一种无控制点支持的分布式SAR系统干涉测高方法

A Multi-baseline InSAR DEM Reconstruction Approach without Ground Control Points

分布式星载合成孔径雷达干涉测高系统提供了多个通道的观测数据,给定位和测高带来冗余信息,基于此提出了一种无需控制点支持的干涉测高方法。介绍了该方法的原理,推导了定位与测高方程组,采用一阶近似进行了误差敏感度分析,并通过Monte—Carlo仿真加以验证。仿真结果表明:(1)可以直接采用误差理论分析结果为系统分析和设计提供支撑;(2)测高精度对系统干涉相位差的误差十分敏感。

Spaceborne interferometric synthetic aperture radar(InSAR)is an important method to reconstruct global dig- ital elevation model(DEM),which measures the terrain heights using two or more SAR images from different angles.DS- InSAR is a novel radar system,which is the of combination of spaceborne SAR and satellite formation flying technology. Because of its advantage such as high DEM reconstruction precision,strong survival capability and anti-jam ability,short cycle of manufacture and low cost,the novel InSAR system has been a research hotspot in the field of spaceflight remote sensing.So far,many institutions have already proposed DS-InSAR plan with the ability of height measurement,such as interferometric Cartwheel plan proposed by CNES,interferometric Pendulum plan proposed by DLR,Radatsat-2/3 tandem plan proposed by Canada and TanDEM-X plane proposed by DLR etc. In single-baseline InSAR system,object geographic coordinates are computed from the observed ranges and Doppler central frequencies which occur when the object points are focused on SAR imaging processing.The height of object on a normal plane is generated finally.Absolute interferometric phase is needed for the above process of DEM reconstruction. However,only relative interferometric phase is obtained from phase unwrapping.So far,the effective way of converting relative interferometric phase to absolute interferometric phase requires at least one ground control point.However,it's dif- ficult to acquire ground control points in the practical applications,which heavily restricts the application of single-base- line InSAR system. DS-InSAR system includes more than one baseline,so it is also called multi-baseline InSAR system.It offers addi- tional observation information for the derivation of position and height of object,compared to the single-baseline InSAR system.On one hand,it offers more than two ranges of information for every object ;on the other hand,it offers more than one interferometric phase difference information between every two objects.Based on the additional information it offers, this paper proposes a new DEM reconstruction approach of multi-baseline InSAR system without ground control points,So it gets rid of the above restriction of the single-baseline system.At first,theory of the approach is introduced and height measurement equations are derived.Then,error sensitivity analysis is made by first order approximation of Taylor expan- ding,which is expected to give instruction and support for the solution of DEM reconstruction equations,system analysis and error distribution etc.Its results are validated by Monte-Carlo simulation,whose results show that the above theoreti- cal error analysis method is available and can offer support for analysis and design of the system directly.