Fusion method of real clutter and wind shear simulation echo data

Abstract

The invention provides a real clutter and wind shear simulation echo data fusion method, and belongs to the technical field of airborne meteorological radars, and the method specifically comprises the steps: building a simulation wind field according with wind shear meteorological characteristics; acquiring different types of clutters by using an airborne radar, and calculating the coordinates of the whole flight path of the aerial carrier relative to the simulated wind field by taking the flight starting point of the aerial carrier as a reference point; inputting the relative path of the aerial carrier, the radar technical parameters and the simulation wind field to echo simulation software, and calculating a simulation echo of the simulation wind field; calculating the gain of each azimuth line of the radar by adopting a system gain or system noise method; superposition of simulation echo data and real clutter data is carried out on each azimuth line and each antenna row; and the fusion effect is measured from the angles of the echo intensity, the wind speed distribution and the distance Doppler graph before and after fusion. Through the processing scheme provided by the invention, fusion of the recorded clutter data and the simulated wind field data can be well completed.

Description

Technical Field

[0001] The present application relates to the field of airborne weather radar, and in particular to a method for fusing real clutter and wind shear simulation echo data. Background Art

[0002] Low-altitude wind shear poses a great threat to the safety of aircraft takeoff and landing. It not only causes the aircraft to deviate from its flight path, but may also cause the aircraft to lose stability. If the pilot makes a misjudgment or handles the situation improperly, the aircraft may be damaged. Low-altitude wind shear is most harmful to micro-downwash. The airflow moving vertically in the horizontal direction has a large velocity gradient, which will produce a particularly strong downward airflow, called micro-downwash. After colliding with the ground, it turns parallel to the ground and becomes horizontal wind. The wind direction diverges in all directions with the impact point as the center, forming horizontal wind shear. Figure 1 As shown in the figure, when the aircraft is landing, if the glide path happens to pass through a slightly downwash airflow, the aircraft may suddenly descend abnormally and deviate from the original glide trajectory. The aircraft may be dangerous if it is too low in altitude. After the aircraft flies out of the slightly downwash airflow, it enters the tailwind airflow. At this time, the relative speed between the aircraft and the airflow suddenly decreases. Since the aircraft is constantly decelerating during the landing process, the flight speed must be greater than the minimum speed to avoid stalling. The sudden deceleration is likely to cause the aircraft to enter a stall state, resulting in uncontrollable flight attitude. At such a low altitude and speed, the pilot's operating space and time are limited, which may cause a flight accident.

[0003] In order to reduce the impact of wind shear on the aviation industry, airborne Doppler weather radars were developed and corresponding standards were formulated, providing a technical basis for the airworthiness certification of airborne weather radar equipment. Relevant researchers have also begun to study algorithms to improve wind shear detection performance. Both radar airworthiness certification and wind shear algorithm research require a large amount of wind shear data containing clutter.

[0004] According to the previous discussion, wind shear is an extremely dangerous atmospheric phenomenon. It is difficult and dangerous to obtain data in a wind shear recording flight test, which may cause damage to the aircraft and crew members. In addition, wind shear is also a dangerous weather with a low probability of occurrence. It is also very difficult to collect various types of wind shear data in actual tests. Therefore, when airborne meteorological radars with wind shear detection functions are certified for airworthiness and researchers conduct research on wind shear-related algorithms, the acquisition of various types of meteorological data sources containing recorded clutter and wind shear becomes the first problem to be solved. Summary of the invention

[0005] In view of this, the present application provides a method for fusing real clutter and wind shear simulation echo data, which solves the problems in the prior art and calculates the real-time gain of the simulation data from the two perspectives of radar system noise and system gain, thereby completing the fusion of real data and simulated wind field data.

