Airborne meteorological radar elevation approximate ground clutter suppression method and device
By constructing a multi-pitch center beam stereo scanning and data fusion method, the terrain height threshold is calculated in real time, which solves the problem of insufficient ground clutter suppression by airborne weather radar in complex terrain and achieves stronger robustness and adaptability.
Patent Information
- Application Number
- CN202511376251.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-25
- Publication Date
- 2025-11-28
AI Technical Summary
Existing airborne weather radars struggle to effectively suppress ground clutter in complex terrain environments, especially in areas with significant elevation changes, such as plateaus and mountains. Existing ground clutter suppression algorithms rely on empirical thresholds, resulting in insufficient robustness.
By constructing a multi-elevation center beam stereo scanning system, combined with angle measurement algorithms and data fusion methods, the terrain height threshold is calculated and updated in real time, approximating the digital elevation map and achieving dynamic suppression of ground clutter.
It improves the ground clutter suppression capability of airborne weather radar in complex terrain environments, enhances robustness, adapts to various terrain changes, and reduces reliance on empirical thresholds.
Smart Images
Figure CN121028092A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of airborne weather radar, and discloses an airborne weather radar height approximate ground clutter suppression method and device. BACKGROUND
[0002] In the actual working process of the airborne weather radar, due to the limitation of the system design parameters, in order to realize the weather detection of a large range and a long distance as much as possible, the radar beam will inevitably irradiate the ground, and then receive the echo signals from various non-weather carriers on the ground, which seriously interferes with the effective identification of the weather echo. Since the ground clutter intensity is usually much higher than the weather target echo, and its spatial distribution has complexity and irregularity, a specific algorithm needs to be used for ground clutter suppression, and the effectiveness of the algorithm determines the working performance of the weather mode.
[0003] In the existing disclosed ground clutter suppression method, the pilot manually adjusts the pitch angle of the radar in the early stage, and makes a human judgment and identification based on different echo displays. This way increases the burden of the pilot and is seriously dependent on the experience of the pilot. Subsequently, multi-scan ground clutter suppression technology and difference angle measurement ground clutter suppression technology have been developed, which have achieved certain ground clutter suppression effect. However, in the areas with large changes in terrain height such as plateau and mountainous areas, there is still a problem of incomplete ground clutter suppression. In order to solve this problem, a digital elevation map is further introduced, so that the factor of terrain height is fully considered in the algorithm. However, due to the large memory occupation of the digital elevation map, it is difficult to be embedded in most airborne weather radar products due to hardware limitations, which leads to the fact that when the related ground clutter suppression algorithm uses the terrain height information, only a fixed threshold value can be selected according to experience, which actually leads to the failure of the introduction of the digital elevation map idea. Therefore, in the case where the terrain height information cannot be used, an approximate method is needed to replace the role of the digital elevation map, instead of the fixed threshold value selected according to experience, so that the airborne ground clutter suppression technology can adapt to various complex terrain environments and improve the robustness of the ground clutter suppression capability. SUMMARY
[0004] The purpose of the present application is to provide an airborne weather radar height approximate ground clutter suppression method and device, which can approximately replace the role of the digital elevation map, so that the airborne weather radar ground clutter suppression technology can adapt to various complex terrain environments and improve the robustness of the ground clutter suppression capability.
[0005] In order to achieve the above technical effects, the technical solution adopted by the present application is: An airborne weather radar height approximate ground clutter suppression method, comprising: Step 1: According to the design parameters of the airborne weather radar system, determine the preset number of each azimuth frame in the scanning line and the detection range covered by each elevation beam center corresponding to the beam main lobe; Step 2: Optionally, one of the azimuth frames, obtain the radar echo data corresponding to the azimuth frame, determine the theoretical irradiation height interval and the ground clearance distance range of each elevation beam main lobe under the azimuth frame; at the same time, according to the radar echo data and the ground clearance distance range, calculate the angle error of each elevation beam, combine the angle error to determine the actual elevation angle corresponding to the echo data of each range gate of each elevation beam, and determine the measured terrain height value of each range gate on each elevation beam main lobe; based on the theoretical irradiation height interval of each elevation beam main lobe, screen the measured terrain height value of each range gate on each elevation beam main lobe to obtain the measured terrain height value corresponding to each elevation beam main lobe after screening; Step 3: Process the range gate in each elevation beam center direction and the range gate in the ground horizontal direction one by one to determine the multiple measured terrain height values corresponding to each range gate in the ground horizontal direction; process and update the multiple measured terrain height values corresponding to each range gate in the ground horizontal direction using numerical methods, and then process and update the multiple measured terrain height values corresponding to each range gate in the ground horizontal direction after processing using data fusion methods to obtain the final terrain height value corresponding to each range gate in the ground horizontal direction; Step 4: Traverse each azimuth frame in the scanning line, repeat steps 2 and 3 to obtain the final terrain height value of each range gate in the ground horizontal direction of each azimuth frame, and obtain the final terrain height value of each range gate in the ground horizontal direction corresponding to the two-dimensional scanning plane of the radar; Step 5: Based on the flight state of the carrier aircraft, read the final terrain height value of each range gate in the ground horizontal direction corresponding to the two-dimensional scanning plane in real time as a terrain height dynamic threshold, which is applied to ground clutter suppression to achieve ground clutter suppression; Step 6: According to the flight speed of the carrier aircraft and the designed meteorological detection distance of the radar, determine the interval time of repeating steps 2-5, and update the final terrain height value of each range gate in the ground horizontal direction corresponding to the two-dimensional scanning plane according to the interval time to complete the update of the terrain height dynamic threshold.
