Low-orbit forward scattering detection method and system and medium

Abstract

The invention provides a low-orbit forward scattering detection method and system and a medium. Comprising the steps that a low-orbit forward scattering detection model based on Walker constellation configuration is constructed, each satellite and a receiver form a detection unit, and after an aerial target is excited by a radiation signal of a satellite group {}, if the kth detection unit meets a bistatic angle, according to the Cavalieri principle and a signal-to-noise ratio threshold condition, the kth detection unit meets the bistatic angle; determining a real effective coverage ratio meeting a geometric constraint condition and a detectable elevation threshold meeting a power constraint condition; an effective detection window is formed in the shadow cone unit based on the true effective coverage ratio and the detectable elevation threshold, and low-orbit forward scattering detection is performed. According to the method, the detection performance of the low-orbit forward scattering detection system under the conditions of different satellite numbers, different detection wavelengths and the like is analyzed, and theoretical support is provided for reliable airspace perception of the low-orbit giant constellation forward scattering detection system.

Description

Technical Field

[0001] This invention relates to the field of forward scattering detection technology, and more particularly to low-orbit forward scattering detection methods, systems, and media. Background Technology

[0002] Bistatic satellite-ground detection systems utilize satellite signals as a radiation source, receiving the scattered signals from the target through ground receiving stations to detect it. Forward scattering detection systems based on large low-Earth orbit (LEO) constellations are a subcategory of this system, utilizing the forward scattering effect generated when a target passes through a constellation of LEO satellites to achieve target detection. In radar technology, forward scattering manifests as a significant increase in the target's radar cross section (RCS) when the angle between the target and the transmitter / receiver is close to 180°. If the transmitted signal wavelength is much smaller than the target size, this effect is primarily determined by the target's shape and is insensitive to material properties. On one hand, forward scattering provides enhanced RCS for long-baseline reconnaissance in power-constrained bistatic satellite-ground detection systems, enhancing their ability to resist stealth detection. On the other hand, the network configuration of large LEO constellations creates physical conditions for all-weather, all-time, wide-area detection that ground-based monostatic radars cannot match.

[0003] The existing space-to-ground bistatic detection scheme still has the following technical problems: (1) Existing technologies mostly focus on medium and high orbit satellite resources, and there is insufficient research and analysis on the performance of forward scattering systems under low orbit satellite resources. In particular, no effective conclusions have been reached on key parameters such as quantization power constraints, detection range limits and estimation of detectable target size. (2) The multi-base forward scattering radar has not yet been fully utilized to meet the excellent multi-satellite networking conditions brought about by future low-Earth orbit mega-constellations, and lacks quantitative indicators of forward scattering detection performance for large-scale satellite networking conditions. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a low-Earth orbit (LEO) forward scattering detection method, system, and medium. Through multi-parameter joint simulation and systematic verification, the detection performance of the LEO forward scattering detection system under different satellite numbers and detection wavelengths is analyzed, providing theoretical support for reliable airspace sensing of LEO mega-constellations of forward scattering detection systems. In a first aspect, the present invention proposes a low-orbit forward scattering detection method, which specifically includes the following steps: A low-Earth orbit forward scattering detection model based on the Walker constellation configuration is constructed. In this model, a receiving station Rx is defined, and the receiving station Rx and K satellites Tx constitute K detection units, where K is the receiver's observation cutoff elevation angle. The above is the number of visible satellites; let the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit be denoted as . The effective size of the aerial target P observed from the k-th detection unit is defined as... ; When aerial targets are affected by satellite constellations After the radiation signal of} is excited, if the k-th ( ) Detection units satisfy bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraint condition and the detectable elevation angle threshold that satisfies the power constraint condition are determined. In the shadow cone unit, an effective detection window is formed based on the true effective coverage ratio and the detectable elevation angle threshold, and low-orbit forward scattering detection is performed. The shadow cone element is defined with the receiving station Rx as the vertex and the unit vector from the receiving station Rx to the k-th satellite as the axis, with a half-vertex angle of . The conical region enclosed by it.

[0005] Furthermore, the Walker constellation configuration includes a total number of satellites. T Number of orbital planes Q and the phase factor between orbits F The position of a satellite on the orbital plane is determined by its basic orbital parameters. Constraints; The satellite sequence numbers in the low-Earth orbit satellite constellation are set as follows: ,satellite Right ascension of the ascending node and the initial true anterior angle They are represented as follows: in, Indicates the semi-major axis of the track. Indicates the orbital eccentricity. Indicates the orbital inclination angle. Indicates the argument of perigee. Indicates the right ascension of the ascending node. Let m represent the true anomaly angle, m represent the m-th orbital plane, and n represent the n-th satellite in a uniform phase configuration. , S represents the number of satellites in each orbital plane; , Let represent the right ascension of the ascending node and the true anomaly angle of the satellite (1,1), respectively.

[0006] Furthermore, based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio satisfying the geometric constraints and the detectable elevation angle threshold satisfying the power constraints are determined. Specifically, this includes setting the vertical distance between the aerial target P and the receiving station Rx as the height. And calculate the height of the kth detection unit at that height. The semi-major axis of the ellipse intercepted from the cross-sectional shape at that point ellipse eccentricity ellipse coverage area and the height Cross-sectional area of ​​the detection area below They are represented as follows: The effective coverage ratio per unit of the k-th detection unit is obtained by calculating the ratio of the coverage area of ​​the truncated ellipse to the area of ​​the detection region. ,when , hour: According to the minimum semi-vertex angle Obtain the minimum coverage performance of the k-th detection unit and thereby obtain the effective coverage ratio under ideal conditions. , which is expressed as the ratio of the area of ​​the k-th smallest covering ellipse to the area of ​​the overall detection cross section: Regarding the effective coverage ratio Introducing an occlusion correction factor Corrections are made to obtain the true effective coverage ratio. : in, Let be the satellite observation elevation angle of the k-th satellite. The cutoff elevation angle for satellites observed by the receiving station, where N is the number of satellites. and These are adaptive parameters.

