A New Approach to Improve Coherence in SAR/GMTI Processing of Distributed Micro-satellites Systems

In order to improve the capability of clutter cancellation in bistatic SAR/GMTI processing, a new method to improve coherence between two sets of echoes from two receivers is developed based on the distributed micro-satellites system with the constellation of SAR-train. According to the idea of equivalent mono-static, the coherence improvement can be achieved by match filter to the spectra of equivalent squint angle, i.e. the bistatic bisector. In this way, the decorrelation component induced by the along-track baseline is removed. Because of Doppler equals to equivalent radial wave multiplied by equivalent squint angle spectra, this method can be realized in two steps, as the first step the compensation of equivalent radial wave number error is achieved through range spectra cut and shift of the narrow band echoes. As the second step, the Doppler spectra not overlapped should be removed, by which the bistatic bisector can be aligned. Simulation results show the decorrelation components introduced by the along-track baseline can be fully eliminated using this method