A single-antenna passive location fast search method based on Doppler frequency measurement

Abstract

The application relates to the technical field of information processing, in particular to a single-antenna passive positioning fast search method based on Doppler frequency measurement. The method comprises the following technical measures: target radiation source carrier frequency estimation, effective carrier frequency selection based on a correlation factor; and grid search positioning based on a target radiation source cost function. In order to solve the real-time requirement of single-antenna positioning of electronic reconnaissance, the improved single-antenna passive positioning search method based on Doppler frequency measurement is adopted, so that the alarm data output time is greatly reduced. The technology can be applied to a satellite-borne, airborne and missile-borne platform, and meets the requirements of different platforms.

Description

Technical Field

[0001] This invention relates to the field of information processing technology, and specifically to a fast search method for passive positioning using a single antenna based on Doppler frequency measurement. Background Technology

[0002] Single-satellite passive positioning technology based on Doppler information has been widely and specifically applied in the field of single-satellite reconnaissance and positioning.

[0003] Traditional single-satellite passive positioning techniques based on Doppler information mostly employ the least squares method to estimate the frequency of each point in the grid, and then use a grid search method to obtain the optimal positioning solution. In engineering implementation, due to the large search volume and limited processor resources, this technique often requires a trade-off between computational complexity and positioning accuracy, and suffers from problems such as long search time and poor real-time performance. Summary of the Invention

[0004] This invention provides a fast search method for passive positioning using a single antenna based on Doppler frequency measurement. Its purpose is to reduce the search time of the positioning algorithm and improve the real-time performance of the algorithm to meet the real-time requirements of the application.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a fast search method for passive localization using a single antenna based on Doppler frequency measurement, comprising the following steps:

[0007] Step 1: Obtain radiation source signal information received by the projectile payload at several moments; and read the ballistic data at the corresponding moments to obtain the projectile coordinate information and attitude information;

[0008] Step 2: Estimate the carrier frequency of the target radiation source signal and calculate the relative Doppler frequency information between the projectile load and the target radar station; select the current position of the projectile and the position of the coverage boundary to estimate the carrier frequency of the signal and calculate the relevant factors. If the threshold is met, the data can be transmitted to the cost function generation module.

[0009] Step 3: Divide the ground latitude and longitude within the coverage area into a grid and calculate the cost function corresponding to each grid point;

[0010] Step 4: Within a preset range, search the two-dimensional grid for the peak value of the cost function, that is, search for the latitude and longitude coordinates corresponding to the minimum cost function, which are the geodetic coordinates of the target radar station.

[0011] Furthermore, the specific calculation formula for the relative Doppler frequency information between the missile body load and the target radar station is derived as follows:

[0012] Furthermore, the coverage range mentioned in step 3 refers to the range of latitude and longitude within ±60° relative to the projectile.

[0013] Furthermore, the ground latitude and longitude within the coverage area are divided into grids with step sizes of 1°, 0.5°, or 0.1°.

[0014] Furthermore, the specific formula for calculating the cost function corresponding to each grid point is as follows:

[0015] The beneficial effects achieved by this invention are as follows:

[0016] To address the real-time positioning requirements of single-antenna electronic reconnaissance, this invention employs an improved passive positioning search method based on Doppler frequency measurement, which significantly reduces alarm data output time. This technology can be applied to spaceborne, airborne, and missile-borne platforms to meet the needs of different platforms. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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 the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the single-antenna positioning model in the principle of this invention.

[0019] Figure 2 This is a flowchart illustrating a fast search method for single-antenna passive localization based on Doppler frequency measurement provided in an embodiment of the present invention.

[0020] Figure 3 This is a simulation result diagram of an embodiment of the present invention.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, if the word "and / or" appears throughout the text, it means including three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] like Figures 1-3 As shown, this invention provides a fast search method for passive localization using a single antenna based on Doppler frequency measurement, including the following technical measures:

[0026] (1) Target radiation source carrier frequency estimation, effective carrier frequency selection based on correlation factors;

[0027] (2) Grid search localization based on target radiation source cost function.

[0028] The principle of the fast search method for single-antenna passive localization based on Doppler frequency measurement is as follows:

[0029] According to the Doppler effect of relative motion, the instantaneous frequency of the received signal is:

[0030] f = f0 + f d (1)

[0031] In the formula:

[0032] f is the instantaneous frequency of the received signal;

[0033] f0 is the carrier frequency of the target radiation source;

[0034] f d It is the Doppler frequency, i.e.