[0007] Furthermore, the steps for determining the detectable elevation angle threshold that satisfies the power constraint include: The distance from the k-th satellite to the airborne target P is calculated based on the motion state of the k-th satellite. Distance from aerial target P to receiving station Rx Estimated as the elevation angle relative to satellite observation. The functions are expressed as follows: and And the distance between the k-th satellite and the receiving station Rx and Approximately and much larger than , and specifically expressed as: ) Will The whole is defined as the product of squares of the probe. : when hour, Follow Increasing and monotonically decreasing, according to the product of the squares of the maximum distance Determine the detectable elevation angle threshold satisfy: in, Let the altitude be the height of the k-th satellite. Let be the radius of the ideal sphere.

[0008] Furthermore, the maximum distance square product Based on the k-th detection unit, the following steps are taken: Estimated based on free-space link loss and target forward scattering characteristics, and the projected area of ​​the airborne target P's profile in the transmission and reception directions. Determine the ground power of the scattered signal and the forward-scattered signal-to-noise ratio model of the receiving station : According to the forward scattering signal-to-noise ratio model Obtain the receive power threshold and the maximum distance square product : Where EIRP is the equivalent radiated power emitted by the satellite. The antenna gain for the satellite radiation source and the ground receiving station Rx. The wavelength of the transmitted signal, For the overall system loss, Thermal noise power and extended to , Boltzmann's constant, The noise temperature of the receiving station. The noise figure of the receiving station. The equivalent bandwidth of the signal after processing by the receiving station Rx. For the coherent integration time, This is used to test performance thresholds.

[0009] Furthermore, the detection performance threshold The value is 14.39 dB.

[0010] Furthermore, the unit vector is used The representation in the station-centered coordinate system is as follows: in, This represents the coordinates in the station-centered coordinate system with the receiving station Rx as the origin.

[0011] Furthermore, the equivalent bandwidth of the signal processed by the receiving station Rx It can be estimated as the coherent integration time. The reciprocal of.

[0012] In a second aspect, the present invention also proposes a low-Earth orbit forward scattering detection system for performing the low-Earth orbit forward scattering detection method as described in the first aspect, comprising: The module is used to build a low-Earth orbit forward scattering detection model based on the Walker constellation configuration. In this detection model, a receiving station Rx is set, and the receiving station Rx and K satellites Tx constitute K detection units, where K is the receiver's observation cutoff elevation angle. The above is the number of visible satellites; let the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit be denoted as . The effective size of the aerial target P observed from the k-th detection unit is defined as... ; The processing module is used when the airborne target is affected by a satellite constellation. After the radiation signal of} is excited, if the k-th detection unit satisfies the bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraint condition and the detectable elevation angle threshold that satisfies the power constraint condition are determined. The execution module is used to form an effective detection window in the shadow cone unit based on the true effective coverage ratio and the detectable elevation angle threshold and to perform low-orbit forward scattering detection; The processing module is used when the airborne target is affected by a satellite constellation { After the radiation signal of} is excited, if the k-th detection unit satisfies the bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraints and the detectable elevation angle threshold that satisfies the power constraints are determined.

[0013] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect.

[0014] This invention first clarifies the mapping mechanism of LEO satellite signal parameters on detection performance based on the forward scattering bistatic power model, and quantifies the performance boundary of a single-satellite, single-station detection unit. Second, it introduces the effective coverage ratio index and the detectable elevation angle threshold index to construct a performance analysis method for multi-satellite, multi-station forward scattering detection systems, reflecting the coverage performance and detection power of regional detection in "multi-transmitter, single-receiver" scenarios. Finally, through multi-parameter joint simulation and systematic verification, the detection performance of the LEO forward scattering detection system under different numbers of satellites and different detection wavelengths is analyzed, providing theoretical support for reliable airspace perception of LEO mega-constellation forward scattering detection systems. Attached Figure Description

[0015] Figure 1 A conceptual diagram of a forward scattering detection system based on a low-Earth orbit mega-constellation.

[0016] Figure 2 This is a spatial topology diagram of a low-orbit forward scattering detection system based on a "single-transmitter-single-receiver" low-orbit forward scattering detection method proposed in this invention.

[0017] Figure 3 This is a spatial topology diagram of a "multiple-single-receiver" low-Earth orbit forward scattering detection system at a specific epoch in the low-Earth orbit forward scattering detection method proposed in this invention.

[0018] Figure 4 This is a schematic diagram illustrating the relationship between received power and simulation parameters in the analysis of a "single-transmitter-single-receiver" low-Earth orbit forward scattering detection scenario proposed in this invention.

[0019] Figure 5 This diagram illustrates the relationship between the maximum distance squared product and system parameters in the analysis of a "single-transmitter-single-receiver" low-Earth orbit forward scattering detection scenario proposed in this invention.

[0020] Figure 6 This diagram illustrates the four-stage evolution of the number of visible satellites at a multi-dimensional receiving station in a specific epoch of the "multiple transmitters-single receiver" low-Earth orbit forward scattering detection scenario proposed in this invention.

[0021] Figure 7This diagram illustrates the analysis of the actual coverage ratio and theoretical model coverage ratio under different relative size factors in a "multiple launches - single receiver" low-Earth orbit forward scattering detection scenario at a specific epoch in the low-Earth orbit forward scattering detection method proposed in this invention.

[0022] Figure 8 This is a schematic diagram illustrating the "multi-transmission-single-receiver" low-Earth orbit forward scattering detection scenario analysis, which combines the effective coverage ratio index and the detectable elevation angle threshold index in the low-Earth orbit forward scattering detection method proposed in this invention. Detailed Implementation

[0023] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Based on the concept of multistatic forward scattering radar, this application proposes a collaborative detection system integrating space and ground segments. A dynamic radiation source network is constructed through a large low-Earth orbit constellation, combined with a ground-based multi-beam receiving array to form a three-dimensional detection architecture. The space segment consists of a dense cluster of satellites at orbital altitudes of 500-1200 km, with its spatial density distribution planned and allocated by the large constellation. The ground segment employs distributed receiving stations, using adaptive beamforming technology to track visible satellites in real time and capture scattered signals from targets that may cross the baseline. The system architecture diagram is shown below. Figure 1 As shown, its core mechanism lies in utilizing a multi-baseline topology constructed from a giant constellation and ground stations to overcome the geometric constraints of traditional bistatic forward scattering, significantly expanding the effective detection area.

