A space-air coordination multi-target sorting positioning method based on position information field

Abstract

This invention relates to a space-air collaborative multi-target sorting and positioning method based on a position information field, belonging to the field of passive positioning. Utilizing the flexibility and maneuverability of a UAV, a shared field of view is constructed between the UAV, satellite, and radiation source. Based on the arrival time delay and angle information of the target radiation source observed by the two satellites and the UAV, a grid is drawn within the UAV's field of view. The time difference window from the grid points to the two satellites is calculated, and coarse pairing of satellite pulses is performed. Then, a position information field is established. Combining the coarse pairing time difference and the angle observed by the UAV, a step-by-step extraction method is used to determine the number and position information of multiple targets, while simultaneously completing fine pulse pairing. This invention integrates the sorting and position estimation involved in traditional multi-target positioning into a single algorithm through a space-air collaborative reconnaissance and positioning model, combined with a position information field algorithm, and by successively extracting the position information field, thus reducing the system's complexity.

Description

Technical Field

[0001] This invention belongs to the field of passive positioning, specifically relating to a multi-target location information field sorting and positioning method based on air-space collaborative reconnaissance, combining signal arrival time difference and signal arrival angle. Background Technology

[0002] Space reconnaissance is the most widely used and effective means of target reconnaissance. Compared with other reconnaissance methods, it is unaffected by air conditions, has a stable operating attitude, and offers a wide field of view, covering the entire globe and is not restricted by airspace. A common passive positioning system in space reconnaissance is the three-satellite time difference positioning system. This system achieves precise positioning of the target radiation source by measuring the time difference between the arrival of the signal from the same target radiation source on the ground at the same time on three satellites, combined with the constraint of the target's location on the Earth's surface.

[0003] However, in actual engineering applications, when the target is far from the three-satellite time difference positioning system, there are cases in the full pulse data received by the three satellites where only two satellites detect the target radiation source at the same time. In this case, the two satellites can only determine one time difference equation, and the Earth constraint equation can only determine one possible trajectory line, and the position of the target cannot be determined.

[0004] In this scenario, using a UAV with reconnaissance and direction-finding capabilities to assist in positioning, and leveraging the advantages of flexible response and strong targeting of aerial reconnaissance, forms an air-space collaborative reconnaissance system. This system can, to some extent, compensate for the shortcomings of low positioning accuracy of long-distance targets and the inability of two satellites to provide instantaneous positioning, while also enabling the UAV to have positioning capabilities.

[0005] In traditional electronic reconnaissance and positioning systems, multi-target localization typically involves sorting pulses according to arrival time, angle of arrival, frequency of arrival, time difference, and frequency difference, transforming the multi-target problem into a single-target problem for processing. However, when the number of targets is unknown and the measurement parameters are indistinguishable, localization becomes difficult. Furthermore, the accuracy of time difference depends on the accuracy of pulse pairing. When signals from multiple radiation sources with similar parameters are superimposed in both the time and frequency domains, a large amount of false time difference information is obtained, further complicating the time difference pairing process. Additionally, when multiple targets have inconsistent repetition frequencies, the number of pulses intercepted by different targets within the same time period also varies, making radiation sources with less pulse information difficult to detect and locate. Summary of the Invention

[0006] The technical problem to be solved by this invention is:

[0007] To address the issue of dual-satellite and single-UAV lacking independent instantaneous positioning capabilities, this invention provides a multi-target location information field sorting and positioning method based on air-space collaborative reconnaissance, combining signal arrival time difference and signal arrival angle.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A space-air cooperative multi-target sorting and positioning method based on location information field, characterized by including:

[0010] The two satellites respectively receive the pulse signals from the target radar radiation source, measure the pulse descriptor of their respective pulse trains, and obtain the pulse data arrival time;

[0011] Divide the visible area of ​​the UAV into grid points, and calculate the time difference at each grid node based on the path difference of the target radar radiation source pulse signal to the two satellites, and extract the maximum and minimum time difference values.

