Application of the Cramer-Rao lower bound for bearing estimation to STAP performance studies

The performance of space-time adaptive processing (STAP) radar is a strong function of array geometry and the particular algorithm implementation. Traditionally, detection performance has been of paramount importance, but recently interest has grown in the accuracy of target direction of arrival (DOA) estimates. This paper describes an evaluation of the Cramer-Rao lower bound (CRLB) for DOA accuracy. The CRLB is useful for bounding the bearing estimation performance of candidate array architectures and STAP algorithms, but often generates counter-intuitive results. Anomalous characteristics of the CRLB are investigated, explained, and placed in the context of maximum likelihood estimation (MLE) properties. The end product is a tool that can be applied to comparative analyses with confidence. The paper concludes by demonstrating the utility of the CRLB in both array and algorithm studies.