A target positioning method based on frustum-conical conformal phased array

Abstract

The present invention discloses a target positioning method based on a frustum conformal phased array, which belongs to the field of radar technology and solves the problem that the existing technology cannot detect and position targets based on frustum conformal phased arrays with high precision. The method includes: step 1, dividing the frustum conformal phased array into sub-arrays along the circumferential sectors and upper and lower frustums and numbering them; step 2, extracting the current frustum phased array beam pointing angle and performing phase calculation; step 3, identifying the occlusion of the antenna unit; step 5, selecting the difference beam synthesis mode to be entered based on the beam pointing off-axis angle θ and the forward / side scanning mode threshold angle θ'; step 6, performing target detection; step 7, extracting the target distance; step 8, extracting the target angle. The present invention realizes high-precision detection and positioning of targets using a frustum conformal phased array.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a target positioning method based on a frustum-conical conformal phased array. Background Art

[0002] Since the beginning of the new century, aircraft platforms have increasingly adopted specialized structural features to meet aerodynamic performance requirements. Furthermore, achieving multifunctional electronic platforms has necessitated the integrated design of antenna systems within the aircraft. Conventional planar antenna systems, due to structural and performance limitations, have proven inadequate to meet these development needs. Conformal phased array technology has gained increasing attention as a key solution.

[0003] The cone is a typical example of a conformal shape, and its key beamforming technologies are highly compatible with other conformal shapes. Conformal phased arrays based on frustum surfaces can simultaneously achieve wide-angle scanning and forward detection capabilities.

[0004] Sum-difference monopulse angle measurement is one of the primary methods for radar angle measurement. Its basic principle is to process received radar target echoes, construct sum and difference path patterns, and generate sum and difference echo information. Using the differences in target echo information between the sum and difference paths, a specific algorithm model is used to extract the target's deviation from the beam pointing axis, thereby determining the target angle.

[0005] On conformal surfaces, the different positions of antenna elements lead to inconsistent pointing directions. Furthermore, wide-angle scanning can create structural obstructions during beam scanning. Using only a fixed sum-and-difference beamforming network cannot meet beamforming requirements and may even prevent the formation of a difference pattern. Therefore, to meet the requirements of single-pulse angle measurement using a conformal phased array, it is necessary to dynamically select and combine the subarrays during beam switching to form the conformal phased array's sum-and-difference beams. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a target positioning method based on a frustum-conical conformal phased array to solve the technical problem that the existing technology cannot perform high-precision detection and positioning of the target based on the frustum-conical conformal phased array.

[0007] The purpose of the present invention is mainly achieved through the following technical solutions:

[0008] The present invention provides a target positioning method based on a frustum-conical conformal phased array, comprising the following steps:

[0009] Step 1: Based on the structural characteristics of the frustum-shaped conformal phased array, the sub-arrays are divided along the circumference into sectors and upper and lower frustums and numbered;

[0010] Step 2: Extract the current frustum phased array beam pointing angle

[0011] Step 3: Based on the shielding of the units in the beam pointing direction, the RF transceiver channels of the unshielded antenna units are opened, and the RF transceiver channels of the shielded antenna units are closed;

[0012] Step 4: The sum echo is formed by superimposing the echoes received by all sub-arrays of the frustum phased array;

[0013] Step 5: Select the difference beam synthesis mode to be entered based on the beam pointing off-axis angle θ and the forward / side scanning mode threshold angle θ';

[0014] Step 6: Perform pulse compression processing on the echo signal to detect the target;

[0015] Step 7: Extract the target distance detected in step 6;

[0016] Step 8: Obtain the target angle according to the extracted target distance and extract it.

[0017] Furthermore, in step 6, the position Np of the target point in the processed data of the Helu pulse pressure is obtained relative to the starting point by a constant false alarm detection method.

[0018] Furthermore, in step 7, the target distance is obtained by the following formula:

[0019]

[0020] where R gate is the distance to the front edge of the echo gate;

[0021] C is the speed of light;

[0022] t s is the echo sampling interval;

[0023] Np is the target point obtained by target detection.