[0012] The pulse coarse pairing time difference window is determined based on the maximum and minimum time difference values. The pulse coarse pairing time difference window is used to perform coarse pairing of the two-star pulses. The time difference for successful pairing is calculated based on the arrival time of the pulse data.

[0013] The UAV receives the pulse signal from the target radar radiation source, measures the pulse descriptor of each pulse train, and obtains the azimuth angle of the target radar radiation source.

[0014] An observation model based on time difference and azimuth angle is established, and a target radiation source position information field function is constructed based on the observation model based on time difference and azimuth angle. Based on the target radiation source position information field function, combined with the time difference of successful pairing and the azimuth angle obtained by the UAV, a step-by-step extraction method is used to determine the position information and parameter measurement values ​​of multiple targets, and at the same time complete the precise pairing of pulses.

[0015] A further technical solution of the present invention: the step of determining the pulse coarse pairing time difference window based on the maximum time difference and the minimum time difference specifically involves:

[0016] The maximum time difference is used as the upper limit of the pulse coarse pairing time difference window, and the minimum time difference is used as the lower limit of the pulse coarse pairing time difference window.

[0017] A further technical solution of the present invention: the method of using a time difference window for coarse pairing of binary satellite pulses, and calculating the time difference for successful pairing based on the arrival time of the pulse data, specifically involves:

[0018] The time axis range for pulse pairing is determined based on the inherent time system error between satellite systems and the pulse coarse pairing time difference window. Pairing pulses between two satellites are found within the time axis range, and the arrival time of the pairing pulses is subtracted to obtain the time difference for successful pairing.

[0019] A further technical solution of the present invention: the determination of the time axis range for pulse pairing based on the inherent time synchronization error between satellite systems and the pulse coarse pairing time difference window specifically includes:

[0020] The sum of the inherent timing error between satellite systems and the lower limit of the pulse coarse pairing time difference window is used as the lower limit of the pulse pairing time axis range, and the sum of the inherent timing error between satellite systems and the upper limit of the pulse coarse pairing time difference window is used as the upper limit of the pulse pairing time axis range.

[0021] A further technical solution of the present invention: the establishment of an observation model based on time difference and azimuth angle, and the construction of a target radiation source position information field function based on the observation model based on time difference and azimuth angle; specifically:

[0022] The measurement errors of time difference and azimuth angle are set to follow a Gaussian distribution. An observation model for time difference and azimuth angle is established. The first nominalized Euclidean distance and the second nominalized Euclidean distance of each grid point are calculated. The first nominalized Euclidean distance is related to the estimated time difference, and the second nominalized Euclidean distance is related to the estimated azimuth angle. The target radiation source position information field function is constructed based on the first nominalized Euclidean distance and the second nominalized Euclidean distance.

[0023] A further technical solution of the present invention: Based on the target radiation source location information field function combined with the time difference of successful pairing and the azimuth angle obtained by the UAV, a step-by-step extraction method is used to determine the location information and parameter measurement values ​​of multiple targets, specifically as follows:

[0024] Find the maximum and minimum values ​​of the target radiation source location information field function at all grid points, and determine whether the set of time difference and azimuth angle contains the target by comparing the absolute value of the difference between the maximum and minimum values ​​with the first threshold.

[0025] If the set of time difference and azimuth contains a target, then the estimated value of the target radiation source position is obtained based on the target radiation source position information field function, and the estimated value of the time difference and azimuth corresponding to the target radiation source is calculated based on the estimated value of the target radiation source position.

[0026] The estimated time difference is compared with the time difference of successful pairing to determine whether the time difference of successful pairing should be retained; the estimated azimuth angle is compared with the azimuth angle acquired by the UAV to determine whether the azimuth angle acquired by the UAV should be retained; the retained time difference and azimuth angle are used as parameter measurement values.

[0027] A further technical solution of the present invention: the step of determining whether the time difference and azimuth angle set contains a target by comparing the absolute value of the difference between the maximum and minimum values ​​with a first threshold is specifically: the time difference set and azimuth angle set contain a target when the following formula is satisfied;

[0028]

[0029] Where Max and Min are the maximum and minimum values ​​of the target radiation source location information field function at all grid points, respectively, and u0 is a given value.

