An Along Track Interferometry (ATI) method based on sub-aperture image series for triple-channel Ultra-Wide Band Synthetic Aperture Radar (UWB SAR) system is proposed.By exploiting the large beamwidth characteristic of UWB SAR

the method generates a series of sub-aperture ATI images with different view-angles for moving target detection and parameter estimation.This method has two improvements over traditional ATI method.Firstly it detects the moving target with non-zero range velocity or non-zero azimuth velocity.Secondly both range velocity and azimuth velocity can be estimated via the method.The experiments based on UWB SAR half-real echo demonstrate the effectiveness of the method.