Method and system for acquiring characteristics of rail-type outfield target and environment radar

Abstract

The present invention belongs to the field of radar target feature information processing technology, and discloses a method and system for acquiring features of rail-type outfield targets and environmental radars. The method comprises: ground object spectrum measurement: measuring ground clutter in various scenes and establishing a ground object spectrum database; target dual-station RCS measurement: based on the radar cross-section calculation principle, using a fully automatic synchronous coordination system to ensure real-time coordination between antennas and targets during the measurement process, measuring target RCS values ​​under various antenna polarization modes and different dual-station angles; Doppler velocity measurement: based on the Doppler principle, using a fully automatic synchronous coordination system, with the aid of a drone suspended target, measuring the radial, lateral and random velocities of the target. While measuring the target features, the present invention provides a method for identifying the background type by analyzing the echo information of the background clutter, providing technical support for subsequent experiments, and overcoming the problem of large error in the results caused by many interference factors in the existing outfield experiment technology.

Description

Technical Field

[0001] The invention belongs to the technical field of radar target feature information processing, and in particular relates to a method and system for acquiring features of a guide rail type outfield target and environment radar. Background Art

[0002] At present, radar target recognition technology is an important technical support means to meet the informationization and intelligentization of weapons. By receiving the echo signal, the type of target can be determined and the moving speed of the target can be calculated. In the military field, radar target recognition technology can be used for target monitoring, intelligence acquisition, fire interception, aerospace, etc. In the civilian field, radar target recognition technology can be used for automatic driving, weather forecasting, geological exploration, etc. Among the characteristic information collected by the radar, the most important is the radar scattering cross section, speed, and azimuth information of the target.

[0003] Radar cross section, or RCS for short, characterizes the echo intensity generated by a target. In various simulations, RCS patterns are not uncommon, but in actual measurements, especially field measurements, there are few continuous RCS curve images that measure changes with angles, because in field tests, facing complex electromagnetic backgrounds, it is difficult to continuously sweep the angle and frequency of the test target. Similarly, in the process of measuring the speed of the target, how to make the antenna beam always illuminate the target and not be affected by the movement of the target is a difficult problem. Because when the target moves randomly, in order to ensure that the antenna beam and the test target remain in the same ray direction, an alignment device must be installed on the antenna, requiring the antenna to be installed on a stable and smoothly movable bracket. Moreover, in actual measurements, the above steps are not enough to extract target information. For example, when a military radar vehicle is moving, the radar itself is also moving while the target is moving, and there is a lack of a device that can make the antenna move in coordination with the target in field tests.

[0004] The external electromagnetic environment is very complex. Civilian and military radars cover almost all electromagnetic frequency bands. For example, aviation radars, satellite signals, mobile phone RF signals, etc. have a great impact on external field measurements, resulting in the experiment not being able to obtain real target echoes. Therefore, it is necessary to extract target feature information from complex background electromagnetic waves, or suppress background noise to obtain the desired target echo. Establishing a database of complex backgrounds has always been a major research topic. Different backgrounds, such as oceans, sand, vegetation, urban roads, etc., have different electromagnetic characteristics, and the differences in these characteristics have a great impact on the extraction of target information.

[0005] There are already a large number of relatively reliable results for modeling and simulation of rough surfaces and RCS measurement of targets. Even if the algorithm is perfect, its core is still the data collected by the antenna. In practical applications, there are a large number of interference factors that are difficult to simulate, and they cannot be limited to indoor experiments and simulations. In this case, outdoor field measurement methods and data are indispensable. In actual outdoor tests, electromagnetic clutter interference is large, and the measurement process is often interfered by terrain, weather and clutter, resulting in large changes in outdoor test scenes. Due to complex conditions and the lack of standardized and systematic experimental processes, the collected data is distorted compared to the true value, making it difficult to accurately control variables, so the experimental results have a certain degree of error. Based on the above analysis, establishing a set of standardized test methods is crucial to the accuracy of experimental results.

[0006] Through the above analysis, the problems and defects of the prior art are as follows:

[0007] (1) In field tests, facing complex electromagnetic backgrounds, it is difficult to continuously scan the angle and frequency of the test target, and there are few continuous RCS curve images that measure changes with angle.

[0008] (2) In actual measurement, the target information is not completely extracted. When the target moves, the radar itself is also moving. However, in the field test, there is a lack of equipment that can make the antenna and the target move in coordination.

[0009] (3) Due to the complex conditions and the lack of a standardized and systematic experimental process, the collected data is distorted compared to the true value, making it difficult to accurately control the variables, so the experimental results have a certain degree of error.

[0010] The difficulty of solving the above problems and defects is to establish an experimental method for measuring background clutter, target RCS and target speed in a trinity, so that angle measurement and RCS measurement are coordinated, and target movement and antenna movement are coordinated.

[0011] The significance of solving the above problems and defects is to improve the quality and efficiency of field experiments, optimize the collected data, and establish a system that can accurately control the experimental process in complex field environments. Summary of the invention

[0012] In view of the problems existing in the prior art, the present invention provides a method, system, device and terminal for acquiring characteristics of a rail-type outdoor target and environment radar, and in particular relates to a method and system for measuring electromagnetic characteristics of a radar target based on an outdoor test stand.

[0013] The present invention is implemented in this way: a method for acquiring characteristics of a rail-type outfield target and an environmental radar, the method comprising the following steps:

[0014] Solution 1: Ground object spectrum measurement: measure ground clutter in various scenes, establish a ground object spectrum database, and provide data support for the combination of targets and complex backgrounds;

[0015] Solution 2: Target dual-station RCS measurement: Based on the radar cross-section calculation principle, a fully automatic synchronous coordination system is used to ensure real-time coordination between the antenna and the target during the measurement process. The target RCS values ​​under various antenna polarization modes and different dual-station angles are measured to obtain important target physical characteristics.

[0016] Solution three, Doppler speed measurement: Based on the Doppler principle, using a fully automatic synchronous coordination system and with the help of a drone suspending the target, the radial, lateral and random speeds of the target are measured to obtain important physical characteristics of the target.

[0017] Further, in the first solution, the ground object spectrum measurement includes:

[0018] (1) Select the experimental site and determine the experimental object; the measurement target of each group of experiments is generally a single type of rough surface;

[0019] (2) Select a sample plot with a side length of 2.1 m, cover it with conical absorbing material, and reserve a small sample plot with a side length of 0.7 m in the center without absorbing material, so that the test site is exposed;

[0020] (3) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level;

[0021] (4) Install the antenna on the adjustable disk at the front end of the arm;

[0022] (5) Use laser for calibration to ensure that the center of the antenna is aligned with the center of the sample plot;

[0023] (6) connecting the antenna to an instrument placed on a mobile test platform, the instrument including a power amplifier and a spectrum analyzer;

[0024] (7) Set up the spectrum analyzer, select S21 mode, select the frequency display range according to the antenna output frequency and the power amplifier effect, select 401 sampling points, automatically adjust the amplitude measurement, start measuring and save the data;

[0025] (8) Adjust the test stand arm, turn the knob between the arm and the bracket, and change the antenna pitch angle according to the scale; measure two sets of data for the antenna vertical reception and 45° pitch angle reception on the rough surface of each material;

[0026] (9) Changing the measurement target, i.e., changing the material in the small sample square, repeating steps (3) to (8), and measuring the echo data of the absorbing material, grass, sand, and road respectively;

[0027] (10) Perform data processing.

[0028] Furthermore, the step of setting the handheld spectrum includes:

[0029] 1) Use a thin line to connect the two diagonal lines of the sample plot to determine the center of the sample plot; fix the laser transmitter vertically to the ground at the center of the sample plot, rotate the bracket arm to ensure that the antenna is vertically downward, and rotate the arm horizontally to ensure that the laser irradiates the center of the antenna;

[0030] 2) The transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2;

[0031] 3) Use the calibration kit to calibrate the spectrum analyzer. After the spectrum analyzer is turned on, select mode S21, mode "Mode" > vector network "NA" > "S21"; select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, frequency "Freq / Dist" > set the start frequency "Start" > stop frequency "Stop"; select the number of sampling points, there are three options: 201, 401, and 801. Considering both accuracy and calculation efficiency, select 401, sweep "Sweep" > "Resolution" > "401"; select the amplitude range, range "Scale" > automatic range selection "Autoscale"; start measuring the first set of data;

[0032] 4) Axially rotate the test stand arm and change the antenna from vertical measurement to 45° measurement according to the scale; measure the second set of data.

[0033] The data processing step comprises:

[0034] 1) Measure multiple sets of data in the vertical measurement and 45° oblique measurement experiments, and take the average value to reduce the error;

[0035] 2) Perform data processing, treat the data of the same ground feature at different antenna angles as the same group with different serial numbers, and then compare the data within the group to obtain the reflection spectrum of the scene for different bands; when the antenna angle is the same, compare different test surface features with each other to obtain the similarities and differences of multiple scenes; draw pictures to intuitively analyze the spectral characteristics of the ground features in different scenes.

