The Equivalent Analysis of Direct Geocoding Model and Spaceborne INSAR Altitude Model in Height Uncertainty
直接地理编码与星载干涉SAR测高不确定度的等效性分析

The height measurement models considering earth curvature of INSAR mainly consist of two kinds- spaceborne interferometric SAR height measurement model and direct geocoding model. Spaceborne interferometric SAR height measurement model gets unambiguous interferometric phases through interferometric SAR, then calculates the terrain height by the spatial geometry considering earth curvature. Direct geocoding model obtains the three-dimensional coordinates using two slant range equations and one Doppler equation, based on the unambiguous interferometric phases. Because the methods getting the terrain height in the two models are different, it is difficult to compare the height measurement uncertainties of the models. Based on matrix theory, the explicit expressions of height uncertainty of direct gecoding model are presented. And it is proven that the height measurement uncertainty formulas of direct geocoding model are the same as that of spaceborne interferometric SAR height measurement model after introducing a new slane range plane coordinate system. Then it is proposed that these two models would lead to the same precision in height measurement. Finally, computer simulation is employed to validate the correctness of the theory analysis.