机载多脉冲激光测距特性及其不确定度研究

Ranging characteristic and uncertainty of airborne multi-pulse laser

针对机载平台特殊环境下激光测距的概率特性,建立了脉冲回波信号的理论分析模型,得出了不同信噪比情况下脉冲回波信号包络的概率密度分布函数.结果表明:信噪比的降低通过回波波形直接导致测距离散数据的不同分布,大信噪比时呈现高斯分布,小信噪比时近似瑞利分布,一般情况符合莱斯分布;根据恒比定时时刻鉴别方法,在获取大量实验数据的基础上,实验结果验证了理论模型的合理性.对以"方差"定义的测距精度不适用的情况下,引入测量不确定度的概念,结合不确定度原理,通过分布区间概率量化了实验结果,提出了一种新的评价机载激光测距性能的方法,该方法能够克服传统评价指标的单一性以及不合理性,同时为机载光电系统的性能测试与评估提供了参考意义.

Under the special environment of airborne platform, the theoretical model is built based on probability characteristic of laser ranging, and the probability density distribution functions of pulse-echo signal envelope under different signal- to-noise ratios （SNRs） are obtained. The theoretical results show that the decrease of SNR causes different distributions of ranging data through echo wave characteristic. The experimental data present Gauss distribution with larger SNR, or Rayleigh distribution with poor SNR, or Rice distribution with general condition. According to the constant-ratio timing method, experimental results verify the rationality of theoretical model under a number of ranging data. When the ranging accuracy defined by variance is not applicable, the concept of uncertainty of measurement is introduced. Combined with the theory of uncertainty, a new method of evaluating airborne laser ranging performance is put forward. This method could overcome the unity and irrationality of traditional evaluating method, and meanwhile, it could provide an important reference for evaluating and testing airborne optoelectronic system performance.