A composite waveform database for airborne weather radar and a weather detection method

Abstract

This invention provides an airborne meteorological radar composite detection waveform database, comprising a single PRF coherent waveform data sub-database, a dual PRF coherent waveform data sub-database, and a single PRF frequency-hopping waveform data sub-database. This detection waveform database optimizes meteorological detection waveforms at different elevation layers in multi-scan modes. Furthermore, radar meteorological detection methods based on this database can improve the detection capability of high-altitude weak-reflectivity meteorological targets and accurately estimate information such as the velocity and spectral width of meteorological targets. The radar utilizes information reflecting meteorological characteristics, such as the intensity, velocity, and spectral width of meteorological targets, to assist in meteorological threat analysis and predict the development trend and motion characteristics of dangerous meteorological targets, thereby improving the radar's detection performance and accurate warning capabilities.

Description

Technical Field

[0001] This invention belongs to the field of airborne meteorological radar technology, specifically relating to an airborne meteorological radar composite waveform database and meteorological detection method. Background Art

[0002] Airborne weather radar detects and displays weather conditions ahead of the aircraft's flight path, allowing pilots to plan routes and ensure flight safety. Therefore, the amount and accuracy of information displayed by weather radar directly impact the pilot's observation and judgment.

[0003] Currently, airborne weather radar can only provide information on weather intensity, but weather reflectivity is not the sole criterion for assessing the threat posed by weather to flight safety. Analysis of weather target characteristics reveals that different types of weather targets exhibit different velocity characteristics. For example, convective clouds, which severely impact flight safety, have intense and complex internal airflow, while non-convective clouds have relatively simple airflow. Therefore, understanding the internal airflow patterns of weather targets can help determine / assess the threat level posed by them to flight safety. Furthermore, ambient wind speed offers significant advantages for tracking and predicting weather targets.

[0004] Existing airborne weather radars use a composite waveform combining one meteorological pulse and four coherent turbulence pulses to roughly estimate the turbulence spectrum width. However, due to the small number of pulses and low signal-to-noise ratio, the velocity estimation accuracy is poor and there is also velocity ambiguity, which seriously restricts the velocity estimation performance of meteorological targets.

[0005] Therefore, there is a need to provide a method that can achieve high-precision detection and estimation of the velocity of meteorological targets without affecting the existing meteorological detection capabilities of radar. Summary of the Invention

[0006] This invention addresses the limitation of existing waveforms in estimating the velocity of meteorological targets. Based on existing technologies, it proposes a new composite detection waveform design and usage method. Without affecting meteorological detection performance, it can obtain relatively accurate velocity and spectral width information of meteorological targets, effectively improving turbulence detection capabilities and the ability to assess threatening meteorological targets, thereby enhancing flight safety.

[0007] The purpose of this invention is to provide an airborne weather radar composite detection waveform database, which includes a single PRF coherent waveform data sub-database, a dual PRF coherent waveform data sub-database, and a single PRF frequency hopping waveform data sub-database.

[0008] The airborne weather radar composite detection waveform database provided by this invention also has the following feature: the database includes pulse repetition period and pulse number; therefore, the single PRF coherent waveform data sub-database is represented as follows:

[0009] SPRI Data =[PRI1 PRI2 ... PRI M ]

[0010] Na SPRF =[Na1 Na2 ... Na] M ],

[0011] Among them, SPRI Data ∈[0.1 1]ms; SPRI Data The data in the file is arranged in ascending order;

[0012] PRI m =SPRI Data (m), m=1,2,...,M, M(M≥1) is the number of waveforms in the single PRF coherent waveform library;

[0013] Na SPRF ∈[1 512],Na m =Na SPRF (m) represents the pulse accumulation number corresponding to the m-th waveform;

[0014] The dual PRF coherent waveform data sub-library is represented as follows:

[0015]

[0016] Na DPRF =[Na1 Na2 ... Na] N ]