[0036] Further, in the second solution, the target dual-station RCS measurement includes:

[0037] (1) Select the measurement target;

[0038] (2) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level;

[0039] (3) Install the antenna on the flange at the front end of the arm and use laser calibration to ensure that the antenna is aligned with the target;

[0040] (4) connecting the antenna to the equipment on the mobile test platform, the equipment including a power amplifier, a spectrum analyzer, and an external mobile power supply;

[0041] (5) Set up the spectrum analyzer: Select the spectrum analyzer's vector network mode NA and channel mode S21; select the frequency display range according to the antenna output frequency and power amplifier effect, taking into account data processing speed and accuracy, and select 401 sampling points; automatically adjust the amplitude measurement, start measuring and save the data;

[0042] (6) Measure the echo power of background clutter;

[0043] (7) Place the target, measure the vertical distance between the target and the rail, and collect antenna position information;

[0044] (8) Debug the drive device so that the antenna beam always illuminates the test target;

[0045] (9) Use a metal ball with known RCS for calibration, measure its echo power, and record the data;

[0046] (10) Measure the target echo power and record the data;

[0047] (11) Change the polarization direction of the antenna, measure horizontal polarization, vertical polarization, and 45° polarization respectively, and repeat steps (7) to (9);

[0048] (12) Perform data processing, calculate the target RCS value, and obtain the relationship between the RCS measurement value and the angle.

[0049] Further, the target dual-station RCS measurement further includes:

[0050] 1) Install the driving device on the flange, the joint between the arm and the bracket and the bracket base to automatically adjust the receiving antenna and the transmitting antenna to automatically align with the target, rotate the flange to adjust the antenna direction, axially rotate the arm to adjust the antenna orientation, and horizontally rotate the arm to adjust the antenna position;

[0051] 2) Use a power amplifier to transmit and receive signals, use a spectrum analyzer to collect and store radar cross-section data, and then process the data on a computer; the transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2;

[0052] 3) After the spectrum analyzer is turned on, select mode S21, mode "Mode" > vector network "NA" > "S21"; select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, frequency "Freq / Dist" > set the start frequency "Start" > stop frequency "Stop"; select the number of sampling points, there are three options: 201, 401, and 801, taking into account both accuracy and calculation efficiency, select 401, sweep "Sweep" > "Resolution" > "401"; select the amplitude range, range "Scale" > automatic range selection "Autoscale";

[0053] 4) Without setting any target, drive the two antennas to approach each other at the same speed on the guide rail, record the changes of the dual-station angle, measure the background echo power, and record the data;

[0054] 5) Place the calibration metal ball, measure the vertical distance between the metal ball and the guide rail, import it into the computer, enter the bi-station angle, and test the RCS values ​​when the bi-station angles are 90°, 45°, and approximately 0°;

[0055] 6) Set the metal ball and antenna to work together, use the automatic alignment device to obtain the target position, drive the turntable at the bottom of the antenna and the test stand arm to rotate, ensure that the antenna is aligned with the metal ball, start calibration, measure the metal ball echo power, and record the data;

[0056] 7) Set the measurement target to coordinate with the antenna, use the automatic alignment device to obtain the target position, drive the turntable at the bottom of the antenna and the test stand arm to rotate, and ensure that the antenna is aligned with the target; measure the target echo power and record the data;

[0057] 8) Rotate the flange to change the polarization direction of the antenna. At the beginning of the experiment, the antenna is horizontally polarized. Rotate the flange 45° clockwise and repeat steps 1) to 7) to obtain the measurement results of the 45° polarized antenna and record the second set of data. Continue to rotate the flange 45° clockwise and repeat steps 1) to 7) to obtain the measurement results of the vertically polarized antenna and record the third set of data.

[0058] The data processing step comprises:

[0059] 1) Radar cross section is a physical quantity that characterizes the echo intensity and is defined as:

[0060]

[0061] The relationship between radar cross section and echo power is shown below:

[0062]

[0063] Among them, R Tis the distance between the target and the transmitting antenna, R R is the distance between the target and the receiving antenna, L is the loss coefficient, G T is the gain of the transmitting antenna, G R is the gain of the receiving antenna, P T is the transmission power, P R is the received power, and λ is the wavelength. By measuring the echo power of a metal ball with a known RCS value, the relationship between the echo power and the RCS value can be obtained. Although the RCS values ​​of the target and the metal ball are different, for the same dual-station test system, the relationship between the echo power and the RCS value of the two is the same. When measuring, be sure to ensure that the antenna is aligned with the metal ball. The gain used in the calculation is generally the gain in the main direction of the antenna. Deviation will lead to increased errors. The metal ball has a symmetrical structure. If a single-station measurement is performed, the RCS value of the metal ball will not change with the change of the angle, but in a dual-station measurement, the dual-station angle will affect the measured RCS value of the metal ball.

[0064] 2) The target RCS value is calculated by the following formula:

[0065]

[0066] Among them, σ1 is the RCS value of the metal ball, σ2 is the RCS value of the target, S0 is the background echo power, S1 is the metal ball echo power, and S2 is the target echo power. Draw its RCS pattern according to the change of the dual-station angle, and observe and analyze the RCS distribution of the target at different angles. Using formula (3) for calculation does not require parameters such as loss coefficient and antenna gain in formula (2).

[0067] For polarized antennas, the RCS value of the target will be affected by the polarization of the transmitting and receiving antennas. Decompose the electric field into two polarization components:

[0068]

[0069] Among them, E t is the electric field of the incident wave, E tv Its vertical polarization component, E th is its horizontal polarization component; E r is the echo electric field, E rv Its vertical polarization component, E rh is its horizontal polarization component; γ t is the angle between the electric field direction of the incident wave and the vertical direction, γ r is the angle between the electric field of the echo and the vertical direction. The electric field component of the incident wave is related to the electric field component of the echo using the scattering coefficient:

[0070]

[0071] Among them, each S component is an element of the scattering matrix:

[0072]

[0073] The RCS scattering matrix is ​​given by:

[0074] σ ij =|S ij | (7)

[0075] Further, in solution three, the Doppler velocity measurement includes:

[0076] (1) Select the test target to be suspended by the UAV, and use rigid materials to suspend the test target to ensure that the UAV and the test target remain relatively static during the movement, and avoid the phenomenon of acceleration and air resistance causing the UAV and the test target to be asynchronous;

[0077] (2) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level;

[0078] (3) Install a driving device and connect a mobile power source to drive the antenna to always align with the target during the test and to drive the antenna to move on the guide rail according to test requirements;

[0079] (4) Use the automatic alignment device to obtain the target position and speed information in real time through the UAV positioning system. According to the information, the automatic alignment device drives the turntable at the bottom of the antenna and the test frame arm to rotate to ensure that the antenna is always aligned with the target;

[0080] (5) Start speed measurement. First, control the UAV to drive the target to move radially toward the antenna direction, save the UAV moving speed as the target's true speed, and record the first set of frequency data;

[0081] (6) Control the lateral movement of the UAV, that is, control the UAV to move in a direction parallel to the guide rail, record the UAV's movement trajectory and the angle between the line between the UAV and the antenna and the UAV's movement direction, save the UAV's movement speed data, and record the second set of frequency data;

[0082] (7) Control the UAV to move randomly. At this time, the target speed is decomposed into a horizontal component parallel to the guide rail and a radial component perpendicular to the guide rail. The radial component is used to measure the speed. The angle between the target movement direction and the guide rail is obtained, and the real movement speed of the target can be obtained; record the UAV trajectory and the relative position of the UAV and the antenna, save the UAV movement speed, record the angle between the UAV and the antenna connection and the UAV movement direction, and record the third set of frequency data;

[0083] (8) Process data.

[0084] Furthermore, the experimental instrument preparation work includes:

[0085] 1) The experiment selects a drone to suspend the target, and the drone's moving speed can be recorded to obtain the target's true moving speed. To prevent the drone from affecting the scattering of the target, the target is suspended under the drone at a certain distance. Rigid materials must be used when suspending to avoid delays in target acceleration or changes in target speed due to air resistance, which can lead to inaccurate verification results.

[0086] 2) When designing the field test stand, the line problems of other measuring equipment were taken into consideration, so a mobile test platform was added to carry power amplifiers, spectrum analyzers, mobile power supplies and other equipment, and a pulley was installed at the bottom to move on the guide rail with the antenna. A drive device was installed at the connection between the flange, the swing arm and the bracket to cooperate with the automatic alignment device to ensure that the antenna is aligned with the target, and a drive device was installed at the bottom of the bracket to ensure that the antenna moves along the guide rail.

[0087] The data processing step comprises:

[0088] 1) In the case of no loss, when the target is stationary, the incident wave generated by the wave source and the received reflected wave have the same frequency; compared to the case where the target is stationary, when the target is close to the wave source, the target receives more waves in the same period of time, and the frequency of the reflected wave increases; when the target is far away from the wave source, the target receives fewer waves in the same period of time, and the frequency of the reflected wave decreases. The same is true when the wave source moves.

