An airborne dual-band weather radar detection method

Abstract

The application provides an airborne dual-band weather radar detection method, which comprises the following steps: S1: adopting a dual-band common-aperture antenna to time-divisionally emit X-band electromagnetic waves and Ka-band electromagnetic waves; S2: a weather radar receives the X-band electromagnetic waves and the Ka-band electromagnetic waves and performs ground clutter suppression; S3: calculating reflectivity Rrf x according to the X-band electromagnetic waves; S4: calculating reflectivity Rrf ka , velocity V ka and spectral width W ka ; S5: performing analysis on weather targets and displaying analysis results. The detection method realizes cloud detection by using the Ka band on the basis of meeting original X-band weather rainfall detection functions, realizes dangerous weather identification and dangerous area warning by comprehensively considering the spatial structure of the cloud and Doppler information, marks weather seriously threatening flight safety in a display picture, and reminds pilots to pay attention. The detection method comprehensively improves the detection perception and display capability of the airborne weather radar on various weathers, further improves flight safety, and reduces unnecessary deviation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of airborne weather radar, and particularly relates to an airborne dual-band weather radar detection method. BACKGROUND

[0002] The airborne weather radar usually adopts an X-band radar to detect weather, and when the aircraft flies at high altitude, the X-band can detect a strong reflectivity weather target several hundred kilometers away without obstruction and give a warning, but when the aircraft flies at low altitude, the X-band radar antenna beam is wide and is easily affected by ground clutter, and the near-distance detection performance is poor; at the same time, for clouds with less water content and small rain, snow and fog, the X-band weather radar is difficult to detect, and when the aircraft flies at the lower layer of the atmosphere, the clouds, rain and fog will seriously interfere with the pilot's vision, and the aircraft may be iced and jolted when flying into the clouds.

[0003] Therefore, it is necessary to provide an airborne weather radar detection method capable of solving the problems of poor near-distance detection performance and low detection precision of the airborne weather radar in the prior art. SUMMARY

[0004] The present application is aimed at the problems existing in the prior art airborne weather radar detection method, and combines the characteristics of the millimeter wave radar to improve the detection perception and realization ability of the airborne weather radar for various weather on the basis of meeting the original X-band weather detection.

[0005] The purpose of the present application is to provide an airborne dual-band weather radar detection method, which comprises the following steps:

[0006] S1: a dual-band common-aperture antenna is adopted to emit X-band electromagnetic waves and Ka-band electromagnetic waves in time division;

[0007] S2: the weather radar receives the X-band electromagnetic waves and the Ka-band electromagnetic waves and performs ground clutter suppression;

[0008] S3: the reflectivity Rrf x is calculated according to the X-band electromagnetic waves;

[0009] S4: the reflectivity Rrf ka , the speed V ka and the spectral width W ka are calculated according to the Ka-band electromagnetic waves;

[0010] S5: the weather target is analyzed according to the reflectivity Rrf x obtained in S3, the reflectivity Rrf ka , the speed V ka and the spectral width W ka obtained in S4, and the analysis result is displayed.

[0011] The airborne dual-band weather radar detection method provided by the application also has the following characteristics: the dual-band common-aperture antenna is designed as a low profile, and the X-band antenna beam width formed by the dual-band common-aperture antenna is 3-5 times the Ka-band antenna beam width.

[0012] The airborne dual-band weather radar detection method provided by the application also has the following characteristics: the X-band electromagnetic wave has no less than 2 rows of pitch detection, and the Ka-band electromagnetic wave has no less than 5 rows of pitch detection.

[0013] The airborne dual-band weather radar detection method provided by the application also has the following characteristics: the time-sharing emission steps of the X-band electromagnetic wave and the Ka-band electromagnetic wave are as follows:

[0014] S1.1: determining the pitch center angle φ0 of beam detection

[0015]

[0016] wherein, R e is the equivalent radius of the earth (8700 km), H0 is the height of the aircraft, H g is the terrain height.

[0017] S1.2: determining the pitch angles of the X-band scanning and the Ka-band scanning according to the number of detection rows and the pitch center angle of detection, respectively;

[0018] S1.3: sequentially emitting the X-band electromagnetic wave and the Ka-band electromagnetic wave in the manner of pitch first and then azimuth, wherein the emission waveform is a composite waveform composed of three segments, and the three segments of the composite waveform are respectively an electromagnetic wave waveform of the X-band for measuring reflectivity Rrf x , an electromagnetic wave waveform of the Ka-band for measuring reflectivity Rrf ka , and an electromagnetic wave waveform of the Ka-band for measuring velocity and spectral width, which are sequentially formed.

