Single-snapshot robust direction finding

The paper presents a novel approach for recursively estimating the directions of arrival of incident signals as measurements are received along a sensor array. Using a single snapshot and without any statistical assumptions, the proposed method employs a robust performance criterion, which is based on worst-case gain minimization. The criterion aims to reduce the estimation error induced by worst-case amplitude and phase perturbations as well as additive noise in the array model. An algorithm that guarantees the criterion-within a first-order approximation-is developed and shown to converge. Moreover, instead of using a trial-and-error method to find a constant, minimum worst-case gain, the minimum worst-case gain is updated as each sensor measurement is processed. A step-by-step implementation of the algorithm is presented, and its computational complexity is analyzed. The performance of the new approach is evaluated by simulating the estimation algorithm for a linear array and comparing its performance with that of an existing single-snapshot algorithm.