[0089] Assume that the distance between the wave source and the target is R, the wavelength of the electromagnetic wave emitted by the wave source is λ, and the transmitting antenna and the receiving antenna are the same antenna. In the process from the antenna emitting the electromagnetic wave to the receiving of the echo, there are 2R / λ complete cycles of waves. When the target does not move, the total phase change caused by the distance between the two ends is When the target moves radially relative to the antenna, the distance and phase will change with time. Then the time derivative of the distance and phase, that is, the angular frequency, is:

[0090]

[0091] Among them, v R is the radial velocity, f d is the Doppler frequency shift, f d =f′-f, f′ is the receiving frequency, f is the transmitting frequency. The positive or negative nature of the Doppler shift is related to the target's moving direction. When the target moves closer to the antenna, the received frequency increases and the Doppler shift is positive; when the target moves away from the antenna, the received frequency decreases and the Doppler shift is negative.

[0092] Rearranging equation (8), the radial velocity is:

[0093]

[0094] The first set of data calculated using formula (9) is basically consistent with the results recorded by the drone.

[0095] 2) In actual situations, the target often does not move exactly radially. When the target moves parallel to the guide rail, it receives electromagnetic waves at two points on the moving route. The path difference between the two points is Δl = d cosθ = vΔt cosθ, and the total phase change during this period is Still taking the time derivative of the distance and phase, the angular frequency is:

[0096]

[0097] Where v is the target speed. It can be sorted as:

[0098]

[0099] The second set of data calculated using formula (11) is basically consistent with the results recorded by the drone.

[0100] 3) Import the target speed direction and the angle data between the target and the antenna, import the echo frequency, and use formula (11) to calculate the target speed with the help of a computer. The result is basically consistent with the drone recording result.

[0101] Another object of the present invention is to provide a rail-type outfield target and environment radar feature acquisition system using the rail-type outfield target and environment radar feature acquisition method, wherein the rail-type outfield target and environment radar feature acquisition system consists of three major parts: a rail, a mobile test platform, and an antenna bracket.

[0102] Among them, a balancing nut is installed at the bottom of the guide rail, and with the help of a spirit level, the test frame can remain level on various uneven grounds; the mobile test platform is used to carry experimental equipment, and a pulley is installed at the bottom to enable the test platform and the antenna bracket to move synchronously, avoiding the safety problem of damaging the adapter between the antenna and the RF cable when the antenna bracket moves when the RF cable is insufficient in length; the antenna bracket adopts a movable design at the connection: the antenna connection is a flange, which can rotate axially to change the polarization direction of the antenna; the swing arm can rotate both axially and horizontally, and its horizontal rotation adjusts the antenna's φ angle (antenna azimuth angle), and the axial rotation can change the antenna's θ angle (antenna downtilt angle); the bracket base adopts a detachable design to change the position of the antenna bracket on the mobile test platform.

[0103] Another object of the present invention is to provide a computer device, the computer device comprising a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0104] Ground feature spectrum measurement: measure ground clutter in various scenarios and establish a ground feature spectrum database; target dual-station RCS measurement: based on the radar scattering cross-section calculation principle, use a fully automatic synchronous coordination system to ensure real-time coordination between the antenna and the target during the measurement process, and measure the target RCS values ​​under various antenna polarization modes and different dual-station angles; Doppler velocity measurement: based on the Doppler principle, use a fully automatic synchronous coordination system, with the help of drones suspending targets, to measure the radial, lateral and random velocities of the target.

[0105] Another object of the present invention is to provide an information data processing terminal, which is used to implement the rail-type outfield target and environment radar feature acquisition system.

[0106] Combined with all the above technical solutions, the advantages and positive effects of the present invention are as follows: the rail-type field target and environment radar feature acquisition method provided by the present invention innovatively proposes a multifunctional experimental method based on a field test frame, adopts the first field test frame, and constructs a multifunctional and standardized test system. The same equipment can be used to perform ground object spectrum measurement, dual-station RCS measurement, and Doppler velocity measurement, measure the target radar scattering cross section, movement speed and azimuth, and fully grasp the target geometry and movement characteristics; in addition, the test of the field target is affected by the electromagnetic clutter signal, which causes the electromagnetic characteristics of the target to be easily covered in the background clutter. The present invention creatively proposes a target-background separation measurement method, which can measure the ground object spectrum data of the complex environment where the target is located and try to eliminate interference. Thereby, a comprehensive and systematic field target test can be achieved, and the azimuth and speed information of the instrument and equipment can be accurately controlled for different test schemes during the measurement process. For example, when measuring the dual-station RCS, the angle between the transmitting and receiving antennas (also called the dual-station angle), the antenna pitch angle, and the antenna moving speed with the test frame are adjusted according to the distance between the target and the antenna.

[0107] The present invention provides a highly integrated, stable and reliable test system that can measure the RCS and speed of the target, and at the same time measure the background category of the target's environment, mainly solving the problem that complex electromagnetic waves in the outdoor field have a great impact on the experimental results, thereby establishing a highly integrated, stable and reliable radar target feature measurement test system. The present invention provides a measurement method that can accurately determine the size of the measurement area and accurately control the height and angle of the antenna placement, accurately control the required angle and height for different test scenarios, eliminate interference to the maximum extent, improve the quality and efficiency of outdoor experiments, optimize the collected data, and establish a system that can accurately control the experimental process in a complex outdoor environment.

[0108] The present invention provides a radar target electromagnetic characteristic measurement method based on an outdoor test frame, including ground object spectrum measurement, target dual-station RCS measurement, and Doppler velocity measurement. For the electromagnetic characteristics of outdoor targets, RCS and velocity are two important characteristic quantities. In addition, ground clutter is measured, and the experimental results can be used for the combination of targets and complex scenes. In the ground object spectrum measurement, the stability and precise scale of the test frame can avoid the interference of artificial and natural factors in the outdoor field on the position and angle reading of the equipment; in the dual-station RCS measurement, the method adopted by the present invention can ensure that the dual-station angle is measured while measuring RCS, and the influence of the dual-station angle in the dual-station RCS measurement is obtained; in Doppler velocity measurement, the antenna and target can be set to cooperate to measure the random velocity of the target, etc.

[0109] The present invention provides a method for identifying the background type by analyzing the echo information of the background clutter while measuring the target characteristics, thus providing technical support for subsequent experiments. The present invention overcomes the problem of large error in the results caused by many interference factors in the existing field experiment technology, and effectively solves the problem of large error in the experimental results caused by the lack of antenna and target coordination devices in the field test. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0111] Figure 1 It is a flow chart of a method for acquiring characteristics of a rail-type outfield target and environment radar provided by an embodiment of the present invention.

[0112] Figure 2 It is a flow chart of ground feature spectrum measurement provided by an embodiment of the present invention.

[0113] Figure 3 It is a dual-station RCS measurement flow chart provided by an embodiment of the present invention.

[0114] Figure 4 This is a Doppler velocity measurement flow chart provided by an embodiment of the present invention.

[0115] Figure 5 It is a schematic diagram of laying the absorbing material provided in an embodiment of the present invention.

[0116] Figure 6 It is a schematic diagram of the tile echo power provided by an embodiment of the present invention.

[0117] Figure 7 It is a schematic diagram of grass echo power provided by an embodiment of the present invention.

[0118] Figure 8 It is a schematic diagram of dual-station RCS measurement provided by an embodiment of the present invention.

[0119] Fig. 9 It is a schematic diagram of a mobile testing platform provided by an embodiment of the present invention.

[0120] Fig.10 It is a schematic diagram of the azimuth and elevation structure provided by an embodiment of the present invention.

[0121] Fig.11 It is a schematic diagram of the guide rail and the bottom balance nut provided in an embodiment of the present invention.

[0122] Fig.12 It is a schematic diagram of the general assembly of an outdoor test stand provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0123] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0124] In view of the problems existing in the prior art, the present invention provides a method, system, device and terminal for acquiring characteristics of a rail-type outfield target and environment radar. The present invention is described in detail below in conjunction with the accompanying drawings.

[0125] like Figure 1 As shown, the method for acquiring characteristics of a rail-type outfield target and environment radar provided by an embodiment of the present invention comprises the following steps:

[0126] S101, ground feature spectrum measurement: measure ground clutter in various scenes and establish a ground feature spectrum database;

[0127] S102, target dual-station RCS measurement: Based on the radar cross-section calculation principle, a fully automatic synchronization coordination system is used to ensure real-time coordination between the antenna and the target during the measurement process, and the target RCS values ​​under various antenna polarization modes and different dual-station angles are measured;

[0128] S103, Doppler velocity measurement: Based on the Doppler principle, using a fully automatic synchronous coordination system and with the aid of a drone suspended target, the radial, lateral and random velocity of the target is measured.

[0129] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0130] In view of the above problems, the present invention innovatively proposes a multifunctional experimental method based on an outdoor test stand.