[0019] The airborne dual-band weather radar detection method provided by the application also has the following characteristics: the terrain height is the average ground height in the detection range.

[0020] The airborne dual-band weather radar detection method provided by the application also has the following characteristics: the pitch angle φx n of the X-band scanning and the pitch angle φka n of the Ka-band scanning in S1.2 are respectively:

[0021]

[0022]

[0023] wherein, σ φxis X-band beam interval, iN x ≮2, x is 1, 2, …, N x , σ φka is Ka-band beam interval, iN ka is 1, 2, …, N ka , N ka ≮5, and is rounded up.

[0024] The airborne dual-band weather radar detection method provided by the application further has the characteristics that the electromagnetic wave form used for measuring the speed and the spectrum width in S1.3 takes φ0 as the beam center, and each frame includes 2 n coherent pulses, where n≮5.

[0025] The airborne dual-band weather radar detection method provided by the application further has the characteristics that S5 includes the following steps:

[0026] S5.1: Extract the X-band weather targets X1, …, XN, and calculate the centroid position, the centroid height, and the weather top height of each weather target according to the X-band reflectivity Rrf x of different elevation layers;

[0027] S5.2: Extract the Ka-band weather targets Ka1, …, KaN, and calculate the centroid position, the centroid height, the weather top height, and the spectrum width average of each weather target according to the Ka-band reflectivity Rrf ka and the spectrum width W ka of different elevation layers;

[0028] S5.3: Associate the X-band detected target with the Ka-band detected target, if the centroid distance of the two is less than 3km, it is judged as the same weather target, and the centroid position, the centroid height, and the weather top height of the two are combined by selecting the larger one;

[0029] S5.4: Perform weather target identification analysis according to the centroid position, the centroid height, and the weather top height:

[0030] If the centroid height is greater than the height of the zero-degree line, and the weather top height is greater than 8000m, it is judged as a thunderstorm target, and a first identifier is set;

[0031] If the centroid height is greater than the height of the zero-degree line, and the spectrum width average is greater than 5m / s, it is judged as a growing thunderstorm, and a second identifier is set;

[0032] If the centroid height is located within 500m above and below the zero-degree line, and the spectrum width average is greater than 3m / s, there is a risk of ice accumulation, and a third identifier is set;

[0033] According to the speed V kaIdentify the area where the speed change is greater than 10 m / s per kilometer, judge it as a shear zone, and set the fourth mark;

[0034] S5.5: According to the flight phase of the carrier aircraft, different mark symbols are superimposed on the display screen.

[0035] The airborne dual-band weather radar detection method provided by the application also has the characteristics that the display screen in S5.5 also includes the display of reflectivity, wherein the reflectivity Rrf x and the reflectivity Rrf ka of multiple elevation angles obtained by Ka-band detection in the same distance are selected and processed, Rrf ka =Rrf x , and Rrf is displayed as the comprehensive reflectivity of the dual-band radar.

[0036] The airborne dual-band weather radar detection method provided by the application also has the characteristics that the reflectivity display range of the airborne weather radar is not less than 0 dBz-40 dBZ, and multi-color step display is adopted, and the color step range is not greater than 10 dBZ.

[0037] Compared with the prior art, the beneficial effects of the application are:

[0038] The airborne dual-band weather radar detection method provided by the application meets the original X-band weather rainfall detection function, realizes cloud detection by using Ka-band, and realizes dangerous weather identification and dangerous area warning by comprehensively considering the spatial structure of the cloud and Doppler information, marks the weather that seriously threatens flight safety in the display screen, and reminds the pilot to pay attention. The airborne weather radar has improved the detection and display capabilities of various weather, and further improved the flight safety and reduced unnecessary deviation.