[0024] Furthermore, in step 8, the target angle extraction process is as follows: according to the target point Np obtained by target detection, the value at the target point Np is extracted from the pulse compression processed data of the road, the pitch difference pulse compression processed data, and the azimuth difference pulse compression processed data, and the angle error value is obtained by the following formula:

[0025]

[0026]

[0027] Wherein, PhiErr / ThetaErr: azimuth error / pitch angle error;

[0028] The value of the target point position in the data after azimuth difference pulse pressure processing / the value of the target point position in the data after pitch difference pulse pressure processing;

[0029] ∑ point : The value at the target point in the data after sum-path difference pulse pressure processing.

[0030] The target azimuth angle PhiAngle and pitch angle ThetaAngle are calculated as follows: PhiAngle = PhiBoshu + (PhiErr × PhiERROR_ADJUST_k + PhiERROR_ADJUST_b) ThetaAngle = ThetaBoshu + (ThetaErr × ThetaERROR_ADJUST_k + ThetaERROR_ADJUST_b)

[0031] Where, PhiBoshu / ThetaBoshu: azimuth / elevation angle of the radar beam;

[0032] PhiErr / ThetaErr: azimuth error / elevation error;

[0033] PhiERROR_ADJUST_k / ThetaERROR_ADJUST_k: azimuth error adjustment coefficient k / pitch error adjustment coefficient k;

[0034] PhiERROR_ADJUST_b / ThetaERROR_ADJUST_b: Azimuth error adjustment coefficient b / Pitch error adjustment coefficient b.

[0035] Furthermore, in step 2, the frustum conformal phased array beam pointing description adopts the right-hand coordinate form. The frustum conformal phased array beam pointing off-axis angle θ is the angle between the beam pointing direction vector and the z-axis. The value increases with the increase of the angle with the z-axis, and the value range is [0°, 180°].

[0036] Furthermore, in step 2, the frustum conformal phased array beam points to an azimuth angle It is the angle between the projection vector of the beam pointing direction vector on the xoy plane and the x-axis. It increases in the counterclockwise direction and has a value range of [-180°, 180°].

[0037] Furthermore, in step 3, the shielding condition of antenna element n is represented by the normal unit vector of element n and the beam pointing unit vector The inner product of Decide if Then the antenna unit n is not blocked; if Then antenna unit n is blocked;

[0038] where θ L is the switching threshold angle of a single antenna element, and its selected value is determined by the amplitude of the antenna unit pattern in the direction deviating from the normal direction.

[0039] Furthermore, in step 5, the selection of the threshold angle θ' is determined by the ratio of the number of occluded elements of the frustum conformal phased array;

[0040] When the beam pointing off-axis angle θ is less than the threshold angle θ', more than half of the elements are not blocked. When differential beamforming is performed on the entire array by sector, there will be no situation where differential beam formation cannot be achieved, and the process enters the forward scanning mode.

[0041] When the beam pointing off-axis angle θ is greater than the threshold angle θ', half of the sector units will be blocked. When differential beamforming is performed on the entire array by sector, the energy of the two echoes participating in the differential beam synthesis will differ greatly, and a differential beam cannot be formed, resulting in the entry into side scanning mode.

[0042] Furthermore, in step 5, if the forward scanning mode is adopted, according to the azimuth angle Determine the array schemes for synthesizing the pitch difference and azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing flow.

[0043] Furthermore, in step 5, if the side scanning mode is adopted, the elevation difference echo signal is composed of the difference between the upper and lower frustums, and the elevation difference echo signal is formed according to the azimuth angle. Determine the array schemes involved in the synthesis of azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing flow.

[0044] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0045] (1) The present invention designs the array sub-array division and superimposes the echo signals of all numbered sub-arrays (1-16) to obtain the sum echo signals of the cone-shaped conformal phased array; and dynamically adjusts the range and combination of sub-arrays participating in the sum and difference beamforming according to the direction of the radar beam, so as to always form a good array sum and difference pattern, obtain sum, elevation difference, and azimuth difference echo signals, and solve the problem of the inability to form a difference beam due to structural obstruction during the beam scanning process of the conformal phased array.

