Direction of arrival estimation with the received signal strength gradient at the lower VHF band

Abstract

Direction of arrival (DoA) estimation has wideranging applications and is particularly challenging in complex propagation environments. Virtually all current approaches estimate the DoA based on the phase of the impinging signal on a sensor array. This approach has several challenges: for example, it requires tight synchronization amongst array elements, and the estimated DoA is very sensitive to the specification of the array geometry. We propose a Bayesian DoA estimation procedure based on the received signal strength (RSS) gradient. RSS is readily computed by most sensors, and the RSS gradient points towards the source when the received signal's dominant component is the direct path. Though non-uniform shadowing, small-scale fading, and multipath generally corrupt the accuracy of the RSS gradient as a DoA estimate, these effects are significantly less at lower VHF. We show through simulations and applications to actual datasets that our approach provides a simple and accurate method to estimate DoA and its associated uncertainty, even in cluttered environments.