Array tilt effect induced by tidal currents in the northeastern East China Sea

Park, Jungyong; Seong, Woojae; Yang, Haesang; Nam, SungHyun; Lee, Seung-Woo

doi:10.1016/j.oceaneng.2019.106654

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…The noise after the arrivals is more suppressed than that of the low frequency case due to its lower correlation with the transmitted signal. The x-shape arrival structures in Figure 11 disappeared, owing to the water current in the experimental site that tilted the receiver array and distorted the arrival structures [ 30 , 31 ] (Refer to simulated CIRs in Figure 4 of reference [ 30 ], which confirm the acoustic structure change by the current). Here, the focus is on clear DOA detection in the time domain—the effects of the current on DOAs are not of interest—while the DOAs should be estimated with bias.…”

Section: Savex15: Experimental Resultsmentioning

confidence: 92%

Detection of Direction-Of-Arrival in Time Domain Using Compressive Time Delay Estimation with Single and Multiple Measurements

Choo

Park

Seong

2020

Sensors

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The compressive time delay estimation (TDE) is combined with delay-and-sum beamforming to obtain direction-of-arrival (DOA) estimates in the time domain. Generally, the matched filter that detects the arrivals at the hydrophone is used with beamforming. However, when the ocean noise smears the arrivals, ambiguities appear in the beamforming results, degrading the DOA estimation. In this work, compressive sensing (CS) is applied to accurately evaluate the arrivals by suppressing the noise, which enables the correct detection of arrivals. For this purpose, CS is used in two steps. First, the candidate time delays for the actual arrivals are calculated in the continuous time domain using a grid-free CS. Then, the dominant arrivals constituting the received signal are selected by a conventional CS using the time delays in the discrete time domain. Basically, the compressive TDE is used with a single measurement. To further reduce the noise, common arrivals over multiple measurements, which are obtained using the extended compressive TDE, are exploited. The delay-and-sum beamforming technique using refined arrival estimates provides more pronounced DOAs. The proposed scheme is applied to shallow-water acoustic variability experiment 15 (SAVEX15) measurement data to demonstrate its validity.

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Section: Savex15: Experimental Resultsmentioning

confidence: 92%

Detection of Direction-Of-Arrival in Time Domain Using Compressive Time Delay Estimation with Single and Multiple Measurements

Choo

Park

Seong

2020

Sensors

Self Cite

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“…Shallow-water Acoustic Variability EXperiment 2015 (SAVEX15) was conducted on 14-28 May 2015, focusing on a relatively small area (water depth: ~100 m, area shown in Figure 1a,b) in the northern ECS [38][39][40][41][42]. During the experiment, two moorings (vertical line arrays [VLAs]) and underway conductivity-temperature-depth (UCTD) instruments were used to collect moored temperature (with no conductivity) time series at multiple depths and vertical profiles [43].…”

Section: Data and Processingmentioning

confidence: 99%

Estimation of Propagation Speed and Direction of Nonlinear Internal Waves from Underway and Moored Measurements

Lee

Nam

2021

JMSE

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Propagation speed and direction of nonlinear internal waves (NLIWs) are important parameters for understanding the generation and propagation of waves, and ultimately clarifying regional ocean circulation. However, these parameters cannot be directly measured from in-situ instruments, but can only be estimated from post-processing in situ data. Herein, we present two methods and an optimal approach to estimate the propagation speed and direction of waves using underway and moored observations. The Doppler shift method estimates these parameters from apparent observations concerning a moving ship using the Doppler shift induced by the changing relative distance of the NLIWs from the moving ship. The time lag method estimates the parameters using the distance between two locations of the NLIW observed at different times and the time lag. To optimize the speed and direction of NLIWs, the difference in the propagation direction independently estimated by the two methods needs to be minimized concerning the optimal propagation speed to yield the optimal propagation direction. The methods were applied to two cases observed in the northern East China Sea in May 2015 and August 2018. This study has practical significance for better estimating the propagation speed and direction of NILWs particularly over a broad continental shelf.

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Position estimation of acoustic elements based on improved delay estimation algorithm

Hu,

Zhang,

et al. 2025

Applied Acoustics

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Array tilt effect induced by tidal currents in the northeastern East China Sea

Cited by 5 publications

References 23 publications

Detection of Direction-Of-Arrival in Time Domain Using Compressive Time Delay Estimation with Single and Multiple Measurements

Detection of Direction-Of-Arrival in Time Domain Using Compressive Time Delay Estimation with Single and Multiple Measurements

Estimation of Propagation Speed and Direction of Nonlinear Internal Waves from Underway and Moored Measurements

Position estimation of acoustic elements based on improved delay estimation algorithm

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