Space-borne radar aerial target height estimation method based on multi-path measurement

Abstract

The invention discloses a satellite-borne radar aerial target height estimation method based on multi-path measurement. The method comprises the following steps: acquiring a signal transmission path when a satellite-borne radar irradiates an aerial target; the signal transmission path comprises a transmitting path, a reflecting path and a scattering path which are acquired under a micro-multipath phenomenon; key point information in the signal transmission path is extracted; solving the height of the aerial target by using the key point information; according to the method, under the condition that the spaceborne radar generates the micro-multipath phenomenon on the air target, the geometrical relationship model is constructed by using the signal transmission path in the micro-multipath phenomenon, and the height of the air target is solved by using a geometric method based on the geometrical relationship model, so that the problem that the measurement error of the pitch angle of the air target by a single spaceborne radar is relatively large is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite-borne radar target tracking, and in particular relates to a satellite-borne radar aerial target height estimation method based on multi-path measurement. Background Art

[0002] Satellite-borne radar has all-weather, all-day strategic and tactical early warning capabilities, and is not restricted by the curvature of the earth and is not easily attacked. It occupies a very important position in the early warning and defense system.

[0003] Generally speaking, when a single satellite-borne radar tracks and locates an aerial target, its pitch angle measurement error is greater than the radial distance measurement error and azimuth measurement error of the aerial target, resulting in the single satellite-borne radar not being able to estimate the altitude of the aerial target. The lack of altitude information of the aerial target seriously amplifies the positioning error of the aerial target, and is not conducive to the attribute discrimination and threat estimation of the aerial target. Summary of the invention

[0004] The purpose of the present invention is to provide a method for estimating the altitude of an aerial target using a satellite-borne radar based on multipath measurement, so as to reduce the measurement error of the pitch angle of an aerial target by a single satellite-borne radar.

[0005] The present invention adopts the following technical solutions:

[0006] A method for estimating the height of an aerial target using a spaceborne radar based on multipath measurement comprises the following steps:

[0007] Obtain the signal transmission path when the spaceborne radar illuminates the aerial target; the signal transmission path includes the transmission path, reflection path and scattering path obtained under the micro-multipath phenomenon;

[0008] Extract key point information in the signal transmission path;

[0009] Use key point information to solve the height of aerial targets.

[0010] Furthermore, the key point information includes: the position of the satellite-borne radar, the position of the aerial target, the position where the signal is reflected or scattered, the projection point of the aerial target on the ground, the symmetric point of the aerial target about the projection point, the position of the center of the earth, the first auxiliary point and the second auxiliary point;

[0011] The first auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the position of the aerial target;

[0012] The second auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the symmetrical point.

[0013] Furthermore, using key point information to solve the height of the aerial target includes:

[0014] The equation for the height of the aerial target is established as:

[0015] (2|GT| 3 +(-|ST'| 2 +2|OS| 2 -2|OG| 2 -|ST| 2 )|GT|-|OG||ST'| 2 +|OG||ST| 2 ) / (|OG|-|GT|)=0

[0016] Among them, |GT| represents the distance from the position of the aerial target to the projection point, that is, the height of the aerial target, |ST'| represents the distance from the position of the satellite-borne radar to the symmetric point, |OS| represents the distance from the position of the satellite-borne radar to the center of the earth, |OG| represents the distance from the projection point to the center of the earth, and |ST| represents the radial distance from the position of the satellite-borne radar to the position of the aerial target.

[0017] Furthermore, using key point information to solve the height of the aerial target also includes:

[0018] The equation of the air target height is converted into a cubic equation and expressed as:

[0019]

[0020] Further, an equation for the height of the aerial target is established based on the first geometric relationship, the second geometric relationship, and the third geometric relationship;

[0021] The first geometric relationship is the proportional geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetrical point, which can be expressed as:

[0022]

[0023] Among them, |MT| represents the distance from the position of the aerial target to the first auxiliary point, |NT'| represents the distance from the second auxiliary point to the symmetrical point, |OM| represents the distance from the center of the earth to the first auxiliary point, |ON| represents the distance from the center of the earth to the second auxiliary point, |SM| represents the distance from the position of the spaceborne radar to the first auxiliary point, and |SN| represents the distance from the position of the spaceborne radar to the second auxiliary point.

