A monopulse airborne weather radar elevation pointing angle adjustment method and radar device

Abstract

The application provides a single-channel airborne weather radar pitch pointing angle adjusting method, and belongs to the field of airborne radar control, and the method comprises the following steps: acquiring real-time position, heading angle, pitch beam width, scanning range and digital elevation map of an airplane, and determining the terrain height of the position directly below the airplane; obtaining the ideal ground-hugging angle of the radar beam center according to the real-time position of the airplane, calculating the height variation of the lower edge of the radar beam, and obtaining the horizontal distance between the lower edge of the radar beam and the ground-hugging point in the area where the airplane is located according to the height variation of the lower edge of the radar beam; determining the target detection area covered by the radar beam and the positions and heights of the scattered points in the target detection area according to the relationship between the horizontal distance and the current range of the radar; determining the pitch pointing angle of the radar beam according to the height of the scattered points; and controlling the radar antenna to perform multiple scans upwards according to the beam width based on the pitch pointing angle of the radar beam, so as to obtain meteorological target data of different scanning layers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of airborne radar control, and particularly relates to a single-channel airborne weather radar pitch pointing angle adjusting method and a radar device. BACKGROUND

[0002] Automatic ground clutter suppression in an airborne weather radar is an important function of weather detection, which can greatly reduce the dependence of pilots on radar product use experience and reduce the operational burden of pilots, and therefore reliable ground clutter suppression in different environments is a basic capability requirement of a weather radar.

[0003] At present, airborne weather radars in the fields of civil aviation, navigation, etc. mainly use traditional mechanical scanning radars due to single use scenarios, and usually only have a single channel, i.e., a horizontal channel. The beam pointing accuracy of the single channel is low, and accurate height measurement cannot be achieved. The airborne weather radars mainly perform automatic ground clutter suppression through multi-scan fusion in the range direction, but need to design the pitch scanning angle in advance. This scheme is suitable for civil aviation and navigation with relatively fixed routes, but is not suitable for small-sized airborne weather radars and complex and variable geographical environments, and cannot easily meet the use needs of pilots. SUMMARY

[0004] The present application aims to provide a single-channel airborne weather radar pitch pointing angle adjusting method and a radar device to solve or alleviate at least one problem in the background art.

[0005] The technical solution of the present application is a single-channel airborne weather radar pitch pointing angle adjusting method, comprising:

[0006] acquiring real-time position, heading angle, pitch beam width, scanning range and digital elevation map of an airplane, obtaining terrain height of a position directly below the airplane according to real-time position data of the airplane and digital elevation map data;

[0007] obtaining an ideal ground-hugging angle of a radar beam center according to the real-time position of the airplane, calculating radar beam lower edge height variation according to the ideal ground-hugging angle, real-time position of the airplane, pitch beam width and terrain height, and obtaining horizontal distance between the radar beam lower edge and the ground-hugging point in a region where the airplane is located according to the radar beam lower edge height variation;

[0008] determining a target detection region covered by the radar beam and the position and height of a scatter point in the target detection region according to the relationship between the horizontal distance and the current range of the radar;

[0009] determining a radar beam pitch pointing angle according to the height of the scatter point;

[0010] Based on the radar beam elevation pointing angle, the radar antenna is controlled to be scanned upward by beam width one by one to obtain meteorological target data of different scanning layers, and after the scanning is completed, the meteorological target data of multiple scans are fused to suppress ground clutter.

[0011] In the preferred embodiment of the present application, the real-time position of the aircraft includes longitude, latitude and absolute pressure altitude.

[0012] In the preferred embodiment of the present application, the calculation method of the ideal ground contact angle of the radar beam center is:

[0013]

[0014] In the formula, is the ideal ground contact angle of the radar beam center;

[0015] R e is the radius of the earth;

[0016] PrH is the absolute pressure altitude.