[0017] Among them, DPRI Data ∈[0.3 2]ms; PRI Data The data in the file is arranged in ascending order;

[0018] DPRI n =DPRI Data (n,:)=[PRI n1 PRI n2 ], n=1,2,...,N, N (N≥1) is the number of combined waveforms in the dual PRF coherent waveform library;

[0019] Na DPRF ∈

[1512] , Na n =Na DPRF (n) represents the number of pulse accumulations corresponding to the nth waveform combination;

[0020] The single PRF frequency hopping waveform data sub-library is represented as follows:

[0021] PRI Data=[PRI1 PRI2 ... PRI K ]

[0022] Na PRF =[Na1 Na2 ... Na] K ]

[0023] Among them, PRI Data ∈[1 5]ms; PRI Data The data in PRI is arranged in ascending order; k =PRI Data (k), k=1,2,...,K, K (K≥1) is the number of waveforms in the single PRF frequency hopping waveform library, K≥1;

[0024] Na PRF ∈[1 128],Na k =Na PRF (k) represents the number of pulse accumulations corresponding to the k-th waveform.

[0025] Another object of the present invention is to provide a weather detection method for airborne weather radar based on the waveform database described in any of the foregoing claims, the method comprising the following steps:

[0026] S1: Set the detection mode;

[0027] S2: Select a probe waveform from the waveform database;

[0028] S3: Process the radar echo corresponding to the waveform obtained in S2 to obtain the intensity, velocity and spectral width information of the meteorological target;

[0029] S4: Based on the intensity, speed, and spectral width information of the meteorological target obtained in S3, determine the degree of threat posed by the meteorological target to flight safety.

[0030] The airborne weather radar weather detection method provided by this invention also has the following feature: the detection mode includes an elevation scanning layer number N. layer (N layer ≥1) Azimuth scanning range Az scan (Az scan ≥0°) and the pitch angle corresponding to each scanning layer

[0031] The airborne weather radar weather detection method provided by this invention also has the following feature: in S2, for the nth (n≤N) layer To select a pitch level, follow these steps:

[0032] S2.1: Based on the aircraft's flight altitude, pitch angle, and beamwidth, determine whether the beam is touching the ground. If it is touching the ground, proceed to S2.2; otherwise, proceed to S2.3.

[0033] S2.2: Calculate the farthest beam distance R groud :

[0034]

[0035] S2.3: Calculate the beam center to reach H max The distance R corresponding to the height beamcenter :

[0036]

[0037] S2.4: Based on the distance values ​​calculated in S2.2 and S2.3 respectively, select the corresponding waveform from the waveform database.

[0038] Where Re is the equivalent radius of the Earth, and H Plane For the height of the aircraft, φ 3dB For the pitch beamwidth, φ n H is the beam pointing angle, with upward being positive. max H represents the developmental altitude of meteorological targets. max ∈[10 15]km.

[0039] The airborne weather radar weather detection method provided by this invention also has the following feature: in step S2.4, a distance threshold R is defined. Threshold =[R1 R2], R l =R Threshold (l), l=1,2 represent the judgment distances corresponding to the three different waveforms, then:

[0040] If R groud ≤R1 or R beamcenter If ≤R1, then select the corresponding single PRF coherent waveform from the single PRF coherent waveform data sub-library;

[0041] If R1 <R groud ≤R2 or R1 <R beamcenter If ≤R2, then select the corresponding dual PRF coherent waveform from the dual PRF coherent waveform data sub-library;

[0042] If R groud >R3 or R beamcenter >R3, then combined with the range R range Then select the corresponding single PRF frequency hopping waveform from the single PRF frequency hopping waveform data sub-library.