[0006] Further, in step 2, according to the main lobe beam width of each elevation beam, the theoretical irradiation height interval and the ground clearance distance range of each elevation beam main lobe are calculated.
[0007] Further, in step 2, the farthest theoretical ground contact distance is determined according to the ground contact distance range of each said elevation beam main lobe, and the radar echo data of the corresponding elevation beam is intercepted according to the farthest theoretical ground contact distance of each elevation beam; the angle error of each elevation beam is calculated by analyzing the radar echo data intercepted by each elevation beam using an angle measurement algorithm, and the actual elevation angle corresponding to the echo data of each distance gate of each elevation beam is determined in combination with the angle error, and the measured terrain height value of each distance gate on the main lobe of each elevation beam is determined.
[0008] Further, in step 3, the method for processing and updating the multiple measured terrain height values corresponding to each distance gate in the horizontal direction of the ground surface includes: For the multiple measured terrain height values corresponding to each distance gate in the horizontal direction of the ground surface, a preset threshold value of abnormal height is determined, and any one of the measured terrain height values is selected as a target measured terrain height value. If the difference between the target measured terrain height value and the immediately preceding value and the difference between the target measured terrain height value and the immediately following value are both greater than the preset threshold value of abnormal height, the target measured terrain height value is determined to be an abnormal value and is discarded. Otherwise, the target measured terrain height value is determined to be a valid value and is retained. Then, the next target measured terrain height value is determined, and this process is repeated until all measured terrain height values are processed, thereby obtaining the multiple processed measured terrain height values corresponding to each distance gate in the horizontal direction of the ground surface.
[0009] Further, in step 3, the method for processing and updating the multiple measured terrain height values corresponding to each distance gate in the horizontal direction of the ground surface includes: For the multiple processed measured terrain height values corresponding to each distance gate in the horizontal direction of the ground surface, a preset threshold value of inter-beam height comparison and a preset threshold value of meteorological height are determined. If the difference between the measured terrain height value of a certain elevation beam and the measured terrain height values of the remaining elevation beams at the same distance gate index is less than 50% of the number of the preset threshold value of inter-beam height comparison, the measured terrain height value of the certain elevation beam is retained. Otherwise, the measured terrain height value of the certain elevation beam is discarded, and the remaining measured terrain height values are compared in a loop. The average of the remaining measured terrain height values is taken as the final terrain height value at the distance gate index. If the difference between the measured terrain height value of any elevation beam and the measured terrain height values of the remaining elevation beams at the same distance gate index is less than 50% of the number of the preset threshold value of inter-beam height comparison, the median of the measured terrain height values of all elevation beams at the distance gate index is taken as the final terrain height value at the distance gate index. If the measured terrain height value corresponding to the distance gate exceeds the preset meteorological height threshold, the measured terrain height value is determined as potential meteorological data and removed. Based on the preset thresholds for inter-beam height comparison and meteorological height, the measured terrain height values on all ground horizontal distance gate indices are compared and processed. Then, missing values are interpolated to obtain the final terrain height value corresponding to each distance gate in the selected azimuth frame in the ground horizontal direction.
