A space-based high-speed target detection full-link simulation method

Abstract

This invention discloses a full-link simulation method for space-based detection of high-speed targets, comprising: calculating the radiation intensity of the target skin and the radiation intensity of the target shock layer to obtain the target skin-shock layer coupled radiation intensity; constructing a simulation model of the surface background infrared radiation and a simulation model of the cloud background infrared radiation, and combining the target skin-shock layer coupled radiation intensity to obtain the infrared radiation under complex background conditions for space-based detection; obtaining the radiation distribution before the entrance pupil of the optical system based on the atmospheric infrared radiation transfer model; superimposing the radiation distribution before the entrance pupil of the optical system with the detector effect to obtain the voltage distribution of the actual target and background; and performing detection performance analysis and imaging simulation based on the voltage distribution of the actual target and background. This method establishes a complete full-link infrared radiation transfer model system, improving the infrared early warning detection capability of space-based infrared detection platforms for high-speed targets, and enhancing the completeness and accuracy of detection band analysis.

Description

Technical Field

[0001] This invention belongs to the field of target detection technology, specifically relating to a full-link simulation method for space-based detection of high-speed targets. Background Technology

[0002] High-speed flying targets are difficult to track effectively due to their extremely high speed. Space-based infrared detection systems, with their advantages of high viewing angle, wide detection range, and long warning time, are one of the effective ways to detect high-speed targets in the future. Therefore, it is of great significance to establish a full-link simulation model for space-based detection of high-speed targets.

[0003] Existing research has made some progress in target radiation calculation and space-based detection capabilities. For example, Chen Hailong et al., in "Research on the Detection Capability of Low-Orbit Infrared Satellites to HTV-2-like Hypersonic Vehicles," used HTV-2-like vehicles as the research object, simulated the surface temperature distribution of the vehicle under typical operating parameters, and combined with typical performance parameters of infrared detectors, gave the relationship between the detector signal-to-noise ratio and the observation angle and operating band at different orbital altitudes, achieving some progress in space-based detection. However, there are still some shortcomings: when modeling target radiation, they only considered the radiation distribution of the vehicle skin and ignored the radiation distribution of the shock layer, resulting in insufficient accuracy in their target radiation modeling; moreover, they did not consider the radiation of the cloud background, nor did they discuss the atmospheric module in the radiation transmission process between the target and the background. Similarly, Dong Shikui et al., in "Research on Radiation Characteristics of Typical Hypersonic Targets," discussed the infrared radiation of typical high-speed target bodies, trailing plumes, and contrails, and analyzed the spectral radiation characteristics in the 0.2–14 μm band, but they did not study the infrared radiation transmission characteristics between the target and the background.

[0004] Therefore, the existing simulation methods for space-based detection of high-speed targets still have the following problems: First, the accuracy of the existing space-based detection simulation for modeling the radiation characteristics between the target and the background, and between the target and the background, is insufficient. It cannot take into account the high-precision modeling of the intrinsic radiation and shock layer radiation of high-speed flying targets, as well as the high-precision modeling of radiation transmission. Second, the existing space-based detection simulation has not established a complete full-link infrared radiation transmission model system. Therefore, it is impossible to fully and accurately analyze the infrared early warning detection capability and detection band of the space-based infrared detection platform for high-speed targets. Summary of the Invention

[0005] To address the shortcomings of existing space-based simulation methods for high-speed targets, such as poor accuracy in modeling high-speed targets and complex background radiation, and the inability to achieve a complete simulation system across the entire target spectrum, this invention provides a full-link simulation method for space-based high-speed targets. The technical problem solved by this invention is achieved through the following technical solution:

[0006] A full-link simulation method for space-based detection of high-speed targets includes:

[0007] Step 1: Calculate the radiation intensity of the target skin and the radiation intensity of the target shock layer respectively to obtain the coupled radiation intensity of the target skin-shock layer;

[0008] Step 2: Construct a simulation model of the infrared radiation of the ground background and the infrared radiation of the cloud background, and combine the target skin-shock layer coupled radiation intensity to obtain the infrared radiation under the complex background of space-based detection;

[0009] Step 3: Calculate the coupled uplink radiation value of the line-of-sight skin and shock layer based on the atmospheric infrared radiation transfer model, and obtain the radiation distribution in front of the entrance pupil of the optical system by combining the infrared radiation of the complex background under the space-based detection.

