Abstract
Aiming at addressing the problem caused by multipath effects in direction of arrival (DOA) estimation for underwater targets, a method based on the active detection on virtual time reversal (ADVTR) Capon algorithm is proposed. Unlike the conventional passive target estimation method ignoring the multipath effects but only considering the direct wave, the proposed method is closer to the actual situation in that the multipath signal propagation model is fully taken into account; in addition, active detection (AD) and virtual time reversal (VTR) processes are added, which use active detection to estimate channels, and virtual time reversal to realize focusing in a computer after the source-receive array (SRA) receives the reflected signal of the target. The combination of the two methods can greatly improve the energy of SRA and the precision of target direction estimation. With the popular acoustic field simulation tool Bellhop, the model proposed in this paper is verified. Compared with the conventional Capon method without time reversal, the simulation results show that the ADVTR Capon estimation method is far better, in terms of resolution and suppressing the sidelobes. It is suitable for the target DOA estimation under low signal-to-noise ratio (SNR) conditions. Further, we also show the ADVTR Capon estimation method works well in a real tank experiment.
Highlights
Direction of arrival (DOA) estimation is an important part of the target parameter estimation which has found broad applications in radar, sonar, wireless communication and so on [1]
Based on [50,51], we propose in this paper a direction of arrival (DOA) estimation method based on active detection on virtual time reversal (ADVTR) for underwater multiple targets from array signal processing perspective
An ADVTR Capon method is proposed to improve the performance of DOA estimation at low signal-to-noise ratio (SNR); The model of conventional multipath and ADVTR multipath for uniform linear array (ULA) are established based on underwater acoustics propagation theory and array signal processing theory; In contrast with the method in [50] which is only confirmed through simulation, the performance of ADVTR Capon algorithm is verified and analyzed by simulation and tank experiment; Our model and method in this paper are readily extended to the DOA estimation of two or more targets with respect to [50], while [50] can only achieve one target’s orientation
Summary
Direction of arrival (DOA) estimation is an important part of the target parameter estimation which has found broad applications in radar, sonar, wireless communication and so on [1]. Reference [48] utilizes PTR to study the DOA estimation performance of a uniform shallow sea target, which proposes a super-directional model based on non-uniform linear array (NLA), establishes the simulation model from the signal detection point of view and uses the conventional beamforming method to achieve the azimuth estimation at low SNR. An ADVTR Capon method is proposed to improve the performance of DOA estimation at low SNR; The model of conventional multipath and ADVTR multipath for ULA are established based on underwater acoustics propagation theory and array signal processing theory; In contrast with the method in [50] which is only confirmed through simulation, the performance of ADVTR Capon algorithm is verified and analyzed by simulation and tank experiment; Our model and method in this paper are readily extended to the DOA estimation of two or more targets with respect to [50], while [50] can only achieve one target’s orientation. (·)∗ , (·)T , (·) H and (·)−1 stand for conjugate, transpose, Hermitian transpose and inverse, respectively; E{·} is the expected value of a random quantity; ⊗ is the convolution of two signal and is the Hadamard product of two vectors or matrices, i.e., the vector or matrix of their components wise product
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