[0010] An airborne weather radar elevation approximate ground clutter suppression device, used in any of the aforementioned airborne weather radar elevation approximate ground clutter suppression methods, comprising: The stereoscopic scanning construction module with different pitch center beams is used to determine the preset number of pitch beam centers in each azimuth frame within the scanning row and the detection range covered by the main lobe of each pitch beam center, based on the design parameters of the airborne meteorological radar system. The measured terrain height calculation module is used to select any azimuth frame, acquire the radar echo data corresponding to the azimuth frame, determine the theoretical illumination height range and ground contact distance range of each elevation beam main lobe under the azimuth frame; simultaneously, based on the radar echo data and the ground contact distance range, calculate the angular error of each elevation beam, combine the angular error to determine the actual elevation angle corresponding to the echo data at each range gate of each elevation beam, and determine the measured terrain height value of each range gate on each elevation beam main lobe; based on the theoretical illumination height range of each elevation beam main lobe, filter the measured terrain height values of each range gate on each elevation beam main lobe to obtain the filtered measured terrain height values corresponding to each elevation beam main lobe; The mapping and numerical processing module is used to map the range gates in the center direction of each pitch beam to the range gates in the horizontal direction of the ground, and determine the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground. The module then processes and updates the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using numerical methods, and finally processes and updates the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using data fusion methods, to obtain the final terrain height value that corresponds one-to-one with each range gate in the horizontal direction of the ground. The scanning plane height distribution module is used to traverse each azimuth frame in the scanning line, repeat steps 2 and 3, obtain the final terrain height value of each range gate in the horizontal direction of the ground in each azimuth frame, and obtain the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the radar two-dimensional scanning plane. The fixed height threshold replacement module is used for reading the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane in real time as a terrain height dynamic threshold based on the flight state of the carrier, and the terrain clutter is suppressed by applying the terrain height dynamic threshold. The periodic updating module is used for determining the preset interval time of repeated execution of the measured terrain height calculation module, the mapping and numerical processing module, the scanning plane height distribution module and the fixed height threshold replacement module according to the flight speed of the carrier and the designed meteorological detection distance of the radar, and updating the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane according to the interval time, so as to complete the updating of the terrain height dynamic threshold.
[0011] Further, in step 2, the theoretical irradiation height interval and the ground contact distance range of each said elevation beam lobe are calculated according to the main lobe width of each said elevation beam in the azimuth frame.
[0012] Further, in step 2, the farthest theoretical ground contact distance is determined according to the ground contact distance range of each said elevation beam lobe, and the radar echo data of the corresponding elevation beam is intercepted according to the farthest theoretical ground contact distance of each elevation beam; the angle error of each elevation beam is calculated by using the angle measurement algorithm to analyze the radar echo data intercepted by each elevation beam, and the actual elevation angle corresponding to the echo data of each range gate of each elevation beam lobe is determined combined with the angle error, and the measured terrain height value of each range gate on each elevation beam lobe is determined.
[0013] Compared with the prior art, the present application has the following beneficial effects: The present application fully considers the radar system design parameters, constructs a variety of elevation center beam three-dimensional scanning systems on the azimuth frame, so that the main lobe part between different elevation center beams is seamlessly connected, and the potential ground irradiation range of the airborne weather radar is completely covered. On this basis, according to the theoretical ground range of different elevation center beams, the echo data is analyzed and intercepted, and an angle measuring method is used for processing, and the height value of each distance gate is calculated. Further, the height value obtained is processed by a numerical method combined with theoretical experience, and the horizontal height distribution value on a certain azimuth frame is constructed. The above operation is performed on all azimuth frames in a scanning row, and finally the height distribution value in the two-dimensional scanning plane is constructed, which is approximately a digital elevation map. The terrain height at different distance gates obtained finally is intercepted according to the speed and flight time of the aircraft, and the horizontal height curve after interception is converted in the distance direction according to the actual elevation angle, and the measured terrain height is calculated, and interpolation processing is performed, so as to replace the terrain height threshold selected according to experience in the subsequent interval time, and the measured terrain height is used to replace the terrain height threshold for ground clutter suppression calculation, which approximately replaces the role of the digital elevation map, so that the airborne ground clutter suppression technology can adapt to various complex terrain environments, and the robustness of the ground clutter suppression ability is improved. BRIEF DESCRIPTION OF DRAWINGS
[0014] Figure 1 A flowchart of the airborne weather radar height approximate ground clutter suppression method in the embodiment; Figure 2 A flowchart of the airborne weather radar height approximate ground clutter suppression method in the embodiment; Figure 3 A result of using the prior art to select a fixed height threshold according to experience and perform ground clutter suppression; Figure 4 A result of using the airborne weather radar height approximate ground clutter suppression method in the embodiment to perform ground clutter suppression; Figure 5 A structural schematic diagram of the airborne weather radar height approximate ground clutter suppression method in the embodiment. DETAILED DESCRIPTION
[0015] The present application will be further described in detail below in combination with the embodiments and the drawings. However, this should not be understood as limiting the scope of the above-mentioned subject matter of the present application to the following embodiments, and any technology realized based on the content of the present application belongs to the scope of the present application.
[0016] EMBODIMENT Reference Figures 1-4 An airborne weather radar height approximate ground clutter suppression method, comprising Step 1: Based on the design parameters of the airborne weather radar system, determine the preset number of elevation beam centers in each azimuth frame within the scanning row and the detection range covered by the beam corresponding to each elevation beam center.