[0017] In the preferred embodiment of the present application, the calculation method of the height variation H down_D of the lower edge of the radar beam is:

[0018]

[0019] In the formula, H down_D is the height variation of the lower edge of the beam;

[0020] n r is the step value;

[0021] R(n r ) is the horizontal detection distance, and the projection of the horizontal detection distance R(n r ) on the horizontal plane is the horizontal distance D1.

[0022] In the preferred embodiment of the present application, the process of determining the target detection area covered by the radar beam and the position and height of the scatter points in the target detection area is:

[0023] When the horizontal projection D1≥current range R, the lower edge of the radar beam has no intersection with the terrain height, and there is no need to determine the scatter points;

[0024] When the horizontal projection D1

[0025] When the horizontal projection D1 is less than the current range R and the current range R is the third predetermined range, the terrain height at the position below the aircraft is taken as the reference, the ground contact range δ of the radar beam center and the terrain height is calculated when the ground contact angle of the radar beam center is the ideal ground contact angle, when the ground contact range δ is not empty, the scattering points are randomly selected in the ground contact range δ, the longitude and latitude of the selected scattering points are calculated, and the height data is obtained by querying the digital elevation map according to the longitude and latitude.

[0026] In the preferred embodiment of the present application, the calculation of the longitude and latitude of the selected scattering points is as follows:

[0027]

[0028] In the formula, Lon i and Lat i are the longitude and latitude coordinates of the i th scattering point; Lon and Lat are the longitude and latitude coordinates of the real-time position of the aircraft; α is the scanning range; d is the randomly generated distance. i i

[0029]

[0030]

[0031]

[0032] In the preferred embodiment of the present application, the process of determining the radar beam elevation pointing angle according to the height of the scattering point is as follows:

[0033] When the horizontal projection D1 is greater than or equal to the current range R, the minimum elevation angle of the radar beam elevation pointing angle is selected as the ideal ground contact angle

[0034] When the horizontal projection D1 is less than the current range R and the current range R is the first predetermined range, the ideal ground contact angle is controlled to be and is increased by a step value when the elevation pointing angle determined according to the formula of the change of the lower edge height of the radar beam satisfies D1 ≥ R, at this time, the minimum elevation angle of the radar beam elevation pointing angle is selected as n is the number of steps;

[0035] When the horizontal projection D1 is less than the current range R and the current range R is the second predetermined range, the ideal ground contact angle is controlled to be and is increased by a step value when the elevation pointing angle determined according to the formula of the change of the lower edge height of the radar beam satisfies (R-D1) ≤ C·R, at this time, the minimum elevation angle of the radar beam elevation pointing angle is selected as C is a coefficient;

[0036] When the horizontal projection D1 is less than the current range R and the current range R is the third predetermined range, the ideal ground contact angle is controlled to be and is increased by a step value​​​​​ When the iteration calculation of the dispersion point height according to the radar beam lower edge height variation calculation formula and the determined dispersion point height makes the ground contact range δ empty, the minimum pitch angle of the radar beam pitch pointing angle is selected as

[0037] In another aspect, the technical solution of the present application is: a radar device, characterized in that the radar device comprises a data processing device, which executes the single-channel airborne weather radar pitch pointing angle adjustment method according to any one of claims 1 to 7.

[0038] The method of the present application has the following beneficial features compared with the prior art:

[0039] 1) On the basis of only the channel, the current height layer front weather target detection requirement is optimized: using the real-time position, height and other data provided by the aircraft itself, and using the digital elevation map on the aircraft, on the basis of only the channel of the traditional airborne weather radar, the radar has the self-adaptive adjustment ability of the antenna pitch angle through algorithm design and software change, and the detection requirement of the current height layer front weather is optimized and satisfied;

[0040] 2) Scene-based adaptive parameter adjustment capability: through real-time calculation in the aircraft, the geographical information in the flight environment is solved in real time, and the scanning parameters are automatically adjusted based on the geographical height information, radar control parameters and the like, compared with the constant parameter route in the past design, the adaptive parameter adjustment can solve the problems of long test flight parameter adjustment time and obvious differentiation of ground clutter suppression effect in different scenes. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions provided by the present application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the present application.