[0030] A further technical solution of the present invention: The step of comparing the estimated time difference with the time difference of successful pairing to determine whether to retain the time difference of successful pairing specifically involves retaining the time difference of successful pairing when the following formula is satisfied:

[0031]

[0032] Among them, tdoa i The time difference between successful pairing at the estimated location of the target radiation source. σ is the time difference estimate. t This represents the standard deviation of the time difference measurement error.

[0033] A further technical solution of the present invention: The step of comparing the estimated azimuth angle with the azimuth angle acquired by the UAV to determine whether to retain the azimuth angle acquired by the UAV specifically involves: retaining the azimuth angle acquired by the UAV when the following formula is satisfied:

[0034]

[0035] Where, θ j The azimuth angle obtained by the UAV is the estimated location of the target radiation source. This is the estimated azimuth angle, σ. θ This represents the standard deviation of the azimuth measurement error.

[0036] A computer system is characterized by comprising: one or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the method described above.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention provides a space-air collaborative multi-target sorting and positioning method based on a position information field. It solves the problem of instantaneous positioning in dual-satellite and single-UAV reconnaissance systems by utilizing the time difference of arrival of measurement signals from two satellites and the angle of arrival of measurement signals from a UAV. Leveraging the flexibility and maneuverability of UAVs, a shared field of view area between the UAV, satellite, and radiation source can be constructed. A grid is divided within the UAV's field of view, and a time difference window for coarse time difference pairing is calculated. An algorithm based on the position information field is used for multi-target radiation source detection, positioning, and time difference pairing and sorting. Compared with existing technologies, this invention has the following three advantages:

[0039] 1. A space-air collaborative reconnaissance and positioning model was constructed, which uses time difference data observed by satellites and azimuth data observed by UAVs for collaborative positioning. This solves the problem that dual satellites and single UAVs cannot achieve independent instantaneous positioning, and greatly improves the utilization rate of satellite detection data.

[0040] 2. By combining the location information field algorithm and setting the threshold of the cost function, the problem of locating multiple targets simultaneously is solved.

[0041] 3. By extracting the location information field one by one, the number and location estimation of multiple radiation sources in the space-air collaborative scenario and the precise matching of time difference measurement values ​​were completed. The sorting and location estimation involved in traditional multi-target positioning are integrated into one algorithm, reducing the complexity of the system. Attached Figure Description

[0042] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0043] Figure 1 This is a flowchart of the multi-target location information field sorting and positioning method for air-space collaborative reconnaissance according to the present invention.

[0044] Figure 2 This is a simulation diagram of the pulse arrival delay.

[0045] Figure 3 Simulation diagram of coarse-matched time difference versus actual time difference.

[0046] Figure 4 The following are the positioning results images for the step-by-step extraction of location information field: (a) Original positioning result image; (b) Original positioning spectrum image; (c) Positioning result image after the first extraction; (d) Positioning spectrum image after the first extraction; (e) Positioning result image after the second extraction; (f) Positioning spectrum image after the second extraction; (g) Positioning result image after the third extraction; (h) Positioning spectrum image after the third extraction.

[0047] Figure 5 This is a simulation diagram of the precise time difference and the actual time difference. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0049] This invention provides a space-air collaborative multi-target sorting and positioning method based on a position information field. Utilizing the flexibility and maneuverability of a UAV, a shared field of view is constructed between the UAV, satellite, and radiation source. By using the arrival time delay and angle information of the target radiation source observed by the two satellites and the UAV, a grid is drawn within the UAV's visible area. The time difference window from the grid points to the two satellites is calculated, and coarse pairing of the satellite pulses is performed. Then, a position information field is established. Combining the coarse pairing time difference and the angle observed by the UAV, a step-by-step extraction method is used to determine the number and position information of multiple targets, while simultaneously completing fine pairing of pulses. Figure 1 As shown, it includes the following steps:

[0050] Step 1: Assume the satellite's current position in the Earth-fixed coordinate system is represented as follows: The location of the drone is There are M radar radiation sources on the Earth's surface, and their locations are: Their pulse repetition periods are PRI m m = 1, 2, ..., M. The satellite receives the pulse signals from the radiation source and measures the pulse description words of each pulse train, having already undergone preprocessing such as frequency and pulse width determination. Satellite S i The arrival time of the pulse data of the target radar radiation source m is:

[0051]

[0052]

[0053] Where, N m Let t0 be the number of pulses emitted by the target radiation source m. Let t0 be the time reference, c be the speed of light, and n be the number of pulses emitted by the target radiation source m. t To account for time delay measurement error, the arrival time of M target radar radiation sources at satellite S is... i The time set can be represented as:

[0054]

[0055] Sort the pulse sequences in the above formula according to their arrival times. The sorted arrival time sequence is denoted as:

[0056] Step 2: Divide the area within the drone's line of sight into grid points. The drone's line of sight distance is R. In the northeast-northeast coordinate system with the drone as the origin, set the radiation source observation area X = {(x,y), -R≤x,y≤R}, and the grid points are X. k,l =(x k ,y l k = 1, 2, ..., N x l = 1, 2, ..., N y , where N xN represents the number of grid points along the x-axis. y The number of grid points along the y-axis;

[0057] Step 3: Based on the observation areas of the satellite and the UAV, the feasible time window for full pulse pairing is calculated by inversion. Based on the path difference of the radar radiation source pulse signal to the two satellites, the time difference value at each grid node can be calculated by inversion.

[0058]

[0059] Among them, X k,l,e These are the coordinates of the grid points in the Earth-Fixed Coordinate System;

[0060] Iterate through all the positioning grid nodes to obtain the time difference corresponding to each grid node. The set of:

[0061]

[0062] Step 4: From the time difference set T 0 The maximum time difference t is obtained from kl,max and minimum time difference t kl,min Based on this, the feasible time difference window Δt = [t] for coarse pulse pairing is determined. kl,min ,t kl,max ].

[0063] Step 5: Receiving the full pulse sequence via satellite Based on a certain pulse A, according to the inherent time system error T between satellite systems fix And the feasible time window Δt for pulse pairing, to determine the time axis range [T] for feasible pairing of pulse A. fix +t kl,min ,T fix +t kl,max If a paired pulse can be found, the full pulse sequence can be detected by the reconnaissance station on the other satellite. For the TOA of the paired pulses, calculate the time difference tdoa1 for successful pairing of generated pulse A;

[0064] Step 6: Next, use the satellite full pulse sequence Using the second pulse B as a reference, repeat step 5 above to calculate the time difference tdoa2 for successful pairing of generated pulse B; and so on, until the entire sequence is successfully paired, obtaining the successfully paired pulse.

[0065] Step 7: Assume the UAV also receives pulse signals from M radar radiation sources on the Earth's surface, measures the pulse descriptors of each pulse train, and has already undergone preprocessing such as frequency and pulse width. The azimuth data of the target radar radiation source m measured by the UAV is as follows:

[0066]

[0067] The set of angles of the M target radar radiation sources measured by the UAV can be expressed as:

[0068] AOA U =[θ U,1 ,θ U,2 ,...,θ U,M ]

[0069] Sort the pulse sequences in the above formula according to their arrival times. The sorted arrival time sequence is denoted as:

[0070] Step 8: Set the number of targets m = 0;

[0071] Step 9: And determine and Does an empty set exist? If an empty set exists, proceed to step 17.

[0072] Step 10: Construct an observation model for time difference and azimuth. Assume the time difference measurement error follows a pattern with a mean of zero and a variance of... The azimuth measurement errors all follow a Gaussian distribution with a mean of zero and a variance of . The Gaussian distribution.

[0073]

[0074]

[0075] Where X represents the position of the target radiation source in the Earth-fixed coordinate system, M is the rotation matrix from the Earth-fixed coordinate system to the Northeast-Sky coordinate system, and D... x = (1,0,0), D y = (0, 1, 0).