[0043] The airborne weather radar weather detection method provided by the present invention also has the following features: in step S3, if a waveform is selected from the single PRF coherent waveform data sub-library, the echo is directly received in a coherent manner; if a dual PRF coherent waveform is selected from the dual PRF coherent waveform data sub-library, the two different PRF waveforms are transmitted alternately, and the echo is received in a coherent manner; if a waveform is selected from the single PRF frequency hopping waveform data sub-library, the echo is directly received in a non-coherent manner.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] The airborne meteorological radar composite detection waveform database provided by this invention optimizes meteorological detection waveforms at different elevation layers in multi-scan modes. Furthermore, the radar meteorological detection method based on this database can improve the detection capability of high-altitude weak reflectivity meteorological targets and accurately estimate information such as the velocity and spectral width of meteorological targets. The radar uses information reflecting meteorological characteristics, such as the intensity, velocity, and spectral width of meteorological targets, to assist in meteorological threat analysis and predict the development trend and motion characteristics of dangerous meteorological targets, thereby improving the radar's detection performance and accurate warning capability for meteorological targets.

[0046] The airborne weather radar composite detection waveform database provided by this invention combines mechanical scanning radar and phased array radar, effectively improving the weather detection and assessment capabilities of aircraft flying in different regions, further enhancing the detection and identification capabilities of hazardous weather, and improving the reliability of weather warnings. It can be applied to both military and civilian weather radar fields. Attached Figure Description

[0047] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 : A schematic diagram of the multi-scan detection mode of the detection method provided in the embodiments of the present invention;

[0049] Figure 2 The multi-layer scanning implementation method of the detection method provided in this embodiment of the invention. Detailed Implementation

[0050] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the airborne meteorological radar composite waveform database and meteorological detection method provided by the present invention.

[0051] In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0052] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0053] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of these terms in this invention based on the specific circumstances.

[0054] A composite detection waveform database for airborne weather radar includes a single PRF coherent waveform data sub-database, a dual PRF coherent waveform data sub-database, and a single PRF frequency-hopping waveform data sub-database. This database includes the pulse repetition period and the number of pulses.

[0055] The waveforms in the single PRF coherent waveform data sub-library have a large unambiguous velocity but a small unambiguous distance, making them suitable for short-range meteorological detection scenarios. They are represented as follows:

[0056] SPRI Data =[PRI1 PRI2 ... PRI M ]

[0057] Na SPRF =[Na1 Na2 ... Na] M ],

[0058] Among them, SPRI Data ∈[0.1 1]ms; SPRI Data The data in the file is arranged in ascending order;

[0059] PRI m =SPRIData (m), m=1,2,...,M, M(M≥1) is the number of waveforms in the single PRF coherent waveform library;

[0060] Na SPRF ∈[1 512],Na m =Na SPRF (m) represents the pulse accumulation number corresponding to the m-th waveform;

[0061] The dual PRF coherent waveform data sub-library contains two different PRF waveforms, offering a large unambiguous range. Furthermore, the dual PRF enables velocity deambiguation, improving the velocity detection range and making it suitable for medium-range meteorological detection scenarios. It is represented as follows:

[0062]

[0063] Na DPRF =[Na1 Na2 ... Na] N ]

[0064] Among them, DPRI Data ∈[0.3 2]ms; PRI Data The data in the file is arranged in ascending order;

[0065] DPRI n =DPRI Data (n,:)=[PRI n1 PRI n2 ], n=1,2,...,N, N (N≥1) is the number of combined waveforms in the dual PRF coherent waveform library;

[0066] Na DPRF ∈[1 512],Na n =Na DPRF (n) represents the number of pulse accumulations corresponding to the nth waveform combination;

[0067] The waveforms in the single PRF frequency-hopping waveform data sub-library adopt large PRI waveforms, are unambiguous, and have long range. Furthermore, the frequency-hopping technology can avoid the problem of strong meteorological secondary echoes, making it suitable for long-distance meteorological detection scenarios. It is represented as follows:

[0068] PRI Data =[PRI1 PRI2 ... PRI K ]

[0069] Na PRF =[Na1 Na2 ... Na] K ]

[0070] Among them, PRI Data ∈[1 5]ms; PRIData The data in PRI is arranged in ascending order; k =PRI Data (k), k=1,2,...,K, K (K≥1) is the number of waveforms in the single PRF frequency hopping waveform library, K≥1;

[0071] Na PRF ∈[1 128],Na k =Na PRF (k) represents the pulse accumulation number corresponding to the k-th waveform. PRI represents the pulse repetition period.