[0131] The field test frame consists of three parts: the guide rail, the mobile test platform, and the antenna bracket. The guide rail is equipped with a balance nut at the bottom, which can keep the test frame level on various uneven grounds with a level gauge. The mobile test platform is used to carry experimental equipment, and a pulley is installed at the bottom, which can make the test platform and the antenna bracket move synchronously to avoid safety problems such as damage to the adapter of the antenna and the RF line when the antenna bracket moves when the RF line is insufficient. It increases the operability of the experiment and also improves the safety of the experimental equipment. In order to meet different test scenarios, the antenna bracket is mostly designed to be movable at the joint: the antenna connection is a flange, which can rotate axially to change the polarization direction of the antenna. The swing arm can rotate axially or horizontally. Its horizontal rotation adjusts the φ angle (antenna azimuth) of the antenna, and the axial rotation can change the θ angle (antenna downtilt angle) of the antenna. The bracket base adopts a detachable design to change the position of the antenna bracket on the mobile test platform.

[0132] The present invention provides a radar target electromagnetic characteristic measurement method based on an outdoor test frame, including ground object spectrum measurement, target dual-station RCS measurement, and Doppler velocity measurement. For the electromagnetic characteristics of outdoor targets, RCS and velocity are two important characteristic quantities. In addition, ground clutter is measured, and the experimental results can be used for the combination of targets and complex scenes. In the ground object spectrum measurement, the stability and precise scale of the test frame can avoid the interference of artificial and natural factors in the outdoor field on the position and angle reading of the equipment; in the dual-station RCS measurement, the method adopted by the present invention can ensure that the dual-station angle is measured while measuring RCS, and the influence of the dual-station angle in the dual-station RCS measurement is obtained; in Doppler velocity measurement, the antenna and target can be set to cooperate to measure the random velocity of the target, etc.

[0133] Example 1

[0134] (1) Spectrum of ground features

[0135] like Figure 2 As shown, the present invention provides a measurement method that can accurately determine the size of the measurement area and accurately control the height and angle of the antenna placement. The required angle and height are accurately controlled for different test scenarios. The steps are as follows:

[0136] Step 1: Select the experimental site and determine the experimental object. The measurement target of each set of experiments is generally a single type of rough surface.

[0137] Step 2: Select a sample plot with a side length of 2.1m, cover it with conical absorbing material, and reserve a small sample plot with a side length of 0.7m in the center without absorbing material, so that the test site is exposed.

[0138] Step 3: Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level.

[0139] Step 4: Install the antenna onto the adjustable disc at the front end of the arm.

[0140] Step 5: Use laser for calibration to ensure that the center of the antenna is aligned with the center of the sample plot.

[0141] Step 6: Connect the antenna to instruments placed on the mobile test platform, such as power amplifiers and spectrum analyzers.

[0142] Step 7: Set up the spectrum analyzer, select S21 mode, select the frequency display range according to the antenna output frequency and the power amplifier effect, select 401 sampling points, automatically adjust the amplitude measurement, start measuring and save the data.

[0143] Step 8: Adjust the test stand arm, turn the knob between the arm and the bracket, and change the antenna pitch angle according to the scale. The rough surface of each material is measured for two sets of data: vertical reception and 45° pitch reception.

[0144] Step 9: Change the measurement target, that is, change the material in the small sample, repeat steps 3 to 8, and measure the echo data of absorbing materials, grass, sand, and roads respectively.

[0145] Step 10: Data processing.

[0146] The following are the steps to set up the handheld spectrum:

[0147] (1.1) Use a thin line to connect the two diagonals of the sample plot to determine the center of the sample plot. Fix the laser transmitter vertically to the ground at the center of the sample plot, rotate the bracket arm axially to ensure that the antenna is vertically downward, and rotate the arm horizontally to ensure that the laser irradiates the center of the antenna.

[0148] (1.2) The transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2.

[0149] (1.3) Use the calibration kit to calibrate the spectrum analyzer. After turning on the spectrum analyzer, select mode S21, "Mode" > "NA" > "S21". Select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, "Freq / Dist" > "Start" > "Stop". Select the number of sampling points. There are three options: 201, 401, and 801. Considering both accuracy and calculation efficiency, select 401, "Sweep" > "Resolution" > "401". Select the amplitude range, "Scale" > "Autoscale". Start measuring the first set of data.

[0150] (1.4) Axially rotate the test stand arm and change the antenna from vertical measurement to 45° measurement according to the scale. Measure the second set of data.

[0151] The following are the data processing steps:

[0152] (1.5) Multiple sets of data can be measured in vertical measurement and 45° inclined measurement experiments, and the average value can be taken to reduce the error.

[0153] (1.6) Perform data processing, treat the data of the same ground feature at different antenna angles as the same group with different serial numbers, and then compare the data within the group to obtain the reflection spectrum of the scene for different bands. Under the same antenna angle, compare different test surface features to obtain the similarities and differences of multiple scenes. Draw pictures to intuitively analyze the ground feature spectrum characteristics of different scenes.

[0154] Example 2

[0155] (2) Dual-station RCS measurement

[0156] like Figure 3 As shown, the present invention provides an RCS measurement method capable of accurately and stably controlling the dual-station angle, and the steps are as follows:

[0157] Step 1: Select the measurement target.

[0158] Step 2: Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level.

[0159] Step 3: Install the antenna on the flange at the front end of the arm and use laser calibration to ensure that the antenna is aligned with the target.

[0160] Step 4: Connect the antenna to the equipment on the mobile test platform, such as the power amplifier, spectrum analyzer, and field mobile power supply.

[0161] Step 5: Set up the spectrum analyzer. First, select the spectrum analyzer's vector network mode (NA), and select S21 for the channel mode; select the frequency display range according to the antenna output frequency and the power amplifier effect, taking into account the data processing speed and accuracy, and select 401 sampling points; automatically adjust the amplitude measurement, start measuring, and save the data.

[0162] Step 6: Measure the echo power of background clutter.

[0163] Step 7: Place the target, measure the vertical distance between the target and the rail, and collect antenna position information.

[0164] Step 8: Debug the drive device so that the antenna beam always illuminates the test target.

[0165] Step 9: Use a metal ball with known RCS for calibration, measure its echo power, and record the data.

[0166] Step 10: Measure the target echo power and record the data.

[0167] Step 11: Change the polarization direction of the antenna, measure horizontal polarization, vertical polarization, and 45° polarization respectively, and repeat steps 7 to 9.

[0168] Step 12: Process the data, calculate the target RCS value, and obtain the relationship between the RCS measurement value and the angle.

[0169] The detailed experimental steps are as follows:

[0170] (2.1) Install the drive device on the flange, the joint between the arm and the bracket and the bracket base to automatically adjust the receiving antenna and the transmitting antenna to automatically align with the target, rotate the flange to adjust the antenna direction, axially rotate the arm to adjust the antenna orientation, and horizontally rotate the arm to adjust the antenna position.

[0171] (2.2) In order to facilitate signal transmission and reception, this experiment uses a power amplifier. In order to obtain radar cross-section data more conveniently and accurately, this experiment uses a spectrum analyzer for data acquisition and storage, and then processes the data on a computer. The transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2.

[0172] (2.3) After the spectrum analyzer is turned on, select mode S21, "Mode" > "NA" > "S21". Select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, "Freq / Dist" > "Start" > "Stop". Select the number of sampling points, there are three options: 201, 401, and 801. Considering both accuracy and calculation efficiency, select 401, "Sweep" > "Resolution" > "401". Select the amplitude range, "Scale" > "Autoscale".

[0173] (2.4) Without setting any target, test the background echo power when the dual-station angles are 90°, 45°, and 0°, and record the data.

[0174] (2.5) Place the calibration metal ball, measure the vertical distance between the metal ball and the guide rail, import it into the computer, and enter the bistatic angle. This experiment tests the RCS values ​​when the bistatic angles are 90°, 45°, and 0° respectively.

[0175] (2.6) Set the metal ball and antenna to work together, use the automatic alignment device to obtain the target position, drive the turntable at the bottom of the antenna and the test frame arm to rotate, ensure that the antenna is aligned with the metal ball, start calibration, measure the echo power of the metal ball, and record the data.

[0176] (2.7) Set the measurement target to coordinate with the antenna, use the automatic alignment device to obtain the target position, drive the antenna bottom turntable and the test frame arm to rotate, and ensure that the antenna is aligned with the target. Measure the target echo power and record the data. Use a computer to control the test frame to change the dual-station angle and test the RCS values ​​when the dual-station angles are 90°, 45°, and 0° respectively.

[0177] (2.8) Rotate the flange to change the polarization direction of the antenna. At the beginning of the experiment, the antenna is horizontally polarized. Rotate the flange 45° clockwise and repeat steps (2.1) to (2.7) to obtain the measurement results of the 45° polarized antenna and record the second set of data. Continue to rotate the flange 45° clockwise and repeat steps (2.1) to (2.7) to obtain the measurement results of the vertically polarized antenna and record the third set of data. The test stand flange has a scale setting to accurately control the polarization direction of the antenna.