[0025] In this embodiment, to implement the low-Earth orbit forward scattering detection method, firstly, a low-Earth orbit forward scattering detection model based on the Walker constellation configuration is constructed. In this detection model, a receiving station Rx is defined, and this receiving station Rx and K satellites Tx constitute K detection units. Therefore, this model includes multiple detection units. To more clearly illustrate the technical solution of this embodiment, the working principle of a single detection unit is first explained, such as... Figure 2 As shown, a space topology diagram of a low-Earth orbit forward scattering detection system based on a single transmitter-single receiver is provided. This diagram illustrates the relationship between the airborne target P, the low-Earth orbit satellite Tx, and the ground receiving station Rx. The altitude of the airborne target P relative to the ground is represented by H, where the angle between the airborne target P and the transceiver station is a bistatic angle. When an aerial target P crosses the baseline neighborhood formed by the low-Earth orbit satellite Tx and the ground receiving station Rx at a height H above the ground plane, at a certain bistatic angle... Below this, the target scattering center will produce a significant forward scattering effect along the transmitter-target extension line. At this time, the electromagnetic wave radiated by the transmitter Tx will travel along the path connecting the transmitter and the target. After propagating to the airborne target P, its forward scattered field intensity exhibits an exponential increase under near-tangential incidence conditions. The receiving station Rx passes through the line connecting the target and the phase center of the receiving station antenna. The unique time-frequency-spatial characteristics of this forward-scattered signal can be captured. Under this topology, the significant forward-scattering effect produced by the airborne target P can be represented by the forward-scattering radar cross-section. The Forward Scatter Radar Cross Section (FS-RCS) is a quantitative description that is related to the wavelength of the source and the effective profile area of ​​the target relative to the observations at both ends of the transmitter and receiver.

[0026] In this embodiment, when analyzing the "single-transmitter-single-receiver" low-Earth orbit forward scattering detection scenario, the first step is to estimate the free-space link loss and target forward scattering characteristics, as well as the projected area of ​​the airborne target P's outline in the transmission and reception observation directions. Determine the ground power of the scattered signal and the forward-scattered signal-to-noise ratio model of the receiving station It should be noted that when determining the ground power of the scattered signal, the ground power model should be determined first. Where EIRP is the equivalent radiated power emitted by the satellite. The antenna gain for the satellite radiation source and the ground receiving station Rx. The wavelength of the transmitted signal, This represents the overall system loss.

[0027] When the target being processed falls within the forward scattering region formed by the satellite radiation source and the ground receiving station, the detection system can utilize its forward scattering RCS (Radar Cross Section). For a target with a characteristic size of length D, if it moves perpendicularly across the receiver-transmitter baseline (i.e., the azimuth angle between the velocity direction of the airborne target and the formed direct path is 90°), the FS-RCS gain will increase with the bistatic angle. Fluctuations and changes, from to The rolling trend of the interval is Change, in The roll-off drops to -3dB from the peak value, where This is half the width of the main lobe of the forward-scattered signal. To achieve performance evaluation of the basic detection unit, [the following is used]. As a geometric constraint on the effective forward scattering region; the -3dB gain value of FS-RCS, i.e., the maximum target forward scattering RCS value. Half of the value is used as an estimate of the target scattering characteristics within the forward scattering region. . The expression is: This represents the projected area of ​​the outline of the aerial target P in the transmission and reception direction. At this point, the landing power... It is expressed as follows: According to the forward scattering signal-to-noise ratio model Obtain the receive power threshold and the maximum distance square product : in, EIRP represents the signal-to-noise ratio of the signal received by the ground station after processing the signal generated by the forward scattering from the target. EIRP is the equivalent radiated power emitted by the satellite. The antenna gain for the satellite radiation source and the ground receiving station Rx. The wavelength of the transmitted signal, For the overall system loss, Thermal noise power and extended to , Boltzmann's constant, The noise temperature of the receiving station. The noise figure of the receiving station. The equivalent bandwidth of the signal after processing by the receiving station Rx. For coherent integration time, This is used to test performance thresholds. It can usually be estimated as the coherent integration time. The reciprocal of, that is Consider using a Generalized Likelihood Ratio Test (GLRT) detector to achieve optimal target detection, and set a false alarm rate. If the expected detection probability is 0.9, then the system's detection performance threshold is... .

[0028] Based on the above, and using the forward scattering signal-to-noise ratio model, this paper systematically analyzes the detection capability of airborne targets under commonly used LEO satellite power and wavelength parameter settings in a "single-transmitter-single-receiver" LEO forward scattering detection scenario. This includes parameter boundaries such as detection range, size of the airborne target P, and maximum distance-square product. By establishing the spatial topology of a single LEO satellite radiation source and a single ground receiving station, the paper systematically quantifies the detection performance boundaries of a single LEO satellite and a single ground receiving station, providing a benchmark detection unit for constructing an LEO forward scattering detection model based on the Walker constellation configuration.

[0029] In this embodiment, the low-Earth orbit forward scattering detection model based on the Walker constellation configuration consists of only one receiving station Rx and K satellites Tx. Each satellite Tx and the receiving station Rx constitute a detection unit as described above, for a total of K detection units, where K is the receiver's observation cutoff elevation angle. The above refers to the number of visible satellites. Based on the definition of bistatic angle in the preceding description of the detection units, in this embodiment, for the low-Earth orbit forward scattering detection model composed of multiple detection units, the bistatic angle between the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit is set as follows: The effective size of the aerial target P observed from the k-th detection unit is .

[0030] The Walker constellation configuration includes the total number of satellites T, the number of orbital planes Q, and the phase factor F between orbits. The positions of the satellites on the orbital planes are determined by the basic orbital parameters. Constraints; The satellite sequence numbers in the low-Earth orbit satellite constellation are set as follows: ,satellite Right ascension of the ascending node and the initial true anterior angle They are represented as follows: in, Indicates the semi-major axis of the track. Indicates the orbital eccentricity. Indicates the orbital inclination angle. Indicates the argument of perigee. Indicates the right ascension of the ascending node. Let m represent the true anomaly angle, m represent the m-th orbital plane, and n represent the n-th satellite in a uniform phase configuration. , S represents the number of satellites in each orbital plane; , Let these represent the right ascension of the ascending node and the true anomaly of the satellite (1,1), respectively. For satellites (m , n Other basic orbital parameters These values ​​are fixed under a fixed Walker constellation configuration. By setting the minimum elevation angle of the receiving station and the relative position of the satellite and the receiving station, a topology diagram of the collaborative working scenario of multiple basic detection units in regional detection can be established. It should be noted that the detection scenario of multiple basic detection units in regional detection is specifically a "multiple transmitters - single receiver" low-Earth orbit forward scattering detection scenario.