[0072] like Figure 1-2 As shown, in some embodiments, an airborne weather radar weather detection method based on the waveform database described in the foregoing embodiments is provided, the method comprising the following steps:

[0073] S1: Set the detection mode: including the number of elevation scan layers N layer (N layer ≥1) Azimuth scanning range Az scan (Az scan ≥0°) and the pitch angle corresponding to each scanning layer The pitch angle corresponding to each scanning layer is determined based on information such as the aircraft's flight altitude, radar beamwidth, meteorological target characteristics, and terrain elevation.

[0074] S2: Select the probe waveform from the waveform database:

[0075] For the nth (n≤N) layer To select a pitch level, follow these steps:

[0076] S2.1: Based on the aircraft's flight altitude, pitch angle, and beamwidth, determine whether the beam is touching the ground. If it is touching the ground, proceed to S2.2; otherwise, proceed to S2.3.

[0077] S2.2: Calculate the farthest beam distance R groud :

[0078]

[0079] S2.3: Calculate the beam center to reach H max The distance R corresponding to the height beamcenter :

[0080]

[0081] S2.4: Based on the distance values ​​calculated in S2.2 and S2.3 respectively, select the corresponding waveform from the waveform database.

[0082] Where Re is the equivalent radius of the Earth, and HPlane For the height of the aircraft, φ 3dB For the pitch beamwidth, φ n H is the beam pointing angle, with upward being positive. max H represents the developmental altitude of meteorological targets. max The value of this parameter should be determined by comprehensively considering the meteorological development characteristics, radar detection performance, and actual conditions, given the range of [10 15] km.

[0083] S3: Process the radar echo corresponding to the waveform acquired in S2 to obtain the intensity, velocity, and spectral width information of the meteorological target; if a waveform is selected from the single PRF coherent waveform data sub-library, the received echo is directly coherent; if a dual PRF coherent waveform is selected from the dual PRF coherent waveform data sub-library, the two different PRF waveforms are transmitted alternately, and the received echo is coherent; if a waveform is selected from the single PRF frequency hopping waveform data sub-library, the received echo is directly non-coherent.

[0084] S4: Based on the intensity, speed, and spectral width information of the meteorological target obtained in S3, determine the degree of threat posed by the meteorological target to flight safety.

[0085] In some embodiments, in S2.4, a distance threshold R is defined. Threshold =[R1 R2], R l =R Threshold (l), l=1,2 represent the judgment distances corresponding to the three different waveforms, then:

[0086] If R groud ≤R1 or R beamcenter If ≤R1, then select the corresponding single PRF coherent waveform from the single PRF coherent waveform data sub-library;

[0087] If R1 <R groud ≤R2 or R1 <R beamcenter If ≤R2, then select the corresponding dual PRF coherent waveform from the dual PRF coherent waveform data sub-library;

[0088] If R groud >R3 or R beamcenter >R3, then combined with the range R range Then select the corresponding single PRF frequency hopping waveform from the single PRF frequency hopping waveform data sub-library.

[0089] In some embodiments, to achieve the aforementioned detection method, two detection methods can be used, both of which are multi-scan detection, such as... Figure 2 As shown, Method 1 involves first completing a horizontal azimuth scan at a specified pitch angle, and then changing the pitch angle to achieve the same horizontal azimuth scan at that pitch angle. Figure 2As shown in (a); Method 2 involves first completing the pitch dimension scan in the specified azimuth direction, and then performing the pitch dimension scan along the next azimuth direction, as shown in (a). Figure 2 As shown in (b). Among them, mode 1 is applicable to mechanically scanned radar and phased array radar, while mode 2 is only applicable to phased array radar. A complete multi-scan detection time is shorter and the information update rate is faster.