[0024] The second geometric relationship is the geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetric point, which is expressed as:

[0025] |MT| 2 +|SM| 2 =|ST| 2

[0026] |NT′| 2 +|SN| 2 =|ST′| 2 ,

[0027] The third geometric relationship is the geometric relationship between the position of the spaceborne radar, the position of the aerial target, the first auxiliary point, the second auxiliary point and the symmetric point, which is expressed as:

[0028] |MT| 2 +|OM| 2 =|OT| 2

[0029] |NT′| 2 +|ON| 2 =|OT′| 2 ,

[0030] Among them, |OT| represents the distance from the position of the aerial target to the center of the earth, and |OT'| represents the distance from the center of the earth to the symmetric point.

[0031] Furthermore, before establishing the equation for the height of the aerial target, the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, the Gaussian distribution of the radial distance from the position of the satellite-borne radar to the position of the aerial target, the Gaussian distribution of the distance from the position of the satellite-borne radar to the symmetric point, and the Gaussian distribution of the distance from the projection point to the center of the earth are obtained, which are expressed as:

[0032]

[0033] in, represents the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, μ S represents the semi-major axis of the spaceborne radar, represents the error of the semi-major axis of the spaceborne radar, represents the Gaussian distribution of the radial distance from the satellite-borne radar to the aerial target, μ T Indicates the radial distance from the position of the satellite-borne radar to the position of the aerial target. It represents the measurement error of the radial distance from the position of the spaceborne radar to the position of the aerial target. represents the Gaussian distribution of the distance from the satellite-borne radar to the symmetric point, μ T′ represents the distance from the position of the satellite-borne radar to the symmetric point, Represents the measurement error of the distance from the position of the spaceborne radar to the symmetric point, Represents the Gaussian distribution of the distance from the projection point to the center of the earth, μ G Represents the distance from the projection point to the center of the earth. Represents the error in the distance from the projected point to the center of the earth.

[0034] Furthermore, the process of solving the cubic equation includes:

[0035] Using the Cardinal formula to solve the cubic equation, we get the root of the equation, expressed as:

[0036]

[0037] in,

[0038] make Calculation shows that Δ≥0, so the cubic equation has 1 real root and 2 complex roots, among which the real root is the height value of the aerial target.

[0039] Furthermore, the satellite-borne radar is a single satellite-borne radar.

[0040] An electronic device, comprising:

[0041] at least one processor;

[0042] and, a memory communicatively coupled to the at least one processor;

[0043] The memory stores instructions that can be executed by at least one processor, and the instructions are executed by at least one processor so that the at least one processor can execute any one of the above methods for estimating the altitude of aerial targets using a satellite-borne radar based on multi-path measurement.

[0044] The beneficial effect of the present invention is that when a satellite-borne radar generates micro-multipath phenomenon to an aerial target, the present invention utilizes the signal transmission path in the micro-multipath phenomenon to construct a geometric relationship model, and utilizes the geometric method based on the geometric relationship model to solve the height of the aerial target, thereby solving the problem that a single satellite-borne radar does not have the ability to estimate the height of the aerial target. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of the method of the present invention;

[0046] Figure 2 This is a schematic diagram of the micro-multipath path of the spaceborne radar to the aerial target;

[0047] Figure 3 A geometric relationship model diagram of the spaceborne radar and the aerial target in the present invention;

[0048] Figure 4 It is the 2D real trajectory diagram of the spaceborne radar tracking the aerial target in STK;

[0049] Figure 5 This is a 3D image of an aerial target. DETAILED DESCRIPTION

[0050] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Spaceborne radar aerial target tracking is a process of high-precision aerial target tracking based on the motion model of the aerial target and the radar measurement, using a nonlinear filtering method. There are two main errors when the spaceborne radar observes the aerial target, one is the measurement error, and the other is the positioning error of the detection platform itself. Both errors have an impact on the tracking of aerial targets. In order to solve the problem of excessive pitch angle measurement error, it is generally assumed that an aerial target height is used, and then the pitch angle is estimated using geometry or other methods to reduce the tracking error. However, the lack of aerial target height information leads to inaccurate aerial target pitch angle methods.