[0031] like Figure 3 As shown, in the "multiple transmitters - single receiver" low-Earth orbit forward scattering detection scenario, there is only one receiving station Rx, where, This represents the position of the receiving station Rx in the Earth-Centered Earth-Fixed (ECEF) coordinate system, for the k-th (k-th) satellite among K satellites. ) satellites Location is Its coordinates in the station-centered coordinate system with Rx as the origin are: At a certain moment, the position of target P is ,exist Figure 3 middle, Let be the satellite observation elevation angle of the k-th satellite. Let this be the cutoff elevation angle for the satellite observed by the receiving station. Assume the unit vector from the receiving station to satellite k is... Its coordinates in the station-centered coordinate system are: In this embodiment, in the "multiple launches - single receiver" low-Earth orbit forward scattering detection scenario, constraints are established from two aspects: the behavior of the airborne target P and the perception of the receiving station. From the perspective of target behavior, after an aerial target P is excited by a signal from transmitter Tx, its profile size and incident direction jointly determine the characteristics of its forward-scattered signal. When there exists a detection unit i (1≤i≤K) that satisfies the bistatic angle constraint... Furthermore, when the signal power exceeds the detection threshold, the signal "shadow" generated by the target will cover the receiving station, forming an effective detection window; from the equivalent perspective of the receiving station's perception, the receiving station, with itself as the vertex, can utilize along... The vector direction forms K semi-vertical angles of size. (1≤k≤K) Related "shadow cone units" are used to detect targets. The detection units are as follows: Figure 3 The gray cone-shaped area is shown.

[0032] It should be noted that this embodiment illustrates how the detection unit is equivalent to half-vertex angle and wavelength. and target effective size Explanation of the shadow cone. Define the receiving station in the ENU coordinate system as point R, with position coordinates (0, 0, 0). At a certain moment, the k-th (1≤k≤K) satellite within the visible elevation angle range is located at point S, with position... The vector from the receiving station at point R to the satellite at point S is Length is The corresponding unit direction vector is Define a point P within the effective forward scattering region formed by the satellite at point S and the receiving station at point R. Let the vector pointing from the receiving station at point R to point P be... The vector from satellite point S to point P is Bibase angle at point P satisfy: Depend on Simplifying by taking the modulus, we get: remember and The included angle is : In the field of satellite-based forward scattering detection Their speeds are all in the 300 km / h range and above, while The magnitude is on the order of ten kilometers and below, and can be approximated as follows: Under bistatic forward scattering conditions and ,but In summary, based on the geometric constraints of the effective forward scattering region, the k-th "detector unit" is modeled with a half-apex angle of... The size of the half-apex angle of the shadow cone is related to the detection wavelength and the effective size of the target.

[0033] In this embodiment, regarding the geometric constraints, when the airborne target is excited by the transmitter signal of the satellite Tx, if there exists a k-th detection unit that satisfies the bistatic angle... Furthermore, when the transmitter signal power exceeds a preset value, at least one shadow cone unit triggered by the trajectory of the aerial target P is considered detectable. Therefore, the coverage performance of the detection system can be quantified by utilizing the coverage of the detection unit set in the detection cone area, and the effective coverage ratio can be defined. The following formula represents: in, It represents the volume of the entire conical detection area determined by the geometry of the detection system, and represents the maximum spatial range that the detection system can theoretically cover. The volume of the set of areas actually effectively covered by each detection cone element within the cone detection region, i.e., in a multiple-transmitter-single-receiver system, each transmitter... The sum of the areas within the cone-shaped detection region where the corresponding detection signal can successfully detect the target and be effectively received by the receiving station Rx reflects the actual spatial range in which the system can work effectively.

[0034] According to the Cavalieri principle This is equivalent to the ratio of the area set of the "shadow cone element" to the total observable cone base area on any parallel height section. Specifically, at height... On the horizontal plane, the projection of the entire conical detection area onto the horizontal plane is a solid elliptical region, the area of ​​which represents the maximum detectable area at that height. The k-th detection unit at that height is calculated. The semi-major axis of the ellipse intercepted from the cross-sectional shape at that point ellipse eccentricity ellipse coverage area and the height Cross-sectional area of ​​the detection area below They are represented as follows: The effective coverage ratio per unit of the k-th detection unit is obtained by calculating the ratio of the coverage area of ​​the truncated ellipse to the area of ​​the detection region. ,when , hour: In the above calculation process, With the half-apex angle of the shadow cone The value increases monotonically with the increase of the satellite elevation angle. It decreases monotonically as it increases, and is related to the height of the detection cross section. Irrelevant. Because the target's trajectory is unknown, the relative relationship between the target's outline and the satellite's motion is difficult to determine. Difficult to model and represent. Considering the effective size of aerial targets. Never larger than the actual size That is, satisfy ,as well as Based on monotonicity, the minimum semi-vertex angle can be used. The minimum coverage performance of each detection unit is obtained through analysis. It is assumed that the elliptical cross-sections formed by the detection units do not overlap. According to the minimum semi-vertex angle Obtain the minimum coverage performance of the k-th detection unit and the effective coverage ratio under ideal conditions. , which is expressed as the ratio of the area of ​​the k-th smallest covering ellipse to the area of ​​the overall detection cross section: Regarding the effective coverage ratio The true effective coverage ratio is obtained by introducing an occlusion correction factor. : in, Let be the satellite observation elevation angle of the k-th satellite. The cutoff elevation angle for satellites observed by the receiving station, where N is the number of satellites. and These are adaptive parameters.

[0035] In this embodiment, the occlusion correction factor The main consideration is the impact of the number of satellites N on the blocking effect. As the number of satellites N increases, the mutual blocking phenomenon between detection units becomes more significant, and therefore decreases as N increases. The main consideration is the satellite observation elevation angle. The impact of the obstruction effect. When the satellite observation elevation angle... When reduced, the effective coverage ratio per unit As the detection unit grows larger, its coverage area becomes more susceptible to obstruction by other detection units. Parameters and It is an adaptive parameter used to adjust the attenuation intensity of the occlusion effect, and can be determined based on the minimum half-apex angle. Make appropriate adjustments to adapt to different detection scenarios.

