Phase-difference measurement-based angle of arrival estimation using long-baseline interferometer

This article presents a direction-finding method based on phase difference measurement for wide-ranging applications of electronic intelligence. By including three processing steps of rotating, re-scaling, and rounding of phase plane, the proposed method is able to obtain the actual phase shift of the longest baseline from the ambiguous phase differences measured from incoming signals with low computational cost. The method's performance is analysed and evaluated in terms of angle of arrival (AOA) estimation accuracy and probability of unambiguity by several interferometers of long baselines designed by multiple antenna elements. Consequently, an optimised array configuration of four antenna elements is taken into account to obtain high AOA estimation accuracy via several productive simulations and intensively validated with device measurement in the practical environment. Regarding the simulation of angle estimation accuracy, the proposed method remarkably outperforms two other existing methods, including second-order difference array and correlative interferometers. In the experimental measurement, high AOA determination performance is achieved with the transmitter located around 35.5 m far from an antenna array and the small average angle estimation error of 1.86 degrees at the direction of 20 degrees. For various directions from -60 degrees to 60 degrees with the steps of 5 degrees, the results satisfy the actual directions of the transmitter with a standard deviation of less than 0.5 degrees.