[0010] Step 4: Superimpose the radiation distribution of the optical system before entering the pupil with the detector effect to obtain the voltage distribution of the actual target and background;

[0011] Step 5: Based on the voltage distribution of the actual target and background, perform detection performance analysis and imaging simulation to achieve full-link infrared radiation simulation of high-speed target-complex imaging background-atmosphere-optical system-imaging detector.

[0012] The beneficial effects of this invention are:

[0013] 1. The full-link simulation method for space-based detection of high-speed targets provided by this invention considers the complete full-link infrared radiation transmission model of high-speed target-complex imaging background-atmosphere-optical system-imaging detector, establishes a complete full-link infrared radiation transmission model system, realizes the systematic full-link simulation of space-based detection of high-speed targets, and improves the infrared early warning detection capability of space-based infrared detection platform for high-speed targets, as well as the completeness and accuracy of detection band analysis.

[0014] 2. This invention utilizes computational fluid dynamics software to model the radiation characteristics of the target, thereby calculating the radiation transmission results of the target shock layer and skin. Furthermore, it uses global satellite imagery files to perform complex background infrared radiation modeling of the surface background and cloud background, thus improving the accuracy of target and background radiation modeling and simulation.

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a full-link simulation method for space-based detection of high-speed targets provided in an embodiment of the present invention.

[0017] Figure 2This is a flowchart illustrating another full-link simulation method for space-based detection of high-speed targets provided in an embodiment of the present invention;

[0018] Figure 3 This is an infrared radiation intensity distribution diagram of the aircraft skin provided in an embodiment of the present invention;

[0019] Figure 4 This is a diagram of a gas radiation calculation model based on the apparent ray method provided in an embodiment of the present invention;

[0020] Figure 5 This is a display diagram of the global surface emissivity data after processing, provided in an embodiment of the present invention.

[0021] Figure 6 This is a display diagram of global surface temperature data processing provided in an embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram illustrating infrared radiation reflection transmission using BRDF as described in an embodiment of the present invention;

[0023] Figure 8 This is a physical data diagram of cirrus cloud environment simulation provided in an embodiment of the present invention;

[0024] Figure 9 yes Figure 8 The normalized BRDF value curve corresponding to the data;

[0025] Figure 10 and Figure 11 These are schematic diagrams illustrating the acquisition of atmospheric uplink / downlink radiation energy via MODTRAN according to embodiments of the present invention;

[0026] Figure 12 This is a schematic diagram of point target imaging under the space-based detection mode provided in an embodiment of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0028] Example 1

[0029] Please refer to the above. Figure 1-2 , Figure 1 This is a flowchart illustrating a full-link simulation method for space-based detection of high-speed targets provided in an embodiment of the present invention. Figure 2 This is a flowchart illustrating another end-to-end simulation method for space-based high-speed target detection provided by an embodiment of the present invention. The end-to-end simulation method for space-based high-speed target detection provided in this embodiment specifically includes the following steps:

[0030] Step 1: Calculate the radiation intensity of the target skin and the radiation intensity of the target shock layer respectively to obtain the coupled radiation intensity of the target skin-shock layer.

[0031] Understandably, accurately describing the spectral radiation characteristics of a target is fundamental to studying the evolution of target imaging features. The infrared radiation characteristics of high-speed targets can be mainly divided into two aspects: skin aerodynamic heating and shock layer gas radiation. Therefore, this embodiment also analyzes the infrared radiation characteristics of the target from these two aspects.

[0032] Specifically, step 1 includes:

[0033] 11) Model the radiation characteristics of the target using fluid dynamics software, and calculate the radiation intensity of the target skin and the radiation intensity of the target shock layer respectively.

[0034] Conventional methods for calculating the radiation characteristics of aircraft targets typically use the stagnation point temperature method to fit the target temperature. In order to establish an accurate temperature field model, in this embodiment, CFD software is used to establish a geometric model of the blunt cone aircraft, and the Fluent software package is used to calculate the flow field temperature and pressure data.

[0035] First, calculate the radiation intensity of the target skin, as follows:

[0036] a. Obtain temperature data T1 of the high-speed aircraft skin and temperature data T2 of the external flow area.