[0052] Since satellite-borne radar uses the reflection of electromagnetic waves to detect aerial targets, when there is mirror reflection in the area detected by the satellite-borne radar, such as the sea, micro-multipath measurements can generally be obtained. Specifically, when the satellite-borne radar emits electromagnetic waves to the area where the aerial target is located, it not only obtains electromagnetic waves directly reflected from the aerial target, but also obtains electromagnetic waves reflected from the aerial target to the ground / sea and then reflected back. Using this multipath measurement, a single satellite-borne radar can estimate the height of an aerial target. However, there is currently no research on estimating the height of an aerial target using a single satellite-borne radar.

[0053] A method for estimating the height of aerial targets using spaceborne radar based on multipath measurement, such as Figure 1 shown.

[0054] S110, obtaining a signal transmission path when the satellite-borne radar illuminates an aerial target; the signal transmission path includes a transmission path, a reflection path, and a scattering path obtained under a micro-multipath phenomenon;

[0055] Specifically:

[0056] How to measure micro-multipath of aerial targets by spaceborne radar Figure 2 As shown in the figure, the solid line represents the transmitted ray (i.e., it is emitted from the satellite-borne radar and then illuminates the aerial target), while the dotted line represents the received ray (i.e., it is scattered from the aerial target and then received by the satellite-borne radar). Considering that the ground is a mirror reflection, after the satellite-borne radar transmits the ray, one ray directly illuminates the aerial target, and at the same time, another ray is reflected by the ground or sea surface and then illuminates the aerial target. Similarly, for the backscattered echo signal of the aerial target, the received ray can be directly reflected to the satellite-borne radar, and another ray is reflected by the ground or sea surface and then reaches the satellite-borne radar.

[0057] Therefore, there are four path combinations for transmitting electromagnetic waves from the spaceborne radar to the aerial target and then scattering from the aerial target to the spaceborne radar. Figure 2As shown, the four paths are: from the satellite-borne radar to the aerial target, and then scattered from the aerial target back to the satellite-borne radar, that is, the ①-②-③ path; from the satellite-borne radar to the aerial target, and then scattered from the aerial target to the sea surface / ground to the satellite-borne radar, that is, the ①-②-④-⑥ path; from the satellite-borne radar to the sea surface / ground, and then reflected to the aerial target and then returned to the satellite-borne radar, that is, the ⑦-⑤-②-③ path; from the satellite-borne radar to the sea surface / ground, and then reflected to the aerial target, and finally scattered from the aerial target to the sea surface / ground to the satellite-borne radar, that is, ⑦-⑤-②-④-⑥. Generally speaking, this situation (i.e., ⑦-⑤-②-④-⑥) rarely occurs because the energy decays quickly and the signal level cannot be detected. Therefore, the measurement of this path is not considered in the present invention.

[0058] The measurements of spaceborne radar generally include radial distance, azimuth, elevation angle and Doppler frequency. When micro-multipath measurement occurs, the radial distance measurement reflected by the ground / sea surface will be larger, while other measurements will not change significantly. Generally speaking, in a sub-beam shot by the spaceborne radar at an aerial target, among the multiple measurements returned, if only the radial distance has a large difference, while the azimuth and Doppler frequency have small differences, then the measurement with a large radial distance can be considered to be a micro-multipath measurement.

[0059] The calculation formula for the radial distance from a satellite-borne radar to an aerial target is generally:

[0060]

[0061] Among them, τ is the delay of signal propagation and c is the speed of light.

[0062] For radial distances that are not micro-multipath measurements, i.e., the ①-②-③ path, (0.1) can accurately calculate the radial distance. However, for micro-multipath measurements, i.e., the ①-②-④-⑥ path and the ⑦-⑤-②-③ path, corrections are required when calculating the radial distance. The calculation formula is:

[0063] R′ mp =2R mp -R (0.2)

[0064] Among them, R mp Represents the radial distance of micro-multipath measurement, R is the radial distance measured by direct path,

[0065] S120, extracting key point information in the signal transmission path; the key point information includes: the position of the satellite-borne radar, the position of the aerial target, the position where the signal is reflected or scattered, the projection point of the aerial target on the ground, the symmetric point of the aerial target about the projection point, the center of the earth, the first auxiliary point and the second auxiliary point;

[0066] The first auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the position of the aerial target;

[0067] The second auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the symmetrical point.