[0090] In some embodiments, the received echoes of single PRF coherent waveforms and dual PRF coherent waveforms are processed to extract information such as the intensity, velocity and spectral width of meteorological targets, thereby improving the radar's detection performance for low-reflectivity meteorological targets; the received echoes of single PRF frequency hopping waveforms are processed to obtain the intensity information of meteorological targets.

[0091] By combining the intensity, speed, and spectral width of meteorological targets obtained from multi-scan airspace data processing with the characteristics of meteorological targets, it is possible to assess the threat level of meteorological targets and predict their development trend, direction of movement, and speed, providing pilots with multi-dimensional information references and improving flight safety.

[0092] In some embodiments, the provided airborne weather radar weather detection method is as follows:

[0093] Step 1: Select Detection Mode

[0094] During the use of the airborne weather radar, the multi-scan detection mode was selected, and the parameters were set as follows: number of scan layers N layer =6 (e.g.) Figure 1 ); Azimuth scanning range ±60°; Range R range = 320km; Aircraft flight altitude H Plane =8000m; beamwidth φ 3dB =3°; the corresponding pitch angles for each scanning layer are Φ = [-9° -5° -2.3° -0.6° 1° 3°].

[0095] Step 2: Establish a waveform database

[0096] Establish a waveform database, which includes a single PRF coherent waveform data sub-database, a double PRF coherent waveform data sub-database, and a single PRF frequency hopping waveform data sub-database.

[0097] A) The single PRF coherent waveform data sub-library is defined as follows:

[0098] SPRI Data =[0.3 0.4 0.5 0.6]ms (1)

[0099] Among them, SPRI m =SPRI Data (m), m = 1, 2, ..., 4;

[0100] B) The dual PRF coherent waveform data sub-library is defined as follows:

[0101]

[0102] Among them, DPRI n =DPRI Data (n,:), n=1,2,...,4;

[0103] C) The single PRF frequency hopping waveform data sub-library is defined as:

[0104] PRI Data =[1.2 1.6 2.4 3.2]ms (3)

[0105] Among them, PRI k =PRI Data (k), k = 1, 2, ..., 4;

[0106] The distance threshold is defined as R Threshold =[90 180], R l =R Threshold (l), l=1,2 represent the judgment distance thresholds corresponding to the three different waveforms.

[0107] Step 3: Waveform Selection

[0108] For beams with different elevation angles, their detection range and target characteristics within the illuminated airspace vary significantly. To better obtain meteorological target parameters, different detection waveforms need to be selected for different elevation angles. Therefore, for the nth (n∈[1 N) beam... layer ]) pitch layers to determine waveform parameters.

[0109] When the pitch angles of the six pitch levels are Φ = [-9° -5° -2.3° -0.6° 1° 3°], the corresponding waveforms are as follows:

[0110] Layer 1, elevation angle -9°, maximum beam distance to ground R groud =67km, satisfying R groud ≤R1, select single PRF coherent waveform, SPRI m =0.5ms, pulse number Na SPRF =64;

[0111] Layer 2, elevation angle -5°, maximum beam distance to ground R groud =153km, satisfying R1 <R groud ≤R2, select dual PRF coherent waveform, DPRI n = [1 1.2] ms, the number of pulses corresponding to both repetition frequencies is Na DPRF =64;

[0112] Layer 3, pitch angle -2.3°, maximum beam distance to ground R groud >R2, at this time the range R range =320km, select single PRF frequency hopping waveform, PRI=2.4ms, pulse number Na PRF =1;

