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Abstract-The preparation of good navigational synthetic aperture radar (SAR) reference image is critical to the SAR scene matching aided navigation system, especially for complex terrain. However, few papers discuss the problem, and almost none of the methods proposed by them are fully automatic. Based on the practical requirements, a fully automated method of SAR reference image preparation is introduced. Firstly, a number of distinctive control points (CP) in the simulated SAR image is detected based on a method of image segmentation and clustering. Then, the corresponding tie-points in the real SAR image are searched based on local similarity by means of template matching. To improve the accuracy of CP, a method for segmentation threshold calculation, outlier screening and sub-pixel location computation is presented. Finally, the real SAR image is warped to the simulated one, and then projected to the frame of digital elevation model (DEM) by the polynomial mapping function. Experimental results on real data sets demonstrate the accuracy and efficiency of the proposed method.

An innovative data-based motion compensation approach is proposed for the highresolution synthetic aperture radar (SAR). The main idea is to extract the displacements in line-of-sight direction and the range-dependent phase errors from raw data, based on an instantaneous Doppler rate estimate. The approach is implemented by a two-step process: (1) the correction of excessive range cell migration; (2) the compensation of range-dependent phase errors. Experimental results show that the proposed method is capable of producing high-resolution SAR imagery with a spatial resolution of 0.17 × 0.2 m 2 (range × azimuth) in Ku band.

This paper analyzes the spatial decorrelation between repeat-pass bistatic synthetic aperture radar (BSAR) images with Global Navigation Satellite Systems as transmitters and a fixed receiver. This study is needed in the development of such a system to monitor temporal changes in a scene. The main challenge is that, in this bistatic configuration, spatial coherence heavily depends on the data acquisition geometry. The appropriate theoretical framework to describe spatial coherence for this case is developed by extending well-established monostatic models and, in principle, can be applied to any fixed-receiver BSAR with a spaceborne transmitter. Theoretical results are initially supported by Monte Carlo simulations. Finally, the validity of the model is confirmed by comparing real images.

Radio Frequency Interference (RFI) suppression is an important technique in the ultra-wideband synthetic aperture radar (UWB SAR). In this paper, we mainly analyze the performance of a notch filter for RFI sup-pression. The theoretical output from notch filter is presented based on RFI signal’s narrowband property. The research conclusion shows that the notch filter has significant effect on sidelobes of the system response, which might be considered to be false targets, however it has little effect on the resolution of the system re-sponse. The theoretical result is verified by simulation and experimental data processing both in one dimen-sion (range dimension) and in two dimensions (range and azimuth dimension)