[0036] In the step of determining the detectable elevation angle threshold that satisfies the power constraint condition based on the shadow cone unit triggered by the trajectory of the aerial target P, under the power constraint condition, the power efficiency improvement achieved by the combined action of each detection unit is not considered for the time being. Therefore, the single-point power model can be extended to spatial region analysis. In a regional detection scenario, if there is a certain altitude... The target falls within the k-th shadow cone unit. As satellite k moves dynamically within this detection unit, the distance from satellite k to the target P in the air is determined based on the motion state of satellite k. Distance from aerial target P to receiving station Rx Estimated as the elevation angle relative to satellite observation. The functions are expressed as follows: and Based on the fact that the aerial target P is in the neighborhood near the baseline, It can be estimated that the baseline and the height are The distance from the intersection of the horizontal planes to the receiving station Rx, and the distance between the k-th satellite and the receiving station Rx. and Approximately and much larger than , and specifically expressed as: ) Will The whole is defined as the product of squares of the probe. : when hour, Follow It increases and monotonically decreases, based on the maximum distance-squared product obtained in the "single-transmit-single-receive" scenario mentioned earlier. Determine the detectable elevation angle threshold satisfy: in, Let the altitude be the height of the k-th satellite. Let be the radius of the ideal sphere.

[0037] In this embodiment, the calculation process under the above power constraint conditions can be used to find that when At that time, The received signal-to-noise ratio of a target falling within a certain point of the detection unit meets the power detection performance requirements, that is, within the effective range of the detection system. Furthermore, the establishment of the detection elevation angle threshold provides an intuitive and effective quantitative condition for evaluating the power performance of K effective detection units within the region.

[0038] The above embodiments illustrate the construction and analysis process of low-Earth orbit forward scattering detection scenarios. The following embodiments provide specific experimental analysis processes, including analysis of low-Earth orbit forward scattering detection scenarios with "single launch-single reception" and "multiple launch-single reception".

[0039] In a "single-launch-single-receive" scenario, the detectability of a flying target is related to its effective outline area, specifically the top outline area S. Based on this, airborne threats of interest (AIR) can be categorized into four types: AIR-Mini, AIR-S, AIR-M, AIR-L, and AIR-XL. Furthermore, considering the different requirements of various practical detection missions, the combination of system parameters such as EIRP can be flexibly adjusted. Due to limitations in satellite platform and antenna size, the peak power of EIRP for low-Earth orbit satellites is typically controlled at 10 kW or below, with typical EIRP values ​​set at [15, 25, 35, 45] dBW. Due to limitations in the main lobe beam time of the target's forward scattering signal, the typical coherence integration time is set at [0.001, 0.1] s. Table 1 summarizes the typical values, typical ranges, and constraints of the parameters used in the design of the satellite-based forward scattering system.

[0040] Table 1. Flight target classification methods applicable to forward scattering detection performance analysis Table 2 Simulation parameters of the low-orbit forward scattering detection system Based on the parameters in Table 1, the analysis method for a low-Earth orbit forward scattering detection scenario using a "single-transmitter-single-receiver" approach is employed. Figure 4 The variation trend of the landing power of the low-Earth orbit forward scattering system with system parameters was quantitatively characterized by filling contour plots. Figure 4 The x-axis of the four subgraphs (a)-(d) represents the product of the distance from the transmitter to the target and the distance from the receiver to the target. For short, it is the detection range product, and its value range is... The vertical axis represents the effective contour area of ​​the target. The value range is Under the above parameter settings, the ground power... The range of values ​​is ,correspond Figure 4 Different colored areas are represented. If the receiver signal coherence integration time is set to 0.001 s, 0.01 s, 0.1 s, and 1 s respectively, based on the received power threshold... The calculation formula is as follows: the received power threshold values ​​required to achieve the target detection condition are respectively: , , , ,like Figure 4 As indicated by the black dashed line markings.

[0041] Depend on Figure 4 It can be seen that low-Earth orbit forward scattering detection systems under different satellite EIRP configurations can meet the detection requirements of different scenarios. Under the parameters set in Table 1, when the EIRP is 15 dBW, it has high detection capability for medium to large targets (AIR-L class and above). For example, at a detection range with a squared product of 1000 km² (with relevant configurations...), it has high detection capability. ; Under the conditions of (etc.), for The target power is estimated at -169.99 dBW. This power level is within the receive power threshold. Above the threshold level, it indicates that under low-power detection conditions, the system can detect medium to large targets at greater distances using a longer coherent integration time. However, for smaller targets (such as...), the detection time is limited. For AIR-S class targets, at the same detection range squared product, the landing power is lower than the threshold lines shown in all figures, limiting detection capability. As satellite EIRP power increases, on the one hand, the landing power threshold contour lines shift significantly towards larger distances and smaller targets; on the other hand, the system can gradually meet the detection needs of various targets from small to large in different airspace scenarios. When EIRP is 45 dBW, at a detection range squared product of 1000 km², for AIR-L class ( ) and AIR-S level ( The target power estimates are -139.99 dBW and -166.02 dBW, respectively, corresponding to power levels located at... , Above the threshold level, it indicates that under high-power detection conditions, the system can simultaneously possess comprehensive detection and sensing capabilities for both small targets in the near airspace and large targets in the far airspace.

[0042] Based on the analysis of the "single-transmitter-single-receiver" low-Earth orbit forward scattering detection scenario and the calculation formula for the product of squares of the maximum effective range, Figure 5 Four typical EIRP configurations were quantitatively characterized using filled contour plots. The maximum detection range squared product varies with the effective contour area of ​​the target. and coherent integration time The changing pattern. Figure 5 (a)-(d) The horizontal axis of the four sub-figures represents the effective contour area of ​​the target. The value range is The vertical axis represents the signal coherence integration time, with a value range of [value range missing]. The color change from blue to red indicates that the product of squares of the detection distance is increasing, with a range of values ​​between [value range missing]. When a low-Earth orbit satellite is used as a transmitter, the typical distance from the target in the airspace is 600 km. Therefore, for targets with a detection range where the product of the squares is less than... That is, the detection distance from the receiver to the target is less than 16.7 m, which indicates... Figure 5 The medium-dark blue area has virtually no detection capability; for areas with a detection range greater than the square product of the distances, detection is not possible. This corresponds to a detection distance of 16.7 km from the receiver to the target, representing... Figure 5 The medium-dark red area has strong airspace coverage capabilities.