[0017] Specifically, a three-dimensional scanning system with different elevation center beams is constructed. This yields the design parameters for the airborne weather radar system: main lobe beamwidth. Distance from potential furthest construction site Determine the preset number of elevation beam centers: , … , n It is the center of the nth elevation beam.
[0018] Determine the detection range covered by each elevation beam center: the elevation beam center is When the upper edge and lower edge of the main lobe of the beam reach the ground, the coverage detection range is: The elevation beam center is When the upper edge and lower edge of the main lobe of the beam reach the ground, the coverage detection range is: ...; The elevation beam center is When the upper edge and lower edge of the main lobe of the beam reach the ground, the coverage detection range is: To ensure that the detection range covered when the main lobe of the center beam of different elevations partially touches the ground, the following conditions are met: ; in, The minimum measurable range of the radar is determined by considering both the actual performance indicators of the airborne weather radar and the lower limit of the possible elevation beam center setting. Given the complexity of the terrain and to ensure the accuracy of subsequent altitude calculations, the determination of the number of beams must satisfy the aforementioned detection range expression while also considering the radar system design parameters and related performance. Through the seamless connection of the main lobe portions of multiple different elevation beam centers, it is possible to ensure coverage of the radar's potential ground cover area while ensuring that all ground targets within that potential ground cover area are illuminated by the main lobe beam width.
[0019] Step 2: Select any one of the azimuth frames, acquire the radar echo data corresponding to the azimuth frame, and determine the theoretical illumination height range and ground contact distance range of each elevation beam main lobe under the azimuth frame; simultaneously, calculate the angular error of each elevation beam based on the radar echo data and the ground contact distance range, and combine the angular error to determine the actual elevation angle corresponding to the echo data on each range gate of each elevation beam, and determine the measured terrain height value of each range gate on each elevation beam main lobe; based on the theoretical illumination height range of each elevation beam main lobe, filter the measured terrain height values of each range gate on each elevation beam main lobe to obtain the filtered measured terrain height values corresponding to each elevation beam main lobe.
[0020] Specifically, the altitude of multiple beams in any azimuth frame is calculated.
[0021] Step 2.1: Based on the beams with different elevation beam centers determined in Step 1, combine the main lobe beamwidth of each beam... The theoretical scanning range of each pitch beam main lobe is calculated one by one, that is, the height range covered by each pitch beam main lobe is determined. and the distance range of the construction site Among them, the lower limit of the height range covered by the main lobe. and upper limit The calculation formula is as follows: ; ; in The equivalent radius of the Earth. For the height of the aircraft, For the target distance, Center of the pitch beam and Target distance The theoretical heights of the upper and lower edges of the main lobe of the beam at the specified location. and Setting all values to 0, the range of distances for setting up the platform can be calculated based on the two formulas mentioned above. .
[0022] Step 2.2: Based on the farthest theoretical grounding distance of each pitch beam main lobe segment The echo data of the corresponding elevation center beam is extracted as follows: ; in, This represents the actual value corresponding to the radar unit range gate index. for Echo data of the azimuth frame corresponding to the elevation beam. For The elevation beam corresponds to the echo data obtained after interception. The echo data of each beam under the azimuth frame is processed as described above, and the intercepted data does not participate in the subsequent angle measurement and height calculation.
[0023] Step 2.3: The echo data of each beam under the azimuth frame is processed using the existing known angle measurement method, the angle error is calculated, the corrected elevation angle value is obtained, and then the terrain height value of each range gate is calculated according to the corrected elevation angle value. After all the processing is completed, the terrain height value within the main lobe irradiation range of each elevation beam under the azimuth frame can be obtained.
[0024] Step 2.4: According to the theoretical height interval covered by the main lobe part of each elevation beam under the azimuth frame calculated in step 2.1, the terrain height value of each elevation beam at all range gates calculated in step 2.3 is screened. If the terrain height value is within the theoretical height value interval, it is retained, and if the terrain height value is outside the theoretical height value interval, it is discarded. Specifically as follows: ; Among them, is the terrain height value actually calculated by the elevation beam at the range gate , is the upper limit of the theoretical height value of the main lobe part of the elevation beam at the range gate , is the lower limit of the theoretical height value of the main lobe part of the elevation beam at the range gate , represents or. For the phenomenon of missing height value for some range gates, an interpolation method is used for processing to ensure that each range gate has a corresponding terrain height value. After all the beams under the azimuth frame are processed, the result value should be as follows: ; Step 3: The range gate in the center direction of each elevation beam is one-to-one mapped with the range gate in the horizontal direction of the ground to determine a plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground; the plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground are processed and updated using a numerical method, and the plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground after updating are processed and updated using a data fusion method, to obtain a final terrain height value corresponding to each range gate in the horizontal direction of the ground.
