Browsing by Author "Wu, Yue Ivan"

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    Hybrid Cram er-Rao bound of direction finding, using a triad of cardioid sensors that are perpendicularly oriented and spatially collocated
    (Acoustical Society of America, 2019-07) Kitavi, Dominic M.; Wong, Kainam Thomas; Lin, Tsair-Chuan; Wu, Yue Ivan
    Cardioid microphones/hydrophones are highly directional acoustical sensors, which enjoy easy availability via numerous commercial vendors for professional use. Collocating three such cardioids in orthogonal orientation to each other, the resulting triad would be sharply directional yet physically compact, while decoupling the incident signal’s time-frequency dimensions from its azimuth-elevation directional dimensions, thereby simplifying signal-processing computations. This paper studies such a cardioid triad’s azimuth-elevation direction-of-arrival estimation accuracy, which is characterized here by the hybrid Cram er-Rao bound. This analysis allows the cardioidicity index (a) to be stochastically uncertain, applies to any cardioidic order (k), and is valid for any real-valued incident signal regardless of the signal’s time-frequency structure.
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    Three-dimensional dislocations in a uniform linear array's isotropic sensors-Direction finding's hybrid Cramér-Rao bound
    (Acoustical Society of America, 2020-05) Ndiku, Morris, Zakayo; Wong, Kainam Thomas; Wu, Yue Ivan
    The linear array’sone-dimensional spatial geometry is simple but suffices forunivariate direction finding, i.e., isadequate for the estimation of an incident source’s direction-of-arrival relative to the linear array axis. However, thisnominalone-dimensional ideality could be often physically compromised in the real world, as the constituentsensors may dislocatethree-dimensionally from their nominal positions. For example, a towed array is subject toocean-surface waves and to oceanic currents [Tichavsky and Wong (2004). IEEE Trans. Sign. Process.52(1),36–47]. This paper analyzes how a nominally linear array’sone-dimensional direction-finding accuracy would bedegraded by thethree-dimensional random dislocation of the constituent sensors. This analysis derives the hybridCram er-Rao bound (HCRB) of the arrival-angle estimate in a closed form expressed in terms of the sensors’ disloca-tion statistics. Surprisingly, the sensors’ dislocation could improve and not necessarily degrade the HCRB, depend-ing on the dislocation variances but also on the incident source’s arrival angle and the signal-to-noise power ratio