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The signal transmission system of the laser terminally guided projectile is the center of the laser terminally guided weapon. The signal of the laser terminally guided projectile has undergone the following transmission process: the laser signal emitted by the illuminator is transmitted in the atmosphere and received by the target's reflective surface. The reflecting surface reflects the laser signal according to a certain rule, and the reflected laser signal is transmitted through the atmosphere and finally reaches the seeker of the laser guided artillery projectile. Taking into account the influence of background noise, the signal finally reaching the seeker has background noise signals in addition to the laser signal. All input signals are photoelectrically converted and processed by the laser seeker system to form a guided output signal, which is the driving signal of the laser terminal guidance projectile [11]. The following is a detailed description of the seeker's received signal power model, 1.06 μm laser atmospheric transmittance model, and target indicator launch laser power model.
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The pulse repetition frequency of the laser target indicator used is usually 10-20 ps. In order to meet the requirements of laser pulse encoding, the repetition frequency may be higher. The laser target indicator generally requires the divergence of the laser beam to be reduced as much as possible. The beam divergence of an ordinary stable laser is 35 mrad [12]; the seeker of the "red earth" laser terminal guided projectile selects the amplitude and difference single pulse. For the laser seeker, the corresponding field of view of the relay area is ±15°, and the main function is to capture the field of view. The linear area corresponds to a small field of view of ±3°, which is used to track the field of view [13], its laser target indication calculation model is shown in formula (1).
$${P_d} = {E_d}/{\tau _d} \cdot {T_d}$$ (1) Where, Pd is the pulse transmitting power of the laser target indicator; Ed is the laser pulse energy of the laser target indicator; τd is the laser pulse width of the laser target indicator; Td is the transmittance of laser target indicator optical system.
Assuming that the average pulse energy of the laser target indicator in each irradiation period is ≥ 35 mJ (40 mJ in this paper), the pulse width is 10-22 ns (5 ns in this paper), and the transmittance of the optical system of the laser target indicator is 0.8, then the pulse transmitting power of the laser target indicator can be calculated as: Pd=2.133×106 W.
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When the target diffusely reflected laser pulse is imaged in the relay area, after the signal processing of the electronic cabin, the precession angular velocity of 11 (°)/s is used to reduce the tendency of the misalignment angle, and the target is introduced from the large field of view to the small field of view. So that the reflected laser pulse of the target is diffusely imaged on the central area of the photodetector, so as to automatically track the target. It includes two processes: the target reflecting surface receives the laser model and the target reflecting surface reflects the laser model. The laser energy received by the target reflecting surface is not only related to the transmittance of the atmosphere, but also related to the area of the receiving surface. Suppose the laser emission power of the laser target indicator is Pd, the atmospheric transmittance is τt, the target reflecting surface is a circular surface with a radius of rl, and the distance between the laser target indicator and the target reflecting surface is rld, and divergence angle of the laser target indicator laser is θ, and the various effects of the atmosphere on the laser beam are the same everywhere, then the energy distribution of the laser spot on the reflecting surface should also conform to the Gaussian distribution, then when the area of the laser scattering spot is smaller than that of the reflecting surface. In terms of area, the laser power Pt received by the target reflecting surface is [14-15]:
$${P_t} = {P_d} \cdot {\tau _t}\left( {{R_{td}}} \right)$$ (2) When the area of the laser scattering spot is larger than the area of the reflecting surface, the laser power Pt received by the target reflecting surface is:
$${P_t} = {P_d}\dfrac{{\displaystyle\int_0^r {\exp } \left( { - \dfrac{{2{r^2}}}{{{w^2}}}} \right){\rm d}r}}{{\displaystyle\int_0^\infty {\exp } \left( { - \dfrac{{2{r^2}}}{{{w^2}}}} \right){\rm d}r}} \cdot {\tau _t}\left( {{R_{td}}} \right)$$ (3) Where, ω is the laser spot radius at the target reflecting surface,
$\omega {\rm{ = }}{\theta {R_{td}}}/2$ .The reflecting surface of the target surface reflects the laser model, and it is assumed that the reflecting surface of the target is a rough plane with a certain area, and the direction of the incident light coincides with the normal of the reflecting surface. The incident light is diffusely reflected on the rough surface and conforms to Lambert's law of cosine reflection, then the distribution of light power reaching the seeker after passing through the target reflecting surface is[14]:
$${I_r} = {\rho _t}\dfrac{{{P_t}}}{{\pi R_{ts}^2}}\cos {\theta _L} \cdot {\tau _t}\left( {{R_{{{rs}}}}} \right)$$ (4) Where, Rts is the distance between the shell and the target; Ir is the laser density received at the seeker; ρt is the diffuse reflection coefficient of the target reflecting surface; Pt is the laser power received on the target reflecting surface; θL is the angle between the eye line of sight and the reflector normal. It is determined by the target reflector normal azimuth (θd, φd) and the eye line of sight azimuth (θs, φs).