[0025] Specifically, the calculated heights of the multiple ground-hugging beams are mapped and processed by using a numerical method combined with theoretical and empirical processing.
[0026] According to the measured terrain height values corresponding to each main lobe of the selected elevation beams after screening under the selected azimuth frame obtained in step 2, horizontal mapping processing is performed. First, according to the measured terrain height values corresponding to each main lobe of the selected elevation beams, the horizontal projection distance of each main lobe is calculated. Calculation The distance gate on the beam The projection distance in the horizontal direction of the ground The distance gate in the horizontal direction of the ground is constructed, that is, the distance index of the measured terrain height values in the horizontal direction of the ground is obtained, so as to realize one-to-one correspondence and determine the multiple measured terrain height values corresponding to each distance gate in the horizontal direction of the ground.
[0027] Then, the abnormal terrain height values are removed from the measured terrain height values corresponding to each main lobe of the selected elevation beams, that is, if the difference between the certain measured terrain height value and the immediately preceding and following values is greater than the abnormal height preset threshold value , it is determined as an abnormal terrain height value and is removed.
[0028] Next, on each distance gate index in the horizontal direction of the ground, longitudinal comparison processing operations are performed on the terrain height values between the beams: If the difference between the terrain height value of a certain beam on the same distance gate index and the terrain height values of the remaining beams is less than the inter-beam height comparison preset threshold value , the number of the remaining elevation beams is more than 50%, the remaining terrain height values are retained, otherwise they are discarded, and the retained terrain height values are processed by mean value to obtain the final terrain height value on the distance gate index; If the difference between the terrain height value of any beam on the same distance gate index and the terrain height values of the remaining beams is less than the inter-beam height comparison preset threshold value , the number of the remaining elevation beams is less than 50%, the intermediate value is taken as the final terrain height value on the distance gate index; If the terrain height value exceeds the meteorological height preset threshold value , it is determined as a potential meteorological phenomenon and is directly removed. The abnormal height preset threshold value , the inter-beam height comparison preset threshold value and the meteorological height preset threshold value are all empirically preset.
[0029] After the longitudinal comparison processing operations on the terrain height values on all horizontal distance gate indexes, interpolation processing is performed on the missing values, and finally the horizontal terrain height values under the azimuth frame are obtained.
[0030] Step 4: traversing each azimuth frame within the scan line, repeating Step 2 and Step 3 to obtain the final terrain height value of each range gate in the horizontal direction of the ground for each azimuth frame, and to obtain the terrain height value of each range gate in the horizontal direction corresponding to the two-dimensional scan plane of the radar.
[0031] Specifically, the height distribution value in the two-dimensional scan plane is obtained. The airborne weather radar scans in the azimuth direction. For the multi-elevation beam echo data under each azimuth frame, the processing operations from Step 2 to Step 4 are performed, thereby obtaining the terrain height value in the horizontal direction under each azimuth frame. After the end of a scan line scan, the terrain height value in the two-dimensional scan plane can be obtained.
[0032] Step 5: replacing the fixed height threshold selected according to experience. Based on the flight state of the aircraft, the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the two-dimensional scan plane is read in real time as a terrain height dynamic threshold, which is applied to ground clutter suppression to achieve ground clutter suppression.
[0033] Step 6: periodically updating the measured terrain height data. According to the flight speed of the aircraft and the designed meteorological detection distance of the radar, the interval time for repeating Steps 2-5 is determined, and the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the two-dimensional scan plane is updated at the interval time to complete the update of the terrain height dynamic threshold.
[0034] Specifically, according to the terrain height value in the two-dimensional scan plane obtained in Step 4, based on the flight speed of the aircraft, in combination with the processing time of Steps 1 to 4 and the interval time for entering the operation next time, the real-time distance flown by the aircraft is determined, thereby real-time intercepting the terrain height value of the corresponding range gate in the two-dimensional scan plane. Further, the one-to-one correspondence of the range gate index is performed with reference to the current radar beam elevation center, and interpolation processing is performed to obtain the corresponding terrain height value, form a new terrain height dynamic threshold, and finally replace the fixed threshold selected according to experience. Every time, the repeating operation of Steps 2 to 5 is performed, thereby realizing the periodic update of the terrain height data.