[0039] The airborne dual-band weather radar detection method provided by the application can be applied to the field of military and civil airborne weather radars, and is especially suitable for small and medium-sized airborne platforms and low-altitude aircraft. The application enhances the detection and early warning capability of the airborne weather radar for weak reflectivity targets, and further improves the flight safety. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] Figure 1 : The flowchart of the detection method provided by the embodiment of the application;

[0042] Figure 2 Figure 1 is a diagram of a dual-band stereo detection method provided by the detection method of the embodiment of the present application;

[0043] Figure 3 Figure 2 is a detection waveform diagram of the detection method provided by the embodiment of the present application;

[0044] Figure 4 Figure 3 is an X-band reflectivity detection result diagram of the detection method provided by the embodiment of the present application;

[0045] Figure 5 Figure 4 is a Ka-band reflectivity detection result diagram of the detection method provided by the embodiment of the present application;

[0046] Figure 6 Figure 5 is a comprehensive display diagram of the detection result of the detection method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the following embodiments will be described in detail in combination with the drawings.

[0048] In the description of the embodiments of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0049] In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0050] The terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] Compared with X-band, millimeter wave radar has the following characteristics in meteorological detection:

[0052] a) The antenna beam is narrow and has good directivity, with very high spatial resolution;

[0053] b) It has strong ability to detect small particles (such as clouds, fog, and light rain, etc.);

[0054] c) The Doppler effect is obvious, with good Doppler velocity resolution and high speed measurement accuracy;

[0055] d) Spatial attenuation is large, cannot penetrate rain targets, and the detection distance is short.

[0056] Based on the characteristics of millimeter wave radar in meteorological detection, the present application provides an airborne dual-band meteorological radar integrated detection system, which uses a common aperture dual-band antenna to emit X-band electromagnetic waves and Ka-band electromagnetic waves at different times, uses X-band to detect rain and monitor long-distance meteorological targets, and uses Ka-band to finely detect and identify low reflectivity clouds (such as supercooled water, freezing rain, etc. that cannot be detected by X-band). The dual-band detection results complement each other, which can guide the aircraft to avoid dangerous rain targets, plan a reasonable flight route in low-visibility clouds, and avoid icing airspace, thereby improving flight safety. The specific implementation is as follows:

[0057] As shown in Figures 1-6 , it is an airborne dual-band meteorological radar detection method, which comprises the following steps:

[0058] S1: Use a dual-band common aperture antenna to emit X-band electromagnetic waves and Ka-band electromagnetic waves at different times;

[0059] S2: The meteorological radar receives X-band electromagnetic waves and Ka-band electromagnetic waves and performs ground clutter suppression;

[0060] S3: Calculate the reflectivity Rrf x from the X-band electromagnetic waves;

[0061] S4: Calculate the reflectivity Rrf ka , velocity V ka and spectral width W ka from the Ka-band electromagnetic waves;

[0062] S5: Analyze the meteorological targets according to the reflectivity Rrf x obtained in S3, the reflectivity Rrf ka , velocity V ka and spectral width W ka obtained in S4, and display the analysis results.

[0063] In some embodiments, the dual-band co-aperture antenna is of low-profile design, and the X-band antenna beam width formed by the dual-band co-aperture antenna is 3-5 times the Ka-band antenna beam width.

[0064] In some embodiments, the elevation detection of the X-band electromagnetic wave is no less than 2 lines, and the elevation detection of the Ka-band electromagnetic wave is no less than 5 lines.

[0065] In some embodiments, the steps of time-sharing transmission of the X-band electromagnetic waves and the Ka-band electromagnetic waves are as follows:

[0066] S1.1: Determine the beam detection pitch center angle φ0

[0067] Among them, R e is the equivalent radius of the Earth (8700km), H0 is the height of the aircraft, H g is the terrain height;

[0068] S1.2: Determine the elevation angles for X-band scanning and Ka-band scanning based on the number of detection rows and the detection elevation center angle;

[0069] S1.3: If Figure 3 As shown, the X-band electromagnetic waves and Ka-band electromagnetic waves are transmitted in sequence in the manner of pitch first and then azimuth. The waveform of the transmission is a composite waveform composed of three waveforms. The three waveforms of the composite waveform are the X-bands formed in sequence for measuring the reflectivity Rrf. x The electromagnetic wave waveform and Ka band are used to measure the reflectivity Rrf ka The electromagnetic wave waveform of the Ka band is used to measure the electromagnetic wave waveform of the velocity and spectrum width, and the X band is used to measure the reflectivity Rrf x The electromagnetic wave waveform is used for rain detection, and a total of 2 pulses are emitted; the Ka band is used to measure the reflectivity Rrf ka The electromagnetic wave waveform is used for cloud detection, with a total of 9 pulses emitted, each pulse corresponding to a pitch angle; the Ka-band electromagnetic wave waveform used to measure velocity and spectral width is used for Doppler information detection.