$$\cos {\theta _L} = \left| {\sin {\theta _d}\sin {\theta _s} + \cos {\theta _d}\cos {\theta _s}\cos \left( {{\varphi _d} - {\varphi _s}} \right)} \right|$$ (5) -
It can be seen from the foregoing that there are mainly two types of factors that affect laser detection: system inherent parameters and external influence parameters. The inherent parameters of the system are determined by the physical properties of the laser and receiver and cannot be changed. The external influence parameters include the attenuation of the atmosphere to the laser, the working distance, and the double-layer transmittance of the smoke screen. This research focuses on the range of action, the attenuation of the laser light by the atmosphere, and the double-layer transmittance of the smoke screen. The operating distance is given by the guidance model, and the double-layer transmittance of the smoke screen is affected by the thickness of the smoke screen and the type of smoke screen.
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Smoke screen is a variable fluid, and the atmosphere is its transmission medium. When studying the properties of smoke screens, it is inseparable from the study of atmospheric diffusion. In the smoke screen diffusion model, there are mainly two types of continuous point source and instantaneous body source concentration distribution modes, since the explosion of the smoke screen shell is instantaneous explosion, the Gaussian mode of instantaneous body source concentration distribution is selected in this paper, and the lead direct to the smoke screen density distribution equation in the instantaneous point source smoke screen density distribution model is as follows[16]:
$${C_{^Z}} = \dfrac{Q}{{\sqrt {\pi /2} u{\sigma _y}}}\exp \left( { - \dfrac{{{y^2}}}{{2\sigma _y^2}}} \right)$$ (6) Where, CZ is the smoke concentration at height Z (g/m3); Q is the smoke velocity of the smoke screen (g/s): u is the average velocity during the release period (m/s); σy is the atmospheric dispersion variance in the y direction (m).
In the Gaussian diffusion model, the smoke screen speed and average wind speed can be obtained by related instruments and methods; the smoke screen speed in this project is determined by the total amount of smoke screens and the duration of the smoke screen. It is considered that the smoke screen speed conforms to the overall distribution. The quality of the smoke screen agent in this project set as 1000 g, and record the duration as 30 s. According to the smoke screen time and the quality of the aerosol, the smoke screen velocity at each moment is obtained; the smoke screen concentration value of different heights can be obtained by bringing it into the smoke screen concentration distribution equation; when the smoke screen concentration value is lower than a certain value, it is considered as invalid smoke. Furthermore, according to the smoke screen concentration threshold, the relationship between the smoke screen height and the smoke screen time can be obtained.
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The transmittance of 1.06 μm laser in the atmosphere consists of two processes[17-18]: the absorption rate of laser τab(L); the transmittance τsc(L) of the atmosphere to the laser, where L is the transmission distance of the laser in the atmosphere(km), and the total transmittance τt(L) of the atmosphere can be expressed as:
$${\tau _t}(L) = {\tau _{ab}}(L) \cdot {\tau _{sc}}(L)$$ (7) (1) The absorption transmittance of the atmosphere to 1.06 μm laser
For a 1.06 μm laser, ozone, carbon dioxide and water vapor in the atmosphere have obvious absorption effects, and the absorption effects of carbon dioxide and ozone can be ignored when the laser semi-active guidance is too long, only the absorption of water vapor can be considered.
$${\tau _{ab}}\left( L \right) = 1 - ERF\left( {0.0167\sqrt W } \right)$$ (8) Where, W =FkL is the amount of water vapor (mm), and Fk is the amount of water vapor per unit distance.
