Ground-to-air target positioning method and system based on direction finding and time difference

Abstract

The invention relates to a ground-to-air target positioning method and system based on direction finding and time difference, belongs to the technical field of target radiation source positioning, and solves the problem of low three-dimensional space target radiation source positioning efficiency in the prior art. The method comprises the specific steps that three vehicle-mounted platforms composed of a main station and two auxiliary stations receive target radiation source signals respectively, time difference information is obtained, and the azimuth angle and the pitch angle of a target signal obtained by the main station are obtained; based on the earth-fixed system position coordinates of the master station, converting the earth-fixed system position coordinates of the target into a master station antenna coordinate system to obtain coordinate representation of the target position in a master station antenna system; based on the coordinate representation of the target position in the main station antenna system, the position coordinates of the three vehicle-mounted platforms and the target position, a target positioning equation set is constructed, the time difference information and the target signal azimuth angle and the pitch angle obtained by the main station are combined for solving, the ground-fixed system position coordinates of the target are obtained, and the ground-to-air target positioning efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of target radiation source positioning, and in particular to a ground-to-air target positioning method and system based on direction finding and time difference. Background Art

[0002] Direct Position Determination (DPD) is a current research hotspot in the field of passive positioning. This positioning system maintains high positioning accuracy even under low signal-to-noise ratios. However, due to the high degree of nonlinearity in the solution, it is difficult to obtain an analytical expression for the emitter's position. A common solution involves using a region-partitioning network to traverse and search the cost function's spectrum peak, where the peak corresponds to the target emitter's location. For aerial target emitters, however, without prior information about the target's location, the computational complexity of direct positioning using a three-dimensional spatial partitioning network traversal search is prohibitive and may require iterative searches, resulting in a cumbersome and time-consuming solution.

[0003] In the traditional parametric two-step positioning system, most studies involving direction-finding information simply establish mathematical models based on the Cartesian coordinate system. However, in actual engineering applications, the direction-finding parameters need to consider the attitude angle information of the observation platform itself, and the final target position estimation result can only be obtained through the transformation of multiple coordinate systems. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a ground-to-air target positioning method and system based on direction finding and time difference, so as to solve the problem of low efficiency in ground-to-air target radiation source positioning in the prior art.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] On the one hand, an embodiment of the present invention provides a ground-to-air target positioning method based on direction finding and time difference, comprising the following steps:

[0007] Three vehicle-mounted platforms, consisting of a master station and two auxiliary stations, receive the target radiation source signals respectively, obtaining time difference information, as well as the azimuth and elevation angles of the target signals obtained by the master station;

[0008] Based on the ground-fixed position coordinates of the master station, the ground-fixed position coordinates of the target are converted to the master station antenna array system to obtain the coordinate representation of the target position in the master station antenna array system; wherein the ground-fixed position coordinates of the target are the quantities to be determined;

[0009] Based on the coordinate representation of the target position in the master station antenna array system, the position coordinates of the three vehicle-mounted platforms, and the target position, a target positioning equation group is constructed. The equation group is solved by combining the time difference information and the azimuth and pitch angles of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

[0010] Furthermore, the target positioning equation group includes two time difference equations between the two auxiliary stations and the main station, and the azimuth positioning equation and pitch angle positioning equation of the target measured by the main station. The time difference information and the obtained azimuth and pitch angle of the target signal are substituted into the two time difference equations and the azimuth positioning equation and pitch angle positioning equation respectively to obtain the ground-fixed system position coordinates of the target.

[0011] Furthermore, constructing the azimuth positioning equation and the elevation positioning equation includes:

[0012] Based on the coordinate representation of the target position in the master station antenna array system, using trigonometric geometric relationships, the azimuth angle equation and the elevation angle equation of the target measured by the master station are obtained respectively;

[0013] Based on the azimuth angle equation and the elevation angle equation and the corresponding direction-finding angle error, the azimuth angle positioning equation and the elevation angle positioning equation of the master station are obtained respectively.

[0014] Furthermore, the master station pitch angle equation is expressed as:

[0015]

[0016] Among them, β is the pitch angle of the target measured by the master station, x g ,y g ,z g They represent the three-dimensional coordinates of the target in the main station antenna array system, x T ,y T ,z T They represent the three-dimensional coordinates of the target in the master station antenna array system, x1, y1, z1 are the three-dimensional coordinates of the ground-fixed system of the master station position, C1 is the coordinate conversion matrix based on the attitude angle of the master station antenna array, A1 is the coordinate conversion matrix based on the longitude and latitude of the master station position, and

[0017]

[0018] Furthermore, the master station azimuth equation is expressed as:

[0019]

[0020] Among them, α is the azimuth of the target measured by the master station.