[0043] pass Figure 5 Analysis shows that by appropriately combining EIRP and coherent integration time, the same detection capability can be achieved under different system configurations. Table 3 summarizes the performance boundaries of the "single-transmitter-single-receiver" low-Earth orbit forward scattering detection scenario under different EIRP configurations. Quantitative analysis is then conducted: comparing system scenarios with EIRP=45 dBW and EIRP=25 dBW, when EIRP=45 dBW and coherent integration time is... Under the parameter configuration, for an effective contour area of The target (AIR-L class target) has a maximum detection range of 3782.04 km², corresponding to a maximum detection range of Rt=600km. The range is 6.30 km. When the satellite EIRP is 45 dBW and the coherence integration time is... At the same time, the same detection power can be obtained for targets with the same effective contour area.

[0044] In summary, under the condition of limited transmit power, the system should optimize the coherent integration time as much as possible within physical constraints to meet the long-range detection requirements of various types of flying targets. With sufficient power budget, the system can be used for both long-range detection of small targets and long-range detection of large targets. However, the EIRP value needs to be rationally selected based on the estimated size of the target of interest and the maximum detection range requirement to balance system performance and resource consumption. Further adjustments and optimizations to relevant parameters will be made based on the analysis in this section, taking into account actual needs, to improve the system's detection performance and enable its development towards detection scenarios involving smaller targets and farther airspace.

[0045] Table 3 Performance Boundaries of Low-Earth Orbit Forward Scattering Probe Scenarios under Different EIRP Configurations In the analysis of the "multiple launches, single reception" low-Earth orbit forward scattering detection scenario, a Starlink-like constellation (SLC) was first established for simulation analysis, possessing the characteristics of the Walker-Delta constellation configuration. Assuming the Earth is an ideal sphere, the constellation operates on a uniform orbital plane formed by the sum of the Earth's radius and orbital altitude, named Constellation A. Table 4 lists the constellation parameter settings for this section, with the ideal Earth radius set at 6371 km. Shells 1 to 4 correspond to four progressive stages of large-scale low-Earth orbit constellation deployment. The available satellite radiation sources for each stage adopt an cumulative mode, meaning the number of available satellites in later stages includes those from earlier stages. This stage-superimposed construction method allows for the study of the evolution of detection performance of low-Earth orbit mega-constellation forward scattering detection systems during different development periods. Considering the good coverage of mid- and low-latitude regions by the Walker-Delta constellation design, the latitude of the receiving station is set at [latitude value missing]. The longitude was set arbitrarily, the receiver station height was set to 100 m, and the minimum satellite observation elevation angle was set to 15°. The relevant parameters are compiled into Table 5. The simulation time was set to 24 hours, the epoch interval was set to 1 minute, and a total of 1440 epochs were calculated.

[0046] Table 4. A Constellation Simulation Parameter Settings Table 5 Receiving Station Parameter Settings By recursively calculating the relative positions of satellites and receiving stations over dynamic epochs, the locations and numbers of usable satellite radiation sources at different epochs can be determined. The analysis of the number of visible satellites and the average number of visible satellites for each receiving station from the first to the fourth phase of the A constellation development is shown below. Figure 6 As shown in Table 6, the statistical results are presented in summary. Figure 6 As shown in Table 6, for the region ranging from 20° to 45° latitude, the number of visible satellites remains stable within a certain range at each stage of satellite development, with the maximum fluctuation not exceeding 1 / 5 of the average. In the early stages of low-Earth orbit (LEO) satellite development (Stage 1), the average number of satellites is in the range of [10, 30]; in the later stages of LEO satellite development (Stage 4), the average number of visible satellites can exceed 100, far exceeding the number of available satellite sources for medium- and high-Earth orbit forward scattering systems. A larger number of visible satellites means a greater number of forward scattering detection baselines for "single-transmitter, single-receiver" systems, i.e., a larger base number of basic detection units for a large LEO constellation.

[0047] Table 6. Statistical analysis of the evolution of the number of visible satellites at multi-latitude receiving stations with a cutoff elevation angle of 15° (latitude range: 20° to 45°, interval: 5°). Considering the potential occlusion effects of each detection shadow cone unit during satellite dynamics, and assuming the existence of a multi-satellite single-station forward scattering detection system consisting of 100 "visible satellite-receiving station nodes," even if its average effective coverage ratio per unit reaches 0.01, it cannot be simply assumed that the system can provide real-time full coverage of the entire scene. Specific detection scene indicators must be taken into account for a comprehensive and in-depth evaluation to accurately determine the system's actual coverage capability. Taking receiving station 5 in Table 5 as an example, a comprehensive analysis of the detection network composed of visible satellites with an elevation angle greater than 15°, centered on its location, shows that the system's coverage capability is... of The detection coverage performance and detection power of targets with effective size and contour.

[0048] For the analysis of regional detection coverage capability, a detailed analysis of regional detection coverage capability under multiple stages was conducted through simulation of dynamic epoch scenarios. Considering epochs 1160 to 1199, the detection wavelength is... , , The corresponding relative size factor is , , The corresponding weights are shown in Table 7.

[0049] Table 7. Weighting of Occlusion Factor under Different Relative Size Factors According to the aforementioned definition, effective coverage ratio In the experiment, the effective coverage ratio can be estimated by dividing the region into discrete grids and calculating the ratio of the number of grid points within the elevation angle region that meet the forward scattering geometric constraints to the total number of grid points in the entire region. This ratio is then combined with the corrected true effective coverage ratio. The calculation formula and model parameters can be used to obtain the theoretical effective coverage ratio of a specific receiving station in its airspace at different epochs. To facilitate the demonstration of detailed changes in coverage capability at different time periods in dynamic scenarios, Figure 7 The different relative size factor conditions shown represent the actual effective coverage ratio and theoretical model coverage ratio results for epochs 1160 to 1199. The coverage performance for other epochs shows a similar trend as a function of epochs. In most observation phases, the two show good consistency; for example, the average deviation is less than 5% in the third phase [epochs 1100-1150], verifying the effectiveness of the theoretical model. In the first phase, due to the relatively small number of satellites, the effective coverage ratio is at a low level, especially when the relative size factor... The relative size factor was 0.05, and the average effective coverage ratio was 2.25%. In the fourth phase, the constellation size expanded to 9998 stars, with a relative size factor of 0.05. With a relative size factor of 0.2, both the actual effective coverage ratio and the theoretical model coverage ratio fluctuate around the average actual effective coverage ratio of 78.36% in the fourth stage. This indicates that a configuration with this parameter can achieve relatively good coverage in a certain area without relying too much on additional receiver resources. The actual effective coverage ratio was 0.05, and it still reached 12.62% in the fourth stage, indicating that a multi-satellite single-station configuration still possesses a certain coverage capability. Further extension to a "multi-satellite, multi-station" network detection configuration could potentially achieve good overall regional coverage. In most observation phases, the actual coverage ratio and the theoretical model coverage ratio showed good consistency, and with... The reduction of the attenuation factor's effect weight , As the coverage ratio gradually decreases, the matching degree between the actual coverage ratio and the theoretical coverage ratio increases, and the occlusion effect between the detection units decreases, thus characterizing the effective coverage ratio.