(2) Atmospheric scattering of 1.06 μm laser
Factors that cause scattering are smoke, clouds, rain, snow, dust, sand. Scattered particles can be divided into three categories: the first category includes smoke screen and cloud; The second category is aerosols in the atmosphere; The third category is rain and snow. The total scattering transmittance can be expressed as[19-20]:
$${\tau _{sc}}\left( L \right) = {\tau _1}\left( L \right){\tau _2}\left( L \right){\tau _3}\left( L \right)$$ (9) The transmittance of the first type of scattering source is:
$${\tau _1}(L) = {{\rm e}^{ - \gamma (1.06)t}}$\$ (10) $$\gamma (1.06) = \dfrac{{3.912}}{{{R_v}}}{(1.93)^{ - q}}$$ (11) Where, Rv is the visibility distance of 1.06 μm laser, and q is constant.
$$q = \left\{ {\begin{array}{l} {1.3,\;{\kern 1pt} {R_v} \geqslant 11\; {\rm km}} \\ {0.585R_v^{1/3},\;{R_v} < 11\;{\rm km}} \end{array}} \right.$$ (12) The transmittance of the second type of scattering source is:
$${\tau _2}(L) = {{\rm e}^{ - \frac{{3.912}}{{{R_v}}}L}}$$ (13) The transmittance of the third type of scattering source is:
$${r_1}(L) = {{\rm e}^{ - \delta L}}$$ (14)
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摘要: 随着精确制导武器的大量应用,实现了常规弹药集群攻击模式向制导弹药精确打击模式的转变,从而达到了最优的作战性价比,其激光武器被广泛应用于军事领域,为有效对抗激光武器,烟幕弹以性价比高等优势受到各国的青睐。以烟幕干扰激光末制导炮弹为例,研究了激光末制导炮弹的制导原理,烟幕干扰激光末制导炮弹的原理,将烟幕对激光导引头的遮蔽效果引入到外弹道仿真过程,以脱靶量为指标,建立了干扰系统仿真模型,实现了烟幕对抗激光末制导炮弹的干扰仿真研究。研究结果表明,该仿真系统可以为烟幕弹对付激光末制导炮弹提供最佳干扰策略,为典型烟幕弹药的作战训练和效能评估提供辅助决策。Abstract: With the large-scale application of precision guided weapons, it has realized the transition from conventional ammunition cluster attack mode to guided munition precision strike mode, thus achieving the best combat cost performance. Its laser weapons are widely used in the military field to effectively combat laser weapons. Smoke screen bombs are favored by all countries due to their high cost-effective advantages. In this study, taking the smoke screen interferes with laser terminal guided projectiles as an example, the guidance principle of laser terminal guided projectiles, and the principle of smoke screen interference with laser terminal guided projectiles were studied. The shielding effect of the smoke screen on the laser seeker was introduced into the simulation process of external ballistic. Taking miss distance as an indicator, the jamming system simulation model was established, and the simulation research of smoke screen against laser terminal guided projectiles was realized. The research results show that the simulation system can provide the best jamming strategy for smoke screens against laser terminal guided projectiles, and can provide auxiliary decision-making for combat training and effectiveness evaluation of typical smoke munitions.