[0021] Furthermore, constructing the two time difference equations includes:

[0022] Based on the fixed position coordinates of each auxiliary station, the relative distance between each auxiliary station and the target is calculated. Combined with the speed of light, the time it takes for the target radiation source signal to reach the corresponding auxiliary station from the target position is obtained, which is recorded as the first time representation.

[0023] Based on the fixed position coordinates of the master station, the relative distance between the master station and the target is calculated. Combined with the speed of light, the time it takes for the target radiation source signal to reach the master station from the target position is obtained, which is recorded as the second time representation.

[0024] The difference between the first time representation and the second time representation is combined with the time difference estimation error corresponding to each auxiliary station to obtain the time difference equation corresponding to the auxiliary station.

[0025] Furthermore, obtaining the ground-fixed position coordinates of the target includes:

[0026] Linearizing the target positioning equations into a matrix representation;

[0027] Based on the linearized matrix representation, the time difference information and the acquired azimuth and elevation angles of the target signal are combined to solve the target position coordinates using a weighted least squares method to obtain the position coordinates of the target on the ground fixed system.

[0028] Furthermore, the main station is equipped with a multi-channel two-dimensional antenna array, and the two auxiliary stations are equipped with single-channel antennas to receive target radiation source signals respectively.

[0029] On the other hand, an embodiment of the present invention provides a ground-to-air target positioning system based on direction finding and time difference, including:

[0030] Three vehicle-mounted platforms are used to receive target radiation source signals respectively, obtain time difference information, and the azimuth and elevation angles of the target signals obtained by the main station;

[0031] A coordinate conversion module is configured to convert the target's ground-fixed position coordinates into the master station's antenna array system based on the master station's ground-fixed position coordinates, thereby obtaining a coordinate representation of the target's position in the master station's antenna array system; wherein the target's ground-fixed position coordinates are the quantity to be determined;

[0032] A positioning modeling module is used to construct a target positioning equation group based on the coordinate representation of the target position in the main station antenna array system, the position coordinates of the three vehicle-mounted platforms and the target position;

[0033] The positioning analysis module is used to solve the target positioning equation group based on the time difference information and the azimuth and pitch angle of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0035] 1. This invention proposes using three vehicle-mounted observation platforms to receive target radiation source signals. Based on the ground-fixed position coordinates of the main observation platform and the ground-fixed position coordinates of the target to be determined, the target position is converted to the main antenna array coordinate system. A target position equation system is constructed, and the target position is analyzed using single-shot measurement parameters of direction finding and time difference information obtained by the observation platforms. This results in an estimated ground-fixed position coordinate of the target, improving the efficiency of aerial target positioning.

[0036] 2. The proposed ground-to-air target positioning method based on direction finding and time difference realizes the unified transformation of the main station antenna array coordinate system by observing the platform's own position and attitude angle information, obtains the representation of the antenna array system at the target position, constructs the time difference equation based on the positions of the three vehicle-mounted platforms in the ground-fixed coordinate system, and constructs the angle equation based on the geometric relationship after the coordinate transformation. The closed-form solution of the target position given in this way does not require cyclic iteration, reduces the amount of calculation, and improves the timeliness of ground-to-air target positioning.

[0037] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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.

[0039] Figure 1 Flowchart of a direction finding and time difference ground-to-air target positioning method according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a two-dimensional antenna array equipped with a master station according to an embodiment of the present invention;

[0041] Figure 3 Schematic diagram of the transition from the ground-fixed coordinate system XYZ to the antenna array initial coordinate system XgYgZg during the direction finding process of the master station according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of a ground-to-air target positioning scenario according to an embodiment of the present invention;

[0043] Figure 5 1 is a curve diagram of the positioning root mean square error and the theoretical positioning error CRLB changing with the signal-to-noise ratio according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0045] Example 1

[0046] A specific embodiment of the present invention discloses a ground-to-air target positioning method based on direction finding and time difference, such as Figure 1 As shown, the following steps are included:

[0047] Step S1: Three vehicle-mounted platforms, consisting of a master station and two auxiliary stations, respectively receive target radiation source signals to obtain time difference information, as well as the azimuth and elevation angles of the target signal obtained by the master station. The master station is equipped with a multi-channel two-dimensional antenna array to obtain the azimuth and elevation angles of the target signal; the two auxiliary stations are equipped with single-channel single antennas.

