A method and device for simulating ground clutter based on digital elevation model data

Abstract

The present invention provides a method and device for simulating ground clutter based on digital elevation model data, and the method includes: obtaining radar actual parameter information and DEM data, extracting terrain data from the DEM data; converting terrain data to the radar station polar coordinate system, and obtaining terrain conversion data; obtaining multiple azimuth lines and multiple distance sampling points on each azimuth line according to the azimuth sampling accuracy and the distance sampling accuracy, and obtaining the pitch angle matrix according to the distance sampling points; determining the clutter scattering cross-sectional area according to the pitch angle matrix; determining the single-beam irradiated clutter area according to the radar actual parameter information; determining the single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area; selecting a clutter probability distribution model, generating a clutter-related random sequence according to the clutter probability distribution model; generating ground clutter data according to the single-beam clutter power and the clutter-related random sequence. The present invention improves the degree of consistency between the simulated ground clutter and the ground clutter in the actual scene.

Description

Technical Field

[0001] The present invention relates to the technical field of radar signal simulation, and in particular to a ground clutter simulation method and device based on digital elevation model data. Background Art

[0002] Radar systems usually work in a certain ground environment. Radar echoes from the ground enter the receiver together with target signals and noise, forming clutter that interferes with radar detection performance. With the continuous improvement of modern radar sensitivity and accuracy, radar systems are increasingly affected by ground clutter. To optimize the design of radar systems, it is necessary to deeply understand and master the interaction between electromagnetic waves and clutter environments.

[0003] The existing radar ground clutter simulation methods are mainly based on signal processing simulation methods, but they do not take into account the ups and downs of the ground, resulting in a large difference between the simulated ground clutter data and the ground clutter data in the real scene.

[0004] Therefore, it is urgent to propose a ground clutter simulation method and device based on digital elevation model data to improve the consistency between the simulated ground clutter and the ground clutter in the real scene. Summary of the invention

[0005] In view of this, it is necessary to provide a ground clutter simulation method and device based on digital elevation model data to solve the technical problem in the prior art that the ground clutter is not considered when simulating the ground clutter, resulting in a low degree of consistency between the simulated ground clutter and the ground clutter in the real scene.

[0006] In one aspect, the present invention provides a method for simulating ground clutter based on digital elevation model data, comprising:

[0007] Acquire radar actual parameter information and digital elevation model data, and extract terrain data of the target area from the digital elevation model data based on the radar actual parameter information;

[0008] Converting the terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system, wherein the terrain conversion data includes an azimuth and an elevation angle;

[0009] The target area is sampled in all directions according to a preset azimuth sampling accuracy and a preset distance sampling accuracy to obtain a plurality of azimuth lines and a plurality of distance sampling points on each azimuth line, and the pitch angles are sorted and reorganized according to the plurality of azimuth lines and the plurality of distance sampling points to obtain a pitch angle matrix;

[0010] Determine the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix;

[0011] Determine a single-beam illumination clutter area according to the radar actual parameter information;

[0012] Determining single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area;

[0013] Selecting a clutter probability distribution model according to the radar actual parameter information, and generating a clutter-related random sequence according to the clutter probability distribution model;

[0014] The ground clutter data is generated according to the radar actual parameter information, the single-beam clutter power and the clutter-related random sequence.

[0015] In some possible implementations, the radar actual parameter information includes the longitude of the radar station, the latitude of the radar station, and the elevation value of the radar station; and extracting the terrain data of the target area from the digital elevation model data based on the radar actual parameter information includes:

[0016] Get the radar detection power value;

[0017] Determine the latitude sequence and longitude sequence of the target area according to the radar detection power value, the longitude of the radar station, the latitude of the radar station and the altitude value of the radar station;

[0018] The terrain data of the target area is extracted from the digital elevation model data according to the latitude sequence and the longitude sequence.

[0019] In some possible implementations, the terrain data is converted from a geocentric geodetic coordinate system to a radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system;

[0020] Converting the terrain data from the geocentric geodetic coordinate system to the geocentric rectangular coordinate system to obtain first terrain data in the geocentric rectangular coordinate system;

[0021] Converting the first terrain data from the geocentric rectangular coordinate system to the radar station rectangular coordinate system to obtain second terrain data in the radar station rectangular coordinate system;

[0022] The second terrain data is converted from the radar station rectangular coordinate system to the radar station polar coordinate system to obtain the terrain conversion data in the radar station polar coordinate system.