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[1] Jiang Dianyuan. Laser guided projectile-copper spotted snake [J]. Aerodynamic Missile Journal, 1989, 1(2): 1-8. (in Chinese) [2] Bai Yi, Zhong Haidong, Qin Yajuan, et al. Overview of foreign guided projectile development [J]. Aerodynamic Missile Journal, 2013, 1(5): 33-38, 49. (in Chinese) [3] Yu Bo. Guidance error analysis of laser terminal guidance shell [J]. Ordnance Industry Automation, 2018, 37(9): 46-48, 52. (in Chinese) [4] Tong Zhongcheng, Sun Xiaoquan, Yang Xiwei, et al. Simulation of laser-barrage-jamming for laser-guided weapon [J]. Journal of Ballistics, 2008, 1(1): 106-110. (in Chinese) [5] Mou Yu, Lin Defu, Qi Zaikang, et al. Performance of proportional navigation law for terminal laser-guided projectile [J]. Infrared and Laser Engineering, 2009, 38(2): 250-255. (in Chinese) [6] Liu Xia, Shan Ning, Wang Zhijing. Design research on transmitting and attenuating system of non-lethal laser weapon in rain [J]. Laser & Infrared, 2018, 48(6): 682-685. (in Chinese) [7] Li Lifang. The study of atmospheric aerosol particles scattering impact on laser propagation in the atmosphere[D]. Taiyuan: North University of China, 2013. (in Chinese) [8] Wang Xuanyu. Development of anti-infrared smoke material and its extinction performance(Invited) [J]. Infrared and Laser Engineering, 2020, 49(7): 20201019. (in Chinese) doi: 10.3788/IRLA20201019 [9] Guo Jing. Study on the characteristics of atmospheric transmission of the near field constant pulse laser in rainfall[D]. Nanjing: Nanjing University of Science and Technology, 2012. (in Chinese) [10] Zong Siguang, Liang Shanyong, Cao Shui, et al. Research of smoke particle measurement with laser backward scattering [J]. Laser & Infrared, 2017, 47(9): 1082-1088. (in Chinese) doi: 10.3969/j.issn.1001-5078.2017.09.005 [11] Zhao Xiaotao. Design and simulation of laser seeker digital signal processing system based on FPGA[D]. Zhengzhou: Zhengzhou University, 2020. (in Chinese) [12] Qiu Xiong, Wang Shicheng, Liu Zhiguo, et al. Modeling research on angle measurement accuracy of four-quadrant detector of laser seeker [J]. Infrared and Laser Engineering, 2020, 49(7): 20190453. (in Chinese) doi: 10.3788/IRLA20190453 [13] Yang Shujuan. Multi-parameter detection system of laser indicator[D]. Changchun: Changchun University of Science and Technology, 2012. (in Chinese) [14] An Yang. Research and design of end guidance control for small artillery[D]. Lanzhou: Lanzhou University of Technology, 2019. (in Chinese) [15] Liu Zhiguo, Qiu Xiong, Wang Shicheng, et al. Influence of laser seeker detection performance on high repetition frequency jamming laser [J]. Chinese Journal of Lasers, 2019, 46(11): 1101001. (in Chinese) doi: 10.3788/CJL201946.1101001 [16] Xu Dao, Hao Xueying, Xiao Kaitao, et al. Simulation study on shielding effectiveness of explosive smoke screen [J]. Acta Armamentarii, 2020, 41(7): 1299-1306. (in Chinese) [17] Lv Gao, Ma Hui, Cheng Yanjie, et al. Atmospheric Scattering Effect on Confrontation in Laser Guided Weapon [J]. Ship Electronic Engineering, 2014, 34(8): 162-165. (in Chinese) [18] Li Tianpeng. Study on 1.06 μm pulsed laser phase locked loop[D]. Chengdu: University of Electronic Science and Technology of China, 2020. (in Chinese) [19] Huang Chaojun, Wu Zhensen, Liu Yafeng. Scattering characteristics of aerosol aggregation particles of 1.06 μm laser [J]. Infrared and Laser Engineering, 2013, 42(9): 2353-2357. (in Chinese) [20] Li Hua, Qin Shiqiao, Hu Xin, et al. Analysis to the effects of Mie Scattering in 1.06 μm laser simulation tests [J]. Journal of National University of Defense Technology, 2008, 1(3): 5-10. (in Chinese) [21] Gao Wei, Sun Yifan. Evaluation method for electronic jamming effect based on field and simulation tests [J]. Journal of Projectiles, Rockets, Missiles and Guidance, 2017, 37(2): 165-169. (in Chinese) [22] Gray G J, Aouf N, Richardson M, et al. Countermeasure effectiveness against an intelligent imaging infrared anti-ship missile [J]. Optical Engineering, 2013, 52(2): 6401-6412. [23] Gao Wei, Sun Yifan, Wei Yanling. Guidance flight with the unmanned airship steered by a homing seeker[C]//Proceeding of the 11th World Congress on Intelligent Control and Automation, 2014: 3810-3814.