[0046] (2) The dynamic array formation method based on the frustum conformal phased array and difference beam forming provided by the present invention can realize the real-time and better formation of the frustum conformal phased array and difference beam during the beam scanning process.

[0047] (3) The present invention achieves high-precision detection and positioning of the target by the frustum conformal phased array through target detection, target distance extraction and target angle extraction.

[0048] (4) The present invention realizes that in conformal array beam synthesis, the occlusion of unit beams can be determined and the unit beams of the occluded parts can be turned off, thereby avoiding the influence of the occluded beams on the accuracy.

[0049] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the embodiments of the description and the contents particularly pointed out in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0051] Figure 1 Schematic diagram of a 384-element frustum-shaped conformal phased array with a 45° half-cone angle provided by an embodiment of the present invention;

[0052] Figure 2 yes Figure 1 The top view of the 16 sub-arrays of the frustum conformal phased array shown;

[0053] Figure 3a Schematic diagram of the polar coordinate system definition used by the frustum-shaped conformal phased array provided by the present invention;

[0054] Figure 3b The azimuth of the beam pointing of the frustum conformal phased array provided by the present invention is Define the schematic diagram;

[0055] Figure 4 This is a schematic diagram of the frustum conformal phased array and difference beamforming logic provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0057] The present invention provides a target positioning method based on a frustum-shaped conformal phased array, which specifically includes the following steps:

[0058] Step 1: Based on the structural characteristics of the frustum-shaped conformal phased array, the sub-arrays are divided along the circumference into sectors and upper and lower frustums and numbered.

[0059] Specifically, the frustum-shaped conformal phased array, or its enveloping telescopic deformable body, can be considered a rotating structure. When dividing the subarray, the circumferential sectors are divided from the projection plane perpendicular to the rotation axis, forming subarray partitions. Furthermore, the frustum-shaped conformal phased array is further divided into subregions along planes parallel to the bottom plane of the frustum. Thus, each minimum partition module constitutes a subarray of the frustum-shaped conformal phased array.

[0060] by Figure 1 Take the frustum conformal phased array shown in the figure as an example. From the perspective of its projection plane xoy perpendicular to the rotation axis z, it is evenly divided into 8 sectors along the circumferential direction, with each sector being 45°. On this basis, it is further divided into two layers of frustum along the plane parallel to the xoy plane. The upper half of the frustum forms 8 sectors, namely 1, 2, 3, 4, 5, 6, 7, and 8, and the lower half of the frustum forms 8 sectors, namely 9, 10, 11, 12, 13, 14, 15, and 16, ultimately forming 16 sub-arrays. Each sub-array is numbered as follows: Figure 2 As shown in the top view of the frustum conformal phased array, the sub-array is numbered counterclockwise starting from the sub-array closest to the x-axis on the upper frustum.

[0061] Step 2: Extract the current frustum conformal phased array beam pointing angle;

[0062] The details are as follows: The frustum conformal phased array beam pointing description is defined in the form of polar coordinate system, such as Figure 3a The coordinate system is in the right-hand coordinate form. The off-axis angle θ of the frustum conformal phased array beam pointing is the angle between the beam pointing direction vector and the z-axis. It increases with the increase of the angle with the z-axis and has a value range of [0°, 180°]. is the projection vector of the beam pointing direction vector on the xoy plane, and the angle between it and the x-axis increases with the counterclockwise direction, and the value range is [-180°, 180°]. Figure 3b shown.

[0063] Step 3: Based on the shielding conditions of the units in the beam pointing direction, the RF transceiver channels of the unshielded antenna units are opened, and the RF transceiver channels of the shielded antenna units are closed.

[0064] Specifically, antenna elements are attached to the surface of a pyramid. For a phased array, the on / off state of each element can be independently controlled by the TR assembly. First, based on the degree of obstruction of the element in the beam direction, the RF transmit / receive channels of the unobstructed antenna elements are opened, while those of the obstructed antenna elements are closed.