[0048] Step S2: Based on the ground-fixed position coordinates of the master station, convert the ground-fixed position coordinates of the target into the master station antenna array system to obtain a coordinate representation of the target position in the master station antenna array system; wherein the ground-fixed position coordinates of the target are the quantities to be determined;

[0049] Step S3: Based on the coordinate representation of the target position in the master station antenna array system, the position coordinates of the three vehicle-mounted platforms, and the target position, a target positioning equation group is constructed. The equation group is solved by combining the time difference information and the azimuth and elevation angles of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

[0050] Through the above method, based on the position coordinates and angle information of the master observation platform among the three vehicle-mounted platforms and the ground-fixed position coordinates of the target to be located, the azimuth and elevation angles of the target signal measured by the master station are expressed in the master station antenna array coordinate system. A target positioning equation group is constructed, and the angle information and time difference information obtained by the vehicle-mounted platform are combined to solve the target position. The target's ground-fixed position coordinate positioning result is obtained, achieving efficient target positioning.

[0051] Specifically, in step S1, three vehicle-mounted platforms, including one master station (observation station) and two auxiliary stations (observation stations), jointly locate the target. Each vehicle-mounted platform is equipped with Beidou GPS to obtain its own position information. Each vehicle-mounted platform receives the target radiation source signal through the deployed antenna array and performs time difference estimation based on the received signal to obtain time difference information. The Xg axis of the two-dimensional antenna array coordinate system of the master station vehicle-mounted platform is initially aligned with the direction of motion of the master station, that is, directly in front of the master station. The Zg axis is initially pointed directly above the master station. The Yg axis, Zg axis, and Xg axis form a right-handed coordinate system.

[0052] Furthermore, the two-dimensional antenna array can rotate around the Xg, Yg and Zg axes, and the on-board navigation device can provide three-dimensional attitude information of the antenna array, namely, the pointing angle γ (rotation angle around the Zg axis in the initial state), the pitch angle θ (rotation angle around the Yg axis in the initial state), and the roll angle ε (rotation angle around the Xg axis in the initial state), where the pointing angle γ represents the angle between Xg and due north, the roll angle ε represents the angle between Yg and due west, and the pitch angle θ represents the angle between Zg and the upward vertical line of the ground.

[0053] Specifically, in step S2, the azimuth and elevation angles of the target signal measured by the master station are expressed as:

[0054]

[0055] Where r g =[x g ,y g ,z g ] T Indicates the coordinates of the target in the master station antenna array coordinate system.

[0056] The coordinates of the target in the antenna array are transformed based on the ground-fixed position coordinates of the master station and the target, which can be expressed as:

[0057] r g =C1A1(X T -X1),

[0058] Right now:

[0059]

[0060] Among them, X T , X1 represents the coordinate vectors of the target and master station positions in the earth-fixed system (i.e., the three-dimensional coordinates with the center of the earth as the coordinate origin), and X1 = [x1, y1, z1] T , X T =[x T ,y T ,z T ] T , C1 is the coordinate conversion matrix based on the master station antenna array attitude angle, A1 is the coordinate conversion matrix based on the longitude and latitude of the master station location, and

[0061]

[0062] [L1, B1] represents the latitude and longitude of the master station's own position in the WGS-84 geodetic coordinate system, γ1 represents the pointing angle of the master station's antenna array, θ1 represents the elevation angle of the master station's antenna array, and ε1 represents the roll angle of the master station's antenna array.

[0063] Specifically, in step S3, the target positioning equation group includes two time difference equations between the two auxiliary stations and the main station, and two time difference equations and two angle equations: an azimuth positioning equation and a pitch angle positioning equation of the target measured by the main station. The time difference information and the obtained azimuth and pitch angle of the target signal are substituted into the two time difference equations, the azimuth positioning equation, and the pitch angle positioning equation, respectively, to obtain the ground-fixed system position coordinates of the target.

[0064] On the one hand, constructing the azimuth positioning equation and the elevation positioning equation includes:

[0065] S311. Based on the coordinate representation of the target position in the master station antenna array system, using trigonometric geometric relationships, the azimuth angle equation and the elevation angle equation of the target measured by the master station are obtained, which are expressed as:

[0066]

[0067]

[0068] Where α is the azimuth angle of the target signal measured by the master station, and β is the elevation angle of the target signal measured by the master station.