[0178] The following are the detailed steps of data processing:

[0179] (2.9) Radar cross section is a physical quantity that characterizes the echo intensity and is defined as

[0180]

[0181] The relationship between radar cross section and echo power is shown below:

[0182]

[0183] Where R T is the distance between the target and the transmitting antenna, R R is the distance between the target and the receiving antenna, L is the loss coefficient, G T is the gain of the transmitting antenna, G R is the gain of the receiving antenna, P T is the transmission power, P Ris the received power, and λ is the wavelength. By measuring the echo power of a metal ball with a known RCS value, the relationship between the echo power and the RCS value can be found. Although the RCS values ​​of the target and the metal ball are different, for the same dual-station test system, the relationship between the echo power and the RCS value of the two is the same. When measuring, be sure to ensure that the antenna is aligned with the metal ball. The gain used in the calculation is generally the gain in the main direction of the antenna. Deviation will lead to increased errors. The metal ball has a symmetrical structure. If a single-station measurement is performed, the RCS value of the metal ball will not change with the change of the angle, but in a dual-station measurement, the dual-station angle will affect the measured RCS value of the metal ball.

[0184] (2.10) The target RCS value is calculated by the following formula

[0185]

[0186] Where σ1 is the RCS value of the metal ball, σ2 is the RCS value of the target, S0 is the background echo power, S1 is the metal ball echo power, and S2 is the target echo power. Draw the RCS pattern according to the change of the dual-station angle, and observe and analyze the RCS distribution of the target at different angles. When using formula (3) for calculation, parameters such as loss coefficient and antenna gain are not required.

[0187] For polarized antennas, the RCS value of the target will be affected by the polarization of the transmitting and receiving antennas. Decompose the electric field into two polarization components:

[0188]

[0189] Where E t is the electric field of the incident wave, E tv Its vertical polarization component, E th is its horizontal polarization component; E r is the echo electric field, E rv Its vertical polarization component, E rh is its horizontal polarization component; γ t is the angle between the electric field direction of the incident wave and the vertical direction, γ r is the angle between the electric field of the echo and the vertical direction. The electric field component of the incident wave is related to the electric field component of the echo using the scattering coefficient:

[0190]

[0191] Each S component is an element of the scattering matrix

[0192]

[0193] The RCS scattering matrix is ​​given by:

[0194] σ ij =|S ij| (7)

[0195] In order to make data storage intuitive and convenient, the following table is given.

[0196] Table 1 RCS measurement information data storage table

[0197]

[0198] Example 3

[0199] (3) Doppler velocity measurement

[0200] like Figure 4 As shown, the present invention provides a Doppler velocity measurement method that enables the antenna and the target to move in coordination.

[0201] Step 1: Select the UAV suspension test target. To avoid the phenomenon of acceleration and air resistance causing the UAV and the test target to be asynchronous, use rigid materials to suspend the test target to ensure that the two remain relatively static during the movement.

[0202] Step 2: Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level.

[0203] Step 3: Install the driving device and connect the mobile power supply to drive the antenna to always align with the target during the test, and drive the antenna to move on the guide rail according to the test needs.

[0204] Step 4: Use the automatic alignment device to obtain the target position and speed information in real time through the drone positioning system. According to the information, the automatic alignment device drives the turntable at the bottom of the antenna and the test frame arm to rotate to ensure that the antenna is always aligned with the target.

[0205] Step 5: Start speed measurement. First, control the drone to drive the target to move radially toward the antenna, save the drone's moving speed as the target's true speed, and record the first set of frequency data.

[0206] Step 6: Control the UAV to move laterally, that is, control the UAV to move in a direction parallel to the guide rail, record the UAV's movement trajectory and the angle between the line between the UAV and the antenna and the UAV's movement direction, save the UAV's movement speed data, and record the second set of frequency data.

[0207] Step 7: Control the drone to move randomly. At this time, the target speed is decomposed into a horizontal component parallel to the guide rail and a radial component perpendicular to the guide rail. The radial component is used to measure the speed. The angle between the target movement direction and the guide rail is obtained to obtain the target's true movement speed. Record the drone trajectory and the relative position of the drone and the antenna, save the drone's movement speed, record the angle between the drone and the antenna connection and the drone's movement direction, and record the third set of frequency data.

[0208] Step 8: Process the data.

[0209] The detailed steps for preparing the experimental equipment are as follows:

[0210] (3.1) The experiment selects a drone to suspend the target, and the drone's moving speed can be recorded, that is, the target's true moving speed can be obtained. In order to prevent the drone from affecting the scattering of the target, the target needs to be suspended under the drone at a certain distance. Rigid materials must be used when suspending to avoid delays in target acceleration or changes in target speed due to air resistance, which can lead to inaccurate verification results.

[0211] (3.2) The design of the field test stand takes into account the line problems of other measuring equipment, so a mobile test platform is added to carry power amplifiers, spectrum analyzers, mobile power supplies and other equipment, and a pulley is installed at the bottom, which can move on the guide rail together with the antenna. A drive device is installed at the connection between the flange, the swing arm and the bracket to cooperate with the automatic alignment device to ensure that the antenna is aligned with the target, and a drive device is installed at the bottom of the bracket to ensure that the antenna can move along the guide rail.

[0212] The detailed steps of data processing are as follows:

[0213] (3.3) In the case of no loss, when the target is stationary, the incident wave generated by the wave source and the received reflected wave have the same frequency; compared with the case where the target is stationary, when the target is close to the wave source, in the same period of time, the target receives more waves and the frequency of the reflected wave increases; when the target is far away from the wave source, in the same period of time, the target receives fewer waves and the frequency of the reflected wave decreases. The same is true when the wave source moves.

[0214] Assume that the distance between the wave source and the target is R, and the wavelength of the electromagnetic wave emitted by the wave source is λ. In this experiment, the transmitting antenna and the receiving antenna are the same antenna. From the time the antenna emits the electromagnetic wave to the time the echo is received, there are 2R / λ complete cycles of waves. When the target does not move, the total phase change caused by the distance between the two ends is When the target moves radially relative to the antenna, the distance and phase will change with time. The time derivative of the distance and phase, that is, the angular frequency, is:

[0215]

[0216] where v R is the radial velocity, f d is the Doppler frequency shift, f d =f′-f, f′ is the receiving frequency, f is the transmitting frequency. The positive or negative nature of the Doppler shift is related to the target's moving direction. When the target moves closer to the antenna, the received frequency increases and the Doppler shift is positive; when the target moves away from the antenna, the received frequency decreases and the Doppler shift is negative.

[0217] Rearranging equation (8), the radial velocity is:

[0218]

[0219] The first set of data calculated using formula (9) is basically consistent with the results recorded by the drone.

[0220] (3.4) In actual situations, the target often does not move exactly radially. When the target moves parallel to the guide rail, it receives electromagnetic waves at two points on the moving route. The path difference between the two points is Δl = d cosθ = vΔt cosθ, and the total phase change during this period is Still taking the time derivative of the distance and phase, the angular frequency is:

[0221]

[0222] Where v is the target speed. It can be sorted as:

[0223]

[0224] The second set of data calculated using formula (11) is basically consistent with the results recorded by the drone.

[0225] (3.5) Import the target speed direction and the angle data between the target and the antenna, import the echo frequency, and use formula (11) to calculate the target speed with the help of a computer. The result is basically consistent with the drone recording result.

[0226] In order to make data storage intuitive and convenient, the following table is given.

[0227] Table 2 Doppler velocity measurement information data storage table

[0228] Serial number θ <![CDATA[f d ]]> v v(true speed) 1 2 …… …… …… …… ……

[0229] Example 2

[0230] For the ground object spectrum measurement experiment, the grassland was used as the test target, and a sphere with a diameter of 10 cm was selected as the measurement target when measuring the dual-station RCS.

[0231] (1) Experimental preparation

[0232] (1.1) Selection of test sites. This experiment selected grass terrain that is common in both urban and wild areas. When selecting test sites, try to avoid locations with severe radar signal interference, such as base stations, radio stations, and cable optical fibers. Try to choose a single type of rough surface, such as grass without protruding shrubs, asphalt roads, and tile floors that are not damaged or missing.

[0233] (1.2) Select the antenna used in the experiment. The experiment selected a 12-18 GHz K-band antenna, which is commonly used in the military. The K-band antenna has a high receiving frequency and is less affected by ground clutter, mobile communication signals, and radio signals. However, the wavelength range of the K-band is close to the diameter range of raindrops and is greatly affected by precipitation. The experiment should be avoided in rainy and snowy weather as much as possible.

[0234] (2) Installation and preparation of experimental equipment

[0235] (2.1) Place the bracket on the test site, adjust the balance nut at the bottom of the bracket to level it, turn on the laser level switch, and if there is no alarm, the automatic correction system is operating normally. Place the laser level on the ground, and start reading after the bubble stabilizes. If it is not zero, adjust the laser level correction nut to zero. After zeroing, fix the laser level on the guide rail, and start reading after the bubble stabilizes. If it is not zero, adjust the balance nut at the bottom of the guide rail to zero. At this time, the guide rail is level.

