Switched-Element Direction Finding

Abstract

We introduce and evaluate the concept of switched-element direction finding. In a switched-element system, simultaneous data collection occurs on only a subset of the array's N elements at any given time. The data collection interval is divided into subintervals, and at each subinterval a multiplexer selects a different subset of M<N elements to connect to the data acquisition channels. Since the switched-element system only collects data on M channels at a time, hardware costs can be reduced at the expense of a time-accuracy tradeoff compared to a full-channel system. We propose two algorithms. The first is a modification of the root-MVDR (minimum variance distortionless-response) algorithm that is appropriate for linear arrays and noncoherent sources. When sources are coherent, a second algorithm based on a compositely formed full-size covariance matrix is proposed. Although performance depends strongly on the number of sources, good performance can be obtained even when the number of sources is greater than M.