[0065] The occlusion of antenna element n can be determined by the normal unit vector of antenna element n and the beam pointing unit vector The inner product of Decision. If Then the antenna unit n is not blocked and its RF channel can be opened; if Then antenna unit n is blocked and its RF channel needs to be closed; where θ L is the antenna unit switching threshold angle, and its selected value is determined by the amplitude of the antenna unit radiation pattern in the direction deviating from the normal direction.

[0066] by Figure 1 Taking the frustum conformal phased array of the structure as an example, the antenna unit pattern decays sharply in the area beyond 70° away from the normal, which is considered to have no contribution to the pattern. Therefore, the unit switching threshold angle θ is L The value is 70°, and the switching state of each antenna unit is controlled accordingly.

[0067] It should be noted that the present invention adopts conformal arrangement of antenna units. Compared with the prior art, the present invention solves the problem of conformal body shielding the antenna units after the antenna units are conformally arranged.

[0068] Step 4: The sum echo is formed by superimposing the echoes received by all sub-arrays of the frustum phased array.

[0069] The details are as follows: Figure 1 Taking the frustum conformal phased array of the structure as an example, based on step 3, the echo signals of all sub-arrays numbered 1 to 16 are superimposed to obtain the frustum conformal phased array and the path echo signal.

[0070] Step 5: Compare the beam pointing off-axis angle θ with the forward / side scanning mode threshold angle θ' and select to enter the corresponding difference beam synthesis mode.

[0071] Specifically, the threshold angle θ' is determined by the proportion of obscured elements in the frustum-shaped conformal phased array. When the beam pointing off-axis angle θ is less than the threshold angle θ', most elements are not obscured. When differential beamforming is performed on a sector-by-sector basis across the entire array, there is no failure to form a differential beam, and the process enters forward scanning mode. When the beam pointing off-axis angle θ is greater than the threshold angle θ', half of the sector elements are obscured. When differential beamforming is performed on a sector-by-sector basis across the entire array, the energy of the two echoes participating in differential beamforming differs significantly, making differential beam formation impossible and the process enters side scanning mode.

[0072] by Figure 1 Taking the frustum-shaped conformal phased array shown in FIG. 1 as an example, the threshold angle θ′ is 30°, which is an empirical value.

[0073] If the forward scanning mode is used, according to the azimuth Determine the array schemes for synthesizing the pitch difference and azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing flow.

[0074] Specifically: in the forward scanning mode, looking from the projection plane xoy of the frustum conformal phased array perpendicular to the rotation axis z, the angle of the projection of each sector sub-array along the busbar boundary line on the xoy plane deviating from the x-axis is used as the boundary angle for switching the array mode. For the current azimuth satisfy Boundary angle The corresponding boundary line is the dividing line between the two groups of sub-array areas forming the azimuth difference, and the boundary line perpendicular to it is the dividing line between the two groups of sub-array areas forming the elevation difference.

[0075] by Figure 1 As an example of the structure of the frustum conformal phased array, the sub-array is divided into 8 large sectors along the circumference, and the boundary angle The possible values ​​are -135°, -90°, -45°, 0°, 45°, 90°, 135°, and 180°.

[0076] like Figure 4 As shown, the current azimuth When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (1, 2, 7, 8, 9, 10, 15, 16) sub-array and the (3, 4, 5, 6, 11, 12, 13, 14) sub-array, and the azimuth difference echo signal is formed by the difference between the (5, 6, 7, 8, 13, 14, 15, 16) sub-array and the (1, 2, 3, 4, 9, 10, 11, 12) sub-array.

[0077] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (1, 6, 7, 8, 9, 14, 15, 16) sub-array and the (2, 3, 4, 5, 10, 11, 12, 13) sub-array, and the azimuth difference echo signal is formed by the difference between the (4, 5, 6, 7, 12, 13, 14, 15) sub-array and the (1, 2, 3, 8, 9, 10, 11, 16) sub-array.

