The Research And Application To Phase Unwrapping Technology Of Low Coherent Radar Interference Information

With the development of spatial information technology, especially the development of radar remote sensing technology, the Interferometic Synthetic Aperture Rader (InSAR) technique has flourished. In recent years, Differential Interferometic SAR (D-InSAR), developed on the basis of InSAR, which is sensitive to the change of topography has been more and more popular in monitoring topography-displacement for its high precision measurement in displacement-field, plus it is all-weather, fargoing and low-cost, etc. However, SAR images always have geometric distortion and the lower coherence, and the resulting interference fringes aren't continuous or occur jumps in practical application because of the geometric constraints of imaging radar, thermal noise decoherence, time decoherence, spatial baseline decoherence etc., which lead to the ultimately accuracy of surface deformation far with the theoretical value. Therefore, this paper further study the phase unwrapping thchnology that is one of the most critical steps of InSAR/D-InSAR data processing, making better use of this technology to the land subsidence monitoring applications. It is a further study hot spots and leading-edge technology and has obvious practical significance and scientific value.This paper proceeds search and analysis to literature of Rader Interferometry; descriptions the phase unwrapping technology comprehensivly and the basic principles of InSAR technology; explains the various existing InSAR phase unwrapping algorithm; compares the advantages and disadvantages and the applicability of various algorithm; conducts simulation experiment to InSAR algorithm which is suitable for actual application. The author proposes a phase unwrapping method targeted to interference fringe pattern of discontinuous images, and apply to the earthquake ground deformation monitoring of WenChuan earthquake. Main achievements are obtained as follows:(1) Put forward a set of phase unwrapping obstruction of factor analysis to low-coherence interferogram discontinuous images. The method analyses geometric distortion of SAR images under the influence of radar side-looking imaging mode and the accuracy,efficiency of the phase unwrapping under the influence of various decoherence.(2) Put forward a method to phase unwrapping of discontinuous interference frige images under the direction of priori konwledge of the control points, and achieve the reliability requirements for the application. This method based on analysising the obstruction of factors of phase unwrapping will be applied to the discontinuous interference frige images of the WenChuan area, and compare the results with those results of other phase unwrapping methods. It finds that the result which is by the unwrapping algorithm to the discontinuous low-coherence interference fringes images is ideal.