Adaptive Pulse Compression for Range Focusing in SAR Imagery

Synthetic aperture radar (SAR) images are focused via range and azimuth compression. Typically, a matched filter is used for range compression. However, its inherent operation introduces target masking due to sidelobes, reducing the recognition and interpretability of the underlying targets. To optimize the focusing quality, adaptive pulse compression (APC) can be applied. In this paper, APC is assessed for range processing in SAR image focusing. The performance of the method is evaluated with airborne SAR imagery and compared with those of traditional schemes. We show that by applying APC under single-channel interferometric and stepped frequency scenarios, the quality of the SAR images, the corresponding phase maps, and interferometric coherence images can be significantly improved, and that APC provides both better amplitude and phase estimates of the range profiles. APC is shown to preserve the characteristics of the azimuth signals and can be applied without restricting the azimuth compression scheme.