基线是干涉合成孔径雷达(InSAR)工作原理中的关键参数，它使得图像对之间有了相干性，同时也是导致图像对相干性损失的一个根源。在数字高程模型(DEM)允许误差的条件下，一定存在最优基线使得DEM精度最佳。最优基线使得InSAR工作在最佳状态，准确地估计它可以大大提高地形高度的测量精度。文中首先根据InSAR测高成像几何关系和回波的信号谱分析了基线的存在引起的两方面影响，从而论证了最优基线的存在性。在此基础之上，从目标高度估计方差着手，对于平坦地区或坡度一定的地形，建立了合成孔径雷达干涉测量中的最优基线模型

Baseline is a key parameter in the pri nc iple of Interferometric SAR. It not only makes image pairs correlative, but also is one of sources inducing their decorrelation. In the condition of acceptable Digital Elevation Model (DEM) error, there must be an optimal baseline which mak es DEM precision highest. The optimal baseline makes interferometric SAR perform in the best status. Accurate optimal baseline estimation would largely increase the precision of terrain height measurement. In this paper the existence of an optimal baseline is demonstrated firstly, basing on the geometric relationship o f InSAR imaging and signal spectrum of echo. Next relying on the expression of t he estimated variance of target altitude, the optimal baseline model is establis hed in InSAR for flat terrain or with a constant slope. Furthermore through test ing on the ERS-1/2 interferometric data, correctness of optimal baseline model is validated. Finally the effects of some system and geometric parameters on the optimal baseline are discussed.

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