In repeat-pass synthetic aperture radar interferometry

the decorrelation caused by azimuth and range spectral shifts leads to a deterioration of the quality of SAR interferogram.There is a need to put proper spectral filters on the main and slave images.The paper discusses a new spectral filtering procedure that performs filtering before and after fine coregistration according to spectral characteristics.The procedure will reduce spectral misalignment

improve the accuracy of fine coregistration

and at last obtain high quality of interfeorgram.Four pairs of ERS-1/2 SLC data with different time interval and nominal baseline are used to analyze the validity of our method.Results show that the average values of coherence after spectral filtering flow are higher than that before spectral filtering flow

moreover the amount of residues is highly decreased.These give evidence to the goodness of the procedure.