SAR回波信号及InSAR干涉相位的统计特性研究

分析了SAR回波信号的构成及干涉相位的统计特性,系统地研究了经多视处理后SAR干涉相位的概率密度函数与相干系数、视数的关系．明确了在不同视数下,噪声对干涉图质量的影响,为干涉图的质量评价和误差消除提供了理论依据．

The Statistic Characteristics of SAR Signals and Interferometric Phases

The phases derived from SAR image pairs are key observables for interferometric processing,so it is important to understand the statistic characteristics of observables to enable assessment of the accuracy of deformation measurements.In this paper,the statistic properties of SAR signal and interferometric phases are analyzed and the probability density function(PDF) of multi-look processed SAR interferometric phase is deduced.Then the relation among PDF coherence and multi-look numbers is investigated.In addition,based on statistic characteristics, the impact of noise on interferogram under different multi-look numbers is derived. The study has shown that the response of a resolution cell on earth to the arriving radar pulse is strongly dependent on the scattering mechanisms involved.But under a set of assumptions, the SAR signals can be taken as Gaussian random variables.The PDFs of these variables we derived are in good agreement with the observed results in actual data experiments.Although the PDF of the phase has a uniform distribution,the interferometric phase is not uniform if the two signals have some degree of correlation.From the relation of coherence and standard deviation under different multi-look numbers,we find that coherence can be enhanced by averaging multiple pixels at the cost of reducing the resolution and areas with high coherence are more sensitive to the noise than those with low coherence.The study results are helpful to assess the quality of interferogram and eliminate errors.