[0078] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (5, 6, 7, 8, 13, 14, 15, 16) sub-array and the (1, 2, 3, 4, 9, 10, 11, 12) sub-array, and the azimuth difference echo signal is formed by the difference between the (3, 4, 5, 6, 11, 12, 13, 14) sub-array and the (1, 2, 7, 8, 9, 10, 15, 16) sub-array.

[0079] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (4, 5, 6, 7, 12, 13, 14, 15) subarray and the (1, 2, 3, 8, 9, 10, 11, 16) subarray, and the azimuth difference echo signal is formed by the difference between the (2, 3, 4, 5, 10, 11, 12, 13) subarray and the (1, 6, 7, 8, 9, 14, 15, 16) subarray.

[0080] Current azimuth angle or When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (3, 4, 5, 6, 11, 12, 13, 14) subarray and the (1, 2, 7, 8, 9, 10, 15, 16) subarray, and the azimuth difference echo signal is formed by the difference between the (1, 2, 3, 4, 9, 10, 11, 12) subarray and the (5, 6, 7, 8, 13, 14, 15, 16) subarray.

[0081] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (2, 3, 4, 5, 10, 11, 12, 13) subarray and the (1, 6, 7, 8, 9, 14, 15, 16) subarray, and the azimuth difference echo signal is formed by the difference between the (1, 2, 3, 8, 9, 10, 11, 16) subarray and the (4, 5, 6, 7, 12, 13, 14, 15) subarray.

[0082] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (1, 2, 3, 4, 9, 10, 11, 12) sub-array and the (5, 6, 7, 8, 13, 14, 15, 16) sub-array, and the azimuth difference echo signal is formed by the difference between the (1, 2, 7, 8, 9, 10, 15, 16) sub-array and the (3, 4, 5, 6, 11, 12, 13, 14) sub-array.

[0083] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line. The corresponding boundary line is the elevation difference boundary line, so the elevation difference echo signal is formed by the difference between the (1, 2, 3, 8, 9, 10, 11, 16) subarray and the (4, 5, 6, 7, 12, 13, 14, 15) subarray, and the azimuth difference echo signal is formed by the difference between the (1, 6, 7, 8, 9, 14, 15, 16) subarray and the (2, 3, 4, 5, 10, 11, 12, 13) subarray.

[0084] If the side scanning mode is used, the pitch difference echo signal is composed of the difference between the upper and lower frustums, and ... Determine the array schemes involved in the synthesis of azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing flow.

[0085] Specifically, in the side scanning mode, the pitch difference echo is obtained by subtracting the sub-array echoes on both sides of the upper and lower frustum interface. Looking from the projection plane xoy of the frustum conformal phased array perpendicular to the rotation axis z, the angle of the projection of each sector sub-array along the busbar boundary line on the xoy plane deviating from the x-axis is used as the boundary angle for switching the array mode. For the current azimuth satisfy Boundary angle The corresponding boundary line is the dividing line between the two groups of sub-array areas that form the azimuth difference.

[0086] by Figure 1 As an example of the structure of the frustum conformal phased array, the sub-array is divided into 8 large sectors along the circumference, and the boundary angle The possible values ​​are -135°, -90°, -45°, 0°, 45°, 90°, 135°, and 180°. The upper and lower frustums are divided along the plane parallel to the xoy plane, forming a total of 16 sub-arrays.

[0087] like Figure 4 As shown, the current azimuth When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (5, 6, 7, 8, 13, 14, 15, 16) subarray and the (1, 2, 3, 4, 9, 10, 11, 12) subarray.

[0088] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (4, 5, 6, 7, 12, 13, 14, 15) subarray and the (1, 2, 3, 8, 9, 10, 11, 16) subarray.

[0089] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (3, 4, 5, 6, 11, 12, 13, 14) subarray and the (1, 2, 7, 8, 9, 10, 15, 16) subarray.

[0090] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (2, 3, 4, 5, 10, 11, 12, 13) subarray and the (1, 6, 7, 8, 9, 14, 15, 16) subarray.