[0023] In some possible implementations, the first terrain data is:

[0024]

[0025] The second terrain data is:

[0026]

[0027] The terrain conversion data is:

[0028]

[0029] Where, (x1, y1, z1) is the first terrain data; is the radius of the umbozone of the earth ellipsoid; is the first eccentricity of the ellipsoid; Latitude longitude The elevation value at the location; (x2, y2, z2) is the second terrain data; is the longitude of the radar station; is the latitude of the radar station; (x0, y0, z0) is the geocentric rectangular coordinate of the radar station; ( , , ) is terrain conversion data; Latitude longitude Elevation The azimuth at Latitude longitude Elevation The pitch angle at Latitude longitude Elevation The radial distance at .

[0030] In some possible implementations, determining the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix includes:

[0031] Determine the clutter backscatter coefficient of the nth range sampling point of the mth azimuth line;

[0032] Determine the area of ​​the clutter scattering unit region of the nth distance sampling point of the mth azimuth line;

[0033] The clutter scattering cross-sectional area is determined according to the clutter backscattering coefficient and the area of ​​the clutter scattering unit region.

[0034] In some possible implementations, determining the clutter scattering unit region area of ​​the nth range sampling point of the mth azimuth line includes:

[0035] Step 1, determine the maximum pitch angle and its position index value in the mth azimuth line;

[0036] Step 2: determine whether the position index value is greater than or equal to 2. If not, determine the area of ​​the first distance sampling point in the mth azimuth line and the elevation angle of the first distance sampling point, and the area of ​​the first distance sampling point is the area of ​​the clutter scattering unit. If yes, proceed to step 3.

[0037] Step 3: determining a pitch angle difference between the nth distance sampling point and the first distance sampling point, and judging whether the pitch angle difference is greater than zero; if so, determining the area of ​​the clutter scattering unit region based on the pitch angle difference, and taking the pitch angle of the nth distance sampling point as the pitch angle of the first distance sampling point; if not, the area of ​​the clutter scattering unit region is zero;

[0038] Step 4: Set n=n+1, and determine whether n is less than or equal to the position index value. If so, return to step 3; if not, proceed to step 5;

[0039] Step 5: Set m=m+1, and determine whether m is less than or equal to a preset value. If so, return to step 1; if not, obtain the area of ​​the clutter scattering unit region.

[0040] In some possible implementations, the radar actual parameter information includes radar beam pointing and lobe width, and the clutter area includes an azimuth line interval and a range ring interval; the azimuth line interval is:

[0041]

[0042] The distance ring interval is:

[0043]

[0044] In the formula, is the interval of the bearing line; is the azimuth sampling accuracy; For radar beam pointing; is the lobe width; is the symbol for the rounding up operation; is the minimum bearing line number; is the maximum azimuth line number; is the distance ring interval; is the distance sampling accuracy; is the shortest radial distance between the clutter area and the radar; is the maximum radial distance from the clutter area to the radar; is the minimum distance sampling point number; is the maximum distance sampling point number.

[0045] In a specific embodiment of the present invention, it is set =5km, =300km, =50m, = 0.1, then the azimuth interval , the distance ring interval corresponding to each azimuth line is .

[0046] In some possible implementations, the single-beam clutter power is:

[0047]

[0048] In the formula, is the single beam clutter power; The radar transmits signal power; For the Line of bearing The antenna transmission gain at the sampling point is For the Line of bearing The antenna receiving gain at the sampling point is is the radar operating wavelength; For the Line of bearing The clutter scattering cross-sectional area at the sampling point; is the maximum value of the longitude sequence of the target area; is the maximum value of the latitude sequence of the target area; is the total number of pulses with the horizontal pointing angle of the beam.

[0049] In some possible implementations, the radar actual parameter information includes a beam incidence angle; and selecting a clutter probability distribution model according to the radar actual parameter information includes:

[0050] When the radar is a low-resolution radar and the beam incidence angle is greater than or equal to the beam preset angle, the clutter probability distribution model is a Rayleigh distribution model;

[0051] When the radar is a high-resolution radar and the beam incident angle is less than the beam preset angle, the clutter probability distribution model is any one of a log-normal distribution model, a Weibull distribution model or a K distribution model.