[0037] b. Based on the temperature data T1 of the aircraft skin surface, the skin mesh of the high-speed aircraft is used as a differential small surface source. The radiance L1 of the differential small surface source of the aircraft skin is calculated using the spectral emissivity ε0 of the aircraft material:

[0038]

[0039] Where, c1 = 3.74 × 10 8 W·μm 4 / m 2 The first radiation constant is c² = 1.44 × 10⁻⁶. 4 μm·K is the second radiation constant; based on the radiance L1 of the small surface source, the radiation intensity I1 produced by the small surface source is calculated as:

[0040] I1=L1cosθ tg ΔA tg

[0041] Where, θ tg Let ΔA be the angle between the surface source and its corresponding normal. tg The area of ​​the small surface source.

[0042] Please see Figure 3 , Figure 3This is an infrared radiation intensity distribution diagram of the aircraft skin provided in an embodiment of the present invention.

[0043] Then, the radiation intensity of the target shock layer is calculated, as follows:

[0044] a. Based on the obtained temperature field data T2 of the shock layer of the high-speed aircraft, calculate its corresponding intrinsic spectral radiance I2:

[0045]

[0046] Where ν is the wave number, and h = 6.62606957 × 10 -34 (J·s) is Planck's constant, c = 2.99792458 × 10 8 m / s is the speed of light, k = 1.380649 × 10 -23 J / K is the Boltzmann constant.

[0047] b. Calculate the gas radiation between shock layers using the apparent ray method gas radiation calculation model and the HITRAN database.

[0048] Please see Figure 4 , Figure 4 This is a diagram of a gas radiation calculation model based on the apparent ray method provided in an embodiment of the present invention. Specifically, the shock layer is divided into N layers according to the ray direction of the line of sight, and the gas composition between the layers is considered to be uniformly isothermally distributed; the total gas transmittance is equal to the product of the uniform gas transmittance of each segment along the path, and the gas transmittance τ1 with wavenumber ν is calculated using the HITRAN database:

[0049] τ1=exp(-H1…-H N )

[0050] Among them, H i Let be the optical thickness of the uniform gas in the i-th segment upon reaching the gas layer surface.

[0051] c. For target shock layers with a layered structure, the line-of-sight path needs to be divided into uniform calculation intervals. The gas properties within each interval are considered as uniform and ideal. The results of the interval calculations are then superimposed to obtain the final radiation value. Therefore, a discrete-format radiation transfer equation between target shock layers is set:

[0052]

[0053] in, and Let i and i-1 represent the radiation intensity and optical transmittance of the i-th gas component at wavenumber ν, respectively, and let i-1 represent the gas medium above in the transmission direction.

[0054] d. Within the wave number Δν calculation range, the radiation intensity I of the target shock layer Δν Represented as:

[0055]

[0056] Where ν1 is the starting wavenumber of the band and ν2 is the ending wavenumber of the band.

[0057] 12) The radiation intensity I1 of the target skin and the radiation intensity I of the target shock layer Δν By combining the results, the coupled radiation intensity I of the target skin-shock layer can be obtained. tg and the coupled radiation intensity I tg Convert to the corresponding radiance I tg .

[0058] This invention utilizes computational fluid dynamics software to model the radiation characteristics of a target, thereby calculating the radiation transmission results of the target shock layer and skin. Furthermore, it uses global satellite imagery files to perform complex background infrared radiation modeling of the surface and cloud backgrounds, thus improving the accuracy of target and background radiation modeling and simulation.

[0059] Step 2: Construct simulation models of surface background infrared radiation and cloud background infrared radiation, and combine the target skin-shock layer coupled radiation intensity to obtain infrared radiation under complex backgrounds for space-based detection.

[0060] 21) Construct a simulation model of the background infrared radiation of the Earth's surface.

[0061] 21.1) Obtain global surface emissivity data ε1 and surface temperature data T3.

[0062] Specifically, global surface emissivity data ε1 and surface temperature data T3 can be obtained from the official websites of satellites such as MODIS and LANDSET. The infrared data of the Earth's surface used in this embodiment is the global satellite image file CAMEL_bbe_202008_V001.nc provided by NASA. Figure 5 and Figure 6 The results are shown below after processing the emissivity data ε1 and temperature data T3 in the file for this example.