[0091] Current azimuth angle or When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (1, 2, 3, 4, 9, 10, 11, 12) subarray and the (5, 6, 7, 8, 13, 14, 15, 16) subarray.

[0092] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (1, 2, 3, 8, 9, 10, 11, 16) subarray and the (4, 5, 6, 7, 12, 13, 14, 15) subarray.

[0093] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (1, 2, 7, 8, 9, 10, 15, 16) subarray and the (3, 4, 5, 6, 11, 12, 13, 14) subarray.

[0094] Current azimuth angle When selecting The corresponding boundary line is the azimuth difference boundary line, and the azimuth difference echo signal is formed by the difference between the (1, 6, 7, 8, 9, 14, 15, 16) subarray and the (2, 3, 4, 5, 10, 11, 12, 13) subarray.

[0095] Step 6: Perform pulse compression processing on the echo signal to detect the target;

[0096] For the data processed by Helu pulse pressure, the constant false alarm rate (CFAR) detection method is used to obtain the position Np of the target point relative to the starting point in the data processed by Helu pulse pressure.

[0097] Step 7: Extract the target distance detected in step 6;

[0098] The target distance can be obtained by the following formula

[0099]

[0100] where R gate is the distance to the front edge of the echo gate;

[0101] C is the speed of light;

[0102] t s is the echo sampling interval;

[0103] Np is the target point obtained by target detection.

[0104] Step 8: Obtain the target angle according to the extracted target distance and extract it.

[0105] According to the target point Np obtained by target detection, the value at the target point Np is extracted from the processed data of the pulse pressure of the road, the processed data of the pitch difference pulse pressure, and the processed data of the azimuth difference pulse pressure, and the angular error value is obtained by the following formula:

[0106]

[0107]

[0108] Wherein, PhiErr / ThetaErr: azimuth error / pitch angle error;

[0109] The value of the target point position in the data after azimuth difference pulse pressure processing / the value of the target point position in the data after pitch difference pulse pressure processing;

[0110] ∑ point : The value at the target point in the data after sum-path difference pulse pressure processing.

[0111] The target azimuth angle PhiAngle and pitch angle ThetaAngle are calculated as follows: PhiAngle = PhiBoshu + (PhiErr × PhiERROR_ADJUST_k + PhiERROR_ADJUST_b) ThetaAngle = ThetaBoshu + (ThetaErr × ThetaERROR_ADJUST_k + ThetaERROR_ADJUST_b)

[0112] Where, PhiBoshu / ThetaBoshu: azimuth / elevation angle of the radar beam;

[0113] PhiErr / ThetaErr: azimuth error / elevation error;

[0114] PhiERROR_ADJUST_k / ThetaERROR_ADJUST_k: azimuth error adjustment coefficient k / pitch error adjustment coefficient k;

[0115] PhiERROR_ADJUST_b / ThetaERROR_ADJUST_b: Azimuth error adjustment coefficient b / Pitch error adjustment coefficient b.

[0116] In existing technology, the phased array antennas used in phased array applications are primarily planar. Each element of the array antenna is mounted on the surface of a platform, conforming to the platform's shape to form a "conformal array antenna." Due to structural and performance limitations, conventional planar antenna systems are no longer able to meet development needs. Conformal phased arrays offer superior scanning beam characteristics compared to traditional planar phased arrays, including scanning range and simultaneous multi-target detection. Conformal phased arrays on a frustum can simultaneously achieve wide-angle scanning and forward detection capabilities. Sum-difference monopulse angle measurement is one of the primary methods for radar angle measurement. Its basic principle is to process received radar target echoes, construct sum and difference path patterns, and generate sum and difference echo information. Using the differences in target echo information between the sum and difference paths, a specific algorithm model is used to extract the target's deviation from the beam pointing axis, thereby determining the target angle.

[0117] On conformal surfaces, the different positions of antenna elements lead to inconsistent pointing directions. At the same time, during wide-angle scanning, there are problems such as structural obstruction during beam scanning. Using only a fixed sum and difference beamforming network cannot meet the beamforming requirements, and may even lead to the inability to form a difference pattern.

