星载激光雷达弱信号增强的随机共振方法

The results in thoery and experiments have showed that noise is not detrimental to signal at all time in nonlinear system. Noise and signal are coupled together nonlinearly in nonlinear system, and this coupling can lead to an energy exchange in which the signal grows at the expense of the noise. This amplification only holds for certain instance, such as the intensity of noise arrives to a special value, which give rise to the term 'stochastic resonance'. Due to the reasons of tele-propagation and atmosphere attenuation, weak receiving signal is a bottlenecked problem in spaceborne lidar. To solve the problem of weak receiving signal in spaceborne lidar, we designed a system frame for signal enhancement based on stochastic resonance. This project will focus on the problems of fundamental principle, enhancement performance and parameter selection under this system frame. Through the studying of sparse representation and time-frequency analysis, we will construct the stochastic resonance equation of complex signal, and analyze the solution of the equation and expression of signal gain. Through the studying of theory analysis, experiments design and response surface analysis, we will obtain the quantificational relationship between enhancement performance and nonlinear parameter, noise parameter and signal feature. Furthermore, numerical simulation will be studied to validate the correctness of principle and to support the selection of system parameter.

现有理论和实验已证明，非线性系统中噪声并不总是起破坏作用，而是与信号非线性耦合在一起，这种耦合使得噪声和信号间可进行能量转换，将噪声的能量转换到信号中，达到消耗噪声来增强信号的目的，但是这种信号放大特性只会出现在某些特殊情况下，如噪声达到特定强度时出现，这就是"随机共振"现象。因为远距离传播、大气衰减等原因，接收信号弱是星载激光雷达的一大瓶颈问题。本项目针对星载激光雷达的弱信号问题，设计了星载激光雷达弱信号随机共振系统框架，在此系统框架下，重点从理论和数值实验上研究随机共振用于激光雷达弱信号增强的原理、性能和参数选取方法。通过稀疏表示、时频分析等方法，构建复杂信号下的随机共振方程，并分析方程的解和信号增益的表达式。通过理论分析、实验设计、响应曲面分析等方法获取系统的非线性参数、信号特征、噪声参数与增强性能之间的定量关系，并结合数值仿真进行验证，进而获得系统参数的最优选取参数选取方法。

现有理论和实验已证明，非线性系统中噪声并不总是起破坏作用，而是与信号非线性耦合在一起，这种耦合使得噪声和信号间可进行能量转换，将噪声的能量转换到信号中，达到消耗噪声来增强信号的目的，但是这种信号放大特性只会出现在某些特殊情况下，如噪声达到特定强度时出现，这就是“随机共振”现象。因为远距离传播、大气衰减等原因，接收信号弱是星载激光雷达的一大瓶颈问题。本项目针对星载激光雷达的弱信号问题，设计了星载激光雷达弱信号随机共振系统，包含时域信号增强的光折变环形腔中的随机共振系统和空域信号增强的调制不稳定性随机共振系统。对这两种随机共振系统分别建立了随机共振方程，并从理论和数值实验上研究了随机共振用于激光雷达弱信号增强的原理、性能和参数选取方法。仿真结果表明，利用本项目所设计的随机共振系统，可以实现从被噪声淹没的信号中提取出真实信号。