[0063] 21.2) Calculate the intrinsic surface radiation M1 based on surface temperature data T3. The calculation formula is as follows:

[0064]

[0065] Where ν is the wave number, and h = 6.62606957 × 10 -34 J·s is Planck's constant, and c = 2.99792458 × 10 8m / s is the speed of light, k = 1.380649 × 10 -23 J / K is the Boltzmann constant.

[0066] 21.3) Calculate the enhanced radiation of the surface to the target based on the intrinsic radiation M1 emitted from the surface and the surface emissivity data ε1.

[0067] Specifically, using MODTRAN software, the cloud height is set as the observation point height, and the high-speed aircraft altitude is set as the target altitude. The atmospheric transmittance τ from the cloud layer to the target aircraft is calculated. Then, using the surface intrinsic infrared radiation M1 and emissivity data ε1, the enhanced radiation E1 from the surface to the target is calculated.

[0068]

[0069] Where ΔA is the area of ​​the small surface source, τ is the atmospheric transmittance from the cloud layer to the target aircraft, and θ T and θ A Let be the angle between the vector between the surface small source and the target and the corresponding normal, and l be the distance between the high-speed aircraft and the surface micro-element.

[0070] 21.4) Calculate the solar radiation E2 reflected from the Earth's surface.

[0071] Specifically, using MODTRAN software, the target altitude, band, and solar zenith angle are set, and the corresponding solar irradiance value E is calculated. s1 Then, using the emissivity data ε1, calculate the solar radiation energy E2 reflected from the Earth's surface:

[0072]

[0073] Where, θ S τ represents the angle between the direction of solar incidence and the normal to the ground micro-element, τ1 represents the atmospheric transmittance from the ground to the target altitude, and θ represents the angle between the direction of solar incidence and the normal to the ground micro-element. T and θ A , respectively, are the angles between the vectors between the small surface source and the target on the ground and the corresponding normals, and l is the distance between the high-speed aircraft and the surface element.

[0074] 22) Construct a simulation model of infrared radiation in the cloud background.

[0075] 22.1) Obtain cloud temperature data T4 and cloud emissivity ε2.

[0076] In this embodiment, the cloud temperature data T4 can be obtained from the National Oceanic and Atmospheric Administration (NOAA). The formula for calculating the cloud emissivity ε2 is:

[0077]

[0078] Where z1 and z2 are the upper and lower bounds of the cloud layer, respectively, σ(z) is the scattering coefficient of water droplets and ice crystals, and k(z) is the extinction coefficient of water droplets and ice crystals.

[0079] 22.2) Calculate the intrinsic radiative exitance M2 of the cloud layer based on the cloud emissivity ε2 and the cloud temperature data T4. The calculation formula is as follows:

[0080]

[0081] 22.3) Calculate the enhanced radiation E3 of cloud radiation on the target based on the intrinsic radiative exitance M2 of the cloud.

[0082] Specifically, using MODTRAN software, the cloud height is set as the observation point height, and the high-speed aircraft altitude is set as the target altitude. The atmospheric transmittance τ from the cloud layer to the target aircraft is calculated. Then, using the cloud emissivity ε2 and the cloud intrinsic radiative exitance M2, the irradiance E3 produced by the cloud radiation on the surface of the high-speed aircraft is calculated.

[0083]

[0084] Where, θ T Let θ be the angle between the vector from the cloud differential surface source to the target and the normal to the cloud differential surface source. A Let H be the angle between the vector from the target to the cloud surface source and the normal to the target, l1 be the distance between the high-speed vehicle and the cloud surface element, and H be the distance between the target and the cloud surface element. cd H1 represents the height of the cloud layer, H2 represents the upper limit of the cloud layer height, and dA represents the differential surface source of the cloud layer.

[0085] 22.4) Calculate the solar radiation L3 reflected by the clouds.

[0086] It should be noted that when calculating the radiation characteristics of clouds, the scattering within the clouds cannot be ignored due to the presence of solid and liquid droplets of varying shapes and sizes. Furthermore, since the absorptivity of clouds cannot be used as an approximation for irregular reflectors like clouds, the bidirectional reflectance distribution function (BRDF) is employed to calculate the proportion of radiance reflected from the clouds to the target surface in a fixed direction.