[0035] Based on the same inventive concept, see Figure 5 The embodiment also provides an airborne weather radar elevation approximate ground clutter suppression device for the foregoing airborne weather radar elevation approximate ground clutter suppression method, which comprises: A different-elevation-center-beam three-dimensional connection scanning construction module is configured to determine a preset number of elevation beam centers under each azimuth frame within a scan line and a detection range covered by a main lobe of each elevation beam center according to system design parameters of an airborne weather radar. The measured terrain height calculation module is configured to, for an optional azimuth frame, acquire radar echo data corresponding to the azimuth frame, determine a theoretical irradiation height interval and a ground clearance distance range of a main lobe of each elevation beam under the azimuth frame, calculate an angle error of each elevation beam according to the radar echo data and the ground clearance distance range, determine an actual elevation angle corresponding to echo data of each range gate of each elevation beam in combination with the angle error, and determine a measured terrain height value of each range gate on the main lobe of each elevation beam. The mapping and numerical processing module is configured to perform one-to-one mapping processing on the range gates in the central direction of each elevation beam and the range gates in the horizontal direction of the ground, determine a plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground, process and update the plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground by using a numerical method, and process the updated plurality of measured terrain height values corresponding to each range gate in the horizontal direction of the ground by using a data fusion method, to obtain a final terrain height value corresponding to each range gate in the horizontal direction of the ground. The scanning plane height distribution module is configured to traverse each azimuth frame in a scanning line, repeat steps 2 and 3, obtain a final terrain height value of each range gate in the horizontal direction of the ground for each azimuth frame, and obtain a final terrain height value of each range gate in the horizontal direction of the ground corresponding to a two-dimensional scanning plane of the radar. The fixed height threshold replacement module is configured to, based on a flight state of an aircraft, read, in real time, a final terrain height value of each range gate in the horizontal direction of the ground corresponding to a two-dimensional scanning plane as a terrain height dynamic threshold, apply the terrain height dynamic threshold to ground clutter suppression, and implement ground clutter suppression. The periodic update module is configured to determine a preset interval time at which the measured terrain height calculation module, the mapping and numerical processing module, the scanning plane height distribution module and the fixed height threshold replacement module are repeatedly executed, according to a flight speed of the aircraft and a designed meteorological detection distance of the radar, update the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane at the interval time, and complete update of the terrain height dynamic threshold.
[0036] Further, in step 2, the theoretical irradiation height interval and the ground clearance distance range of each main lobe of the elevation beam are calculated according to a main lobe beam width of each elevation beam under the azimuth frame.
[0037] Further, in step 2, the farthest theoretical ground contact distance is determined according to the ground contact distance range of each of the main lobes of the elevation beams, and the radar echo data of the corresponding elevation beam is intercepted according to the farthest theoretical ground contact distance of each elevation beam; the angle error of each elevation beam is calculated by analyzing the radar echo data intercepted by each elevation beam using an angle measurement algorithm, and the actual elevation angle corresponding to the echo data of each range gate of each elevation beam is determined in combination with the angle error, and the measured terrain height value of each range gate on the main lobe of each elevation beam is determined.
[0038] When the digital elevation map is limited by hardware limitations and cannot be introduced into the airborne weather radar, the height of the terrain is calculated to replace the fixed threshold value selected according to experience. Specifically, the present application fully considers the design parameters of the radar system to construct a variety of elevation center beam three-dimensional scanning systems on the azimuth frame, so that the main lobe part between different elevation center beams is seamlessly connected and completely covers the potential ground irradiation range of the airborne weather radar. On this basis, the echo data is analyzed and intercepted according to the theoretical ground contact range of different elevation center beams, and the height value of each range gate is calculated by using the angle measurement method. Further, the height value obtained is processed by using numerical methods combined with theoretical experience to construct the horizontal height distribution value on a certain azimuth frame. The above operation is performed on all azimuth frames in a scanning row, and finally the height distribution value in the two-dimensional scanning plane is constructed, which is approximately a digital elevation map. The terrain height at different range gates is obtained, and according to the speed of the aircraft and the flight time, the corresponding interception is performed. The horizontal height curve after interception is converted to the distance direction according to the actual elevation angle, the measured terrain height is calculated, and interpolation processing is performed to replace the terrain height threshold value selected according to experience in the subsequent interval time. By replacing the terrain height threshold value with the measured terrain height for ground clutter suppression calculation, the role of the digital elevation map is approximately replaced, so that the airborne ground clutter suppression technology can adapt to various complex terrain environments, and the robustness of the ground clutter suppression capability is improved. Figure 3 For the results of using the existing technology to select a fixed height threshold value according to experience and perform ground clutter suppression, Figure 4 For the results of using the airborne weather radar elevation approximate ground clutter suppression method of the present embodiment to perform ground clutter suppression, Figure 3 and Figure 4 It can be seen that by using the airborne weather radar elevation approximate ground clutter suppression method of the present embodiment, the measured terrain height is used to replace the terrain height threshold value for ground clutter suppression calculation, which approximately replaces the role of the digital elevation map, so that the airborne ground clutter suppression technology can adapt to various complex terrain environments, and the robustness of the ground clutter suppression capability is improved.
