本文選題：激光雷達散射截面 + 大氣后向散射��； 參考：《西安電子科技大學》2014年碩士論文

【摘要】：激光雷達主要工作在戶外甚至是戰(zhàn)場環(huán)境,既要面對復雜的天氣情況和障礙物的干擾,又要應對復雜工作環(huán)境的突發(fā)變化。尤其在激光雷達散射截面的測量中,探測目標對激光信號的后向散射回波信號本身就相當微弱,且要受到接收系統(tǒng)自身的系統(tǒng)噪聲以及激光在大氣中傳輸產(chǎn)生的雜散光等背景噪聲的影響,回波信號極其難以探測甚至可能出現(xiàn)被噪聲淹沒的情況。激光在大氣中傳輸,產(chǎn)生的大氣后向散射光是可以預見的能直接影響激光雷達探測性能的主要噪聲之一。通過研究激光的大氣后向散射問題可以探索消除大氣后向散射影響的新方法,從而降低總體噪聲,改善信噪比,提高激光雷達散射截面測量的可行性和準確性。這對促進激光雷達散射截面測量中微弱信號探測技術的完善和提高有較為重要的意義�；诩す饫走_散射截面的基本理論和測量的基本過程,本文從大氣介質的空間組成出發(fā),分析了激光在大氣中傳輸時產(chǎn)生大氣后向散射的原因,給出了激光大氣后向散射的定義,并對大氣后向散射對激光雷達散射截面測量過程中的影響做了詳盡的分析和討論。進而,建立了激光大氣后向散射理論模型,并對該模型進行了計算和分析,給出了不同的距離范圍內(nèi)產(chǎn)生的大氣后向散射相對總大氣后向散射所占的比重,為消除大氣后向散射的研究提供了理論指導和數(shù)據(jù)支撐。然后,提出了基于空間濾波的消除大氣后向散射影響的新方案,并應用新實驗方案在霧霾天氣和晴朗天氣兩種天氣條件下進行了模擬實驗,對實驗結果進行了分析討論。最后,將理論模型和實驗方案進行了對比分析結果顯示,能夠進入探測系統(tǒng)的大氣后向散射主要集中在一定的距離范圍內(nèi)。將二者相結合,對一個實際測量的外場實驗進行了工程應用的分析發(fā)現(xiàn),可以通過調節(jié)發(fā)射和接收系統(tǒng)的距離間隔來控制絕大部分的大氣后向散射進入探測系統(tǒng),而剩余的仍然能產(chǎn)生影響的大氣后向散射完全可以用本文提出的空間濾波的方法進行控制。本文的研究思路是先根據(jù)大氣后向散射理論建立理論模型,再對外場實驗數(shù)據(jù)進行分析來完善和優(yōu)化理論模型,并提出了基于空間濾波的消除大氣后向散射的實驗方法,實現(xiàn)了對大氣后向散射影響的消除,大大提高激光雷達散射截面測量的可行性和準確性。然而,在本文的研究中仍然存在著理論模型建立背景與工程實際有差異的不足,在接下來的工作中仍需要繼續(xù)在尊重工程實際的前提下深入完善理論模型,改進和提高實驗分析辦法,做好對工程實際更細致的應用指導。另外實驗的天氣條件與理論天氣條件的差異帶來的誤差需要做進一步的研究,以求進一步縮小理論和實測的誤差。
[Abstract]:The lidar mainly works in the outdoor and even battlefield environment. It not only faces the complex weather and obstacle interference, but also deals with the sudden changes of the complex working environment. Especially in the measurement of the laser radar cross section, the backscattering echo signal of the target to the laser signal itself is very weak. It is also affected by the system noise of the receiving system and the stray light produced by the laser in the atmosphere. The echo signal is extremely difficult to detect and even may be submerged by the noise. The atmospheric backscattering light produced by laser propagation in the atmosphere is one of the main noises which can directly affect the detection performance of lidar. By studying the atmospheric backward scattering of laser, a new method to eliminate the influence of atmospheric backscattering can be explored, which can reduce the total noise, improve the signal-to-noise ratio, and improve the feasibility and accuracy of laser radar cross section measurement. It is of great significance to improve the detection technology of weak signal in the measurement of laser radar cross section. Based on the basic theory of laser radar cross section (LRCS) and the basic process of measurement, this paper analyzes the causes of atmospheric backscattering when laser propagates in the atmosphere from the space composition of atmospheric media. The definition of laser atmospheric backscattering is given, and the influence of atmospheric backscattering on the measurement of laser radar cross section is analyzed and discussed in detail. Furthermore, the theoretical model of laser atmospheric backscattering is established, and the calculation and analysis of the model are carried out. The proportion of atmospheric backscattering relative to total atmospheric backscattering in different distance range is given. It provides theoretical guidance and data support for the study of eliminating atmospheric backscattering. Then, a new scheme based on spatial filtering to eliminate atmospheric backscattering is proposed, and the experimental results are analyzed and discussed under two weather conditions: haze weather and sunny weather. Finally, the theoretical model and the experimental scheme are compared and analyzed. The results show that the atmospheric backscattering which can enter the detection system is mainly concentrated in a certain range of distances. By combining the two methods, the engineering application of an actual field experiment is carried out. It is found that most of the atmospheric backscattering can be controlled into the detection system by adjusting the distance between the transmitting and receiving systems. The remaining backscattering can be controlled by the spatial filtering method proposed in this paper. The research idea of this paper is to establish a theoretical model based on the atmospheric backscattering theory, then to analyze the experimental data of the external field to perfect and optimize the theoretical model, and to propose an experimental method to eliminate the atmospheric backscattering based on spatial filtering. The effect on atmospheric backscattering is eliminated, and the feasibility and accuracy of LRCS measurement are greatly improved. However, in the research of this paper, there are still some differences between the background of the theoretical model and the engineering practice. In the following work, we still need to further improve the theoretical model on the premise of respecting the engineering reality. Improve and improve the method of experimental analysis, and make a more detailed application guidance to engineering practice. In addition, the errors caused by the difference between the experimental weather conditions and the theoretical weather conditions need to be further studied in order to further reduce the theoretical and measured errors.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN958.98

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