[0087]

[0088] Where i and r represent the incident direction and the reflection direction, respectively, and θ and These represent the zenith angle and the azimuth angle, respectively, that is, θ. i θ represents the angle between the incident sunlight ray and the surface normal. rThe angle between the light rays reflected onto the surface of the aircraft and the surface normal is represented; P(Φ) is the scattering phase function of the cloud layer, and w is the single albedo of the cloud layer.

[0089] Please see Figure 7 , Figure 7 This is a schematic diagram illustrating infrared radiation reflection transmission using BRDF as described in an embodiment of the present invention.

[0090] Then, using MODTRAN software, the solar irradiance E was calculated by setting the cirrus cloud target altitude, band, and solar zenith angle. s2 And the atmospheric transmittance τ from the cloud layer to the target spacecraft; calculate the solar radiation energy L3 reflected by the cirrus clouds as:

[0091]

[0092] Please see Figure 8-9 , Figure 8 This is a physical data diagram of cirrus cloud environment simulation provided in this embodiment of the invention. The data was obtained from the website of the U.S. National Oceanic and Atmospheric Administration (NOAA). Figure 9 yes Figure 8 The normalized BRDF value curve corresponding to the data.

[0093] 23) Establish a radiation calculation model under the complex background of space-based detection.

[0094] 23.1) Couple the target skin-shock layer radiance L tg The enhanced radiation E1 from the ground surface and the enhanced radiation E3 from clouds are superimposed to obtain the actual radiance L of the target. tg ′.

[0095] 23.2) Superimpose the intrinsic surface radiation M1 and the solar radiation E2 reflected from the surface to obtain the actual surface radiation L. b1 Simultaneously, the intrinsic radiation of the cloud layer M2 and the radiation of the sun reflected by the cloud layer L3 are superimposed to obtain the actual radiation of the cloud layer L. b2 Combined surface actual radiation L b1 And the actual radiation of clouds L b2 Infrared radiation L against a complex background under space-based detection was obtained. b ′.

[0096] Step 3: Calculate the coupled uplink radiation values ​​of the line-of-sight skin and shock layer based on the atmospheric infrared radiation transfer model, and obtain the radiation distribution in front of the entrance pupil of the optical system by combining the infrared radiation of the complex background under space-based detection.

[0097] Specifically, step 1 established a coupled radiation calculation model for the target skin-shock layer, and step 2 established a complex background radiation calculation model with surface and cloud layers under space-based detection, thus obtaining the actual radiance L of the target.tg Infrared radiation L against complex backgrounds b Step 3 establishes a radiative transfer model of the target and background models transmitted through the atmosphere to the entrance pupil of the optical system.

[0098] Generally speaking, the role of the atmosphere in radiation calculation is mainly reflected in two aspects: (1) the absorption and attenuation of target radiation energy by the atmosphere; (2) atmospheric path radiation generated after the atmosphere absorbs infrared radiation.

[0099] Specifically, step 3 includes:

[0100] 31) Obtain the path radiation energy L from the target and background to the upper atmospheric boundary. pt L pb .

[0101] Based on space-based detection, using MODTRAN software, the observation altitude, target altitude, observation zenith angle, and observation spectral band are set to calculate the upward radiation of the target and background reaching the upper atmospheric boundary, as well as the atmospheric transmittance τ. a The path radiation energy L from the target and background to the upper atmospheric boundary was obtained respectively. pt L pb .

[0102] Optionally, in this example, the observation altitude is set to 100km, the detector's observation zenith angle is 180°, the target altitudes are set to 20km, 30km, and 40km respectively, and the observation spectral band is set to 1-6μm. The atmospheric uplink / downlink radiative energy is calculated using MODTRAN, as shown below. Figure 10 and Figure 11 As shown.

[0103] 32) Based on the actual radiance L of the target tg Infrared radiation L against a complex background under space-based detection b Calculate the radiation distribution L of the target and background before the entrance pupil of the optical system. tg "、L b The calculation formula is:

[0104] L tg " = L tg ′·τ a +L pt

[0105] L b " = L b ′·τ a +L pb

[0106] Where, τ a It represents the upward radiation of the target and background reaching the upper boundary of the atmosphere, as well as atmospheric transmittance.

