Abstract: Three-dimensional sparse distribution of the antennas and squint SAR in distributed-satellite SAR systems makes it difficult to estimate the along-track baseline accurately. Thus, an along-track baseline determination method is proposed based on ephemeris data and radar echoes. The geometric model of squint SAR systems with satellites distributed in three-dimensional space is established after the non-parallel track compensation. And the formula for calculating the along-track baseline is deduced. The squint angle is obtained according to the Doppler centroid estimated from the radar echoes. Compared with some approximate methods, more accurate results can be achieved with this method in the case of long baseline and large squint angle. Simulation results illustrate that accurate velocity estimation and relocation of moving targets can be obtained by using the proposed method to determinate the along-track baseline.

Key words: Distributed-satellite, Ground moving target indication, AlonG-track baseline, Target parameter estimation