[0052] On the other hand, the present invention also provides a ground clutter simulation device based on digital elevation model data, comprising:

[0053] A terrain data extraction unit, used to obtain radar actual parameter information and digital elevation model data, and extract terrain data of a target area from the digital elevation model data based on the radar actual parameter information;

[0054] A terrain data conversion unit, used to convert the terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system, and obtain terrain conversion data in the radar station polar coordinate system, wherein the terrain conversion data includes an azimuth and an elevation angle;

[0055] A pitch angle matrix determination unit, configured to perform omnidirectional sampling on the target area according to a preset azimuth sampling accuracy and a preset distance sampling accuracy, obtain a plurality of azimuth lines and a plurality of distance sampling points on each azimuth line, and sort and reorganize the pitch angles according to the plurality of azimuth lines and the plurality of distance sampling points to obtain a pitch angle matrix;

[0056] a clutter scattering cross-sectional area determination unit, configured to determine the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix;

[0057] A single-beam illumination clutter area determination unit, used to determine the single-beam illumination clutter area according to the radar actual parameter information;

[0058] A single-beam clutter power determination unit, configured to determine the single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area;

[0059] A clutter-related random sequence generating unit, used for selecting a clutter probability distribution model according to the radar actual parameter information, and generating a clutter-related random sequence according to the clutter probability distribution model;

[0060] A ground clutter data generating unit is used to generate ground clutter data according to the radar actual parameter information, the single-beam clutter power and the clutter-related random sequence.

[0061] The beneficial effect of adopting the above embodiment is that the ground clutter simulation method based on digital elevation model data provided by the present invention extracts terrain data of the target area from the data elevation model data based on radar actual parameter information, and can simulate ground clutter based on digital elevation model data, taking into account the ups and downs of the ground, thereby improving the degree of consistency between the simulated ground clutter and the ground clutter in the actual scene, and providing strong support for the debugging of the radar system and the inspection of the performance and indicators of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0063] Figure 1 A schematic flow chart of an embodiment of a method for simulating ground clutter based on digital elevation model data provided by the present invention;

[0064] Figure 2 For the present invention Figure 1 A schematic flow chart of an embodiment of S101;

[0065] Figure 3 For the present invention Figure 1 A schematic flow chart of an embodiment of S102;

[0066] Figure 4 For the present invention Figure 1 A schematic flow chart of an embodiment of S104;

[0067] Figure 5 For the present invention Figure 4 A schematic flow chart of an embodiment of S402;

[0068] Figure 6 For the present invention Figure 1 A schematic flow chart of an embodiment of S107;

[0069] Figure 7 The present invention provides a schematic structural diagram of an embodiment of a ground clutter simulation device based on digital elevation model data. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0071] It should be understood that the schematic drawings are not drawn to scale. The flow chart used in the present invention shows the operations implemented according to some embodiments of the present invention. It should be understood that the operations of the flow chart can be implemented out of order, and the steps without logical context can be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flow chart under the guidance of the content of the present invention, and can also remove one or more operations from the flow chart.

[0072] Some of the block diagrams shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor systems and / or microcontroller systems.

[0073] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0074] The embodiments of the present invention provide a method and device for simulating ground clutter based on digital elevation model data, which are described below respectively.

[0075] Figure 1 A schematic flow chart of an embodiment of a method for simulating ground clutter based on digital elevation model data provided by the present invention is shown in FIG. Figure 1 As shown in FIG. 1 , the ground clutter simulation method based on digital elevation model data includes:

[0076] S101, obtaining radar actual parameter information and digital elevation model (DEM) data, and extracting terrain data of the target area from the digital elevation model data based on the radar actual parameter information;

[0077] S102, converting terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system, where the terrain conversion data includes an azimuth and an elevation angle;

[0078] S103, performing omnidirectional sampling of the target area according to a preset azimuth sampling accuracy and a preset distance sampling accuracy, obtaining a plurality of azimuth lines and a plurality of distance sampling points on each azimuth line, and sorting and reorganizing the pitch angles according to the plurality of azimuth lines and the plurality of distance sampling points, to obtain a pitch angle matrix;

[0079] S104, determining the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix;

[0080] S105, determining a single-beam illumination clutter area according to radar actual parameter information;

[0081] S106, determining the single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area;

[0082] S107, selecting a clutter probability distribution model according to radar actual parameter information, and generating a clutter-related random sequence according to the clutter probability distribution model;

[0083] S108. Generate ground clutter data according to radar actual parameter information, single-beam clutter power, and clutter-related random sequences.

[0084] Compared with the prior art, the ground clutter simulation method based on digital elevation model data provided by the embodiment of the present invention extracts terrain data of the target area from the data elevation model data based on radar actual parameter information, and can simulate ground clutter based on digital elevation model data, taking into account the ups and downs of the ground, thereby improving the degree of consistency between the simulated ground clutter and the ground clutter in the actual scene, and providing strong support for the debugging of the radar system and the inspection of the performance and indicators of the whole machine.

