Gain analysis for vertical linear array in deep ocean

Xiao, Peng; Xia, Huijun; Guo, Xuhong

doi:10.1109/oceansap.2016.7485387

Cited by 6 publications

(3 citation statements)

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“…Based on the development of the correlation theory for the acoustic field, AG research of the VLA is also carried out. Under the Gaussian White noise assumption in deep water, AG of the VLA in the range-independent and weak range-dependent waveguide disturbed by the random internal waves are estimated [15]. Moreover, the modelling method for the ambient noise field caused by the wind is proposed, the AG of the VLA in the non-isotropic noise field affected by wind-driven ambient noise is analyzed [16].…”

Section: Introductionmentioning

confidence: 99%

Vertical Correlation and Array Gain Analysis for Vertical Line Array in Deep Water

et al. 2020

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Array gain (AG) is significant in evaluating the detection performance of the vertical line array, which is directly determined by the correlation of signal and noise, respectively. In this paper, we analyze the vertical correlation for a 16-element vertical line array experimented in the deep ocean in 2016. The ray interference theory is utilized to interpret the mechanism of the vertical correlation of the sound field in different zones. In the direct-arrival zone, the direct rays and once-surface-reflected rays are two dominated components, whose arrival time difference for each element are nearly the same, and the vertical correlation is high. In the shadow zone, the sound field is mainly dominated by bottom-reflected rays and the vertical correlation decreases due to different grazing angles and arrival times of each ray. Different from the previous assumption of noise independence, the effect of noise correlation on the AG is analyzed through the measured marine environmental noise. Results indicate that the noise correlation coefficients in two zones are low but not 0. In the direct-arrival zone, AG is about 10 dB, very close to the ideal value of 10 log M . AG even exceeds it when NG is negative. Moreover, AG in the direct-arrival zone is higher than the one in the shadow zone.

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Section: Introductionmentioning

confidence: 99%

Vertical Correlation and Array Gain Analysis for Vertical Line Array in Deep Water

et al. 2020

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“…The array gain is a key factor for a sonar system. A concern that arises when considering a deep ocean, which is range independent, is that the spatial gain of the vertical array is influenced by the signal distortion that results from the multipath effect and the vertical correlation of the noise [ 5 , 6 ]. If it is assumed that the incident signal is a plane wave and the noise from the array elements are uncorrelated, the gain of the vertical array can be calculated with a simple equation.…”

Section: Introductionmentioning

confidence: 99%

“…However, because the above two assumptions are difficult to achieve, the spatial gain and its variation must be estimated properly. In [ 5 , 7 ], the approach to calculating the spatial gain is proposed when the arrival signals at the vertical array are not plane waves but the ambient noise is assumed to be Gaussian white. In fact, the noise constituents of different elements are not independent in the real ocean.…”

Section: Introductionmentioning

confidence: 99%

Reliable Acoustic Path and Direct-Arrival Zone Spatial Gain Analysis for a Vertical Line Array

Qiu

Chen

et al. 2018

Sensors

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A method is developed in this paper to calculate the spatial gain of a vertical line array when the plane-wave assumption is not applicable and when the oceanic ambient noise is correlated. The proposed optimal array gain (OAG), which can evaluate the array’s performance and effectively guide its deployment, can be given by an equation in which the noise gain (NG) is subtracted from the signal gain (SG); hence, a high SG and a negative NG can enhance the performance of the array. OAGs and SGs with different array locations are simulated and analyzed based on the sound propagation properties of the direct-arrival zone (DAZ) and the reliable acoustic path (RAP) using ray theory. SG and NG are related to the correlation coefficients of the signals and noise, respectively, and the vertical correlation is determined by the structures of the multipath arrivals. The SG in the DAZ is always high because there is little difference between the multipath waves, while the SG in the RAP changes with the source-receiver range because of the variety of structure in the multiple arrivals. The SG under different conditions is simulated in this work. The “dual peak” structure can often be observed in the vertical directionality pattern of the noise because of the presence of bottom reflection and deep sound channel. When the directions of the signal and noise are close, the conventional beamformer will enhance the correlation of not only the signals but also the noise; thus, the directivity of the signals and noise are analyzed. Under the condition of having a typical sound speed profile, the OAG in some areas of the DAZ and RAP can achieve high values and even exceed the ideal gain of horizontal line array 10 logN dB, while, in some other areas, it will be lowered because of the influence of the NG. The proposed method of gain analysis can provide analysis methods for vertical arrays in the deep ocean under many conditions with references. The theory and simulation are tested by experimental data.

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