[0113] Layer 4, pitch angle -0.6°, beamout not touching the ground and R beamcenter >R2, at this time the range R range =320km, select single PRF frequency hopping waveform, PRI=2.4ms, pulse number Na PRF =1;

[0114] Level 5, pitch angle 1°, R beamcenter =152km, satisfying R1 <R beamcenter ≤R2, select dual PRF coherent waveform, DPRI n = [1 1.2] ms, the number of pulses corresponding to both repetition frequencies is Na DPRF =128;

[0115] Level 6, pitch angle 3°, R beamcenter =70km, satisfying R beamcenter ≤R1, select single PRF coherent waveform, SPRI m =0.5ms, pulse number Na SPRF =256.

[0116] In summary, this invention addresses the lack of velocity estimation capabilities for meteorological targets using existing waveforms by proposing a novel composite detection waveform design and application method based on existing technologies. During radar meteorological detection, a multi-scan approach is employed to achieve wide-area meteorological detection and display. The difference lies in that the radar selects waveforms with corresponding pitch and pointing angles from a waveform library based on aircraft flight parameters and scanning methods. This enables meteorological detection in different airspaces and the acquisition of velocity and spectral width information of meteorological targets. The radar can then fuse the intensity, velocity, and spectral width information obtained from multiple scans to identify meteorological target types, assess their threat level, and predict their development trends, speed, and direction. This invention, without compromising meteorological detection performance, provides relatively accurate velocity and spectral width information for meteorological targets, effectively improving turbulence detection capabilities and the ability to assess threatening meteorological targets, thereby enhancing flight safety.

[0117] 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 should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A meteorological detection method using airborne meteorological radar, characterized in that, The method includes the following steps: S1: Set the detection mode; S2: Select a probe waveform from the waveform database; S3: Process the radar echo corresponding to the waveform obtained in S2 to obtain the intensity, velocity and spectral width information of the meteorological target; S4: Based on the intensity, velocity, and spectral width information of the meteorological target obtained in S3, determine the degree of threat posed by the meteorological target to flight safety. The waveform database includes a single PRF coherent waveform data sub-database, a dual PRF coherent waveform data sub-database, and a single PRF frequency-hopping waveform data sub-database. The detection mode includes elevation scan layers. Azimuth scanning range and the corresponding pitch angles of each scanning layer , , ≥0°, In S2, for the first One pitch layer, The selection steps are as follows: S2.1: Based on the aircraft's flight altitude, pitch angle, and beamwidth, determine whether the beam is touching the ground. If it is touching the ground, proceed to S2.2; otherwise, proceed to S2.

3. S2.2: Calculate the farthest beam distance. : S2.3: Calculate the beam center to reach Distance corresponding to height : S2.4: Based on the distance values ​​calculated in S2.2 and S2.3 respectively, select the corresponding waveform from the waveform database. in, The equivalent radius of the Earth. For the height of the aircraft, For pitch beamwidth, This is the beam pointing angle, with upward being positive. To the development height of meteorological targets, .

2. The airborne weather radar weather detection method according to claim 1, characterized in that, In S2.4, a distance threshold is defined. , ,but: like or Then select the corresponding single PRF coherent waveform from the single PRF coherent waveform data sub-library; like or Then select the corresponding dual PRF coherent waveform from the dual PRF coherent waveform data sub-library; like or Then, based on the range Then select the corresponding single PRF frequency hopping waveform from the single PRF frequency hopping waveform data sub-library.

3. The airborne weather radar weather detection method according to claim 1, characterized in that, In step S3, if a waveform is selected from the single PRF coherent waveform data sub-library, the echo is directly received in a coherent manner; if a dual PRF coherent waveform is selected from the dual PRF coherent waveform data sub-library, the two different PRF waveforms are transmitted alternately, and the echo is received in a coherent manner; if a waveform is selected from the single PRF frequency hopping waveform data sub-library, the echo is directly received in a non-coherent manner.

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