[0107] Step 4: Superimpose the radiation distribution in front of the optical system's entrance pupil with the detector effect to obtain the voltage distribution of the actual target and background.

[0108] 41) Calculate the detector voltage signal.

[0109] Specifically, the detector voltage signal includes the detector voltage signal U caused by the background. b The detector voltage signal U caused by the target tg .

[0110] a. Calculate the detector voltage signal U caused by the background. b

[0111] Since the energy at the entrance pupil of an ideal optical system is positively correlated with the voltage of the imaging pixel, the voltage signal of the detector caused by background radiation can be expressed using the single-pixel quantization equation U. b Represented as:

[0112]

[0113] Where θ1 represents the angle between the incident ray and the imaging optical axis, A det dΩ is the area of ​​a unit detector pixel, dΩ is the solid angle of a unit pixel in image space, R(λ) is the spectral responsivity function of the detector, and t int t represents the integration time for a single pixel; int This represents the integration time for a single pixel.

[0114] b. Calculate the detector voltage signal U caused by the target. tg

[0115] Please see Figure 12 , Figure 12 This is a schematic diagram of point target imaging under the space-based detection mode provided in an embodiment of the present invention.

[0116] Space-based detection often involves point target imaging. Since the target's spatial size is smaller than the object space corresponding to a detector pixel, it's necessary to consider both the radiance from the point source and the radiance of the object space background. Because the energy at the entrance pupil of an ideal optical system is positively correlated with the voltage of the imaging pixel, and considering the detector's spectral responsivity R(λ), the imaging voltage U of the target at the corresponding detection band can be obtained. tg for:

[0117]

[0118] Where R(λ) is the spectral responsivity function of the detector, S tg A is the area of ​​a unit pixel object space. d S represents the spatial area of ​​the target point source.pr For the rest of the background, θ2 is the angle between the direction of the target radiation energy emission and the optical axis, and F is the F-number of the ideal optical system.

[0119] 42) Calculate detector noise.

[0120] Specifically, infrared detectors on space-based platforms are mainly semiconductor detectors, and the main types of noise are: thermal noise and current noise. The thermal noise I generated at a temperature T and a working bandwidth Δf is... temp for:

[0121]

[0122] Among them, R d Let k be the resistance value of the resistor, k = 1.380649 × 10⁻⁶. -23 J / K is the Boltzmann constant; the detector's current noise I 1 / f for:

[0123]

[0124] Among them, I d is the operating current of the detector, and A is the cross-sectional area of ​​the semiconductor.

[0125] 43) Based on the detector voltage signal U caused by the background b With thermal noise I temp Current noise I 1 / f The background imaging voltage U after adding noise is obtained by superimposing the data. b ′.

[0126] Step 5: Analyze the detection performance and perform imaging simulation based on the voltage distribution of the actual target and background to achieve full-link infrared radiation simulation of high-speed target-complex imaging background-atmosphere-optical system-imaging detector.

[0127] 51) Performance Analysis of Space-Based Detection

[0128] The detector voltage signal U caused by the target tg and the background imaging voltage U after adding noise b The signal-to-back ratio (SBR) is calculated to assess the detectability of the target. The formula is as follows:

[0129] SBR=U tg / U b ′

[0130] 52) Detection and Imaging Simulation

[0131] The detector voltage signal U caused by the target tg and the background imaging voltage U after adding noise bThe data is integrated to obtain the detector's imaging voltage distribution U. d .

[0132] Imaging voltage distribution U of the detector d Grayscale quantization is performed to obtain infrared grayscale images of high-speed targets for space-based detection.