[0085] In a specific embodiment of the present invention, the digital elevation model data is a square grid, each grid represents 1 degree of longitude and 1 degree of latitude, and the dimension size is , , are the latitude and longitude resolution intervals respectively.

[0086] In some embodiments of the present invention, the radar parameter information includes the longitude, latitude and elevation of the radar station. Figure 2 As shown, step S101 includes:

[0087] S201, obtaining radar detection power value;

[0088] S202, determining the latitude sequence and longitude sequence of the target area according to the radar detection power value, the longitude of the radar station, the latitude of the radar station, and the altitude value of the radar station;

[0089] S203: extracting terrain data of the target area from the digital elevation model data according to the latitude sequence and the longitude sequence.

[0090] In a specific embodiment of the present invention, the latitude of the target area is a degrees, and the longitude is b degrees, that is, the latitude sequence is:

[0091]

[0092] The longitude sequence is:

[0093]

[0094] The terrain data extracted from the digital elevation model data is:

[0095]

[0096] In the formula, is the latitude value matrix; is the longitude value matrix; is the elevation value matrix; Latitude longitude The elevation value at the location.

[0097] In some embodiments of the present invention, Figure 3 As shown, step S102 includes:

[0098] S301, converting terrain data from a geocentric geodetic coordinate system to a geocentric rectangular coordinate system to obtain first terrain data in the geocentric rectangular coordinate system;

[0099] S302, converting the first terrain data from the geocentric rectangular coordinate system to the radar station rectangular coordinate system to obtain second terrain data in the radar station rectangular coordinate system;

[0100] S303: Convert the second terrain data from the radar station rectangular coordinate system to the radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system.

[0101] In a specific embodiment of the present invention, the first terrain data is:

[0102]

[0103] in,

[0104]

[0105] The second terrain data is:

[0106]

[0107] The terrain conversion data is:

[0108]

[0109] Where, (x1, y1, z1) is the first terrain data; is the radius of the umbozone of the earth ellipsoid; is the first eccentricity of the ellipsoid; Latitude longitude The elevation value at the location; (x2, y2, z2) is the second terrain data; Radar station longitude; is the latitude of the radar station; (x0, y0, z0) is the geocentric rectangular coordinate of the radar station; ( , , ) is terrain conversion data; Latitude longitude Elevation The azimuth at Latitude longitude Elevation The pitch angle at Latitude longitude Elevation The radial distance at is the major radius of the ellipsoid; is the minor radius of the ellipsoid.

[0110] The terrain transformation data matrix form is:

[0111]

[0112] It should be noted that if the azimuth , then correct the azimuth, and the other azimuth .

[0113] In some embodiments of the present invention, the all-round sampling of the target area in step S103 is specifically as follows: first, the target area is sampled according to a preset azimuth sampling accuracy to divide it into multiple azimuth lines; secondly, distance sampling is performed on each azimuth line at a distance according to a preset distance sampling accuracy to obtain multiple distance sampling points.

[0114] Among them, the azimuth is divided into , the distance direction is divided into , is the maximum pitch angle.

[0115] In some embodiments of the present invention, in step S103, the pitch angles are sorted and reorganized to obtain a pitch angle matrix, specifically:

[0116] For Azimuth lines with an angle interval of , first find the index value of the terrain data in its area:

[0117]

[0118] The above formula means finding the azimuth matrix Satisfied The angle of the line row and column col If the line row or Column col is an empty matrix, ; If the line row or Column col Is a non-empty matrix, extract the slope distance of the current azimuth line terrain data , Pitch angle , and then find the Distance sampling point area The terrain data index value in:

[0119]

[0120] If the line row1 and column col1 is an empty matrix, ;otherwise, ,in Indicates that when there are multiple terrain data in the sampling point area, the maximum elevation angle value is taken.

[0121] Repeat the above process, and finally get the elevation angle matrix after terrain data reorganization .

[0122] in, is the azimuth sampling accuracy; is the distance sampling accuracy.

[0123] In some embodiments of the present invention, Figure 4 As shown, step S104 includes:

[0124] S401, determining the clutter backscattering coefficient of the nth range sampling point of the mth azimuth line;

[0125] S402, determining the area of ​​the clutter scattering unit region of the nth distance sampling point of the mth azimuth line;

[0126] S403: Determine a clutter scattering cross-sectional area according to the clutter backscattering coefficient and the clutter scattering unit area.

[0127] Among them, the clutter scattering cross-sectional area is:

[0128]

[0129] In the formula, is the clutter scattering cross-sectional area; is the clutter backscatter coefficient; is the area of ​​the clutter scattering unit.