[0236] (2.2) Install the antenna on the flange at the front end of the bracket's arm. A total of two antennas and two brackets are required, of which two antennas are required for the ground feature spectrum measurement and RCS measurement parts, and only one antenna is required for the Doppler velocity measurement part. Adjust the bases of the two antenna brackets so that they are close enough, and the dual stations can be approximated as a single station for measurement. The field test frame used in the present invention adopts a rotating mechanism and a hole design at the joint of the arm, which can not only reduce weight and facilitate movement, but also facilitate adjustment of the antenna direction and change of the antenna installation position. Adjust the bracket height according to different experimental contents, keep the antenna height the same in the same set of experiments, and avoid interference caused by different beam irradiation areas.

[0237] (2.3) Place the power amplifier, spectrum analyzer and mobile power supply on the mobile test platform. The transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2.

[0238] (2.4) Calibrate the spectrum analyzer to reduce errors. After turning on the spectrum analyzer, select mode S21, "Mode" > "NA" (vector network) > "S21". Start calibration, "Cal" > "Mechanical Cal ECal". Select the calibration part. In this experiment, select the 2.4mm 85056D calibration part, "Change DUT Connectors" > "2.4mm" > "Next Port 2" > "2.4mm" > "85056D:2.4mm Calibration Kit". Select the calibration type, "Change Cal Type" > "ForwardEnhanced Response". Select "Start Calibration" to start calibration, and replace the calibration part according to the instructions of the spectrum analyzer. After completing the four steps, the calibration is completed and enter the result interface. The calibration is completed when the absolute value of the clutter amplitude is within 1dB.

[0239] (2.5) Set up the spectrum analyzer. Select the frequency display range according to the antenna output frequency, receiving frequency, and power amplifier effect. "Freq / Dist" (Frequency) > "Start" (Set the start frequency) > "Stop" (Stop frequency). Select the number of sampling points. There are three options: 201, 401, and 801. Considering both accuracy and calculation efficiency, select 401. "Sweep" (Sweep) > "Resolution" > "401". Select the amplitude range, "Scale" (Range) > "Autoscale" (Automatically select the range).

[0240] (3) Ground feature spectrum measurement

[0241] (3.1) Select a sample plot with a side length of 2.1 m and cover it with absorbing material (see Figure 5 ), a small sample square with a side length of 0.7m is reserved in the center without absorbing materials. Two types of absorbing materials were tested in the experiment, namely conical absorbing materials and single-layer flat absorbing materials. The conical absorbing materials and flat absorbing materials used in this experiment are both made of carbon sponge. The results show that the conical absorbing materials have better absorbing effects. The design of the cone angle can absorb electromagnetic waves to the greatest extent or dissipate electromagnetic waves during reflection and scattering. The flat absorbing materials have poor absorbing effects and are greatly affected by the incident angle.

[0242] (3.2) Use laser to calibrate and ensure that the center of the antenna is aligned with the center of the sample plot. Use a thin wire to connect the two diagonals of the sample plot to determine the center of the sample plot. Fix the laser transmitter vertically to the ground at the center of the sample plot, rotate the bracket arm to ensure that the antenna is vertically downward, and rotate the arm horizontally to ensure that the laser irradiates the center of the antenna.

[0243] (3.3) Start the test, measure multiple sets of data, and take the average value to reduce the error. Use the spectrum analyzer to save the data, "Run / Hold" > "Save".

[0244] (3.4) Adjust the test stand arm, turn the knob between the arm and the bracket, change the antenna pitch angle according to the scale, and measure the ground feature spectrum data obtained by the 45° inclined receiving antenna.

[0245] (3.5) Start the test, measure multiple sets of data, and take the average value to reduce the error. Use the spectrum analyzer to save the data, "Run / Hold" > "Save".

[0246] (4) Dual-station RCS measurement

[0247] (4.1) Install the drive device on the flange, the joint between the arm and the bracket, and the bracket base to automatically adjust the antenna alignment direction and drive the antenna to move on the guide rail. The flange at the front end of the arm and the joint between the arm and the bracket are movable and have holes. A 180° rotating mechanism is used to facilitate the adjustment of the antenna direction and line connection. Connect the drive device to the power supply on the mobile test platform.

[0248] (4.2) Without setting any target, measure the background echo power and record the data.

[0249] (4.3) Calibrate using a metal sphere with a known RCS value.

[0250] (4.4) Place the metal ball on the ground. The metal ball should be on the mid-vertical line of the guide rail. Measure the vertical distance between the metal ball and the guide rail, import it into the computer, and enter the size of the dual-station angle at the same time. Set the metal ball and antenna to cooperate. Use the automatic alignment device to obtain the positions of the two antennas, drive the turntable at the bottom of the antenna and the test frame to rotate, and ensure that the antenna is aligned with the metal ball. Change the size of the dual-station angle, measure three sets of data when the dual-station angle is 0°, 45°, and 90° respectively, measure the metal ball echo power, and use the spectrum analyzer to save the data, "Run / Hold" (Pause) > "Save" (Save).

[0251] (4.5) Replace the metal ball with the target and return the antenna to both ends of the rail. Set the measurement target to work with the antenna, use the automatic alignment device to obtain the antenna position, drive the turntable at the bottom of the antenna and the test stand arm to rotate, and ensure that the antenna is aligned with the target. Change the size of the dual-station angle, measure three sets of data when the dual-station angle is 0°, 45°, and 90°, measure the echo power, and use the spectrum analyzer to save the data. "Run / Hold" (Pause) > "Save" (Save) to save the data.

[0252] (4.6) Rotate the flange to change the polarization direction of the antenna. At the beginning of the experiment, the antenna is horizontally polarized. Rotate the flange 45° clockwise and repeat steps (4.2) to (4.3) to obtain the measurement results of the 45° polarized antenna and save the data. Continue to rotate the flange 45° clockwise and repeat steps (4.3) to (4.3) to obtain the measurement results of the vertically polarized antenna and save the data.

[0253] (5) Doppler velocity measurement

[0254] (5.1) Install the drive device on the flange, the joint between the arm and the bracket, and the bracket base to automatically adjust the antenna alignment direction and drive the antenna to move on the guide rail. The front disc of the arm and the joint between the arm and the bracket are movable and have holes. A 180° rotating mechanism is used to facilitate the adjustment of the antenna direction and line connection. Connect the drive device to the power supply on the mobile test platform.

[0255] (5.2) The UAV suspension test target was selected and rigid material suspension was used to avoid the influence of acceleration and air resistance.

[0256] (5.3) Use the automatic alignment device to obtain the target position in real time through the drone signal, drive the turntable at the bottom of the antenna and the test frame arm to rotate, and ensure that the antenna is always aligned with the target.

[0257] (5.4) First, control the drone to drive the target to move radially toward the antenna, save the drone's moving speed as the target's true speed, and record the first set of frequency data.

[0258] (5.5) Control the UAV to move laterally, that is, control the UAV to move in a direction parallel to the guide rail, save the UAV movement speed data, record the speed direction and the angle between the UAV and the antenna line, and record the second set of frequency data.

[0259] (5.6) Control the UAV to move randomly. At this time, the target velocity has a lateral component. Save the UAV moving speed, record the angle between the UAV and antenna connection and the UAV movement direction, and record the third set of frequency data.

[0260] (6) Data processing

[0261] (6.1) Save the ground feature spectrum data, measure multiple scenes, and draw a picture to summarize the electromagnetic characteristics of each scene. Compare the data within and between groups for each scene.

[0262] (6.2) RCS value calculation

[0263] The target RCS value is calculated by the following formula. This method requires the RCS value of the calibration object to be known, but does not require parameters such as antenna gain and loss coefficient.

[0264]

[0265] Among them, σ1 is the RCS value of the metal ball, σ2 is the RCS value of the target, S0 is the background echo power, S1 is the metal ball echo power, and S2 is the target echo power. Draw its RCS directional diagram according to the change of the dual-station angle, and observe and analyze the RCS distribution of the target at different angles.

[0266] For polarized antennas, the RCS value of the target will be affected by the polarization of the transmitting and receiving antennas. Decompose the electric field into two polarization components:

[0267]

[0268] Where E t is the electric field of the incident wave, E tv Its vertical polarization component, E th is its horizontal polarization component; E r is the echo electric field, E rv Its vertical polarization component, E rh is its horizontal polarization component; γ t is the angle between the electric field direction of the incident wave and the vertical direction, γ r is the angle between the electric field of the echo and the vertical direction. The electric field component of the incident wave is related to the electric field component of the echo using the scattering coefficient:

[0269]

[0270] The S components are the elements of the scattering matrix:

[0271]

[0272] The RCS scattering matrix is ​​given by:

[0273] σ ij =|S ij | (16)

[0274] The results of this case are shown in Table 3. It can be seen that although the antenna polarization mode has an angle change, it is all linear polarization, which has little effect on the RCS value measurement; the larger the bistatic angle, the lower the RCS value. The calibration metal ball has a symmetrical structure and is less affected by the change of the bistatic angle; the target has an irregular structure and is greatly affected by the change of the bistatic angle.