[0006] The present application provides a method for fusing real clutter and wind shear simulation echo data using the following technical solution:

[0007] A method for fusing real clutter and wind shear simulation echo data comprises the following steps:

[0008] Establish a simulated wind field that meets the meteorological characteristics of wind shear;

[0009] Using airborne radar to collect different types of clutter;

[0010] Extract the longitude, latitude, altitude information and ground speed from the collected recorded clutter data, and calculate the coordinates of the entire flight trajectory of the carrier aircraft relative to the simulated wind field with the flight starting point of the carrier aircraft as the reference point;

[0011] Input the relative path of the carrier aircraft, radar technical parameters and simulated wind field into the echo simulation software to calculate the simulated echo of the simulated wind field;

[0012] The gain of each radar azimuth line is calculated using the system gain or system noise method;

[0013] Superposition of simulated echo data and real clutter data for each azimuth line and antenna row;

[0014] The fusion effect is measured from the perspectives of echo intensity, wind speed distribution, and range Doppler map before and after fusion;

[0015] If the clutter and meteorological positions are not suitable, adjust the wind field position; if the clutter intensity and wind field intensity do not meet the requirements, adjust the minimum reflectivity of the wind field or replace the wind field.

[0016] Optionally, the method of using the system gain to calculate the radar azimuth line gain includes:

[0017] The gain G of each azimuth line is calculated based on the radar system gain Gs and the automatic gain control coefficient AGC:

[0018]

[0019] Optionally, the method of calculating the radar azimuth line gain using the system noise method includes:

[0020] Calculate the system noise level Noise_L1 of the simulated echo, and calculate the gain G of each azimuth line according to the clutter noise level Noise_L0 of each antenna row:

[0021] G=Noise_L0 / Noise_L1.

[0022] Optionally, the method of superimposing the simulated echo data and the real clutter data for each orientation line and each antenna row includes:

[0023] Take out the simulated wind field echo Rain_IQ(i,j) of each azimuth line;

[0024] Take out the recorded clutter data CLU_IQ(i,j) of each azimuth line, and calculate the fusion data of each azimuth line, Fusion_IQ(ij)=Rain_IQ(ij)*G+CLU_IQ(i,j).

[0025] Optional methods for measuring fusion effect from the perspective of echo intensity include:

[0026] Compare the echo intensity of clutter and simulated wind field. The intensity of the clutter part of the fused data is greater than that of the simulated wind field, which is one of the fusion goals. If the intensity does not meet the requirements, change other wind fields or adjust the minimum reflectivity of the echo simulation software to make the fusion effect meet the requirements.

[0027] Optional methods for measuring the fusion effect from the perspective of wind speed distribution include:

[0028] Compare the wind speed distribution before and after data fusion. After fusion, the clutter submerges the meteorological target in the wind field, so that the wind speed of the fused data is between -5 and +5 m / s as one of the fusion targets. If the wind speed does not meet the requirements, adjust the position of the simulated wind field to ensure that the ground clutter submerges the meteorological target.

[0029] Optional methods for measuring the fusion effect from the perspective of the range Doppler map include:

[0030] Observe the range Doppler diagram of the fused data after compensating for the aircraft speed to ensure that the clutter is distributed on both sides of the zero frequency. Determine whether the meteorological simulation echo is symmetrically distributed on both sides of the zero frequency. If it does not meet the requirements, check whether the ground speed and longitude and latitude information in the flight parameters are correct and check the correctness of the relative path after conversion; determine whether the clutter submerges the meteorological simulation echo in spatial position. If it does not meet the requirements, adjust the simulated wind field position to ensure that the ground clutter submerges the meteorological target.

[0031] In summary, this application includes the following beneficial technical effects:

[0032] This application combines radar technical parameters and actual flight parameters, calculates the real-time gain of simulation data from the two perspectives of radar system noise and system gain, thereby completing the fusion of actual data and simulated wind field data. It has been verified that the method of this application can well complete the fusion of actual clutter data and simulated wind field data.

[0033] This application can support the study of different types of wind shear in various clutter scenarios, greatly enriching the source of wind shear data containing real clutter, solving the danger and scarcity problems of wind shear data acquisition, and can be applied to the optimization of wind shear clutter suppression algorithms and the verification of wind shear functions of airborne meteorological radars, providing new ideas for the airworthiness certification of wind shear meteorological radars, and has good market promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a low-level wind shear model;

[0036] Figure 2 This is a flow chart of the data fusion algorithm for this application;

[0037] Figure 3 is the unprocessed wind field and clutter echo intensity;

[0038] Figure 4 is the wind field echo intensity after being processed by the system gain method and the system noise method;

[0039] Figure 5 The echo intensity of the fused data after being processed by the system gain method and the system noise method. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0041] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0042] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0043] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0044] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0045] The embodiment of the present application provides a method for fusing real clutter and wind shear simulation echo data.