[0130] In a specific embodiment of the present invention, the clutter backscatter coefficient of the nth range sampling point of the mth azimuth line is for:

[0131]

[0132] Where: To take the logarithm with base 10; is the pitch angle of the nth distance sampling point of the mth azimuth line in the pitch angle matrix; is the radar operating frequency, in GHz; A1, A2, and A3 vary with the ground type of the target area. For example, the values ​​for cement ground are -49, 32, and 20, respectively; and the values ​​for grass with a height of less than 0.5m are -21, 10, and 63, respectively.

[0133] In some embodiments of the present invention, Figure 5 As shown, step S402 includes:

[0134] S501, determining the maximum pitch angle and position index value in the mth azimuth line;

[0135] S502, determine whether the position index value is greater than or equal to 2, if not, determine the area of ​​the first distance sampling point in the mth azimuth line and the pitch angle of the first distance sampling point, and the area of ​​the first distance sampling point is the area of ​​the clutter scattering unit, if yes, proceed to step S503;

[0136] S503, determining the pitch angle difference between the nth distance sampling point and the first distance sampling point, and judging whether the pitch angle difference is greater than zero, if so, determining the area of ​​the clutter scattering unit region based on the pitch angle difference, and taking the pitch angle of the nth distance sampling point as the pitch angle of the first distance sampling point; if not, the area of ​​the clutter scattering unit region is zero;

[0137] S504, set n=n+1, and determine whether n is less than or equal to the position index value, if so, return to step S503, if not, proceed to step S505;

[0138] S505, set m=m+1, and determine whether m is less than or equal to a preset value, if so, return to step S501, if not, obtain the area of ​​the clutter scattering unit region.

[0139] Among them, the area of ​​the first distance sampling point in the mth azimuth line is:

[0140]

[0141] The pitch angle of the first distance sampling point is:

[0142]

[0143] The pitch angle difference is:

[0144]

[0145] The area of ​​the clutter scattering unit is:

[0146]

[0147] The area of ​​the clutter scattering unit region can be obtained by looping through steps S501-S505.

[0148] When the radar transmits a beam to radiate the space environment, the area illuminated by the beam is the clutter area. The simulation mainly processes the space area illuminated by the main lobe beam. For a certain wave position of the radar, the number of transmitted pulses is K, the maximum number of distance units in the receiving area is N, and the clutter data received is a matrix with a dimension of K×N.

[0149] That is, in some embodiments of the present invention, the radar parameter information includes the radar beam pointing and the lobe width, and the clutter area includes the azimuth line interval and the range ring interval; the azimuth line interval is:

[0150]

[0151] The distance ring interval is:

[0152]

[0153] In the formula, is the interval of the bearing line; is the azimuth sampling accuracy; For radar beam pointing; is the lobe width; is the symbol for the rounding up operation; is the minimum bearing line number; is the maximum azimuth line number; is the distance ring interval; is the distance sampling accuracy; is the shortest radial distance between the clutter area and the radar; is the maximum radial distance from the clutter area to the radar; is the minimum distance sampling point number; is the maximum distance sampling point number.

[0154] The distance sampling points correspond to the pitch angle values ​​one by one. The distance sampling points correspond to the pitch angle .

[0155] In some embodiments of the present invention, the single beam clutter power is:

[0156]

[0157] In the formula, is the single beam clutter power; The radar transmits signal power; For the Line of bearing The antenna transmission gain at the sampling point is For the Line of bearing The antenna receiving gain at the sampling point is is the radar operating wavelength; For the Line of bearing The clutter scattering cross-sectional area at the sampling point; is the maximum value of the longitude sequence of the target area; is the maximum value of the latitude sequence of the target area; is the total number of pulses with the horizontal pointing angle of the beam.

[0158] In order to further improve the consistency between the simulated ground clutter and the ground clutter in the actual scene, in some embodiments of the present invention, the radar actual parameter information includes the beam incidence angle. Figure 6 As shown, step S107 includes:

[0159] S601. When the radar is a low-resolution radar and the beam incident angle is greater than or equal to the beam preset angle, the clutter probability distribution model is a Rayleigh distribution model;

[0160] S602: When the radar is a high-resolution radar and the beam incident angle is less than the beam preset angle, the clutter probability distribution model is any one of a lognormal distribution model, a Weibull distribution model, or a K distribution model.

[0161] The embodiment of the present invention can further improve the degree of consistency between the simulated ground clutter and the actual ground clutter by selecting a clutter probability distribution model according to the resolution and beam incidence of the radar.

