High-resolution DOA estimation of noncircular signals without source enumeration and eigendecomposition

This paper presents a fast method for estimating directions of arrival (DOAs) of multiple narrowband noncircular signals (such as AM, ASK, and BPSK signals), which involves neither eigende-composition nor source enumeration. This method also eliminates the need for knowledge of the spatial characteristics of the circular noise and interference, by exploiting merely the conjugate spatial coherence, namely the conjugate correlations between the received signals at different sensor positions. The proposed approach is still applicable to the integer conjugate minimum redundancy linear arrays (CMRLA), designed by Gelli and Izzo, to accommodate possibly more uncorrelated noncircular signals and enhance the DOA estimation accuracy for a given number of sensors.