[0042] Figure 1 It is a schematic diagram of the beam center ideal ground contact angle and the beam lower edge ground contact point horizontal distance in the present application.

[0043] Figure 2 It is a schematic diagram of the automatically selected ground contact angle when D1≥R in the present application.

[0044] Figure 3 It is a schematic diagram of the determined dispersion point when D1

[0045] Figure 4 It is a schematic diagram of the determined dispersion point when D1

[0046] Figure 5 It is a schematic diagram of the beam center and the actual ground contact area in the present application.

[0047] Figure 6 The height profile is calculated and obtained for automatic spot selection in the detection range in the present application.

[0048] Figure 7 The beam elevation angle self-adaptive adjustment diagram in the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the present application will be described in more detail below in combination with the drawings in the present application embodiment.

[0050] The purpose of the present application is to provide an elevation angle self-adaptive adjustment method based on digital elevation map for single-channel airborne weather radar, to automatically suppress ground clutter, and to provide the pilot with weather target information in front of the flight path for the aircraft flying in the current height and complex geographical environment. According to the real-time longitude, latitude, height, elevation beam width, scanning range, current range and other information of the aircraft, the terrain height information of the position where the beam irradiation covers the target area is obtained, so that the airborne weather radar can accurately measure the height without difference, and the detection area of the current multi-scan technology is focused in front of the flight path by automatically adjusting the radar elevation angle to the appropriate value. Finally, the pilot is provided with weather information on the flight path after the ground clutter is suppressed, so as to solve the problem of long-term flight test adjustment and different ground clutter suppression effects in different geographical environments in the traditional way, and to improve the autonomous level of the airborne weather radar.

[0051] In combination with Figures 1 to 7 As shown in the figure, the single-channel airborne weather radar elevation pointing angle adjustment method provided by the present application includes the following steps:

[0052] Step S10: Obtain the real-time position (longitude Lon, latitude Lat, absolute pressure height PrH), heading angle (HAngle), elevation beam width θ, scanning range α, current range R and digital elevation map sent by the avionics system, and obtain the terrain height Hg of the position directly below the aircraft based on the real-time position data of the aircraft and the digital elevation map.

[0053] For example, in an embodiment of the present application, the airborne weather radar receives the real-time position coordinates L1(lon, lat) sent by the avionics system, the absolute pressure height PrH is 5000m, and the heading angle is 30°. In combination with the digital elevation map on the aircraft, the terrain height Hg of the position directly below the aircraft is obtained according to the real-time position coordinates of the aircraft. g =1000m.

[0054] Step S20: Calculate the beam center ideal ground angle corresponding to the current absolute pressure height PrH of the aircraft according to the real-time position of the aircraft

[0055] In the formula, R eR is the earth radius, PrH is the absolute height of the aircraft.

[0056] Then, the ideal ground contact angle of the beam center is calculated based on the absolute height of the aircraft PrH The beam width θ, the scanning range α, and the terrain height H of the position where the aircraft is located are obtained. g The height variation H of the lower edge of the beam is calculated. down-D The horizontal distance D1 when the lower edge of the beam contacts the ground is obtained through the height variation H of the lower edge of the beam. down_D

[0057] In this application, the method for calculating the height variation of the lower edge of the radar beam is as follows:

[0058]

[0059] In the formula, H down_D is the height variation of the lower edge of the beam, R(n r ) is the horizontal detection distance, n r is the step value, which is usually 1 kilometer, and the projection of the horizontal detection distance R(n r ) on the horizontal plane is the horizontal distance D1.

[0060] The horizontal projection distance D1 of the ground contact point of the lower edge of the beam in the area where the aircraft is located can be calculated according to the height variation H down_D of the lower edge of the beam.