[0162] It should be understood that the beam preset angle can be adjusted or set according to actual conditions or experience. In a specific embodiment of the present invention, the beam preset angle is 5°.

[0163] When the clutter probability distribution model is a Rayleigh distribution model, the clutter-related random sequence generated in step S107 is specifically:

[0164] ① Generate obedience Mutually independent Gaussian white noise sequences and ;

[0165] ② The two sequences are respectively The linear filter (the filter is designed by Fourier series expansion method) is filtered to obtain and ;

[0166] ③Calculation , ,in is the Rayleigh parameter;

[0167] ④Nonlinear transformation of filtering results , that is, the amplitude follows the Rayleigh distribution, and the power spectrum follows the Gaussian distribution. Clutter-correlated random sequence .

[0168] When the clutter probability distribution model is a Weibull distribution model, the clutter-related random sequence generated in step S107 is specifically:

[0169] ① Generate independent Gaussian distributions Two random variables and ;

[0170] ② The two sequences are respectively The linear filter is filtered to obtain and ;

[0171] ③Calculate the standard deviation of clutter ,renew , ,in and is the Weibull parameter;

[0172] ④Nonlinear transformation of filtering results , that is, the amplitude follows the Weibull distribution, and the power spectrum follows the Gaussian distribution. Clutter-correlated random sequence .

[0173] When the clutter probability distribution model is a log-normal distribution model, the clutter-related random sequence generated in step S107 is specifically:

[0174] ①Generate Gaussian distribution A random variable ;

[0175] ②Sequence Sutra The linear filter is filtered to obtain ;

[0176] ③The filtering results are linearly transformed to obtain a normal distribution A random variable , is the mean parameter, is the variance parameter;

[0177] ④ Random variables Perform nonlinear transformation , that is, the amplitude follows the log-normal distribution, and the power spectrum follows the Gaussian distribution. Clutter-correlated random sequence .

[0178] When the clutter probability distribution model is a K distribution model, the clutter-related random sequence generated in step S107 is specifically:

[0179] ① Generate two independent sets of Gaussian distributions A random variable , and , ;

[0180] ② Random variables , through The linear filter is filtered to obtain , ,random variable , through The linear filter is filtered to obtain , ;

[0181] ③The filtering result undergoes nonlinear transformation , that is, the amplitude follows the K distribution, and the length of the power spectrum following the Gaussian distribution is Clutter-correlated random sequence .

[0182] In some embodiments of the present invention, step S108 is specifically:

[0183] The radar transmits the signal in step S101 Perform power modulation, Doppler spectrum modulation, and delay modulation to ultimately generate clutter data received by a certain radar beam , specifically:

[0184]

[0185] In the formula, ; To perform convolution operation; The first radar The delay time of the first pulse relative to the first pulse is , For the The repetition period of a pulse.

[0186] In summary, the ground clutter simulation method based on digital elevation model data proposed in the embodiment of the present invention uses digital elevation model data to model the ground clutter of the ground-based radar system, considers the ups and downs of the ground, makes an occlusion judgment on each distance sampling point, and calculates the radar echo of each sampling unit based on the actual parameter information, and finally obtains the total radar ground clutter, realizes the calculation of the time domain amplitude echo data of the ground clutter of the entire ground, and the calculated ground clutter data satisfies a certain clutter probability distribution and the actual radar parameter characteristics at the same time. Under the premise of ensuring the amount of calculation and the performance of use, this method further enhances the degree of consistency between the simulated clutter data and the clutter data in the real scene compared with the traditional ground clutter simulation method, and at the same time enhances the effectiveness and position adaptability of the simulated training equipment, and also provides strong support for the debugging of the radar system and the inspection of the whole machine performance and indicators.

[0187] In order to better implement the ground clutter simulation method based on digital elevation model data in the embodiment of the present invention, on the basis of the ground clutter simulation method based on digital elevation model data, the embodiment of the present invention also provides a ground clutter simulation device based on digital elevation model data, such as Figure 7 As shown, the ground clutter simulation device 700 based on digital elevation model data includes:

[0188] A terrain data extraction unit 701 is used to obtain radar actual parameter information and digital elevation model data, and extract terrain data of a target area from the digital elevation model data based on the radar actual parameter information;

[0189] A terrain data conversion unit 702 is used to convert terrain data from a geocentric geodetic coordinate system to a radar station polar coordinate system, and obtain terrain conversion data in the radar station polar coordinate system, where the terrain conversion data includes an azimuth and an elevation angle;