[0275] Table 3 RCS measurement information data storage table

[0276]

[0277] (6.3) Doppler velocity measurement

[0278] Assume that the distance between the wave source and the target is R, and the wavelength of the electromagnetic wave emitted by the wave source is λ. In this experiment, the transmitting antenna and the receiving antenna are the same antenna. From the time the antenna emits the electromagnetic wave to the time the echo is received, there are 2R / λ complete cycles of waves. When the target does not move, the total phase change caused by the distance between the two ends is When the target moves radially relative to the antenna, the distance and phase will change with time. Then the time derivative of the distance and phase, that is, the angular frequency, is:

[0279]

[0280] where v R is the radial velocity, f d is the Doppler frequency shift, f d =f′-f, f′ is the receiving frequency, f is the transmitting frequency. The positive or negative nature of the Doppler shift is related to the target's moving direction. When the target moves closer to the antenna, the received frequency increases and the Doppler shift is positive; when the target moves away from the antenna, the received frequency decreases and the Doppler shift is negative.

[0281] Rearranging equation (17), the radial velocity is:

[0282]

[0283] The first set of data calculated using formula (19) is basically consistent with the results recorded by the drone.

[0284] In actual situations, the target often does not move exactly radially. When the target moves parallel to the guide rail, it receives electromagnetic waves at two points on the moving route. The path difference between the two points is Δl = d cosθ = vΔt cosθ, and the total phase change during this period is Still taking the time derivative of the distance and phase, we get the angular frequency:

[0285]

[0286] Where v is the target speed. It can be sorted as:

[0287]

[0288] The first and second sets of data are calculated using formula (19), which is basically consistent with the drone recording results. The target speed direction and the angle between the target and the antenna are imported, the echo frequency is imported, and the target speed is calculated by computer using formula (20). The result is basically consistent with the drone recording result.

[0289] The amount of data is large, and the following table shows a part of the third set of data.

[0290] Table 4 Doppler velocity measurement information data storage table

[0291] θ(°) <![CDATA[f d (Hz)]]> v(m / s) v(true speed)(m / s) 15 75.30 0.95 1.00 30 180.80 2.23 2.00 50 352.70 4.32 5.00

[0292] The tile echo power is as follows Figure 6 As shown, the grass echo power is Figure 7 The schematic diagram of dual-station RCS measurement is shown in Figure 8 As shown in Figure 2, the mobile test platform is Fig. 9 As shown, the azimuth and elevation structures are as follows: Fig.10 As shown, the guide rail and bottom balance nut are as follows Fig.11 As shown in the figure, the field test frame is assembled as follows Fig.12 shown.

[0293] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0294] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for acquiring characteristics of a rail-type outfield target and environment radar, establishing an experimental method for measuring background clutter, target RCS, and target speed in one, characterized in that: The method for acquiring characteristics of a guide rail type outfield target and environment radar comprises the following steps: Solution 1: The method of measuring ground object spectrum is: measuring ground clutter in various scenes and establishing a ground object spectrum database; Solution 2: The method of measuring the target dual-station RCS is: based on the radar cross-section calculation principle, a fully automatic synchronous coordination system is used to ensure real-time coordination between the antenna and the target during the measurement process, and the target RCS values ​​under various antenna polarization modes and different dual-station angles are measured; Solution 3, the Doppler velocity measurement method is: based on the Doppler principle, using a fully automatic synchronous coordination system, with the help of a drone suspending the target, to measure the radial, lateral and random velocity of the target; In the second solution, the target dual-station RCS measurement includes: (1) Select the measurement target; (2) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level; (3) Install the antenna on the flange at the front end of the arm and use laser calibration to ensure that the antenna is aligned with the target; (4) connecting the antenna to the equipment on the mobile test platform, the equipment including a power amplifier, a spectrum analyzer, and an external mobile power supply; (5) Set up the spectrum analyzer: Select the spectrum analyzer's vector network mode NA and channel mode S21; select the frequency display range according to the antenna output frequency and power amplifier effect, taking into account data processing speed and accuracy, and select 401 sampling points; automatically adjust the amplitude measurement, start measuring and save the data; (6) Measure the echo power of background clutter; (7) Place the target, measure the vertical distance between the target and the rail, and collect antenna position information; (8) Debug the drive device so that the antenna beam always illuminates the test target; (9) Use a metal ball with known RCS for calibration, measure its echo power, and record the data; (10) Measure the target echo power and record the data; (11) Change the polarization direction of the antenna, measure horizontal polarization, vertical polarization, and 45° polarization respectively, and repeat steps (7) to (9); (12) Perform data processing, calculate the target RCS value, and obtain the relationship between the RCS measurement value and the angle; The target dual-station RCS measurement further includes: 1) Install the driving device on the flange, the joint between the arm and the bracket and the bracket base to automatically adjust the receiving antenna and the transmitting antenna to automatically align with the target, rotate the flange to adjust the antenna direction, axially rotate the arm to adjust the antenna orientation, and horizontally rotate the arm to adjust the antenna position; 2) Use a power amplifier to transmit and receive signals, use a spectrum analyzer to collect and store radar cross-section data, and then process the data on a computer; the transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2; 3) After the spectrum analyzer is turned on, select mode S21, mode "Mode" > vector network "NA" > "S21"; select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, frequency "Freq / Dist" > set the start frequency "Start" > stop frequency "Stop"; select the number of sampling points, there are three options: 201, 401, and 801, taking into account both accuracy and calculation efficiency, select 401, sweep frequency "Sweep" > "Resolution" > "401"; select the amplitude range, range "Scale" > automatic selection range "Autoscale"; 4) Without setting any target, drive the two antennas to approach each other at the same speed on the guide rail, record the changes of the dual-station angle, measure the background echo power, and record the data; 5) Place the calibration metal ball, measure the vertical distance between the metal ball and the guide rail, import it into the computer, enter the bi-station angle, and test the RCS values ​​when the bi-station angles are 90°, 45°, and approximately 0°; 6) Set the metal ball and antenna to work together, use the automatic alignment device to obtain the target position, drive the turntable at the bottom of the antenna and the test stand arm to rotate, ensure that the antenna is aligned with the metal ball, start calibration, measure the metal ball echo power, and record the data; 7) Set the measurement target to coordinate with the antenna, use the automatic alignment device to obtain the target position, drive the turntable at the bottom of the antenna and the test stand arm to rotate, and ensure that the antenna is aligned with the target; measure the target echo power and record the data; 8) Rotate the flange to change the polarization direction of the antenna. At the beginning of the experiment, the antenna is horizontally polarized. Rotate the flange 45° clockwise and repeat steps 1) to 7) to obtain the measurement results of the 45° polarized antenna and record the second set of data. Continue to rotate the flange 45° clockwise and repeat steps 1) to 7) to obtain the measurement results of the vertically polarized antenna and record the third set of data. In Solution 2, the data processing steps include: 1) Radar cross section is a physical quantity that characterizes the echo intensity and is defined as: The relationship between radar cross section and echo power is shown below: Among them, R T is the distance between the target and the transmitting antenna, R R is the distance between the target and the receiving antenna, L is the loss coefficient, G T is the gain of the transmitting antenna, G R is the gain of the receiving antenna, P T is the transmission power, P R is the received power, and λ is the wavelength. By measuring the echo power of a metal ball with a known RCS value, the relationship between the echo power and the RCS value can be obtained. Although the RCS values ​​of the target and the metal ball are different, for the same dual-station test system, the relationship between the echo power and the RCS value of the two is the same. When measuring, be sure to ensure that the antenna is aligned with the metal ball. The gain used in the calculation is generally the gain in the main direction of the antenna. Deviation will lead to increased errors. The metal ball has a symmetrical structure. If a single-station measurement is performed, the RCS value of the metal ball will not change with the change of the angle. However, in dual-station measurements, the dual-station angle will affect the measured RCS value of the metal ball. 2) The target RCS value is calculated by the following formula: Among them, σ1 is the RCS value of the metal ball, σ2 is the RCS value of the target, S0 is the background echo power, S1 is the metal ball echo power, and S2 is the target echo power. The RCS pattern is drawn according to the change of the dual-station angle, and the RCS distribution of the target at different angles is observed and analyzed. The loss coefficient and antenna gain parameters in formula (2) are not required when using formula (3) for calculation. For polarized antennas, the RCS value of the target is affected by the polarization of the transmitting and receiving antennas; decomposing the electric field into two polarization components: Among them, E t is the electric field of the incident wave, E tv Its vertical polarization component, E th is its horizontal polarization component; E r is the echo electric field, E rv Its vertical polarization component, E rh is its horizontal polarization component; γ t is the angle between the electric field direction of the incident wave and the vertical direction, γ r is the angle between the electric field of the echo and the vertical direction; the electric field component of the incident wave is related to the electric field component of the echo using the scattering coefficient: Among them, each S component is an element of the scattering matrix: The RCS scattering matrix is ​​given by: s ij =|S ij | (7); In solution three, the Doppler velocity measurement includes: (1) Select the test target to be suspended by the UAV, and use rigid materials to suspend the test target to ensure that the UAV and the test target remain relatively static during the movement, and avoid the phenomenon of acceleration and air resistance causing the UAV and the test target to be asynchronous; (2) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level; (3) Install a driving device and connect a mobile power source to drive the antenna to always align with the target during the test and to drive the antenna to move on the guide rail according to test requirements; (4) Use the automatic alignment device to obtain the target position and speed information in real time through the UAV positioning system. According to the information, the automatic alignment device drives the turntable at the bottom of the antenna and the test frame arm to rotate to ensure that the antenna is always aligned with the target; (5) Start speed measurement. First, control the UAV to drive the target to move radially toward the antenna direction, save the UAV moving speed as the target's true speed, and record the first set of frequency data; (6) Control the lateral movement of the UAV, that is, control the UAV to move in a direction parallel to the guide rail, record the UAV's movement trajectory and the angle between the line between the UAV and the antenna and the UAV's movement direction, save the UAV's movement speed data, and record the second set of frequency data; (7) Control the UAV to move randomly. At this time, the target speed is decomposed into a horizontal component parallel to the guide rail and a radial component perpendicular to the guide rail. The radial component is used to measure the speed. The angle between the target movement direction and the guide rail is obtained, and the real movement speed of the target can be obtained; record the UAV trajectory and the relative position of the UAV and the antenna, save the UAV movement speed, record the angle between the UAV and the antenna connection and the UAV movement direction, and record the third set of frequency data; (8) Process data.

