Direction estimation using time-varying arrays

Considers the problem of finding the directions of narrowband signals using a time-varying array, i.e., an array whose elements move during the observation interval in an arbitrary but known way. The authors derive the Cramer Rao bound and the maximum likelihood estimator for the direction-of-arrival estimates, for the Gaussian signal model. The single source case is studied in detail. Time-varying arrays are shown to be more robust to ambiguity errors than static arrays of comparable dimensions