[0190] The pitch angle matrix determination unit 703 is used to perform omnidirectional sampling on the target area according to a preset azimuth sampling accuracy and a preset distance sampling accuracy, obtain multiple azimuth lines and multiple distance sampling points on each azimuth line, and sort and reorganize the pitch angles according to the multiple azimuth lines and the multiple distance sampling points to obtain a pitch angle matrix;

[0191] A clutter scattering cross-sectional area determination unit 704, configured to determine the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix;

[0192] A single beam illumination clutter region determining unit 705 is used to determine the single beam illumination clutter region according to radar actual parameter information;

[0193] A single-beam clutter power determination unit 706, configured to determine the single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area;

[0194] A clutter-related random sequence generating unit 707 is used to select a clutter probability distribution model according to radar actual parameter information, and generate a clutter-related random sequence according to the clutter probability distribution model;

[0195] The ground clutter data generating unit 708 is used to generate ground clutter data according to radar actual parameter information, single beam clutter power and clutter related random sequence.

[0196] The ground clutter simulation device 700 based on digital elevation model data provided in the above embodiment can implement the technical solution described in the above embodiment of the ground clutter simulation method based on digital elevation model data. The specific implementation principles of the above modules or units can refer to the corresponding contents in the above embodiment of the ground clutter simulation method based on digital elevation model data, which will not be repeated here.

[0197] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware (such as a processor, a controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0198] The ground clutter simulation method and device based on digital elevation model data provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A ground clutter simulation method based on digital elevation model data, characterized in that: include: Acquire radar actual parameter information and digital elevation model data, and extract terrain data of the target area from the digital elevation model data based on the radar actual parameter information; Convert the terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system, wherein the terrain conversion data includes an azimuth and an elevation angle; The target area is sampled in all directions according to a preset azimuth sampling accuracy and a preset distance sampling accuracy to obtain a plurality of azimuth lines and a plurality of distance sampling points on each azimuth line, and the pitch angles are sorted and reorganized according to the plurality of azimuth lines and the plurality of distance sampling points to obtain a pitch angle matrix; Determine the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix; Determine a single-beam illumination clutter area according to the radar actual parameter information; Determining single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area; Selecting a clutter probability distribution model according to the radar actual parameter information, and generating a clutter-related random sequence according to the clutter probability distribution model; The ground clutter data is generated according to the radar actual parameter information, the single-beam clutter power and the clutter-related random sequence.

2. The method for simulating ground clutter based on digital elevation model data according to claim 1, characterized in that: The radar actual parameter information includes the longitude, latitude and elevation of the radar station; and extracting the terrain data of the target area from the digital elevation model data based on the radar actual parameter information includes: Get the radar detection power value; Determine the latitude sequence and longitude sequence of the target area according to the radar detection power value, the longitude of the radar station, the latitude of the radar station and the altitude value of the radar station; The terrain data of the target area is extracted from the digital elevation model data according to the latitude sequence and the longitude sequence.

3. The method for simulating ground clutter based on digital elevation model data according to claim 2, characterized in that: Converting the terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system to obtain terrain conversion data in the radar station polar coordinate system; Converting the terrain data from the geocentric geodetic coordinate system to the geocentric rectangular coordinate system to obtain first terrain data in the geocentric rectangular coordinate system; Converting the first terrain data from the geocentric rectangular coordinate system to the radar station rectangular coordinate system to obtain second terrain data in the radar station rectangular coordinate system; The second terrain data is converted from the radar station rectangular coordinate system to the radar station polar coordinate system to obtain the terrain conversion data in the radar station polar coordinate system.

4. The method for simulating ground clutter based on digital elevation model data according to claim 3, characterized in that: The first terrain data is: The second terrain data is: The terrain conversion data is: Where, (x1, y1, z1) is the first terrain data; is the radius of the umbozone of the earth ellipsoid; is the first eccentricity of the ellipsoid; Latitude longitude The elevation value at the location; (x2, y2, z2) is the second terrain data; is the longitude of the radar station; is the latitude of the radar station; (x0, y0, z0) is the geocentric rectangular coordinate of the radar station; ( , , ) is terrain conversion data; Latitude longitude Elevation The azimuth at Latitude longitude Elevation The pitch angle at Latitude longitude Elevation The radial distance at .

5. The method for simulating ground clutter based on digital elevation model data according to claim 1, characterized in that: The determining the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix includes: Determine the clutter backscatter coefficient of the nth range sampling point of the mth azimuth line; Determine the area of ​​the clutter scattering unit region of the nth distance sampling point of the mth azimuth line; The clutter scattering cross-sectional area is determined according to the clutter backscattering coefficient and the area of ​​the clutter scattering unit region.