2. The method for acquiring characteristics of a guide rail type outfield target and environment radar as claimed in claim 1, characterized in that: In the first solution, the ground object spectrum measurement includes: (1) Select the experimental site and determine the experimental object; the measurement target of each group of experiments is generally a single type of rough surface; (2) Select a sample plot with a side length of 2.1 m, cover it with conical absorbing material, and reserve a small sample plot with a side length of 0.7 m in the center without absorbing material, so that the test site is exposed; (3) Use a laser level to calibrate and adjust the balance nut at the bottom of the test frame rail until the rail is level; (4) Install the antenna on the adjustable disk at the front end of the arm; (5) Use laser for calibration to ensure that the center of the antenna is aligned with the center of the sample plot; (6) connecting the antenna to an instrument placed on a mobile test platform, the instrument including a power amplifier and a spectrum analyzer; (7) Set up the spectrum analyzer, select S21 mode, select the frequency display range according to the antenna output frequency and the power amplifier effect, select 401 sampling points, automatically adjust the amplitude measurement, start measuring and save the data; (8) Adjust the test stand arm, turn the knob between the arm and the bracket, and change the antenna pitch angle according to the scale; measure two sets of data for the vertical reception and 45° pitch angle reception of the antenna on the rough surface of each material; (9) Changing the measurement target, that is, changing the material in the small sample square, repeating steps (3) to (8), and measuring the echo data of the absorbing material, grass, sand, and road respectively; (10) Perform data processing.

3. The method for acquiring characteristics of a guide rail type outfield target and environment radar as claimed in claim 2, characterized in that: The steps to set up the spectrum analyzer include: 1) Use a thin line to connect the two diagonal lines of the sample plot to determine the center of the sample plot; fix the laser transmitter vertically to the ground at the center of the sample plot, rotate the bracket arm to ensure that the antenna is vertically downward, and rotate the arm horizontally to ensure that the laser irradiates the center of the antenna; 2) The transmitting antenna is connected to the "output" interface of the power amplifier, and the "input" interface of the power amplifier is connected to the spectrum analyzer interface 1; the receiving antenna is connected to the "input" interface of another power amplifier, and the "output" interface of the power amplifier is connected to the spectrum analyzer interface 2; 3) Use the calibration kit to calibrate the spectrum analyzer. After the spectrum analyzer is turned on, select mode S21, mode "Mode" > vector network "NA" > "S21"; select the frequency display range according to the antenna output frequency, receiving frequency and power amplifier effect, frequency "Freq / Dist" > set the start frequency "Start" > stop frequency "Stop"; select the number of sampling points, there are three options: 201, 401, and 801. Considering both accuracy and calculation efficiency, select 401, sweep frequency "Sweep" > "Resolution" > "401"; select the amplitude range, range "Scale" > automatic range selection "Autoscale"; start measuring the first set of data; 4) Axially rotate the test stand arm and change the antenna from vertical measurement to 45° measurement according to the scale; measure the second set of data; The data processing step comprises: 1) Measure multiple sets of data in the vertical measurement and 45° oblique measurement experiments, and take the average value to reduce the error; 2) Perform data processing, treat the data of the same ground feature at different antenna angles as the same group with different serial numbers, and then compare the data within the group to obtain the reflection spectrum of the scene for different bands; when the antenna angle is the same, compare different test surface features with each other to obtain the similarities and differences of multiple scenes; draw pictures to intuitively analyze the spectral characteristics of the ground features in different scenes.

4. The method for acquiring characteristics of a guide rail type outfield target and environment radar as claimed in claim 1, characterized in that: In scheme 3, the preparation of experimental instruments includes: 1) The experiment selects a suspended target from a drone, and the moving speed of the drone can be recorded, that is, the real moving speed of the target can be obtained; to avoid the drone affecting the scattering of the target, the target is suspended under the drone at a certain distance; rigid materials must be used when suspending to avoid the target acceleration delay or air resistance causing the target speed to change during acceleration, which will lead to inaccurate verification results; 2) When designing the field test stand, the line problems of other measuring equipment were taken into consideration, so a mobile test platform was added to carry the power amplifier, spectrum analyzer, and mobile power supply equipment, and a pulley was installed at the bottom to move on the guide rail together with the antenna; a driving device was installed at the connection between the flange, the swing arm and the bracket to cooperate with the automatic alignment device to ensure that the antenna is aligned with the target, and a driving device was installed at the bottom of the bracket to ensure that the antenna moves along the guide rail; The data processing step comprises: 1) In the case of no loss, when the target is stationary, the incident wave generated by the wave source and the received reflected wave have the same frequency; compared with the case where the target is stationary, when the target is close to the wave source, the target receives more waves in the same period of time, and the frequency of the reflected wave increases; when the target is far away from the wave source, the target receives fewer waves in the same period of time, and the frequency of the reflected wave decreases; the same is true when the wave source moves; Assume that the distance between the wave source and the target is R, the wavelength of the electromagnetic wave emitted by the wave source is λ, and the transmitting antenna and the receiving antenna are the same antenna. In the process from the antenna emitting the electromagnetic wave to the receiving of the echo, there are 2R / λ complete cycles of waves. When the target does not move, the total phase change caused by the distance between the two ends is When the target moves radially relative to the antenna, the distance and phase will change with time. Then the time derivative of the distance and phase, that is, the angular frequency, is: Among them, v R is the radial velocity, f d is the Doppler frequency shift, f d =f′-f, f′ is the receiving frequency, f is the transmitting frequency; the positive or negative nature of the Doppler shift is related to the target's moving direction. When the target moves closer to the antenna, the received frequency increases and the Doppler shift is positive; when the target moves away from the antenna, the received frequency decreases and the Doppler shift is negative. Rearranging equation (8), the radial velocity is: The first set of data calculated using formula (9) is basically consistent with the drone recording results; 2) In actual situations, the target often does not move exactly radially; when the target moves parallel to the guide rail, it receives electromagnetic waves at two points on the moving route. The path difference between the two points is Δl = dcosθ = vΔtcosθ, and the total phase change during this period is Still taking the time derivative of the distance and phase, the angular frequency is: Among them, v is the target speed; it can be sorted as follows: The second set of data calculated using formula (11) is basically consistent with the drone recording results; 3) Import the target speed direction and the angle data between the target and the antenna, import the echo frequency, and use formula (11) to calculate the target speed with the help of a computer. The result is basically consistent with the drone recording result.

5. A rail-type outfield target and environment radar feature acquisition system for implementing the rail-type outfield target and environment radar feature acquisition method according to any one of claims 1 to 4, characterized in that: The rail-type outfield target and environment radar feature acquisition system consists of three parts: a rail, a mobile test platform, and an antenna bracket; Among them, a balancing nut is installed at the bottom of the guide rail, and with the help of a spirit level, the test frame can remain level on various uneven grounds; the mobile test platform is used to carry experimental equipment, and a pulley is installed at the bottom to enable the test platform and the antenna bracket to move synchronously, avoiding the safety problem of damaging the adapter between the antenna and the RF cable when the antenna bracket moves when the RF cable is insufficient in length; the antenna bracket adopts a movable design at the connection: the antenna connection is a flange, which can rotate axially to change the polarization direction of the antenna; the swing arm can rotate both axially and horizontally, and its horizontal rotation can adjust the antenna's φ angle, and the axial rotation can change the antenna's θ angle. The bracket base adopts a detachable design to change the position of the antenna bracket on the mobile test platform.

6. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for acquiring characteristics of a rail-type outfield target and environment radar as described in any one of claims 1 to 4.

7. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the rail-type outfield target and environment radar feature acquisition system as described in claim 5.

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