[0061] For example, in this embodiment of the application, the ideal ground contact angle of the beam center at the absolute barometric height PrH of the current aircraft is calculated using the ground contact angle formula

[0062] The terrain height H of the position where the aircraft is located is obtained in combination with the radar beam width θ and the terrain height H of the real-time position of the aircraft g , and the height variation formula is used to obtain the height variation curve of the lower edge of the beam at the terrain height of the position where the aircraft is located, as shown in FIG. 2. Figure 5 The distance between the beam center and the actual ground is shown in FIG. 2, and the three lines are the upper edge of the beam, the beam center, and the lower edge of the beam. The horizontal dashed line is the terrain height Hg. According to the height variation curve and the terrain height, the horizontal distance D1 = 50 km when the horizontal ground is contacted is obtained.

[0063] In step S30, the relationship between the horizontal projection distance D1 and the current range R of the radar is determined, and according to the relationship between the two, the target detection area covered by the radar beam and the position and height of the scatter point in the target detection area are determined.

[0064] The specific process is as follows:

[0065] 1) When D1 ≥ R, that is, the radar beam does not contact the ground in this range, the angle can be directly used as the minimum pitch angle of the multi-scan of the radar beam. ​

[0066] 2) When D1 < R and R is a small range, use random function to randomly select points in the target detection area range covered by the radar beam with the real-time position of the aircraft as the center and the current range R as the radius, calculate the coordinates of the selected points, and obtain the height thereof by querying the digital elevation map, as shown in the following formula: Figure 3

[0067] For example, in this embodiment, the real-time position coordinates L1(lon, lat) of the aircraft is taken as the center, the current range R = 80 km is taken as the radius, the heading angle HAngle = 30° and the azimuth scanning range a are taken as the basis, points are randomly selected in the range of the beam coverage area in the radial distance interval (50 km, 80 km), and the following formula is used to calculate the latitude and longitude coordinates L i (Lati, loni) of the randomly selected points:

[0068]

[0069] wherein d is the randomly generated radial distance in the radial distance interval (50 km, 80 km).

[0070] 3) When D1 < R and R is a large range, the real-time position of the aircraft is taken as the center, the terrain height H g below the aircraft is taken as the reference, the ground contact range d of the beam center and the actual ground is calculated by the height change formula when the beam center is ideally contacted with the ground, when the ground contact range d is not empty, points are randomly selected in the range by the random function, and the latitude and longitude coordinates of the selected points are calculated, and the height thereof is obtained by querying the digital elevation map, as shown in the following formula: Figure 4

[0071] For example, in this embodiment, the real-time position coordinates L1(lon, lat) of the aircraft is taken as the center, the absolute barometric height PrH of the aircraft, the terrain height H g at the real-time position, the heading angle HAngle = 30°, etc. are taken as the basis, the ground contact range d(d1, d2) of the radar beam and the corresponding horizontal ground of the terrain height Hg is calculated. When the ground contact range d is not empty, points are randomly selected in the range of the ground contact range d(d1, d2), and the latitude and longitude coordinates L i (Lati, loni) of the randomly selected points are calculated by the above-mentioned coordinate formula, wherein d is the randomly generated radial distance in the ground contact range d(d1, d2).

[0072] ​​Finally, the height of the obtained scatter points is statistically analyzed to calculate the mean or variance of the height of the scatter points in the target detection area, so as to determine the geographical environment of the target detection area. For example, when the variance of the height of the scatter points is large, it is determined that there is a sudden terrain in the target detection area, and vice versa, when the mean of the height of the scatter points is large, it is determined that the target detection area belongs to a typical plateau, and vice versa, it is a plain.

[0073] Step S40: determining the multi-beam elevation angle of the radar according to the height of the scatter points.