[0118] Compared with the existing technology, the present invention can always form a good array sum and difference pattern by designing its array sub-array division and dynamically adjusting the range and combination of sub-arrays participating in sum and difference beamforming in a certain logical manner according to the direction of the radar beam pointing. It can obtain sum, pitch difference, and azimuth difference echo signals, and solve the problem of the inability to form a difference beam due to structural obstruction and other problems during the beam scanning process of the conformal phased array.

[0119] Firstly, the present invention can judge the occlusion of unit beams in conformal array beam synthesis and close the unit beams of the occluded parts, thereby avoiding the influence of the occluded beam on the accuracy. In addition, the present invention improves the phase accuracy between beams through phase control by designing the array sub-array division, thereby improving the working accuracy of the phased array and obtaining a high-precision combined beam. Subsequently, the range and combination form of the sub-arrays participating in the sum and difference beamforming can be dynamically adjusted in a certain logical manner according to the pointing direction of the radar beam, so as to always form a good array sum and difference pattern, obtain sum, pitch difference, and azimuth difference echo signals, and solve the problem of the inability to form a difference beam due to structural occlusion and other problems during the beam scanning process of the conformal phased array.

[0120] By designing the array sub-array division, the present invention can dynamically select and combine the sub-arrays during the beam switching process to form the sum and difference beams of the conformal phased array, which can meet the single-pulse angle measurement requirements of the conformal phased array.

[0121] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A target positioning method based on a frustum-conical conformal phased array, characterized in that: The following steps are involved: Step 1: Based on the structural characteristics of the frustum-shaped conformal phased array, the sub-arrays are divided along the circumference into sectors and upper and lower frustums and numbered; Step 2: Extract the current frustum phased array beam pointing angle ;in, is the beam pointing off-axis angle, is the beam pointing azimuth; beam pointing off-axis angle is the angle between the beam pointing direction vector and the z-axis, and the beam pointing azimuth is the angle between the projection vector of the beam pointing direction vector on the xoy plane and the x-axis; Step 3: Based on the shielding of the units in the beam pointing direction, the RF transceiver channels of the unshielded antenna units are opened, and the RF transceiver channels of the shielded antenna units are closed; Step 4: The sum echo is formed by superimposing the echoes received by all sub-arrays of the frustum phased array; Step 5: Point the beam to the off-axis angle Threshold angle for forward / side scan mode Size, select the difference beamforming mode to enter, threshold angle It is determined by the ratio of the number of occluded elements of the frustum conformal phased array; the difference beamforming mode includes a forward scanning mode and a side scanning mode; If the forward scanning mode is used, according to the azimuth Determine the array schemes for synthesizing the pitch difference and azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing process; in the forward scanning mode, looking from the projection plane xoy of the frustum conformal phased array perpendicular to the rotation axis z axis, the angle of the projection of each sector sub-array along the busbar boundary line on the xoy plane deviating from the x-axis is used as the boundary angle for switching the array mode. ; For the current azimuth ,satisfy Boundary angle The corresponding boundary line is the dividing line between the two groups of sub-array areas that form the azimuth difference, and the boundary line perpendicular to it is the dividing line between the two groups of sub-array areas that form the elevation difference; If the side scanning mode is used, the pitch difference echo signal is composed of the difference between the upper and lower frustums, and ... Determine the array schemes involved in the synthesis of azimuth difference echo signals respectively, synthesize the pitch difference and azimuth difference echo signals, and enter the subsequent signal processing process; in the side scanning mode, the pitch difference echo is obtained by subtracting the sub-array echoes on both sides of the upper and lower frustum interfaces; looking from the projection plane xoy of the frustum conformal phased array perpendicular to the rotation axis z axis, the angle of the projection of each sector sub-array along the busbar boundary line on the xoy plane deviating from the x-axis is used as the boundary angle for switching the array mode. ; For the current azimuth ,satisfy Boundary angle The corresponding boundary line is the dividing line between the two groups of sub-array areas that form the azimuth difference; Step 6: performing pulse compression processing on both the sum path echo signal and the difference path echo signal to perform target detection; Step 7: Extract the target distance of the target detected in step 6; Step 8: Obtain the target angle according to the extracted target distance and extract it; Step 9: Target positioning is achieved based on target distance and target angle information.