[0035]

[0036] In the formula It is the derivative of the radial distance between the missile and the target radiation source, i.e., the relative velocity; c is the speed of light in a vacuum; v r Let u be the velocity of the relative motion. i =r i / ||r i || is a unit vector in the direction of the distance between the two, then at the i-th time... The relationship between the coordinates of the radiation source and the target radiation source can be established using the following formula:

[0037]

[0038] In the formula, It is the transpose of the unit vector in the direction of distance between the missile and the target radiation source;

[0039] v i It is the velocity vector of the missile at time i;

[0040] v xi It is the missile's velocity component in the x-direction at time i;

[0041] v yi It is the missile's velocity component in the y-direction at time i;

[0042] v zi It is the velocity component of the missile in the z-direction at the i-th moment;

[0043] x i It is the x-coordinate value of the missile at the i-th moment;

[0044] y i It is the y-coordinate value of the missile at time i;

[0045] z i It is the z-coordinate value of the missile at time i;

[0046] x is the x-coordinate value of the target radiation source;

[0047] y is the y-coordinate value of the target radiation source;

[0048] z is the z-coordinate value of the target radiation source;

[0049] r i The distance between the missile and the target is:

[0050]

[0051] According to equations (1) and (3), the signal frequency measured by the missile-borne reconnaissance receiver at the i-th moment is:

[0052]

[0053] In the formula, ξi Let be the noise measured at time i, and let be the noise measured at each time step, which follows an independent Gaussian distribution. The measured frequencies at N times can be represented in matrix form as follows:

[0054] Ψ=f0·F+ξ (5)

[0055] In the formula: ξ=[ξ1ξ2…ξ i …ξ N ] T .

[0056] Furthermore, based on the transformation relationship between the WGS-84 geodetic coordinate system and the Earth-fixed rectangular coordinate system, the transformation from latitude, longitude, and altitude geodetic coordinates to the rectangular coordinate system has the following relationships:

[0057]

[0058] In the formula: H is the ground height;

[0059] B is latitude;

[0060] L is longitude;

[0061] e is the eccentricity of the ellipsoid;

[0062] N is the local radius of curvature of the zonal circle, i.e.

[0063]

[0064] In the formula, a is the major radius of the reference sphere.

[0065] Replacing the radiation source location coordinates (x, y, z) in F with the transformation in equation (6), we can obtain the matrix equation for the geodetic coordinates (L, B) of the radiation source. Since there are 4 unknown variables, theoretically, as long as N≥4, the stationary radiation source on the ground can be located. At this time, a grid is divided in latitude and longitude within a certain area of ​​the ground containing the radiation source location.

[0066] Define a 2D grid point set Σ. Traditional single-satellite passive positioning techniques based on Doppler information will assign each grid point (L...) to a different location. k B k The least squares solution is calculated for )∈Σ, i.e.

[0067]

[0068] In the formula: F k =[f1(L k B k )f2(L k B k )…f i (L k B k )…fN (L k B k )] T .

[0069] Then, substitute the estimation result of equation (8) into the following equation to perform the grid search solution, that is, select the one that makes

[0070]

[0071] The smallest (L) k B k ) is the optimal estimate of the location of the radiation source (see "Principles of Space Electronic Reconnaissance and Positioning", Guo Fucheng et al., pp. 163-164).

[0072] In the fast search method described in this invention, the estimation strategy for the carrier frequency of the radiation source signal is modified in light of the missile-borne application background. Based on the update frequency characteristics of the missile's position and operational data, the least-squares estimate of the target radiation source's carrier frequency has a small deviation at different grid points. Therefore, this invention modifies the carrier frequency estimation stage of traditional single-satellite passive positioning technology based on Doppler information. Instead of calculating the least-squares solution for carrier frequency f0 point-by-point at each grid point, the least-squares solution is only performed at the current position of the missile and the grid boundary. A usable carrier frequency estimate is selected based on relevant factors. This saves the two-dimensional grid search time for the carrier frequency and significantly reduces the search time for single-antenna passive positioning based on Doppler frequency measurement, making it more suitable for scenarios with high real-time requirements, such as missile-borne alarms.

[0073] Preferably, the target radiation source carrier frequency estimation and grid search in the method include the following steps:

[0074] Step 1: Read the ballistic data to obtain the (x,y,z) position coordinates and attitude information of the WGS-84 series;

[0075] Step 2: Estimate the carrier frequency of the target radiation source signal, calculate the relative Doppler frequency information between the projectile load and the target radar station, see Equation (8), select the current position of the projectile and the position of the coverage boundary to estimate the carrier frequency of the signal, and calculate the relevant factors. If the threshold is met, the data can be transmitted to the cost function generation module.