[0068] Specifically:

[0069] According to the signal transmission path, the geometric relationship between the satellite-borne radar and the aerial target is further established. Figure 3 As shown. Point O represents the center of the earth, point S represents the position of the satellite-borne radar, point T represents the position of the aerial target, point P is the position where the signal is reflected or scattered, that is, the position where the micro-multipath measurement intersects the ground / sea surface, point G is the projection point of the aerial target on the ground, point T′ is the symmetric point of the aerial target about the projection point G, point M is the first auxiliary point, located on the line connecting the position of the satellite-borne radar and the center of the earth, and is in the same horizontal plane as the position of the aerial target, and point N is the second auxiliary point, located on the line connecting the position of the satellite-borne radar and the center of the earth, and is in the same horizontal plane as the symmetric point.

[0070] |ST| represents the radial distance from the satellite-borne radar to the aerial target, and |SP|+|PT| can represent the radial distance measurement obtained by the micro-multipath phenomenon when the satellite-borne radar illuminates the aerial target. |OS| represents the distance from the satellite-borne radar to the center of the earth, and |OT| represents the distance from the aerial target to the center of the earth. According to the symmetry, the height of the aerial target |GT|=|GT′|, and |PT|=|PT′|, then the micro-multipath measurement |SP|+|PT| can be equivalent to |ST′|. |ST′| is the distance from the satellite-borne radar to the symmetric point T′, and |OG| is the distance from the projection point G to the center of the earth.

[0071] The distance from the satellite-borne radar to the center of the earth, the radial distance from the satellite-borne radar to the aerial target, and the distance from the projection point to the center of the earth are relatively easy to obtain, and the error is very small; the distance from the satellite-borne radar to the symmetric point can be approximated as the radial distance of the micro-multipath measurement. In order to utilize this measurement, the present invention approximates it to the distance from the satellite-borne radar to the symmetric point when solving the geometric relationship. The approximate error is not only very small, but can also be used for altitude estimation; therefore, selecting the above distances and reference points is more convenient for calculation and measurement, and the calculation results are more accurate.

[0072] S130, using key point information to solve the height of the aerial target;

[0073] Specifically:

[0074] Obtain the Gaussian distribution of known quantities (i.e., the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, the Gaussian distribution of the radial distance from the position of the satellite-borne radar to the position of the aerial target, the Gaussian distribution of the distance from the position of the satellite-borne radar to the symmetric point, and the Gaussian distribution of the distance from the projection point to the center of the earth), expressed as:

[0075]

[0076] in, represents the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, μ S represents the semi-major axis of the spaceborne radar, represents the error of the semi-major axis of the spaceborne radar, represents the Gaussian distribution of the radial distance from the satellite-borne radar to the aerial target, μ T Indicates the radial distance from the position of the satellite-borne radar to the position of the aerial target. It represents the measurement error of the radial distance from the position of the spaceborne radar to the position of the aerial target. represents the Gaussian distribution of the distance from the satellite-borne radar to the symmetric point, μ T′ represents the distance from the position of the satellite-borne radar to the symmetric point, Represents the measurement error of the distance from the position of the spaceborne radar to the symmetric point, Represents the Gaussian distribution of the distance from the projection point to the center of the earth, μ G Represents the distance from the projection point to the center of the earth. Represents the error in the distance from the projected point to the center of the earth.

[0077] The area detected by the spaceborne radar is generally known, and |OG| can be approximated by the latitude of the center of the detection area, where the mean μ G can be calculated as:

[0078]

[0079] Among them, a = 6378.137 km is the equatorial radius of the earth, b = 63563.752 km is the polar radius of the earth, and φ is the latitude of the center of the detection area.

[0080] Next, the expression of the aerial target height |GT| is derived based on the geometric relationship.

