不同分布模式电离层对星载InSAR测高精度的影响及校正

Influence and Correction of Different Distribution Patterns Ionosphere on Spaceborne InSAR Elevation Measurement Accuracy

电离层总电子含量(TEC)会使合成孔径雷达干涉测量(In SAR)信号产生相位延迟,进而影响生成DEM的精度,特别是对L和P等长波段信号的影响不可忽略。因此,针对不同TEC分布模式的电离层开展研究,构建了电离层对星载In SAR测高精度的影响模型,提出了相应的校正方法,并进行了仿真实验。实验表明对于特定波长的In SAR信号,不同TEC分布模式对In SAR测高精度的影响不同:TEC均匀分布的电离层模型对In SAR测高精度的影响较小,并可通过相位解缠、基线估计等环节进行很好的补偿;而TEC不均匀分布的电离层模型对In SAR精度的影响较大,仅靠相位解缠等过程不能较好地消除,必须通过向干涉图中加入电离层影响模型予以纠正。

The total electron content（ TEC） of the ionosphere will cause In SAR signal phase delay, thereby affecting the accuracy of DEM, especially the effect on L, P and other long wavelength signals can＇t be ignored. Therefore, the research was carried out for different distribution patterns of TEC, the model of ionosphere effect on spaceborne In SAR measurement precision was constructed,then the corresponding correction methods were proposed and simulation experiment was carried out. The experimental results show that for a particular wavelength of the InSAR signal, the effects of the different distribution patterns of TEC on In SAR measurement accuracy are different：the impact of the uniform distribution of TEC on In SAR measurement precision is less, and the effect can be well compensated through phase unwrapping and baseline estimate; for the uneven distribution of TEC, the impact is greater, and it can＇t be eliminated well through phase unwrapping and baseline estimate, it must be corrected by adding ionosphere effect model to the interference pattern.