[0039] The present application adopts a multi-beam three-dimensional scanning coverage mode, alleviates the problem of limited coverage range caused by the upper and lower two kinds of beams of the multi-scanning algorithm being limited by radar system parameters; the present application selects the main lobe part of multiple pitch center beams to cover the potential ground irradiation range of the airborne weather radar, and as much as possible eliminates the influence of sidelobe clutter on height measurement; the present application adopts a processing method of layering and splicing combined with a voting mechanism, while covering the radar potential ground irradiation range as much as possible, the accuracy of the final height measurement is ensured; the present application does not need to load a digital elevation map database, and approximately obtains the actual terrain height value, ensuring the algorithm adaptability under different terrain conditions; the present application method does not need to change the existing radar antenna and hardware equipment, and has strong engineering implementability, and the robustness of the ground clutter suppression technology is effectively improved.
[0040] The above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for suppressing approximate ground clutter in elevation from an airborne weather radar, characterized in that, include: Step 1: Based on the design parameters of the airborne weather radar system, determine the preset number of elevation beam centers in each azimuth frame within the scanning row and the detection range covered by the main lobe of each elevation beam center. Step 2: Select any one of the azimuth frames, acquire the radar echo data corresponding to the azimuth frame, and determine the theoretical illumination height range and ground contact distance range of each elevation beam main lobe under the azimuth frame; simultaneously, based on the radar echo data and the ground contact distance range, calculate the angular error of each elevation beam, and combine the angular error to determine the actual elevation angle corresponding to the echo data on each range gate of each elevation beam, and determine the measured terrain height value of each range gate on each elevation beam main lobe; based on the theoretical illumination height range of each elevation beam main lobe, filter the measured terrain height values of each range gate on each elevation beam main lobe to obtain the filtered measured terrain height values corresponding to each elevation beam main lobe; Step 3: Map the range gates in the center direction of each pitch beam to the range gates in the horizontal direction of the ground to determine the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground; process and update the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using numerical methods; then process and update the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using data fusion methods to obtain the final terrain height values that correspond one-to-one with each range gate in the horizontal direction of the ground. Step 4: Traverse each azimuth frame in the scan line, repeat steps 2 and 3, obtain the final terrain height value of each range gate in the horizontal direction of the ground in each azimuth frame, and obtain the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the radar two-dimensional scanning plane. Step 5: Based on the aircraft's flight status, read in real time the final terrain height value of each distance gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane, and use it as a dynamic terrain height threshold to suppress ground clutter. Step 6: Based on the aircraft's flight speed and the radar's designed meteorological detection range, determine the interval for repeating steps 2-5, and update the final terrain height value of each distance gate in the horizontal direction corresponding to the two-dimensional scanning plane according to the interval, thus completing the update of the terrain height dynamic threshold.
2. The method for suppressing approximate ground clutter on the elevation of an airborne weather radar according to claim 1, characterized in that, In step 2, under the azimuth frame, the theoretical illumination height range and ground contact distance range of each pitch beam main lobe are calculated based on the main lobe beamwidth of each pitch beam.
3. The method for suppressing approximate ground clutter on the elevation of an airborne meteorological radar according to claim 2, characterized in that, In step 2, the farthest theoretical ground contact distance is determined based on the ground contact distance range of the main lobe of each pitch beam, and the radar echo data of the corresponding pitch beam is intercepted based on the farthest theoretical ground contact distance of each pitch beam; the radar echo data intercepted by each pitch beam is analyzed using an angle measurement algorithm, the angular error of each pitch beam is calculated, and the actual pitch angle corresponding to the echo data of each range gate of each pitch beam is determined based on the angular error, and the measured terrain height value of each range gate on the main lobe of each pitch beam is determined.
4. The method for suppressing approximate ground clutter on the elevation of an airborne weather radar according to claim 3, characterized in that, In step 3, the method for processing and updating multiple measured terrain height values corresponding to each distance door in the horizontal direction of the ground using numerical methods includes: For each distance gate in the horizontal direction of the ground, multiple measured terrain height values are determined, and an abnormal height preset threshold is established. One of the measured terrain height values is randomly selected as the target measured terrain height value. If the difference between the target measured terrain height value and its immediate preceding value, and the difference between the target measured terrain height value and its immediate following value, are both greater than the abnormal height preset threshold, then the target measured terrain height value is determined to be an abnormal value and removed. Conversely, if the difference is less than the threshold, then the target measured terrain height value is determined to be a valid value and retained. The process continues until all measured terrain height values are traversed, resulting in multiple measured terrain height values corresponding to each distance gate in the horizontal direction of the ground.