[0076] The results of the p-th observation from the satellite can be modeled as follows:

[0077] z 1,p =h 1,p (X)+v 1,p p = 1, 2, ..., P

[0078] The result of the qth observation by the UAV is established as follows:

[0079] z 2,q =h 2,q (X)+v 2,q ,q=1,2,...,Q

[0080] The specific expressions for each item are as follows:

[0081]

[0082] Step 11: Traverse all grid points in the grid and calculate the nominal Euclidean distance d1(z) for each grid point. 1,p ,h 1,p (X)) and d2(z) 2,q ,h 2,q (X)).

[0083]

[0084]

[0085] Step 12: Calculate the position information field function f X The value of (X / Z).

[0086]

[0087] Where p0(X) is the prior probability density of the target located in X, and C[·] is a cost function that can be used to locate multiple indistinguishable targets.

[0088]

[0089] In the formula, u0 is the threshold.

[0090] Step 13: Find the maximum value (Max) and minimum value (Min) of the position information field function at all grid points. If the set of time difference and the set of azimuth contain a target, let the number of radiation sources m = m + 1; otherwise, go to step 17.

[0091] Step 14: Find the value that makes f X (X / Z) reaches its maximum value in X. k,l This is an estimate of the location of one of the radiation sources. And add it to the set of radiation source locations. middle.

[0092] Step 15: Based on the estimated location of the radiation source and the location of the observation station X Si,e X U,e Calculate the time difference and azimuth angle corresponding to the radiation source using the following formula:

[0093]

[0094] in, Location of radiation source Position in the Earth-fixed coordinate system.

[0095] Step 16: For the time difference data set Calculate all time difference pairs in the data. If e t,i If ≤u0, then tdoa i For position The time difference value of the target measured by the satellite is obtained and appended to the parameter measurement set TDOA of the target m. m In, and will meet condition e t,i ≤u0 of tdoa i from After removing the target m, the updated result is obtained. Similarly, for azimuth data vectors calculate If e θ,j ≤u0, θ j The parameter measurement set AOA added to the target m m In, and will meet condition e θ,j θ ≤u0 j from After removing the target m, the updated result is obtained. Proceed to step 9;

[0096] Step 17: The location information field is now complete after extraction at each level.

[0097] To enable those skilled in the art to better understand the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0098] Example 1:

[0099] Step 1: Assume the satellite's current position in the Earth-fixed coordinate system is represented as X. S1,e =[-4371.5km, 5213.6km, 2639.7km] T X S2,e =[-4359.4km, 5274.9km, 2533.4km] T The drone's location is X U,e =[-4371.5km, 5213.6km, 2639.7km] T There are three radar radiation sources on the Earth's surface, and their positions in the Earth-fixed coordinate system can be represented as: X 1,e =[-4616.1km, 3148.2km, 3094.1km] T X 2,e =[-4624.3km, 3521.7km, 2646.4km] T X 3,e =[-4823.3km, 3356.4km, 2512.1km] TTheir positions in the northeast-central coordinate system, with the UAV as the origin, are X and X'. 1,n =[100km,300km,0km] T ,X 2,n = [-200km, -200km, 0km] T ,X 3,n =[50km, -350km, 0km] T The pulse repetition periods of the target radar radiation sources are 500µs, 800µs, and 1200µs, respectively. The satellite and UAV observe the three radiation sources for 10ms. Since the satellite and UAV travel short distances within 10ms, the influence of the angle on the time difference is negligible; therefore, the satellite and UAV can be considered stationary. The satellite receives the pulse signals from the radiation sources and measures the pulse descriptors of each pulse train, having already undergone preprocessing such as frequency and pulse width adjustments. Satellite S i The arrival time of the pulse data of the target radar radiation source m is:

[0100]

[0101] Where, N m Let m be the number of pulses emitted by the target radar source. If the three target radar sources emit 20, 12, and 8 pulses respectively, then the pulse counts of the three target radar sources reaching satellite S are... i The time set can be represented as:

[0102]

[0103] Sort the pulse sequences in the above formula according to their arrival times. The sorted arrival time sequence is denoted as: The simulation diagram of pulse arrival delay is as follows: Figure 2 As shown in the figure, since the radiation source is closer to the UAV, the overall delay of the signal reaching the UAV is less than that of the satellite. At the same time, the pulses from different target radiation sources will arrive at different observation platforms in an interleaved manner.