[0050] For the analysis of regional detection power performance, the satellite parameter settings and the detection scenario at a specific epoch can be considered comprehensively. The satellite EIRP is set to 45 dBW, the coherence integration time to 1 ms, and other processing parameters are as shown in Table 2. Under these parameter settings, the maximum detection range square product of receiving station 5 is calculated to be 3782.04 km². Based on the detection square product mentioned earlier... and detectable elevation angle threshold The calculation conditions, since the satellite's orbital altitude is fixed, can be defined as follows: Given the maximum satellite altitude of constellation A, i.e., 560 km, the threshold analysis problem of the product of squares of the maximum detection range is transformed into a power coverage analysis of a specific multi-base detection scenario. Calculations show that at a horizontal altitude of 1 km, the detectable elevation angle threshold is... It is 20.20°. Figure 8 Characterizing the coverage and detection performance of effective detector units in a "multiple launches-single receiver" LEO forward scattering detection scenario at different constellation development stages with a relative size factor of 0.2 at epoch 1130, the scattered elliptical regions in the figure represent effective detector units in the "multiple launches-single receiver" LEO forward scattering detection scenario at specific altitude profiles. The color change from blue to yellow within these regions indicates an increasing range of ground power values, ranging from [-151.42, -126.75] dBW. The solid black line represents the projected boundary of the 15° cutoff elevation angle on a horizontal plane at an altitude of 1 km, while the dashed black line represents the detectable elevation angle threshold determined based on the constellation's highest orbital altitude and other system parameters. The projected boundary on a horizontal plane at an altitude of 1 km corresponds to the zenith of the receiving station. With m as the center and a radius of 2.74 km, the received power is greater than or equal to... The limits of its detection power.

[0051] from Figure 8 It is evident that the detection units in the zenith region have higher ground power, appearing as yellowish-green patches; however, the detection network composed of these units has relatively sparse coverage in this region, indicating limited coverage of the zenith region. Conversely, the detection units in the lower elevation angle region have lower ground power, appearing as bluish-green patches; however, the detection network composed of these units has relatively dense coverage in this region, indicating stronger coverage of the zenith region. Figure 8 (a) to Figure 8 (d) As the development stages of low-Earth orbit satellites progressed, the actual effective coverage ratio significantly improved, with the corresponding values ​​increasing from 23.81% to 43.88%, 65.32%, and 76.26%, respectively. Figure 7 The indicator analysis results match. Further analysis of the correlation between the detection network's power and system parameters reveals that detection power is represented by the square product of detection distances, comprising the distance from the satellite node to the target and the distance from the target to the receiving station. The distance from the satellite node to the target is influenced by factors such as orbital altitude. If the constellation altitude is reduced from 560 km (set in Table 4) to 530 km, the detection elevation threshold can be increased. Decreasing from 20.20° to 19.6° allows for an expansion of the effective coverage area centered on the receiving station, corresponding to the projected boundary of the detectable elevation angle threshold. Conversely, increasing the constellation's orbital altitude increases the number of visible satellites under the same receiving station cutoff elevation angle, improving coverage but causing a contraction of the effective coverage area enclosed by the detectable elevation angle threshold. In summary, through analysis of effective coverage ratio and detectable elevation angle threshold, a radial collaborative architecture with ground receiving stations as hubs and LEO mega-constellations as nodes expands the effective detection area from single-baseline constraints to multi-baseline joint coverage. Based on this analysis, subsequent optimization of system parameters can harmonize coverage performance and detection power, providing a quantifiable benchmark system for forward scattering detection by LEO mega-constellations.

[0052] This embodiment also provides a low-Earth orbit forward scattering detection system for performing the low-Earth orbit forward scattering detection method as described in the first aspect, including: The module is used to build a low-Earth orbit forward scattering detection model based on the Walker constellation configuration. In this detection model, a receiving station Rx is set, and the receiving station Rx and K satellites Tx constitute K detection units, where K is the receiver's observation cutoff elevation angle. The above is the number of visible satellites; let the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit be denoted as . The effective size of the aerial target P observed from the k-th detection unit is defined as... ; The processing module is used when the airborne target is affected by a satellite constellation { After the radiation signal of} is excited, if the k-th detection unit satisfies the bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraint condition and the detectable elevation angle threshold that satisfies the power constraint condition are determined. The execution module is used to form an effective detection window in the shadow cone unit based on the true effective coverage ratio and the detectable elevation angle threshold and to perform low-orbit forward scattering detection; The processing module is used when the airborne target is affected by a satellite constellation { After the radiation signal of} is excited, if the k-th detection unit satisfies the bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraints and the detectable elevation angle threshold that satisfies the power constraints are determined.

[0053] This embodiment also provides a computer-readable storage medium. One or more non-volatile computer-readable storage media containing computer-executable instructions, which, when executed by one or more processors, cause the processors to perform the steps of a low-orbit forward scattering detection method. A computer program product containing instructions, which, when run on a computer, causes the computer to perform a low-orbit forward scattering detection method.