[0046] like Figure 2 As shown, a method for fusing real clutter and wind shear simulation echo data includes the following steps:

[0047] Establish a simulated wind field that conforms to the meteorological characteristics of wind shear.

[0048] Airborne radar is used to collect different types of clutter, which are then used in subsequent simulation software to generate simulated echoes of wind shear weather.

[0049] The flight parameters and radar parameters are extracted from the collected recorded clutter data. The flight parameters include longitude, latitude, altitude information and ground speed. The radar parameters include azimuth line AZ_Num, antenna scanning speed Scan_Speed, number of range gates M, antenna frame interval T, carrier frequency f, pulse width t, clutter noise level Noise_L0, system gain G_Sys, automatic gain control AGC, quantization level N and maximum quantization level Umax. Taking the flight starting point of the carrier as the reference point, the coordinates of the entire flight trajectory of the carrier relative to the simulated wind field are calculated.

[0050] The relative path of the carrier aircraft, radar technical parameters and simulated wind field are input into the echo simulation software. The echo simulation software will simulate the process of electromagnetic waves being emitted from the antenna and reflected back to the antenna end by the wind shear in the wind field. The echo simulation software will output the weak receiving signal Rain_IQ at the antenna end, thereby calculating the simulated echo of the simulated wind field.

[0051] The system gain method or the system noise method is used to calculate the gain of each radar azimuth line. Which paradigm is used to calculate the gain of each radar azimuth line mainly depends on the convenience of obtaining the system noise and system gain. The method can also be selected by comparing the effects of different fusion methods in different scenarios.

[0052] The simulated echo data and the real clutter data are superimposed on each azimuth line and each antenna row.

[0053] The fusion effect is measured from multiple angles, including the echo intensity before and after fusion, wind speed distribution, and range Doppler diagram.

[0054] If the clutter and meteorological positions are not suitable, adjust the wind field position; if the clutter intensity and wind field intensity do not meet the requirements, adjust the minimum reflectivity of the wind field or replace the wind field.

[0055] Specific:

[0056] The method of using system gain to calculate the gain of each azimuth line of the radar includes: calculating the gain G of each azimuth line according to the system gain Gs of the radar and the automatic gain control coefficient AGC:

[0057] The method for calculating the gain of each azimuth line of the radar using the system noise method includes: calculating the system noise level Noise_L1 of the simulated echo, and calculating the gain G of each azimuth line according to the clutter noise level Noise_L0 of each antenna row: G=Noise_L0 / Noise_L1.

[0058] The method for superimposing simulated echo data and real clutter data for each azimuth line and each antenna row includes: taking out the simulated wind field echo Rain_IQ(i,j) of each azimuth line; taking out the recorded clutter data CLU_IQ(i,j) of each azimuth line, and calculating the fusion data of each azimuth line, Fusion_IQ(ij)=Rain_IQ(ij)*G+CLU_IQ(i,j).

[0059] The steps to measure the fusion effect are:

[0060] The method of measuring the fusion effect from the perspective of echo intensity includes: comparing the echo intensity of clutter and simulated wind field. The intensity of the clutter part of the fused data is greater than that of the simulated wind field, which is one of the fusion targets. If the intensity does not meet the requirements, replace other wind fields or adjust the minimum reflectivity of the echo simulation software to make the fusion effect meet the requirements.

[0061] The method of measuring the fusion effect from the perspective of wind speed distribution includes: comparing the wind speed distribution before and after data fusion, and making the clutter after fusion submerge the meteorological target in the wind field, so that the wind speed of the fused data is between -5 and +5m / s as one of the fusion targets. If the wind speed does not meet the requirements, adjust the position of the simulated wind field to ensure that the ground clutter submerges the meteorological target. Among them, -5 to +5m / s represents the wind speed direction upward or downward.