6. The method for simulating ground clutter based on digital elevation model data according to claim 5, characterized in that: The determining of the clutter scattering unit area of ​​the nth distance sampling point of the mth azimuth line includes: Step 1, determine the maximum pitch angle and its position index value in the mth azimuth line; Step 2: determine whether the position index value is greater than or equal to 2. If not, determine the area of ​​the first distance sampling point in the mth azimuth line and the elevation angle of the first distance sampling point, and the area of ​​the first distance sampling point is the area of ​​the clutter scattering unit. If yes, proceed to step 3. Step 3: determining a pitch angle difference between the nth distance sampling point and the first distance sampling point, and judging whether the pitch angle difference is greater than zero; if so, determining the area of ​​the clutter scattering unit region based on the pitch angle difference, and taking the pitch angle of the nth distance sampling point as the pitch angle of the first distance sampling point; if not, the area of ​​the clutter scattering unit region is zero; Step 4: Set n=n+1, and determine whether n is less than or equal to the position index value. If so, return to step 3; if not, proceed to step 5; Step 5: Set m=m+1, and determine whether m is less than or equal to a preset value. If so, return to step 1; if not, obtain the area of ​​the clutter scattering unit region.

7. The method for simulating ground clutter based on digital elevation model data according to claim 1, characterized in that: The radar actual parameter information includes radar beam pointing and lobe width, and the clutter area includes azimuth line interval and range ring interval; the azimuth line interval is: The distance ring interval is: In the formula, is the interval of the bearing line; is the azimuth sampling accuracy; For radar beam pointing; is the lobe width; is the symbol for the rounding up operation; is the minimum bearing line number; is the maximum azimuth line number; is the distance ring interval; is the distance sampling accuracy; is the shortest radial distance between the clutter area and the radar; is the maximum radial distance from the clutter area to the radar; is the minimum distance sampling point number; is the maximum distance sampling point number.

8. The method for simulating ground clutter based on digital elevation model data according to claim 7, characterized in that: The single beam clutter power is: In the formula, is the single beam clutter power; The radar transmit signal power; For the Line of bearing The antenna transmission gain at the sampling point is For the Line of bearing The antenna receiving gain at the sampling point is is the radar operating wavelength; For the Line of bearing The clutter scattering cross-sectional area at the sampling point; is the maximum value of the longitude sequence of the target area; is the maximum value of the latitude sequence of the target area; is the total number of pulses with the horizontal pointing angle of the beam.

9. The method for simulating ground clutter based on digital elevation model data according to claim 1, characterized in that: The radar actual parameter information includes a beam incidence angle; and selecting a clutter probability distribution model according to the radar actual parameter information includes: When the radar is a low-resolution radar and the beam incidence angle is greater than or equal to the beam preset angle, the clutter probability distribution model is a Rayleigh distribution model; When the radar is a high-resolution radar and the beam incident angle is less than the beam preset angle, the clutter probability distribution model is any one of a log-normal distribution model, a Weibull distribution model or a K distribution model.

10. A ground clutter simulation device based on digital elevation model data, characterized in that: include: A terrain data extraction unit, used to obtain radar actual parameter information and digital elevation model data, and extract terrain data of a target area from the digital elevation model data based on the radar actual parameter information; A terrain data conversion unit, used to convert the terrain data from the geocentric geodetic coordinate system to the radar station polar coordinate system, and obtain terrain conversion data in the radar station polar coordinate system, wherein the terrain conversion data includes an azimuth and an elevation angle; A pitch angle matrix determination unit, configured to perform omnidirectional sampling on the target area according to a preset azimuth sampling accuracy and a preset distance sampling accuracy, obtain a plurality of azimuth lines and a plurality of distance sampling points on each azimuth line, and sort and reorganize the pitch angles according to the plurality of azimuth lines and the plurality of distance sampling points to obtain a pitch angle matrix; a clutter scattering cross-sectional area determination unit, configured to determine the clutter scattering cross-sectional area of ​​the target area according to the pitch angle matrix; A single-beam illumination clutter area determination unit, used to determine the single-beam illumination clutter area according to the radar actual parameter information; A single-beam clutter power determination unit, configured to determine the single-beam clutter power based on the clutter scattering cross-sectional area and the single-beam irradiated clutter area; A clutter-related random sequence generating unit, used for selecting a clutter probability distribution model according to the radar actual parameter information, and generating a clutter-related random sequence according to the clutter probability distribution model; A ground clutter data generating unit is used to generate ground clutter data according to the radar actual parameter information, the single-beam clutter power and the clutter-related random sequence.

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