[0104] Step 2: Divide the area within the UAV's line of sight into grid points. The UAV's line of sight is 400km. In a northeast-northeast coordinate system with the UAV as the origin, set the radiation source observation area X = {(x,y), -400km≤x,y≤400km}, and the grid points are X. k,l =(x k ,y l ), k = 1, 2, ..., 160, l = 1, 2, ..., 160, where the number of grid points along the x-axis is N. x =160, the number of grid points along the y-axis is N y =160, grid interval is 400 / 16 = 5km;

[0105] Step 3: Based on the observation areas of the satellite and the UAV, the feasible time window for full pulse pairing is calculated by inversion. Based on the path difference of the radar radiation source pulse signal to the two satellites, the time difference value at each grid node can be calculated by inversion.

[0106]

[0107] Iterate through all the positioning grid nodes to obtain the time difference corresponding to each grid node. The set of:

[0108]

[0109] Step 4: From the time difference set T 0 The maximum time difference t is obtained from kl,max = -0.1790ms and minimum time difference t kl,min = -0.3071ms, based on this, the feasible time difference window for pulse coarse pairing is determined to be Δt = [-0.1790ms, -0.3071ms].

[0110] Step 5: Receiving the full pulse sequence via satellite Taking a certain pulse A as a reference, it is assumed here that the inherent time synchronization error between satellite systems is 0, i.e., T fix =0, and the feasible time window Δt for pulse pairing, determine the time axis range [T] for feasible pairing of pulse A. fix +t kl,min ,T fix +t kl,max ]=Δt=[-0.1790ms,-0.3071ms],If a paired pulse can be found, the full pulse sequence can be detected by the other satellite reconnaissance station. The TOA of the paired pulses is calculated, and the time difference tdoa1 is calculated for successful pulse pairing.

[0111] Step 6: Next, use the satellite full pulse sequence Using the second pulse B as a reference, repeat step 5 above to calculate the time difference tdoa2 for successful pairing of pulse B; and so on, until the entire sequence is successfully paired, obtaining the successfully paired pulses. The pairing results and the simulation diagram of the actual time difference are as follows: Figure 3 As shown in the figure, some coarsely paired time difference pulse pairs have values ​​close to the true time difference, but there are also some false time difference pulse pairs. These false pulse pairs will affect the positioning performance.

[0112] Step 7: Assume the UAV also receives pulse signals from three radar radiation sources on the Earth's surface, measures the pulse descriptors of each pulse train, and has already undergone preprocessing such as frequency and pulse width. The azimuth data of the target radar radiation source m measured by the UAV is as follows:

[0113]

[0114] The set of angles of the three target radar radiation sources measured by the UAV can be expressed as:

[0115]

[0116] Sort the pulse sequences in the above formula according to their arrival times. The sorted arrival time sequence is denoted as:

[0117] Step 8: Set the number of targets m = 0;

[0118] Step 9: And determine and Does an empty set exist? If an empty set exists, proceed to step 17.

[0119] Step 10: Construct an observation model for time difference and azimuth. Assume the time difference measurement error follows a pattern with a mean of zero and a variance of... The azimuth measurement errors all follow a Gaussian distribution with a mean of zero and a variance of . The Gaussian distribution.

[0120]

[0121]

[0122] Where X represents the position of the target radiation source in the Earth-fixed coordinate system, M is the rotation matrix from the Earth-fixed coordinate system to the Northeast-Sky coordinate system, and D... x = (1,0,0), D y = (0, 1, 0).

[0123] The results of the p-th observation from the satellite can be modeled as follows:

[0124] z 1,p =h 1,p (X)+v 1,p p = 1, 2, ..., P

[0125] The result of the qth observation by the UAV is established as follows:

[0126] z 2,q =h 2,q (X)+v 2,q ,q=1,2,...,Q

[0127] The specific expressions for each item are as follows:

[0128]

[0129] Step 11: Traverse all grid points in the grid and calculate the nominal Euclidean distance d1(z) for each grid point. 1,p ,h 1,p (X)) and d2(z) 2,q ,h 2,q (X)).

