Abstract
Direction-of-arrival (DOA) and range estimation is an important issue of sonar signal processing. In this paper, a novel approach using Hilbert-Huang transform (HHT) is proposed for joint bearing and range estimation of multiple targets based on a uniform linear array (ULA) of hydrophones. The structure of this ULA based on micro-electro-mechanical systems (MEMS) technology, and thus has attractive features of small size, high sensitivity and low cost, and is suitable for Autonomous Underwater Vehicle (AUV) operations. This proposed target localization method has the following advantages: only a single snapshot of data is needed and real-time processing is feasible. The proposed algorithm transforms a very complicated nonlinear estimation problem to a simple nearly linear one via time-frequency distribution (TFD) theory and is verified with HHT. Theoretical discussions of resolution issue are also provided to facilitate the design of a MEMS sensor with high sensitivity. Simulation results are shown to verify the effectiveness of the proposed method.
Highlights
With the rapid development of marine activities in recent years, underwater detection technologies have been applied extensively in areas such as offshore oil exploration, marine environmental pollution monitoring, crash vehicle search, aquaculture, marine scientific data collection, unmanned underwater vehicle, and marine fisheries
It is assumed that a uniform linear array (ULA) is used and that the space has two targets: one is from a range of 1000 m and a bearing of 56◦, and the other is from a range of 1500 m and a bearing of 10◦, respectively, at the signal-to-noise ratio (SNR) of 15 dB
From the linear regression line, the intercept is 0.8217, and the slope is −1.83 × 10−6, leading to the estimated angle of 55.9614◦ and the estimated range of 763.71 m, so the estimation errors are equal to 0.0386◦ and 236.29 m; and Figure 2e shows the continuous spatial instantaneous frequency (IF) at the direction angle of 10◦ as well as the linear regression line from which the intercept is 0.17302 and the slope is −3.42 × 10−6, leading to an estimated angle of 9.9635◦
Summary
With the rapid development of marine activities in recent years, underwater detection technologies have been applied extensively in areas such as offshore oil exploration, marine environmental pollution monitoring, crash vehicle search, aquaculture, marine scientific data collection, unmanned underwater vehicle, and marine fisheries. In a passive sonar system, an array of acoustic hydrophones is used as a sensing device to observe the sound wave generated by the underwater target itself, and the received signal is processed to decide the target’s direction-of-arrival (DOA) (bearing or azimuth) and range [1]. Traditional DOA estimation technology makes use of the time difference or phase difference for a sound wave reaching each element of the array to estimate the bearing of the target [2,3]. The analysis method varies according to the stationary or nonstationary characteristics of the target signal. In the analysis of stationary sound signals, traditional popular methods include Fast Fourier transform (FFT) [4,5]. The nonstationary signal analysis methods include short-time Fourier transform [6], wavelet transform [7] and Wigner–Ville distribution (WVD) [8,9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
