Detection and estimation in the presence of signals with uncalibrated spatial signature

This paper considers the problem of signal detection and direction of arrival (DOA) estimation in situations where signals that generate an uncalibrated array response are present. Situations such as this often arise in airborne direction finding when skywave multipath is present. A parameterization that accounts for “uncalibrated” spatial signatures (USS) is proposed, and the identifiability of the resulting model is established. The asymptotically optimal signal and noise subspace fitting algorithms are applied to the USS model, and efficient implementations for each are derived that involve a search only for the DOAs of signals with “calibrated” spatial signatures (CSS). In addition, a sequential detection scheme is proposed for individually determining the number of USS and CSS signals. The results of several simulation examples are included to validate the analysis.