[0062] The method of measuring the fusion effect from the perspective of the range Doppler map includes: observing the range Doppler map of the fused data after compensating for the aircraft speed, ensuring that the clutter is distributed near the zero frequency, and judging whether the meteorological simulation echo is symmetrically distributed near the zero frequency. If it does not meet the requirements, check whether the ground speed and longitude and latitude information in the flight parameters are correct and check the correctness of the relative path after conversion; judge whether the clutter submerges the meteorological simulation echo in the spatial position. If it does not meet the requirements, adjust the simulated wind field position to ensure that the ground clutter submerges the meteorological target.

[0063] like Figures 3 to 5 As shown, Figure 3 a and b are the unprocessed wind field and clutter echo intensity, respectively. Figure 4 a and b are the wind field echo intensity after processing by the system gain method and the system noise method, respectively. Figure 5 In the figure, a and b are the echo intensities of the fused data after being processed by the system gain method and the system noise method, respectively.

[0064] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for fusing real clutter and wind shear simulation echo data, characterized in that: The steps include: Establish a simulated wind field that meets the meteorological characteristics of wind shear; Using airborne radar to collect different types of clutter; Extract the longitude, latitude, altitude information and ground speed from the collected recorded clutter data, and calculate the coordinates of the entire flight trajectory of the carrier aircraft relative to the simulated wind field with the flight starting point of the carrier aircraft as the reference point; Input the relative path of the carrier aircraft, radar technical parameters and simulated wind field into the echo simulation software to calculate the simulated echo of the simulated wind field; The gain of each radar azimuth line is calculated using the system gain or system noise method; Superposition of simulated echo data and real clutter data for each azimuth line and antenna row; The fusion effect is measured from the perspectives of echo intensity, wind speed distribution, and range Doppler map before and after fusion; If the clutter and meteorological positions are not suitable, adjust the wind field position; if the clutter intensity and wind field intensity do not meet the requirements, adjust the minimum reflectivity of the wind field or replace the wind field.

2. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: The method of using system gain to calculate the gain of each radar azimuth line includes: The gain G of each azimuth line is calculated based on the radar system gain Gs and the automatic gain control coefficient AGC: G=10 (G s +AGC) / 2 3. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: The method of calculating the radar azimuth line gain using the system noise method includes: Calculate the system noise level Noise_L1 of the simulated echo, and calculate the gain G of each azimuth line according to the clutter noise level Noise_L0 of each antenna row: G=Noise_L0 / Noise_L1.

4. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: The method of superimposing the simulated echo data and the real clutter data on each azimuth line and each antenna row includes: Take out the simulated wind field echo Rain_IQ(i,j) of each azimuth line; Take out the recorded clutter data CLU_IQ(i,j) of each azimuth line, and calculate the fusion data of each azimuth line, Fusion_IQ(ij)=Rain_IQ(ij)*G+CLU_IQ(i,j).

5. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: Methods for measuring fusion effect from the perspective of echo strength include: Compare the echo intensity of clutter and simulated wind field. The intensity of the clutter part of the fused data is greater than that of the simulated wind field, which is one of the fusion goals. If the intensity does not meet the requirements, change other wind fields or adjust the minimum reflectivity of the echo simulation software to make the fusion effect meet the requirements.

6. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: Methods for measuring the fusion effect from the perspective of wind speed distribution include: Compare the wind speed distribution before and after data fusion. After fusion, the clutter submerges the meteorological target in the wind field, so that the wind speed of the fused data is between -5 and +5 m / s as one of the fusion targets. If the wind speed does not meet the requirements, adjust the position of the simulated wind field to ensure that the ground clutter submerges the meteorological target.

7. The method for fusing real clutter and wind shear simulation echo data according to claim 1, characterized in that: Methods for measuring fusion effects from the perspective of range Doppler maps include: Observe the range Doppler diagram of the fused data after compensating for the aircraft speed to ensure that the clutter is distributed on both sides of the zero frequency. Determine whether the meteorological simulation echo is symmetrically distributed on both sides of the zero frequency. If it does not meet the requirements, check whether the ground speed and longitude and latitude information in the flight parameters are correct and check the correctness of the relative path after conversion; determine whether the clutter submerges the meteorological simulation echo in spatial position. If it does not meet the requirements, adjust the simulated wind field position to ensure that the ground clutter submerges the meteorological target.

Images