5. The method for suppressing approximate ground clutter on the elevation of an airborne weather radar according to claim 4, characterized in that, In step 3, the method for processing the updated measured terrain height values corresponding to each distance gate in the horizontal direction of the ground using a data fusion approach includes: For each distance gate in the horizontal direction of the ground after processing, a preset threshold for inter-beam height comparison and a preset threshold for meteorological height are determined. If, on the same range gate index, the number of times the difference between the measured terrain height value of a certain pitch beam and the measured terrain height values of the remaining pitch beams is less than the preset threshold for inter-beam height comparison exceeds 50% of the number of remaining pitch beams, then the measured terrain height value of the pitch beam is retained; otherwise, the measured terrain height value of the pitch beam is discarded. The comparison is repeated, and the retained measured terrain height values are averaged to obtain the final terrain height value on the range gate index. If the number of times the difference between the measured terrain height value of any pitch beam and the measured terrain height value of the remaining beams on the same range gate index is less than the preset threshold for inter-beam height comparison is less than 50% of the number of remaining pitch beams, then the median value of the measured terrain height values of all pitch beams on the range gate index is taken as the final terrain height value on the range gate index. If the measured terrain height value corresponding to the distance gate exceeds the preset meteorological height threshold, the measured terrain height value is determined as potential meteorological data and removed. Based on the preset thresholds for inter-beam height comparison and meteorological height, the measured terrain height values on all ground horizontal distance gate indices are compared and processed. Then, missing values are interpolated to obtain the final terrain height value corresponding to each distance gate in the selected azimuth frame in the ground horizontal direction.
6. An airborne weather radar elevation approximate ground clutter suppression device, used to implement the airborne weather radar elevation approximate ground clutter suppression method according to any one of claims 1-5, characterized in that, include: The stereoscopic scanning construction module with different pitch center beams is used to determine the preset number of pitch beam centers in each azimuth frame within the scanning row and the detection range covered by the main lobe of each pitch beam center, based on the design parameters of the airborne meteorological radar system. The measured terrain height calculation module is used to select any azimuth frame, acquire the radar echo data corresponding to the azimuth frame, determine the theoretical illumination height range and ground contact distance range of each elevation beam main lobe under the azimuth frame; simultaneously, based on the radar echo data and the ground contact distance range, calculate the angular error of each elevation beam, combine the angular error to determine the actual elevation angle corresponding to the echo data at each range gate of each elevation beam, and determine the measured terrain height value of each range gate on each elevation beam main lobe; based on the theoretical illumination height range of each elevation beam main lobe, filter the measured terrain height values of each range gate on each elevation beam main lobe to obtain the filtered measured terrain height values corresponding to each elevation beam main lobe; The mapping and numerical processing module is used to map the range gates in the center direction of each pitch beam to the range gates in the horizontal direction of the ground, and determine the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground. The module then processes and updates the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using numerical methods, and finally processes and updates the multiple measured terrain height values corresponding to each range gate in the horizontal direction of the ground using data fusion methods, to obtain the final terrain height value that corresponds one-to-one with each range gate in the horizontal direction of the ground. The scanning plane height distribution module is used to traverse each azimuth frame in the scanning line, repeat steps 2 and 3, obtain the final terrain height value of each range gate in the horizontal direction of the ground in each azimuth frame, and obtain the final terrain height value of each range gate in the horizontal direction of the ground corresponding to the radar two-dimensional scanning plane. The fixed height threshold replacement module is used to read the final terrain height value of each distance gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane in real time based on the flight status of the carrier aircraft. This value is used as a dynamic terrain height threshold to suppress ground clutter. The periodic update module is used to determine the preset interval time for the repeated execution of the measured terrain height calculation module, mapping and numerical processing module, scanning plane height distribution module and fixed height threshold replacement module based on the aircraft flight speed and the radar's designed meteorological detection range. It updates the final terrain height value of each distance gate in the horizontal direction of the ground corresponding to the two-dimensional scanning plane according to the interval time, thus completing the update of the dynamic terrain height threshold.
7. The airborne weather radar elevation approximate ground clutter suppression device according to claim 6, characterized in that, In step 2, under the azimuth frame, the theoretical illumination height range and ground contact distance range of each pitch beam main lobe are calculated based on the main lobe beamwidth of each pitch beam.
8. The airborne weather radar elevation approximate ground clutter suppression device according to claim 6, characterized in that, In step 2, the farthest theoretical ground contact distance is determined based on the ground contact distance range of the main lobe of each pitch beam, and the radar echo data of the corresponding pitch beam is intercepted based on the farthest theoretical ground contact distance of each pitch beam; the radar echo data intercepted by each pitch beam is analyzed using an angle measurement algorithm, the angular error of each pitch beam is calculated, and the actual pitch angle corresponding to the echo data of each range gate of each pitch beam is determined based on the angular error, and the measured terrain height value of each range gate on the main lobe of each pitch beam is determined.