[0076] Step 3: Divide the ground latitude and longitude within the coverage area into grids and calculate the cost function corresponding to each grid point, as shown in Equation (9);

[0077] Step 4: Within a preset range, search the two-dimensional grid for the peak value of the cost function, that is, search for the latitude and longitude coordinates corresponding to the minimum cost function, which are the geodetic coordinates of the target radar station.

[0078] To address the real-time positioning requirements of single-antenna electronic reconnaissance, this invention employs an improved passive positioning search method based on Doppler frequency measurement, which significantly reduces alarm data output time. This technology can be applied to spaceborne, airborne, and missile-borne platforms to meet the needs of different platforms.

[0079] This invention provides a fast search method for single-antenna passive localization based on Doppler frequency measurement, such as... Figure 2 As shown, the method used in this embodiment runs on the ZedBoard Zynq Evaluation and Development Kit. The method flow includes the following steps:

[0080] Step 1, as follows Figure 1 As shown, the projectile and radiation source can be approximated as point masses during flight. Assume the position coordinates of a stationary ground-based radiation source in a fixed geocentric coordinate system are r = [x, y, z]. T During the missile's leap phase, the values ​​t1, t2, t3...t are observed in the air. i At time r, the coordinates of the projectile are i =[x i ,y i ,z i ] T The velocity of the projectile is v i =[v xi ,v yi ,v zi ] T The missile-borne warning device receives signals at time i and measures their Doppler frequency for passive positioning.

[0081] Step 2: First, calculate the carrier frequency of the radar signal of the target radiation source according to Equation (8), calculate the carrier frequency value of the key position, calculate the relevant factor, and check whether the preset threshold is met.

[0082] Step 3: The effective carrier frequency estimate that meets the conditions is transmitted to the cost function. The coverage area is divided into grids with a step size of 1°, 0.5°, or 0.1°. The cost function corresponding to each grid point is calculated as shown in Equation (9). The smaller the step size, the longer the search time.

[0083] Step 4, search each grid point (L) k B k All correspond to cost functions, and the one that minimizes the cost function is (L). k B k This is the optimal estimate of the radiation source target location.

[0084] During flight, the missile will search both left and right sides. The coverage range mentioned in step 3 is ±60°, specifically referring to searching within a latitude and longitude range of -60° to 60° relative to the missile body. This coverage range is not specific but depends on the antenna design parameters. Naturally, this coverage range can be narrowed; that is, the coverage range mentioned in step 3 can be ±55°, ±50°, ±40°, ±30°, ±25°, ±20°, ±18°, or ±10°, etc., without being specified, as long as the absolute upper limit is less than 60°. However, it is worth noting that a larger coverage range requires more time, making it more difficult to meet real-time requirements; but a smaller coverage range may result in missed scans. Therefore, preferably, the coverage range is ±20° to achieve a balance between high real-time performance and a low missed scan rate. Specific data can be found in the appendix. Figure 3 .

[0085] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A fast search method for single-antenna passive location based on Doppler frequency measurement, characterized in that, Includes the following steps: Step 1: Obtain radiation source signal information received by the projectile payload at several moments; and read the ballistic data at the corresponding moments to obtain the projectile coordinate information and attitude information; Step 2: Estimate the carrier frequency of the target radiation source signal and deduce the relative Doppler frequency information between the missile load and the target radar station; The signal carrier frequency is estimated by selecting the current position of the projectile and the position of the coverage boundary, and the relevant factors are calculated. If the threshold is met, the data can be transmitted to the cost function generation module. Step 3: Divide the ground latitude and longitude within the coverage area into a grid and calculate the cost function corresponding to each grid point; Step 4: Within a preset range, search the two-dimensional grid for the peak value of the cost function, that is, search for the latitude and longitude coordinates corresponding to the minimum cost function, which are the geodetic coordinates of the target radar station.

2. The fast search method for single-antenna passive location based on Doppler frequency measurement according to claim 1, characterized in that: The specific calculation formula for calculating the relative Doppler frequency information between the projectile body load and the target radar station is 3. The fast search method for single-antenna passive location based on Doppler frequency measurement according to claim 1, characterized in that: The coverage area mentioned in step 3 refers to the range of latitude and longitude within ±60° relative to the projectile.

4. The fast search method for single-antenna passive location based on Doppler frequency measurement according to claim 3, characterized in that: The ground latitude and longitude within the coverage area are divided into grids with a step size of 1°, 0.5° or 0.1°.

5. The fast search method for single-antenna passive location based on Doppler frequency measurement according to claim 4, characterized in that: The specific formula of the cost function corresponding to each grid point is

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