[0069] S312: Based on the azimuth angle equation and the elevation angle equation and the corresponding direction finding angle error, obtain the azimuth angle positioning equation and the elevation angle positioning equation of the master station, respectively, which are expressed as:

[0070] α'=α+Δα

[0071] β'=β+Δβ,

[0072] Among them, α' and β' are the direction-finding results of the target signal azimuth and elevation angles obtained by the master station, and Δα and Δβ are the corresponding direction-finding errors.

[0073] On the other hand, constructing the two time difference equations includes:

[0074] S321. Based on the fixed position coordinates of each auxiliary station, calculate the relative distance between each auxiliary station and the target. Combined with the speed of light, the time it takes for the target radiation source signal to reach the corresponding auxiliary station from the target position is obtained, which is recorded as the first time representation.

[0075] S322. Calculate the relative distance between the master station and the target based on the fixed position coordinates of the master station. Combined with the speed of light, obtain the time it takes for the target radiation source signal to reach the master station from the target position, which is recorded as the second time representation.

[0076] S323. The difference between the first time representation and the second time representation is combined with the time difference estimation error corresponding to each auxiliary station to obtain the time difference equation corresponding to the auxiliary station, which is expressed as:

[0077]

[0078]

[0079] Among them, X i =[x i ,y i ,z i ] T where τ1 and τ2 represent the coordinate vectors of the positions of the three vehicle-mounted platforms in the ground-fixed system, i represents the vehicle-mounted platform number, i=1 represents the main station vehicle-mounted platform, and i=2 or 3 represents the two auxiliary stations, respectively. τ1 and τ2 are the time difference information obtained by the second and third auxiliary stations, respectively (i.e., the time difference information between each auxiliary station and the main station), c is the speed of light, Δτ1 and Δτ2 are the time difference estimation errors of the second and third auxiliary stations, respectively. Both the time difference error and the direction-finding error can be obtained based on the prior knowledge of the performance indicators of the equipment used (i.e., the sensors and other equipment that obtain the corresponding parameters).

[0080] In summary, the constructed target positioning equation group is expressed as:

[0081]

[0082] Furthermore, the target positioning equations are solved to obtain the analytical solution of the target position in the ground-fixed coordinate system, including:

[0083] S331, using the target position coordinates as the variables to be solved, linearizing the target positioning equations into a matrix representation;

[0084] Specifically, the linearized matrix of the above formula is expressed as:

[0085] H.X T + N = Y,

[0086] in,

[0087]

[0088]

[0089]

[0090] S332. Based on the linearized matrix representation, the target position coordinates are solved using a weighted least squares method by combining the time difference information and the acquired target signal azimuth and elevation angle to obtain the target position coordinates in the ground-fixed coordinate system.

[0091] Furthermore, in step S3, the analytical solution of the target position in the ground fixed system can be expressed as: T =(H T W -1H)- 1 H T W - 1 Y,

[0092] Among them, the weight matrix

[0093] W≈diag{[r1 2 (cosβcosα) 2 (Δα) 2 ,r1 2 (cosβ) 2 (Δβ) 2 ,(r2c) 2 (Δτ1) 2 ,(r3c) 2 (Δτ2) 2 ]}.

[0094] Furthermore, r1, r2, and r3 in the above weighted matrix are unknown. When the distance between the target and the vehicle platform is relatively far, r1≈r2≈r3. The weighted matrix can be simplified as follows:

[0095] W≈diag{[(cosβcosα) 2 (Δα) 2 ,(cosβ) 2 (Δβ) 2 ,c 2 (Δτ1) 2 ,c 2 (Δτ2) 2 ]}.

[0096] Furthermore, the above target position analytical solution X T There is still an unknown number r1 in the equation, so substitute r1 2 =(x T -x1) 2 +(y T -y1) 2 +(z T -z1) 2 Solving the quadratic equation gives r1, which can be substituted back to obtain the target position estimate X under the ground-fixed system. T .

[0097] Through the above method, starting from the direction-finding angle information of the target signal measured by the master station (the master station antenna array coordinate system), based on the vehicle-mounted platform's own position and attitude angle information, the target's ground-fixed position coordinates are converted to the master station antenna array system, and the azimuth and elevation angle positioning equations are established. The positioning modeling and solution are combined with the time difference equation. This does not involve the cyclic iterative solution process in the Cartesian coordinate system positioning method, and can achieve more efficient ground-to-air target positioning.

