Flat-earth phase removal algorithm improved with frequency information of interferogram

As is well known, Interferometric synthetic aperture radar (InSAR) has been widely used in remote sensing field, which can reflect actual topographic trend or possible surface deformation. The precision of interferometric phase is critical to the final measurement. Due to the orbit attitude influence, such phase difference between the scattering elements on the same height level, which is named as flat-earth phase, usually causes the complex interferogram dense and difficult to be used in further procedures. Before phase unwrapping, interferogram must be flattened to derive accurate topographic or deformation information. Traditional methods pose problem to retrieve accurate flat-earth phase, which finally lead to inaccurate elevation or deformation information. A new algorithm of flat-earth phase removal is proposed in this paper based on SAR satellite system geometry and spectrum information of actual interferogram. The basic procedure of the method is firstly introduced and then the test results are following listed. From the comparison between the new algorithm and conventional ones, some advantages can be easily shown: The whole calculation can be easily understood and applied; accurate flat-earth phase can be retrieved and removed not only airborne SAR image but also satellite SAR image, which will improves the quality of complex interferogram to be well unwrapped;