[0081] According to the proportional geometric relationship between triangle OMT and triangle ONT′ (i.e. the proportional geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetrical point), we can get:

[0082]

[0083] And according to the geometric relationship between triangle OMT and triangle ONT′ (i.e. the geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetrical point), we have:

[0084]

[0085] According to the geometric relationship between triangle SMT and triangle SNT′ (i.e., the geometric relationship between the position of the spaceborne radar, the position of the aerial target, the first auxiliary point, the second auxiliary point and the symmetric point), we have:

[0086]

[0087] Combining formulas (0.5), (0.6) and (0.7), we finally get the equation for the height of the aerial target:

[0088] (2|GT| 3 +(-|ST'| 2 +2|OS| 2 -2|OG| 2 -|ST| 2 )|GT|-|OG||ST'| 2 +|OG||ST| 2 ) / (|OG|-|GT|)=0

[0089] For the convenience of representation, the following symbols are used for simplification:

[0090] x=|GT|, a=|ST′|, b=|OS|, c=|OG|, d=|ST| (0.8)

[0091] Then the equation for the height of the aerial target is simplified to:

[0092] (2x 3 +(-a 2 +2b 2 -2c 2 -d 2 )x-ca 2 +cd 2 ) / (cx)=0 (0.9)

[0093] In the above formula, since the height of the aerial target will not be equal to |OG|, that is, (cx)≠0, the cubic equation for the height x of the aerial target is obtained:

[0094]

[0095] Simplified to:

[0096]

[0097] This equation is a standard cubic equation and can be solved by applying the Cardinal formula.

[0098]

[0099] For equation (0.10), we can apply the Cardinal formula to solve it, and the roots we get are:

[0100]

[0101] From this equation, we obtain three solutions. When Δ≥0, the equation has 1 real root and two complex roots; when Δ<0, the equation has 3 real roots. Let's analyze the sign of Δ.

[0102] first, and Depends on the sign of p. Since the orbital altitude of the satellite-borne radar is very high, and the altitude of the aerial target is usually within 30km, Figure 3 The middle triangle OSG can get b 2 -c 2 >d 2 The radial distance of the micro-multipath of an aerial target is generally only a dozen kilometers greater than the radial distance of the direct path. 2 -c 2 >a 2 , so p>0, then Δ>0. Therefore, this equation can only get one real root and two complex roots, among which the real root is the required solution, that is, the height value of the aerial target.

[0103] In the simulation test, if the height of the aerial target is known, the micro-multipath measurement a can be solved according to the equation in formula (0.10), and the expression is:

[0104]

[0105] The satellite-borne radar used in the present invention is a single satellite-borne radar. Compared with the height estimation by multiple radars, the geometric model constructed when estimating the height by using a single radar is also simpler, which reduces the amount of calculation and complexity, while also ensuring the accuracy of the calculation. At the same time, the difficulty of single satellite-borne radar in height estimation is overcome, and the method of the present invention can still be used for multiple satellite-borne radars to estimate the height of the same aerial target.

[0106] Regarding the present invention's use of the micro-multipath phenomenon to estimate the altitude of aerial targets, there is currently no method for using micro-multipath measurement on a satellite-borne radar to estimate the altitude, nor is there any other effective method for estimating the altitude on a single satellite-borne radar; secondly, micro-multipath measurement is very common, and micro-multipath measurement is equivalent to a supplement to the radar's measurement of the direct path to the same target point, so it can have more information about the target; finally, the present invention uses radial distance measurement of direct path and micro-multipath, and the ranging error of this measurement is very small, so a more accurate target altitude can be estimated.

[0107] Example 1

[0108] Case 1 (Using micro-multipath measurement to estimate the altitude of an aerial target using a single satellite-borne radar)

[0109] Using STK software, the orbital parameters of the spaceborne radar satellite are set as shown in Table 1.

[0110] Table 1 Number of satellite orbits

[0111]

[0112] The attitude angle of the radar body coordinate system relative to the orbital coordinate system is: rolling angle r c =75°, pitch angle Yaw angle φ c = 5°. Assume that the latitude and longitude of the center of the detection area are 116.5° and 21.5° respectively, add an aerial simulation target to move in a straight line, and its altitude rises from 0.1km to 11km. Figure 4 and Figure 5 shown. Figure 4 This is the 2D real trajectory diagram of the satellite-borne radar tracking the aerial target in STK. The blue part is the sea surface, the purple arc is the projection of the satellite-borne radar's orbit on the 2D plane, the purple fan-shaped part is the detection field of view of the satellite-borne radar, the purple box part is the aerial target, and the orange line is the trajectory projection of the satellite-borne radar that can detect the aerial target. Figure 5 This is a 3D picture of an aerial target, where the blue part is the sea surface, the brown part is the sky, the yellow dots are aerial targets, and the yellow lines are the 3D trajectory of the aerial target.

