Adaptive Scan-On-Receive Based on Spatial Spectral Estimation for High-Resolution Wide-Swath Synthetic Aperture Radar

Kurzfassung

This work investigates the possibility of applying direction of arrival (DOA) estimation methods to spaceborne Synthetic Aperture Radar (SAR) systems for high-resolution wide-swath imaging, based on receive beam steering. The conventional algorithm for receive beam steering, denoted as SCORE (Scan-On-Receive), shows a loss of performance in presence of topographic height. In fact, according to SCORE, the steering direction of the receive pattern corresponds to the expected DOA of the echo, which is computed under the hypothesis of a stringent spherical Earth model. In presence of topographic height, SCORE works under model mismatch and losses of several dB could be reached with respect to ideal operational conditions. The work studyes the possibility of overcome SCORE loss of performance by using a data-dependent, adaptive, mechanism for receive beam steering. In particular, a new algorithm for receive beam pattern steering, based on the actual spatial distribution of received signal power, is proposed. The performance of the proposed algorithm is evaluated by Monte Carlo simulations and compared with that of the conventional, not adaptive, SCORE, in different operational scenarios versus the SAR system parameters. Moreover, based on Cramér Rao Lower Bound analysis, the optimal performance achievable by the adaptive approach has been evaluated and used as a benchmark on the performance of the proposed algorithm.