[0054] Any references to memory, storage, database, or other media used in the embodiments of this application may include non-volatile and / or volatile memory. Suitable non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM), which is used as external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0055] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A low-orbit forward scattering detection method, characterized in that, Specifically, the steps include the following: A low-Earth orbit forward scattering detection model based on the Walker constellation configuration is constructed. In this model, a receiving station Rx is defined, and the receiving station Rx and K satellites Tx constitute K detection units, where K is the receiver's observation cutoff elevation angle. The above is the number of visible satellites; let the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit be denoted as . The effective size of the aerial target P observed from the k-th detection unit is defined as... ; When aerial targets are affected by satellite constellations After the radiation signal of} is excited, if the k-th ( ) Detection units satisfy bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraint condition and the detectable elevation angle threshold that satisfies the power constraint condition are determined. In the shadow cone unit, an effective detection window is formed based on the true effective coverage ratio and the detectable elevation angle threshold, and low-orbit forward scattering detection is performed. The shadow cone element is defined with the receiving station Rx as the vertex and the unit vector from the receiving station Rx to the k-th satellite as the axis, with a half-vertex angle of . The conical region enclosed by it.

2. The low-orbit forward scattering detection method according to claim 1, characterized in that, The Walker constellation configuration includes the total number of satellites. T Number of orbital planes Q and the phase factor between orbits F The position of a satellite on the orbital plane is determined by its basic orbital parameters. Constraints; The satellite sequence numbers in the low-Earth orbit satellite constellation are set as follows: ,satellite Right ascension of the ascending node and the initial true anterior angle They are represented as follows: in, Indicates the semi-major axis of the track. Indicates the orbital eccentricity. Indicates the orbital inclination angle. Indicates the argument of perigee. Indicates the right ascension of the ascending node. Let m represent the true anomaly angle, m represent the m-th orbital plane, and n represent the n-th satellite in a uniform phase configuration. , S represents the number of satellites in each orbital plane; , Let represent the right ascension of the ascending node and the true anomaly angle of the satellite (1,1), respectively.

3. The low-orbit forward scattering detection method according to claim 2, characterized in that, Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio satisfying the geometric constraints and the detectable elevation angle threshold satisfying the power constraints are determined. Specific steps include: setting the vertical distance between the aerial target P and the receiving station Rx as the height. And calculate the height of the kth detection unit at that height. The semi-major axis of the ellipse intercepted from the cross-sectional shape at the location ellipse eccentricity ellipse coverage area and the height Cross-sectional area of ​​the detection area below They are represented as follows: The effective coverage ratio per unit of the k-th detection unit is obtained by calculating the ratio of the coverage area of ​​the truncated ellipse to the area of ​​the detection region. ,when , hour: According to the minimum semi-vertex angle Obtain the minimum coverage performance of the k-th detection unit and thereby obtain the effective coverage ratio under ideal conditions. , which is expressed as the ratio of the area of ​​the k-th smallest covering ellipse to the area of ​​the overall detection cross section: Regarding the effective coverage ratio Introducing an occlusion correction factor Corrections are made to obtain the true effective coverage ratio. : in, Let be the satellite observation elevation angle of the k-th satellite. The cutoff elevation angle for satellites observed by the receiving station, where N is the number of satellites. and These are adaptive parameters.

4. The low-orbit forward scattering detection method according to claim 3, characterized in that, The steps for determining the detectable elevation angle threshold that satisfies the power constraint include: The distance from the k-th satellite to the airborne target P is calculated based on the motion state of the k-th satellite. Distance from aerial target P to receiving station Rx Estimated as the elevation angle relative to satellite observation. The functions are expressed as follows: and And the distance between the k-th satellite and the receiving station Rx and Approximately and much larger than , and specifically expressed as: ) Will The whole is defined as the product of squares of the probe. : when hour, Follow Increasing and monotonically decreasing, according to the product of the squares of the maximum distance Determine the detectable elevation angle threshold satisfy: in, Let the altitude be the height of the k-th satellite. Let be the radius of the ideal sphere.

5. The low-orbit forward scattering detection method according to claim 4, characterized in that, The maximum distance square product Based on the k-th detection unit, the following steps are taken: Estimated based on free-space link loss and target forward scattering characteristics, and the projected area of ​​the airborne target P's profile in the transmission and reception directions. Determine the ground power of the scattered signal and the forward-scattered signal-to-noise ratio model of the receiving station : According to the forward scattering signal-to-noise ratio model Obtain the receive power threshold and the maximum distance square product : Where EIRP is the equivalent radiated power emitted by the satellite. The antenna gain for the satellite radiation source and the ground receiving station Rx. The wavelength of the transmitted signal, For the overall system loss, Thermal noise power and extended to , Boltzmann's constant, The noise temperature of the receiving station. The noise figure of the receiving station. The equivalent bandwidth of the signal after processing by the receiving station Rx. For the coherent integration time, This is used to test performance thresholds.

6. The low-orbit forward scattering detection method according to claim 5, characterized in that, The detection performance threshold The value is 14.39 dB.

7. The low-orbit forward scattering detection method according to claim 1, characterized in that, The unit vector is used The representation in the station-centered coordinate system is as follows: in, This represents the coordinates in the station-centered coordinate system with the receiving station Rx as the origin.

8. The low-orbit forward scattering detection method according to claim 5, characterized in that, The equivalent bandwidth of the signal after processing by the receiving station Rx It can be estimated as the coherent integration time. The reciprocal of.

9. A low-orbit forward scattering detection system, characterized in that, For performing the low-orbit forward scattering detection method as described in any one of claims 1-8, comprising: The module is used to build a low-Earth orbit forward scattering detection model based on the Walker constellation configuration. In this detection model, a receiving station Rx is set, and the receiving station Rx and K satellites Tx constitute K detection units, where K is the receiver's observation cutoff elevation angle. The above is the number of visible satellites; let the position of the airborne target P at a certain moment and the bistatic angle formed by the k-th detection unit be denoted as . The effective size of the aerial target P observed from the k-th detection unit is defined as... ; The processing module is used when the airborne target is affected by a satellite constellation. After the radiation signal of} is excited, if the k-th detection unit satisfies the bistatic angle Based on the Cavalieri principle and the signal-to-noise ratio threshold condition, the true effective coverage ratio that satisfies the geometric constraint condition and the detectable elevation angle threshold that satisfies the power constraint condition are determined. The execution module is used to form an effective detection window in the shadow cone unit based on the true effective coverage ratio and the detectable elevation angle threshold and to perform low-orbit forward scattering detection; The shadow cone element is defined with the receiving station Rx as the vertex and the unit vector from the receiving station Rx to the k-th satellite as the axis, with a half-vertex angle of . The conical region enclosed by it.

10. A computer storage medium for receiving user input programs, characterized in that, When the computer program stored in the storage medium is executed by the processor, it implements the low-orbit forward scattering detection method according to any one of claims 1 to 8.

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