinates of the building from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system to obtain the coordinates (X s , Y s , Z s ), (X T , Y T , Z T ); Step S12: transform the coordinates of the radar station and the single longitude and latitude point of the building in the geocentric rectangular coordinate system into the local rectangular coordinate system with the radar station as the origin, and obtain the relative coordinates (X r ,Y r ,Z r ); Step S13: The relative coordinates (X r ,Y r ,Z r ) is transformed into a spherical coordinate system with the radar station as the origin, and the relative coordinates (ro, Az, phi) of a single longitude and latitude point of the building in the spherical coordinate system with the radar station as the origin are obtained.

3. The method for evaluating the shielding impact of a radar station according to claim 1, characterized in that: The relationship from the WGS84 geodetic coordinate system to the geocentric rectangular coordinate system satisfies: Where X, Y, and Z are the coordinates of the geocentric rectangular coordinate system, L, B, and H are the geodetic longitude, latitude, and altitude coordinates of the WGS84 geodetic coordinate system, a is the radius of the major axis of the earth, and e is the eccentricity of the ellipse; The relative coordinates of a single latitude and longitude point of a building in the local rectangular coordinate system (X r ,Y r ,Z r )for: Among them, L T , B T They represent the latitude and longitude coordinates of a single latitude and longitude point of a building in the WGS84 geodetic coordinate system, (X s , Y s , Z s ) is the coordinate of the radar station in the geocentric rectangular coordinate system, (X T , Y T , Z T ) is the coordinate of a single longitude and latitude point of a building in the geocentric rectangular coordinate system; The relative coordinates (ro, Az, phi) of a single latitude and longitude point of a building in the spherical coordinate system with the radar station as the origin are: Among them, atan2(Y r ,X r ) means to find Y r / X r The arc tangent value of, R is the radius of the earth at a single longitude and latitude point of the building, h is the altitude of the radar station.

4. The method for evaluating the shielding impact of a radar station according to claim 3, characterized in that: For radar stations and single longitude and latitude points of buildings, the value of the height coordinate H of the WGS84 geodetic coordinate system is uniformly set to the altitude of the radar station.

5. The method for evaluating shielding effects of a radar station according to claim 1, characterized in that: In step S2, the obstacle altitude limit B is: Wherein, B represents the upper limit of the obstacle, in meters, T represents the altitude of the radar station, in meters, and D represents the relative distance between the radar station and the obstacle, in kilometers. In step S3, the obstacle width limit W satisfies the following formula: Where W represents the obstacle width limit in meters, and D represents the relative distance between the radar station and the obstacle in kilometers.

6. The method for evaluating the shielding impact of a radar station according to claim 1, characterized in that: The step S4 specifically includes: Determine whether there are multiple radar stations in the area where the obstacle is located; If there are multiple radar stations, repeat steps S1 to S3 to sequentially calculate the obstacle altitude limit B and horizontal shielding angle or obstacle width limit W of each longitude and latitude point of the obstacle relative to each radar station; then, for each longitude and latitude point, take the minimum value from the obstacle altitude limit B of the single longitude and latitude point relative to all radar stations to obtain the comprehensive altitude limit of the single longitude and latitude point; for each obstacle, take the minimum value from the horizontal shielding angle or obstacle width limit W of the obstacle relative to each radar station to obtain the comprehensive horizontal shielding angle or comprehensive width limit of the obstacle; On the contrary, the obstacle altitude limit B and horizontal shielding angle or obstacle width limit W of each latitude and longitude point of the obstacle relative to the only radar station are directly used as the shielding impact assessment results.

7. The method for evaluating the shielding impact of a radar station according to claim 1, characterized in that: The method further comprises step S5: judging whether the building meets the requirements of the comprehensive altitude limit, the comprehensive horizontal shielding angle or the comprehensive width limit according to the shielding impact assessment result.

8. A radar station shielding impact assessment system, characterized in that: include: The OCR recognition module is configured to automatically extract the longitude and latitude coordinates of the building from the review materials containing GIS information to obtain a coordinate file of the building; and The shielding angle calculation module is used to execute the shielding impact assessment method of the radar station according to one of claims 1-7 according to the latitude and longitude coordinates extracted by the OCR recognition module and / or the latitude and longitude coordinates manually input to determine the shielding impact assessment result.

9. The radar station shielding impact assessment system according to claim 8, characterized in that: It also includes a visual verification module, which is configured to mark the location and draw the outline according to the input longitude and latitude coordinates of the building, so as to visually display the longitude and latitude coordinates of the building to be evaluated on the electronic map.

10. The radar station shielding impact assessment system according to claim 9, characterized in that: The visual verification module is also configured to verify the distance and orientation of the building target relative to the radar station.

Images