[0070] In some embodiments, the terrain height is the average ground height within the detection range, which can be obtained by extracting digital elevation information within the detection range in front of the carrier aircraft and calculating the average ground height. If the height information cannot be obtained, it is set to a fixed value.

[0071] In some embodiments, the pitch angle φx of the X-band scan in S1.2 is n and the Ka-band scanning elevation angle φka n They are:

[0072]

[0073]

[0074] wherein σ φx is the X-band beam interval, N x ≮2, iN x is 1, 2, …, N x , σ φka is the Ka-band beam interval, iN ka is 1, 2, …, N ka , N ka ≮5, and is rounded up.

[0075] In some embodiments, the electromagnetic wave waveform used for measuring the velocity and spectral width in S1.3 is centered at the beam center φ0, and each frame includes 2 n mutually coherent pulses, where n≮5.

[0076] In some embodiments, S5 includes the following steps:

[0077] S5.1: Extract the X-band meteorological targets X1, …, XN, and calculate the centroid position, centroid height, and meteorological top height of each meteorological target according to the X-band reflectivity Rrf x of different elevation layers;

[0078] S5.2: Extract the Ka-band meteorological targets Ka1, …, KaN, and calculate the centroid position, centroid height, meteorological top height, and spectral width W ka of each meteorological target according to the Ka-band reflectivity Rrf ka of different elevation layers;

[0079] S5.3: Associate the X-band detected targets with the Ka-band detected targets. If the centroid distance between the two is less than 3 km, it is determined to be the same meteorological target, and the centroid position, centroid height, and meteorological top height of the two are combined by selecting the larger one;

[0080] S5.4: Perform meteorological target identification analysis according to the centroid position, centroid height, and meteorological top height:

[0081] If the centroid height is greater than the zero-degree line height, and the meteorological top height is greater than 8000 m, it is determined to be a thunderstorm target, and a first flag is set;

[0082] If the centroid height is greater than the zero-degree line height, and the spectral width mean is greater than 5 m / s, it is determined to be a growing thunderstorm, and a second flag is set;

[0083] If the centroid height is within 500 m above and below the zero-degree line, and the spectral width mean is greater than 3 m / s, there is a risk of ice accumulation, and a third flag is set;

[0084] According to the speed V ka ,identify the area where the speed change per kilometer is greater than 10m / s, determine it as a shear area, and set the fourth flag;

[0085] S5.5: Different identification icons are superimposed on the display screen according to the flight phase of the carrier aircraft.

[0086] In some embodiments, the display screen in S5.5 also includes a display of reflectivity, wherein the reflectivity Rrf at multiple pitch angles is obtained by X-band detection within the same distance. x And the reflectivity Rrf at multiple elevation angles obtained by Ka-band detection ka Perform large selection processing, Rrf=max(Rrf ka ,Rrf x ), Rrf is displayed as the comprehensive reflectivity of the dual-band radar.

[0087] In some embodiments, the reflectivity display range of the airborne weather radar is not less than 0dBZ-40dBZ, and a multi-color scale display is used, and the color scale range is not greater than 10dBZ.

[0088] In some embodiments, the Figures 4-6 The results shown are from a detection scenario where there are weakly reflective supercooled water clouds and mature thunderstorms 20-40 km ahead of the aircraft.

[0089] A) If Figure 4 As shown, the X-band can only detect mature thunderstorms;

[0090] B) Figure 5 As shown, the Ka band detected weak reflectivity supercooled water clouds and mature thunderstorms, but the mature thunderstorms were severely attenuated and the reflectivity was seriously weak;

[0091] C) Based on the dual-band detection results, the meteorological threat assessment is carried out, and the dual-band reflectivity detection results are integrated and displayed. The identified thunderstorms are warned by character markings, and the super-cooled water areas are warned by discrete points. Figure 6 .

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and variations without departing from the technical principles of the present invention, and such improvements and variations shall also be considered within the scope of protection of the present invention.