[0098] For example, the Yg axis spacing of the two-dimensional antenna array baseline of the master station vehicle platform is: 0.39 meters, 0.71 meters, 0.5 meters; the Zg axis spacing is: 0.39 meters, 0.71 meters, 0.9 meters, such as Figure 2 First, rotate the ground fixed system around the Z axis to the longitude L1 of the master station, then rotate the master station around the Y axis to the latitude B1, and finally rotate the coordinate system based on the antenna array attitude angle to obtain the coordinate position of the antenna array in the initial coordinate system XgYgZg, as shown in the figure. Figure 3 The application scenario of using these three vehicle-mounted platforms to locate the radiation source of aerial targets is as follows: Figure 4 As shown. The latitude and longitude height of the aerial target in the geodetic coordinate system is [L T ,B T ,h T ]=[120.11°,28.2°,10km], the latitude and longitude of the three vehicle-mounted platforms in the geodetic coordinate system are [L1,B1,h1]=[120°,28.5°,0km], [L2,B2,h2]=[120.3°,28.9°,0km], [L3,B3,h3]=[119.7°,28.9°,0km], the antenna array attitude angle of the master station vehicle-mounted platform γ=0°, θ=0°, ε=0°. The positioning results are as follows Figure 5 As shown in Figure 3, when the signal-to-noise ratio is above 5, the positioning error of this method meets the theoretical error requirements.

[0099] Compared with the existing technology, this embodiment provides a ground-to-air target positioning method and system based on direction finding and time difference, which obtains the target signal angle information obtained by a single measurement of the main station in the three vehicle-mounted platforms. By unifying the position coordinates of the three vehicle-mounted platforms into the main station antenna array coordinate system, constructing the time difference equation and the angle equation, the expression of the target position is determined, and finally the estimated result of the target radiation source position is obtained. The solution process does not require cyclic iteration, which ensures the positioning accuracy while reducing the computational complexity of the target positioning, thereby improving the efficiency of the target positioning.

[0100] Example 2

[0101] Another specific embodiment of the present invention discloses a ground-to-air target positioning system based on direction finding and time difference, comprising:

[0102] Three vehicle-mounted platforms are used to respectively receive target radiation source signals, obtain time difference information, and the azimuth and elevation angles of the target signals obtained by the main station;

[0103] A coordinate conversion module is configured to convert the target's ground-fixed position coordinates into the master station's antenna array system based on the master station's ground-fixed position coordinates, thereby obtaining a coordinate representation of the target's position in the master station's antenna array system; wherein the target's ground-fixed position coordinates are the quantity to be determined;

[0104] A positioning modeling module is used to construct a target positioning equation group based on the coordinate representation of the target position in the main station antenna array system, the position coordinates of the three vehicle-mounted platforms and the target position;

[0105] The positioning analysis module is used to solve the target positioning equation group based on the time difference information and the azimuth and pitch angle of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

[0106] The system can perform aerial target positioning according to the method described in any one of the solutions in Example 1. The relevant parts are referenced from each other and are not described repeatedly in this embodiment.

[0107] Compared with the existing technology, this embodiment provides a ground-to-air target positioning system based on direction finding and time difference, which uses three vehicle-mounted platforms to measure the target radiation source signal in real time, and uses a coordinate conversion module, a positioning modeling module, and a positioning analysis module to analyze and calculate the information obtained from a single measurement, and finally obtains an estimated result of the target radiation source position. The solution process does not require cyclic iteration, thereby improving the efficiency of target positioning.

[0108] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0109] 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 ground-to-air target positioning method based on direction finding and time difference, characterized in that: The steps include: Three vehicle-mounted platforms, consisting of a master station and two auxiliary stations, receive the target radiation source signals respectively, obtaining time difference information, as well as the azimuth and elevation angles of the target signals obtained by the master station; Based on the ground-fixed position coordinates of the master station, the ground-fixed position coordinates of the target are converted to the master station antenna array system to obtain the coordinate representation of the target position in the master station antenna array system; wherein the ground-fixed position coordinates of the target are the quantities to be determined; Based on the coordinate representation of the target position in the master station antenna array system, the position coordinates of the three vehicle-mounted platforms, and the target position, a target positioning equation group is constructed. The equation group is solved by combining the time difference information and the azimuth and pitch angles of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

2. The ground-to-air target positioning method according to claim 1, characterized in that: The target positioning equation group includes two time difference equations between the two auxiliary stations and the main station, and the azimuth positioning equation and pitch angle positioning equation of the target measured by the main station. The time difference information and the obtained azimuth and pitch angle of the target signal are substituted into the two time difference equations and the azimuth positioning equation and pitch angle positioning equation respectively to obtain the ground-fixed system position coordinates of the target.