[0133] The full-link simulation method for space-based high-speed target detection provided in this embodiment first establishes a refined radiation model of the high-speed target by calculating the radiation transmission results of the target's shock layer and skin. Secondly, it models and simulates the intrinsic radiation and reflected solar radiation of the surface and clouds respectively, establishing a radiation calculation model for complex backgrounds in space-based detection. Thirdly, based on the atmospheric infrared radiation coupling transmission model, it calculates the coupled upward radiation values ​​of the line-of-sight skin and shock layer to obtain the radiation distribution before the entrance pupil of the optical system. Finally, it superimposes the detector effect to obtain the voltage distribution of the actual target and background, and uses the signal-to-background ratio to evaluate the target's detectability, thereby improving the accuracy of radiation modeling and simulation of the target and complex background. This method can be used to analyze the infrared early warning detection capability of space-based infrared detection platforms for high-speed targets. This method considers a complete full-link infrared radiation transmission model of high-speed target-complex imaging background-atmosphere-optical system-imaging detector, establishing a complete full-link infrared radiation transmission model system, realizing a systematic full-link simulation of high-speed targets in space-based detection, and improving the infrared early warning detection capability of space-based infrared detection platforms for high-speed targets, as well as the completeness and accuracy of detection band analysis.

[0134] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for full-link simulation of space-based detection of high-speed targets, characterized in that, include: Step 1: Calculate the radiation intensity of the target skin and the radiation intensity of the target shock layer respectively to obtain the coupled radiation intensity of the target skin-shock layer; 11) Model the radiation characteristics of the target using fluid dynamics software, and calculate the radiation intensity of the target skin and the target shock layer, respectively. The formula for calculating the radiation intensity of the target skin is: wherein, is the radiance of a micro facet source of an aircraft skin, is the radiance intensity produced by a facet source, is the angle between the facet source and the corresponding normal, is the area of the facet source; The formula for calculating the radiation intensity of the target shock layer is: in, Indicating in wavenumber Radiation intensity of the target shock layer within the calculation range, Indicates the starting wave number of the band. Indicates the ending wave number of the band. Indicates the intrinsic spectral radiance; 12) The radiation intensity of the target skin and the radiation intensity of the target shock layer By combining the results, the coupled radiation intensity of the target skin-shock layer can be obtained. and the coupled radiation intensity Convert to corresponding radiance ; Step 2: Construct a simulation model of infrared radiation from the ground background and a simulation model of infrared radiation from the cloud background, and combine the target skin-shock layer coupled radiation intensity to obtain the infrared radiation of the complex background under space-based detection; Step 3: Calculate the coupled uplink radiation value of the line-of-sight skin and shock layer based on the atmospheric infrared radiation transfer model, and obtain the radiation distribution in front of the entrance pupil of the optical system by combining the infrared radiation of the complex background under the space-based detection. Step 4: Superimpose the radiation distribution of the optical system before entering the pupil with the detector effect to obtain the voltage distribution of the actual target and background; Step 5: Based on the voltage distribution of the actual target and background, perform detection performance analysis and imaging simulation to achieve full-link infrared radiation simulation of high-speed target-complex imaging background-atmosphere-optical system-imaging detector.

2. The end-to-end simulation method for space-based high-speed target detection according to claim 1, characterized in that, In step 2, constructing the simulation model of the Earth's surface background infrared radiation includes: 21.1) Obtain global surface emissivity data Surface temperature data ; 21.2) Based on the aforementioned surface temperature data Calculate the intrinsic radiation of the Earth's surface The calculation formula is: in, It is Planck's constant. For wave number, At the speed of light, Boltzmann's constant; 21.3) Based on the intrinsic radiation emitted from the Earth's surface and the emissivity data of the Earth's surface Calculate the enhanced radiation of the Earth's surface to the target. The calculation formula is: in, Atmospheric transmittance from clouds to the target aircraft. and Let be the angle between the vector between the small surface source and the target and the corresponding normal. It is the distance between a high-speed aircraft and a micro-element on the Earth's surface; 21.4) Calculate the solar radiation reflected from the Earth's surface. The calculation formula is: in, This represents the solar irradiance value corresponding to a specific target altitude, wavelength, and solar zenith angle. This represents the angle between the direction of solar incidence and the normal to the micro-surface element of the ground. and These are the angles between the vectors between the surface small source and the target, and the corresponding normals. It represents the atmospheric transmittance from the ground to the target altitude.