[0130]

[0131]

[0132] Step 12: Calculate the position information field function f X The value of (X / Z).

[0133]

[0134] Since the prior probability density of target X is unknown, p0(X) = 1, and C[·] is a cost function, it is possible to locate multiple indistinguishable targets.

[0135]

[0136] Where u0 is the threshold, set to 10.

[0137] Step 13: Find the maximum value (Max) and minimum value (Min) of the position information field function at all grid points. If the set of time difference and the set of azimuth contain a target, let the number of radiation sources m = m + 1; otherwise, go to step 17.

[0138] Step 14: Find the value that makes f X (X / Z) reaches its maximum value in X. k,l This is an estimate of the location of one of the radiation sources. And add it to the set of radiation source locations. middle.

[0139] Step 15: Based on the estimated location of the radiation source and the location of the observation station X U,e Calculate the azimuth and time difference corresponding to the radiation source using the following formula:

[0140]

[0141] in, Location of radiation source Position in the Earth-fixed coordinate system.

[0142] Step 16: For the time difference data set All time difference pairs, calculate If e t,i If ≤u0, then tdoa i For position The time difference value of the target measured by the satellite is obtained and appended to the parameter measurement set TDOA of the target m. m In, and will meet condition e t,i ≤u0 of tdoa i from After removing the target m, the updated result is obtained. Similarly, for azimuth data vectors calculate If e θ,j ≤u0, θ j The parameter measurement set AOA added to the target m m In, and will meet condition e θ,j θ ≤u0 j from After removing the target m, the updated result is obtained. Proceed to step 9.

[0143] Step 17: Location information field extraction completed. The location result is as follows: Figure 4 As shown in the figure, the comparison chart between the precise time difference and the actual time difference is as follows. Figure 5 As shown. From Figure 4 As can be seen in (a), there are multiple relatively parallel curves in the position information field. These are hyperbolic positioning lines obtained from satellite time difference observations, and the three lines intersecting the hyperbolic curves are direction-finding lines calculated from the UAV's azimuth angle. Figure 4 (b) It can be seen that there is a sharp peak in the location information field. This location is considered as an estimated value of a target radiation source (100km, 305km), and relevant measurement parameters are extracted from the time difference measurement set and the azimuth measurement set. Figure 4 As shown in (c), after the first extraction, the location information field is reduced by one time difference line and one direction finding line. The location of the second target radiation source (-195km, -195km) can be estimated from the extracted location information field. Figure 4 (e) and (f) estimated the location of the third radiation source (50 km, -345 km), which is close to the actual location. Figure 4 As can be seen in (g), the azimuth measurement set is empty after three extractions, so the extraction process ends. Figure 5 The precise time difference for each target was extracted and compared with the actual time difference, showing that false time difference values ​​have been successfully eliminated.

[0144] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A space-air cooperative multi-target sorting and positioning method based on a location information field, characterized in that, include The two satellites respectively receive the pulse signals from the target radar radiation source, measure the pulse descriptor of their respective pulse trains, and obtain the pulse data arrival time; Divide the visible area of ​​the UAV into grid points, and calculate the time difference at each grid node based on the path difference of the target radar radiation source pulse signal to the two satellites, and extract the maximum and minimum time difference values. The pulse coarse pairing time difference window is determined based on the maximum and minimum time difference values. Coarse pairing of the two satellite pulses is then performed using this window, and the time difference for successful pairing is calculated based on the pulse data arrival times. Specifically: The time axis range for pulse pairing is determined based on the inherent time system error between satellite systems and the pulse coarse pairing time difference window. Pairing pulses between two satellites are found within the time axis range, and the arrival time of the pairing pulses is subtracted to obtain the time difference for successful pairing. The UAV receives the pulse signal from the target radar radiation source, measures the pulse descriptor of each pulse train, and obtains the azimuth angle of the target radar radiation source. Establish an observation model based on time difference and azimuth angle, and construct a target radiation source position information field function based on the observation model based on time difference and azimuth angle; based on the target radiation source position information field function combined with the time difference of successful pairing and the azimuth angle obtained by the UAV, use a step-by-step extraction method to determine the position information and parameter measurement values ​​of multiple targets, and at the same time complete the fine pairing of pulses; The establishment of the observation model based on time difference and azimuth angle, and the construction of the target radiation source position information field function based on the observation model based on time difference and azimuth angle; specifically: The measurement errors of time difference and azimuth angle are set to follow a Gaussian distribution. An observation model for time difference and azimuth angle is established. The first nominalized Euclidean distance and the second nominalized Euclidean distance of each grid point are calculated. The first nominalized Euclidean distance is related to the estimated time difference, and the second nominalized Euclidean distance is related to the estimated azimuth angle. The target radiation source position information field function is constructed based on the first nominalized Euclidean distance and the second nominalized Euclidean distance.

2. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 1, characterized in that, The determination of the pulse coarse pairing time difference window based on the maximum and minimum time difference is specifically as follows: The maximum time difference is used as the upper limit of the pulse coarse pairing time difference window, and the minimum time difference is used as the lower limit of the pulse coarse pairing time difference window.

3. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 1, characterized in that, The determination of the pulse pairing time axis range based on the inherent timing errors between satellite systems and the pulse coarse pairing time difference window is specifically as follows: The sum of the inherent timing error between satellite systems and the lower limit of the pulse coarse pairing time difference window is used as the lower limit of the pulse pairing time axis range, and the sum of the inherent timing error between satellite systems and the upper limit of the pulse coarse pairing time difference window is used as the upper limit of the pulse pairing time axis range.

4. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 1, characterized in that, The method of determining the position information and parameter measurements of multiple targets is based on the target radiation source location information field function, combined with the time difference of successful pairing and the azimuth angle obtained by the UAV, using a step-by-step extraction method. Specifically: Find the maximum and minimum values ​​of the target radiation source location information field function at all grid points, and determine whether the set of time difference and azimuth angle contains the target by comparing the absolute value of the difference between the maximum and minimum values ​​with the first threshold. If the set of time difference and azimuth contains a target, then the estimated value of the target radiation source position is obtained based on the target radiation source position information field function, and the estimated value of the time difference and azimuth corresponding to the target radiation source is calculated based on the estimated value of the target radiation source position. The estimated time difference is compared with the time difference of successful pairing to determine whether the time difference of successful pairing should be retained; the estimated azimuth angle is compared with the azimuth angle acquired by the UAV to determine whether the azimuth angle acquired by the UAV should be retained; the retained time difference and azimuth angle are used as parameter measurement values.

5. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 4, characterized in that, The method of determining whether the time difference and azimuth set contain a target by comparing the absolute value of the difference between the maximum and minimum values ​​with a first threshold is as follows: if the following formula is satisfied, the measurement time difference set and azimuth set contain a target; in, Max , Min These represent the maximum and minimum values ​​of the target radiation source location information field function at all grid points, respectively. For a given value.

6. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 4, characterized in that, The process of comparing the estimated time difference with the time difference of successful pairing to determine whether to retain the time difference of successful pairing is as follows: the time difference of successful pairing is retained when the following formula is satisfied: in, The time difference between successful pairing at the estimated location of the target radiation source. This is an estimate of the time difference. This represents the standard deviation of the time difference measurement error.

7. The air-space cooperative multi-target sorting and positioning method based on a location information field according to claim 4, characterized in that, The step of comparing the estimated azimuth angle with the azimuth angle acquired by the UAV to determine whether to retain the azimuth angle acquired by the UAV is as follows: the azimuth angle acquired by the UAV is retained if the following formula is satisfied: in, The azimuth angle obtained by the UAV is the estimated location of the target radiation source. This is the estimated azimuth angle. This represents the standard deviation of the azimuth measurement error.

8. A computer system, characterized in that... include: One or more processors, a computer-readable storage medium, for storing one or more programs, wherein, when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to perform the method of any one of claims 1-7.

Images