Claims

1. An airborne dual-band weather radar detection method, characterized in that, The method comprises the following steps: S1: using a dual-band common-aperture antenna to time-share transmit X-band electromagnetic waves and Ka-band electromagnetic waves; S2: the weather radar receives the X-band electromagnetic waves and the Ka-band electromagnetic waves, and performs ground clutter suppression; S3: Calculate reflectivity from X-band electromagnetic waves ; S4: Calculate reflectivity from Ka-band electromagnetic waves , velocity , and spectral width ; S5: reflectivity acquired according to S3 , reflectivity acquired according to S4 , velocity and spectral width performing analysis of the meteorological target and displaying the analysis result, The time-sharing transmission steps of the X-band electromagnetic waves and the Ka-band electromagnetic waves are as follows: S1.1: Determine beam sounding pitch center angle wherein, Rearthis the equivalent radius of the earth, Rairis the height of the aircraft, Rterrainis the height of the terrain; S1.2: determining the elevation angles of X-band scanning and Ka-band scanning according to the number of detection rows and the detection elevation center angle, respectively; S1.3: Adopting the way of pitching first and azimuth second to carry out the emission of X-band electromagnetic wave and Ka-band electromagnetic wave in sequence, the waveform of the emission is a composite waveform composed of three section waveforms, the three section waveforms of the composite waveform are respectively X-band electromagnetic wave waveform for measuring reflectivity, Ka-band electromagnetic wave waveform for measuring reflectivity and Ka-band electromagnetic wave waveform for measuring velocity and spectral width formed in sequence. ​​ 2. The airborne dual-band weather radar detection method of claim 1, wherein, The dual-band common-aperture antenna is designed with a low profile, and the X-band antenna beam width formed by the dual-band common-aperture antenna is 3-5 times the Ka-band antenna beam width.

3. The airborne dual-band weather radar detection method of claim 1, wherein, The elevation detection of the X-band electromagnetic waves is not less than 2 rows, and the elevation detection of the Ka-band electromagnetic waves is not less than 5 rows.

4. The airborne dual-band weather radar detection method according to claim 1, characterized in that: The terrain height is the average ground height in the detection range.

5. The airborne dual-band weather radar detection method of claim 1, wherein, The elevation angle of the X-band scan in S1.2 The elevation angle of the Ka-band scan respectively: wherein, is an X-band beam interval, > 2, is 1, 2,... , is a Ka-band beam interval, is 1, 2,... , > 5, and rounded up.

6. The airborne dual-band weather radar detection method of claim 1, wherein, The electromagnetic waveforms used to measure the velocity and spectral width in S1.3 are such that For a beam center, each frame includes n≈5.

7. The airborne dual-band weather radar detection method of claim 1, wherein, The S5 comprises the following steps: S5.1: Extract X-band weather targets X1, …, XN according to X-band reflectivity of different elevation layers Calculate the centroid position, centroid height and weather height of each weather target; S5.2: Extract the weather targets Ka1, …, KAN in Ka band, and calculate the Ka band reflectivity according to different elevation layers and spectral width Calculate the centroid position, centroid height, weather top height and spectral width mean value of each weather target; S5.3: associating the X-band detection target with the Ka-band detection target, if the distance between the two centers is less than 3km, it is judged that they are the same weather target, and the center position, center height and weather top height of the two are combined by selecting the larger one; S5.4: performing weather target identification analysis according to the center position, center height and weather top height: If the center height is greater than the zero-degree line height, and the weather top height is greater than 8000m, it is judged to be a thunderstorm target, and a first mark is set; If the center height is greater than the zero-degree line height, and the spectral width average is greater than 5m / s, it is judged to be a growing thunderstorm, and a second mark is set; If the center height is located on or below the zero-degree line by 500m, and the spectral width average is greater than 3m / s, there is a risk of ice accumulation, and a third mark is set; According to the speed , identify the area where the speed change per kilometer is greater than 10 m / s, judge it as a shear zone, and set the fourth mark; S5.5: according to the flight phase of the aircraft, different mark symbols are superimposed on the display screen.

8. The airborne dual-band weather radar detection method of claim 7, wherein, The display screen in S5.5 also includes the display of reflectivity, wherein the reflectivity of multiple pitch angles obtained by X-band detection within the same distance is required. And Ka-band detection to obtain reflectivity at multiple elevation angles Perform large selection processing, ,Will Displayed as the comprehensive reflectivity of the dual-band radar.

9. The airborne dual-band weather radar detection method of claim 8, wherein, The reflectivity display range of the airborne weather radar is not less than 0dBz-40dBZ, and multi-color step display is adopted, and the color step range is not greater than 10dBZ.

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