[0074] 1) When D1≥R, the minimum elevation angle of the radar multi-beam is selected as the ideal ground contact angle

[0075] For example, in this embodiment of the present application, when the current range is 40km, the minimum elevation angle of the radar multi-beam is selected as the ideal ground contact angle Other elevation pointing angles are adjusted on the basis of the ideal ground contact angle ;

[0076] 2) When D1 with a step value , when the elevation pointing angle determined according to the height change calculation formula of the lower edge of the radar beam satisfies D1≥R, the minimum elevation angle of the radar multi-beam is selected as n is the number of steps, and the step value is , usually 0.1°;

[0077] 3) When D1 with a step value , when the elevation pointing angle determined according to the height change calculation formula of the lower edge of the radar beam satisfies (R-D1)≤C·R, the minimum elevation angle of the radar multi-beam is selected as , where the coefficient C can be 15% to 20%

[0078] For example, in this embodiment of the present application, when D1 is increased by 0.2° by 5 iterations, so that (R-D1)≤15%*R is satisfied, and the minimum elevation angle of the radar multi-beam is selected as -1.9°+5*0.2°, and other elevation pointing angles are adjusted on the basis of the ideal ground contact angle .

[0079] 4) When D1 with a step value When D1 Figure 5 When D1

[0080] For example, in the embodiment of the present application, when D1 with a step value of 0.2°, the minimum elevation angle of the multi-beam is -1.9° when the beam center does not touch the ground according to the real-time terrain height. Otherwise, with a step value of 0.2°, the minimum elevation angle of the multi-beam is -1.9°+4*0.2°, i.e., -3.8°, when the beam center does not touch the ground according to the real-time terrain height.

[0081] Step S50: Based on the radar multi-beam pointing angle obtained in step S40, the radar beam is controlled to be scanned in multiple layers according to the beam width, target data of different scanning layers is obtained, and after the scanning is completed, the multi-scan meteorological target data is fused to suppress ground clutter.

[0082] The method of the present application has the following beneficial features compared with the prior art:

[0083] 1) Optimizing the current height layer front meteorological target detection requirement on the basis of only the channel: using the real-time position, height, etc. provided by the aircraft itself, and using the digital elevation map on the aircraft, on the basis of only the channel of the traditional airborne weather radar, the radar has the adaptive adjustment ability of the antenna elevation angle through algorithm design and software modification, and optimizes and meets the detection requirement of the current height layer front meteorological target;

[0084] 2) Scene-based adaptive parameter adjustment capability: through real-time calculation in the aircraft, the geographical information in the flight environment is solved in real time, and the scanning parameters are automatically adjusted based on the geographical height information, radar control parameters, etc. Compared with the constant parameter route in the previous design, the adaptive parameter adjustment can solve the problems of long test flight parameter adjustment time and obvious differentiation of ground clutter suppression effect in different scenes.

[0085] Finally, the present application also provides a radar device, which is mainly applied to an airborne weather radar and can be extended to other airborne radars using the multi-beam fusion, and the radar device comprises a data processing device which executes the single-channel airborne weather radar elevation pointing angle adjustment method as above.

[0086] The processing device may include one or more processing units. For example, the processing device may include an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU). The different processing units may be independent devices or integrated into one or more processors. The controller may generate an operation control signal based on the instruction opcode and timing signal to complete the control of instruction fetching and execution.

[0087] The processing device may also include a memory for storing instructions and data. In some embodiments, the memory in the processing device is a cache memory. This memory can store instructions or data that have just been used or are being recycled by the processing device. If the processing device needs to use the instruction or data again, it can directly call it from the memory, thereby avoiding repeated access, reducing the processing device's waiting time, and thus improving system efficiency.

[0088] In some embodiments, the processing device may include one or more interfaces, such as an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a subscriber identity module (SIM) interface, and / or a universal serial bus (USB) interface.

[0089] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of adjusting the elevation pointing angle of a single-channel airborne weather radar, characterized in that, The method comprises the following steps: acquiring real-time position, heading angle, beam width, scanning range and digital elevation map of the aircraft, and obtaining the terrain height of the position directly below the aircraft according to the real-time position data and the digital elevation map data of the aircraft; obtaining the ideal ground-hugging angle of the radar beam center according to the real-time position of the aircraft, calculating the height variation of the lower edge of the radar beam according to the ideal ground-hugging angle, the real-time position of the aircraft, the beam width and the terrain height, and obtaining the horizontal distance between the lower edge of the radar beam and the ground-hugging point in the area where the aircraft is located according to the height variation of the lower edge of the radar beam; determining the target detection area covered by the radar beam and the position and height of the scattered points in the target detection area according to the relationship between the horizontal distance and the current range of the radar; determining the radar beam elevation pointing angle according to the height of the scattered points; controlling the radar antenna to perform multiple scans upwards according to the beam width based on the radar beam elevation pointing angle, acquiring meteorological target data of different scanning layers, and performing multi-beam fusion on the meteorological target data of multiple scans to suppress ground clutter after the scanning is completed.

2. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 1, wherein, The real-time position of the aircraft includes longitude and latitude and absolute barometric height.

3. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 2, wherein, The calculation method of the ideal ground-hugging angle of the radar beam center is: In the formula, is the ideal ground angle of the radar beam center; R e R is the radius of the earth; PrH is the absolute barometric height.

4. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 3, wherein, The radar beam lower edge height variation H down_D The calculation method is: In the formula, H down_D is the height variation of the beam lower edge; n r is a step value; R(n r ) is the horizontal detection distance, and the projection of the horizontal detection distance R(n r ) on the horizontal plane is the horizontal distance D1.

5. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 4, wherein, The process of determining the target detection area covered by the radar beam and the position and height of the scattered points in the target detection area is: When the horizontal projection D1 is greater than or equal to the current range R, the lower edge of the radar beam has no intersection with the terrain height, and it is not necessary to determine the scattered points; When the horizontal projection D1 is less than the current range R and the current range R is the first and second predetermined ranges, the scattered points are randomly selected in the radial distance interval (D1, R) in the radar beam coverage range with the real-time position of the aircraft as the center and the current range R as the radius, the longitude and latitude of the selected scattered points are calculated, and the height thereof is obtained by querying the digital elevation map according to the longitude and latitude; When the horizontal projection D1 is less than the current range R and the current range R is the third predetermined range, the ground-hugging range δ of the radar beam center and the terrain height when the ground-hugging angle of the radar beam center is the ideal ground-hugging angle of the beam center is calculated with the real-time position of the aircraft as the center and the terrain height of the position below the aircraft as the reference, and when the ground-hugging range δ is not empty, the scattered points are randomly selected in the ground-hugging range δ, the longitude and latitude of the selected scattered points are calculated, and the height data thereof is obtained by querying the digital elevation map according to the longitude and latitude.

6. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 5, wherein, The calculation of the longitude and latitude of the selected scattered points is: where Lon i , Lat i are the longitude and latitude coordinates of the ith scatter point; Lon and Lat are the longitude and latitude coordinates of the real-time position of the aircraft; α is the scanning range; d is a randomly generated distance.

7. The single-channel airborne weather radar elevation pointing angle adjustment method of claim 6, wherein, The process of determining the radar beam elevation pointing angle according to the height of the scattered points is: When the horizontal projection D1 ≥ the current range R, the minimum pitch angle of the radar beam pitch pointing angle is selected as the ideal ground contact angle When the horizontal projection D1 < the current range R and the current range R is the first predetermined range, control the ideal ground contact angle with a step value When the pitch pointing angle determined according to the radar beam lower edge height variation calculation formula satisfies D1≥R, at this time the minimum pitch angle of the radar beam pitch pointing angle is selected as n is the step number; When the horizontal projection D1 is less than the current range R and the current range R is the second predetermined range, control the ideal ground contact angle in steps When the pitch pointing angle determined according to the radar beam lower edge height variation calculation formula satisfies (R-D1)≤C·R, at this time the minimum pitch angle of the radar beam pitch pointing angle is selected as C is a coefficient; When the horizontal projection D1 < the current range R and the current range R is the third predetermined range, control the ideal ground contact angle in steps of When the iteration calculation of the dispersion point height according to the radar beam lower edge height variation calculation formula and the determination makes the ground contact range δ empty, at this time the minimum tilt angle of the radar beam tilt pointing angle is selected as 8. A radar device, characterized by The radar device comprises a data processing device which performs the single-channel airborne weather radar elevation pointing angle adjustment method according to any one of claims 1 to 7.

Images