Time synchronization based on the direct signal for spaceborne/airborne hybrid bistatic SAR

Spaceborne/airborne hybrid bistatic SAR(SABSAR) has a special structure, its time synchronization system produces a great effect on the subsequent imaging processing. In view of the receiver, the impact of time synchronization errors is discussed in this paper, a time synchronization approach based on the direct signal is proposed. In this scenario, in order to compensate for time synchronization error in echo signal, it is necessary to extract the Doppler centroid from the direct signal timely. A novel method, which has small amount of computation, is put forward to estimate the Doppler centroid of the direct signal.