[0113] First, the simulation generates the true values ​​of |OS|, |ST|, |ST′| and |OG| of the aerial target within the detection field of view of the satellite-borne radar within a period of 180 seconds with a sampling interval of 3 seconds. Among them, |OS| is obtained by the value of the semi-major axis of the satellite-borne radar in STK, |ST| is obtained by the ECEF coordinate system position of the satellite-borne radar and the aerial target; |ST′| is solved by substituting the true height |GT| of the aerial target into equation (0.13); |OG| is calculated by substituting the true latitude of the aerial target into equation (0.4).

[0114] The following is the simulation content.

[0115] Simulation 1: Uncertainty estimation of the height of a single aerial target, that is, sampling the Gaussian variables |OS|, |ST|, |ST′|, and |OG| at a single moment, and then estimating the height of the aerial target. Through Monte Carlo simulation, the mean and variance are obtained from the estimate of the height of the aerial target.

[0116] An aerial target is analyzed at a sampling time, and its longitude is 116.3844°, latitude is 21.4349°, and altitude is 5.5197km. Set |OS|, |ST|, |ST′|, and |OG| to follow the distribution as follows:

[0117]

[0118] Then, 1000 Monte Carlo (MCMC) simulations are performed. In a single MCMC, |OS|, |ST|, |ST′|, and |OG| are sampled, and the sampled values ​​are substituted into formula (0.12) to calculate the height of the aerial target. For the aerial target height calculated by 1000 Monte Carlo simulations, the root mean square error RMSE of the height estimation is calculated as follows:

[0119]

[0120] Where N is the number of simulations calculated, is the estimated value of the aerial target height obtained by the ith Monte Carlo solution, x true It is the true altitude value of the aerial target.

[0121] Estimated altitude of aerial targets obtained from 1000 Monte Carlo simulations The mean of the aerial target height estimates is calculated as follows:

[0122]

[0123] in, is the mean of the Monte Carlo aerial target height estimates.

[0124] The final results are shown in Table 2:

[0125] Table 2 Target height estimation results of 1000 Monte Carlo simulations

[0126]

[0127]

[0128] Simulation 2: Estimate the height of the aerial target at multiple sampling moments. The height of the aerial target varies from 0.1km to 11km. Finally, compare the RMSE of the aerial target height estimation.

[0129] Set the standard deviations of |OS|, |ST|, |ST′|, and |OG| as follows:

[0130]

[0131] Corresponding noise is added to the true values ​​of |OS|, |ST|, |ST′| and |OG|, and a total of 360 sampling point data are generated in the process of the aerial target height changing from 0.1km to 11km. Then the RMSE of the aerial target height estimation is calculated to be 0.0639km, which is small. It can be seen that the height estimation value obtained by the method of the present invention has a small error and the result is more accurate.

Claims

1. A method for estimating the height of an aerial target using a spaceborne radar based on multipath measurement, characterized in that: The following steps are involved: Acquire a signal transmission path when the satellite-borne radar illuminates an aerial target; the signal transmission path includes a transmission path, a reflection path, and a scattering path acquired under a micro-multipath phenomenon; Extract key point information in the signal transmission path; Use key point information to solve the height of aerial targets.

2. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 1, characterized in that: The key point information includes: the position of the satellite-borne radar, the position of the aerial target, the position where the signal is reflected or scattered, the projection point of the aerial target on the ground, the symmetrical point of the aerial target about the projection point, the center of the earth, the first auxiliary point and the second auxiliary point; The first auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the position of the aerial target; The second auxiliary point is on the line connecting the position of the satellite-borne radar and the position of the center of the earth, and is in the same horizontal plane as the symmetrical point.

3. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 2, characterized in that: Using key point information to solve the height of aerial targets includes: The equation for the height of the aerial target is established as: (2|GT| 3 +(-|ST'| 2 +2|US| 2 -2|AND| 2 -|ST| 2 )|GT|-|OG||ST'| 2 +|AND||ST| 2 ) / (|OG|-|GT|)=0 Among them, |GT| represents the distance from the position of the aerial target to the projection point, that is, the height of the aerial target, |ST'| represents the distance from the position of the satellite-borne radar to the symmetric point, |OS| represents the distance from the position of the satellite-borne radar to the center of the earth, |OG| represents the distance from the projection point to the center of the earth, and |ST| represents the radial distance from the position of the satellite-borne radar to the position of the aerial target.

4. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 3, characterized in that: Using key point information to solve the height of aerial targets also includes: The equation of the air target height is converted into a cubic equation and expressed as:

5. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 4, characterized in that: The equation for the height of the aerial target is established based on the first geometric relationship, the second geometric relationship and the third geometric relationship; The first geometric relationship is an equiproportional geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetrical point, which is expressed as: Wherein, |MT| represents the distance from the position of the aerial target to the first auxiliary point, |NT'| represents the distance from the second auxiliary point to the symmetrical point, |OM| represents the distance from the center of the earth to the first auxiliary point, |ON represents the distance from the center of the earth to the second auxiliary point, |SM| represents the distance from the position of the spaceborne radar to the first auxiliary point, and |SN| represents the distance from the position of the spaceborne radar to the second auxiliary point; The second geometric relationship is the geometric relationship between the position of the aerial target, the position of the center of the earth, the first auxiliary point, the second auxiliary point and the symmetrical point, which is expressed as: |MT| 2 +|SM| 2 =|ST| 2 |NT′| 2 +|SN| 2 =|ST′| 2 , The third geometric relationship is the geometric relationship between the position of the satellite-borne radar, the position of the aerial target, the first auxiliary point, the second auxiliary point and the symmetrical point, which is expressed as: |MT| 2 +|OM| 2 =|OT| 2 |NT′| 2 +|ON| 2 =|OT′| 2 , Wherein, |OT| represents the distance from the position of the aerial target to the center of the earth, and |OT'| represents the distance from the center of the earth to the symmetric point.

6. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 5, characterized in that: Before establishing the equation for the height of the aerial target, the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, the Gaussian distribution of the radial distance from the position of the satellite-borne radar to the position of the aerial target, the Gaussian distribution of the distance from the position of the satellite-borne radar to the symmetric point, and the Gaussian distribution of the distance from the projection point to the center of the earth are obtained, which are expressed as: in, represents the Gaussian distribution of the distance from the satellite-borne radar to the center of the earth, μ s represents the semi-major axis of the spaceborne radar, represents the error of the semi-major axis of the spaceborne radar, represents the Gaussian distribution of the radial distance from the satellite-borne radar to the aerial target, μ T Indicates the radial distance from the position of the satellite-borne radar to the position of the aerial target. It represents the measurement error of the radial distance from the position of the spaceborne radar to the position of the aerial target. represents the Gaussian distribution of the distance from the satellite-borne radar to the symmetric point, μ T′ represents the distance from the position of the satellite-borne radar to the symmetric point, represents the measurement error of the distance from the position of the spaceborne radar to the symmetric point, represents the Gaussian distribution of the distance from the projection point to the center of the earth, μ G represents the distance from the projection point to the center of the earth, Represents the error of the distance from the projection point to the center of the earth.

7. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 6, characterized in that: The process of solving the cubic equation includes: Using the Cardinal formula to solve the cubic equation, we get the root of the equation, expressed as: in, make Calculation shows that Δ≥0, so the cubic equation has 1 real root and 2 complex roots, among which the real root is the height value of the aerial target.

8. The method for estimating the height of an aerial target using a space-borne radar based on multipath measurement according to claim 7, characterized in that: The satellite-borne radar is a single satellite-borne radar.

9. An electronic device, characterized in that: include: at least one processor; and, a memory communicatively coupled to at least one of the processors; Wherein, the memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that at least one of the processors can execute a method for estimating the height of aerial targets using a satellite-borne radar based on multipath measurement as described in any one of claims 1 to 8.

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