Doppler ambiguity estimation of stepped-frequency SAR system

This paper presents a novel method to estimate the Doppler ambiguity number of the stepped-frequency synthetic aperture radar (SFSAR) system based on echo data. The method exploits characteristics of the stepped frequency signal. In the method, it´s unnecessary to know the velocity of the platform ahead of time which is different from the traditional methods. Firstly, The method estimates the Doppler centroids of the sub-band signals. Secondly, it calculates the Doppler centroid and the Doppler ambiguity of the combined signal by curve fitting and theoretical calculation. Finally, The accuracy analysis and the simulation result are shown to verify the validity of this method.