3. The end-to-end simulation method for space-based high-speed target detection according to claim 2, characterized in that, In step 2, constructing the cloud background infrared radiation simulation model includes: 22.1) Obtain cloud temperature data and cloud emissivity The cloud emissivity The calculation formula is: in, and These represent the upper and lower boundaries of the cloud layer, respectively. The scattering coefficient of water droplets and ice crystals. The extinction coefficient of water droplets and ice crystals; 22.2) Based on the cloud emissivity and the cloud temperature data Calculate the intrinsic radiative exitance of clouds The calculation formula is: 22.3) Based on the intrinsic radiative exitance of the cloud layer Calculate the enhanced radiation of cloud layer on the target. The calculation formula is: in, Let be the angle between the vector from the cloud differential surface source to the target and the normal to the cloud differential surface source. Let be the angle between the vector from the target to the differential surface source of the cloud and the normal to the target. It is the distance between a high-speed aircraft and a micro-element on the surface of a cloud. The height of the clouds. This represents the upper limit of cloud height. This represents the lower limit of cloud height. 22.4) Calculate the solar radiation reflected by clouds. The calculation formula is: in, This indicates the solar irradiance corresponding to the altitude, wavelength, and solar zenith angle of a specific cirrus cloud target. Atmospheric transmittance from clouds to the target aircraft. It represents the proportion of irradiance reflected from clouds in a fixed direction to the irradiance incident on the target surface. and These represent the incident direction and the reflected direction, respectively. and These represent the zenith angle and the azimuth angle, respectively.

4. The end-to-end simulation method for space-based high-speed target detection according to claim 3, characterized in that, In step 2, the infrared radiation of the complex background under space-based detection is obtained by combining the coupled radiation intensity of the target skin-shock layer, including: 23.1) Couple the target skin-shock layer radiance The enhanced radiation of the ground surface to the target The enhanced radiation of the cloud layer on the target By superimposing the data, the actual radiance of the target can be obtained. ; 23.2) The intrinsic surface radiation and the solar radiation reflected by the Earth's surface By superimposing the data, the actual surface radiation can be obtained. Simultaneously, the intrinsic radiative exitance of the cloud layer... and the clouds reflect solar radiation By superimposing the data, the actual radiation of the cloud layer can be obtained. Combined with the actual surface radiation and the actual radiation of the cloud layer Infrared radiation against a complex background obtained by space-based detection .

5. The end-to-end simulation method for space-based high-speed target detection according to claim 4, characterized in that, Step 3 includes: 31) Obtain the path radiation energy from the target and background to the upper atmospheric boundary. , ; 32) Based on the actual radiance of the target Infrared radiation against a complex background under the aforementioned space-based detection Calculate the radiation distribution of the target and background in front of the entrance pupil of the optical system. , The calculation formula is: in, It represents the upward radiation of the target and background reaching the upper boundary of the atmosphere, as well as atmospheric transmittance.

6. The end-to-end simulation method for space-based high-speed target detection according to claim 5, characterized in that, Step 4 includes: 41) Calculate the detector voltage signal, including the detector voltage signal caused by the background. and the detector voltage signal caused by the target The calculation formula is: in, This indicates the angle between the incident ray and the imaging optical axis. It is the area of ​​a unit detector pixel. It is the solid angle of a unit pixel in image space. It is the spectral responsivity function of the detector. Indicates the integration time for a single pixel; The area of ​​a unit pixel object space. The spatial area of ​​the target point source. For the background of the rest, The angle between the direction of the target's radiated energy emission and the optical axis. The F-number is the number of an ideal optical system. 42) Calculate detector noise, including thermal noise. and current noise The calculation formula is: in, The resistance value of the resistor. It is the detector's operating current. It is the cross-sectional area of ​​the semiconductor; 43) The detector voltage signal caused by the background With the thermal noise The current noise The background imaging voltage after adding noise is obtained by superimposing the data. .

7. The end-to-end simulation method for space-based high-speed target detection according to claim 6, characterized in that, Step 5 includes: 51) Performance Analysis of Space-Based Detection Based on the detector voltage signal caused by the target and the background imaging voltage after adding noise Calculate the signal-to-back ratio To assess the detectability of a target, the calculation formula is as follows: 52) Detection and Imaging Simulation The detector voltage signal caused by the target and the background imaging voltage after adding noise Integrate the data to obtain the detector's imaging voltage distribution. ; Imaging voltage distribution of the detector Grayscale quantization is performed to obtain infrared grayscale images of high-speed targets for space-based detection.

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