2. The target positioning method based on a frustum-conical conformal phased array according to claim 1, characterized in that: In step 6, the position Np of the target point relative to the starting point in the data after the S-Pulse Compression Processing is obtained by using a constant false alarm detection method.

3. The target positioning method based on a frustum-conical conformal phased array according to claim 2, characterized in that: In step 7, the target distance is obtained by the following formula: （1） in is the distance to the front edge of the echo gate; C is the speed of light; is the echo sampling interval; Np is the target point obtained by target detection.

4. The target positioning method based on a frustum-conical conformal phased array according to claim 3, characterized in that: In step 8, the target angle extraction process is: According to the target point Np obtained by target detection, the value at the target point Np is extracted from the data after pulse compression processing of the sum pulse, the data after pulse compression processing of the pitch difference pulse, and the data after pulse compression processing of the azimuth difference pulse, and the angular error value is obtained by the following formula: （2） （3） Among them, PhiErr is the azimuth error; ThetaErr is the pitch angle error; is the value of the target point position in the data after azimuth difference pulse compression processing, is the value of the target point position in the data after pitch difference pulse compression processing; : The value of the target point in the data after the sum of the path difference pulse compression processing; The target azimuth angle PhiAngle and pitch angle ThetaAngle calculation formula are as follows: ； Among them, PhiBoshu is the azimuth angle of the radar beam, ThetaBoshu is the pitch angle of the radar beam; PhiErr is the azimuth error, ThetaErr is the elevation error; PhiERROR_ADJUST_k is the azimuth error adjustment coefficient k, ThetaERROR_ADJUST_k is the pitch error adjustment coefficient k; PhiERROR_ADJUST_b is the azimuth error adjustment coefficient b, and ThetaERROR_ADJUST_b is the pitch error adjustment coefficient b.

5. The target positioning method based on a frustum-conical conformal phased array according to claim 4, characterized in that: In step 2, the frustum conformal phased array beam pointing description adopts the right-hand coordinate form, and the frustum conformal phased array beam pointing off-axis angle is the angle between the beam pointing direction vector and the z-axis. Its value increases with the increase of the angle with the z-axis. Its value range is [0°, 180°].

6. The target positioning method based on a frustum-conical conformal phased array according to claim 5, characterized in that: In step 2, the frustum conformal phased array beam points to the azimuth angle It is the angle between the projection vector of the beam pointing direction vector on the xoy plane and the x-axis. It increases in the counterclockwise direction and has a value range of [-180°, 180°].

7. The target positioning method based on a frustum-conical conformal phased array according to claim 6, characterized in that: In step 3, the occlusion of antenna element n is determined by the normal unit vector of element n. and the beam pointing unit vector The inner product of Decide if , then antenna unit n is not blocked; if , then antenna unit n is blocked; in is the switching threshold angle of a single antenna element, and its selected value is determined by the amplitude of the antenna unit pattern in the direction deviating from the normal direction.

8. The target positioning method based on a frustum-conical conformal phased array according to any one of claims 1 to 7, characterized in that: In step 5, the threshold angle Determined by the ratio of the number of obscured elements in the frustum conformal phased array; When the beam is pointed at an off-axis angle Less than the threshold angle When , more than half of the units are not blocked. When the entire array performs differential beamforming by sector, there will be no situation where differential beams cannot be formed, and the process enters the forward scanning mode. When the beam is pointed at an off-axis angle Greater than the threshold angle When the array is in the side scanning mode, half of the sector units will be blocked. When the difference beam is formed by sectors in the entire array, the energy of the two echoes participating in the difference beam synthesis will be very different, and the difference beam cannot be formed, and the array enters the side scanning mode.

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