3. The ground-to-air target positioning method according to claim 2, characterized in that: Constructing the azimuth positioning equation and the elevation positioning equation includes: Based on the coordinate representation of the target position in the master station antenna array system, using trigonometric geometric relationships, the azimuth angle equation and the elevation angle equation of the target measured by the master station are obtained respectively; Based on the azimuth angle equation and the elevation angle equation and the corresponding direction-finding angle error, the azimuth angle positioning equation and the elevation angle positioning equation of the master station are obtained respectively.

4. The ground-to-air target positioning method according to claim 3, characterized in that: The master station elevation angle equation is expressed as: Among them, β is the pitch angle of the target measured by the master station, x g ,y g ,z g They represent the three-dimensional coordinates of the target in the main station antenna array system, x T ,y T ,z T They represent the three-dimensional coordinates of the target in the master station antenna array system, x1, y1, z1 are the three-dimensional coordinates of the ground-fixed system of the master station position, C1 is the coordinate conversion matrix based on the attitude angle of the master station antenna array, A1 is the coordinate conversion matrix based on the longitude and latitude of the master station position, and 5. The ground-to-air target positioning method according to claim 4, characterized in that: The master station azimuth equation is expressed as: Among them, α is the azimuth of the target measured by the master station.

6. The ground-to-air target positioning method according to claim 2, characterized in that: Constructing the two time difference equations includes: Based on the fixed position coordinates of each auxiliary station, the relative distance between each auxiliary station and the target is calculated. Combined with the speed of light, the time it takes for the target radiation source signal to reach the corresponding auxiliary station from the target position is obtained, which is recorded as the first time representation. Based on the fixed position coordinates of the master station, the relative distance between the master station and the target is calculated. Combined with the speed of light, the time it takes for the target radiation source signal to reach the master station from the target position is obtained, which is recorded as the second time representation. The difference between the first time representation and the second time representation is combined with the time difference estimation error corresponding to each auxiliary station to obtain the time difference equation corresponding to the auxiliary station.

7. The ground-to-air target positioning method according to claim 2, characterized in that: Obtaining the ground-fixed position coordinates of the target includes: Linearizing the target positioning equations into a matrix representation; Based on the linearized matrix representation, the time difference information and the acquired azimuth and elevation angles of the target signal are combined to solve the target position coordinates using a weighted least squares method to obtain the position coordinates of the target on the ground fixed system.

8. The ground-to-air target positioning method according to any one of claims 1 to 7, characterized in that: The main station is equipped with a multi-channel two-dimensional antenna array, and the two auxiliary stations are equipped with single-channel antennas to receive target radiation source signals respectively.

9. A ground-to-air target positioning system based on direction finding and time difference, characterized in that: include: Three vehicle-mounted platforms are used to receive target radiation source signals respectively, obtain time difference information, and the azimuth and elevation angles of the target signals obtained by the main station; A coordinate conversion module is configured to convert the target's ground-fixed position coordinates into the master station's antenna array system based on the master station's ground-fixed position coordinates, thereby obtaining a coordinate representation of the target's position in the master station's antenna array system; wherein the target's ground-fixed position coordinates are the quantity to be determined; A positioning modeling module is used to construct a target positioning equation group based on the coordinate representation of the target position in the main station antenna array system, the position coordinates of the three vehicle-mounted platforms and the target position; The positioning analysis module is used to solve the target positioning equation group based on the time difference information and the azimuth and pitch angle of the target signal obtained by the master station to obtain the ground-fixed system position coordinates of the target.

10. The ground-to-air target positioning system according to claim 9, characterized in that: The target positioning equation group includes two time difference equations between the two auxiliary stations and the main station, and the azimuth positioning equation and pitch angle positioning equation of the target measured by the main station. The time difference information and the obtained azimuth and pitch angle of the target signal are substituted into the two time difference equations and the azimuth positioning equation and pitch angle positioning equation respectively to obtain the ground-fixed system position coordinates of the target.

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