• Title/Summary/Keyword: 수동 선배열 소나

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Implementation of the omnidirectional target bearing detector utilizing towed linear arrays (예인선배열 센서를 이용한 전방위 표적방위 탐지기 구현)

  • 이성은;천승용;황수복;이형욱
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.1
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    • pp.59-64
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    • 2002
  • Passive sonar system forms the various beams in any desired directions to obtain the improvement in Signal-to-Noise(S/N) ratio, bearing detection and localization of targets, and the attenuation of interferences from other directions. Detection of modern underwater targets is becoming increasingly difficult as noise reduction technology leads to considerably low-level acoustic emissions. Therefore, the improvement of beamforming is very important to detect modern underwater targets at the long range in the complex environmental sea. Also, to react to the fast attack mobiles such as torpedoes, port and starboard discrimination is required to be performed very quickly. In this paper, we proposed the implementation of omnidirectional target bearing detector without port and starboard ambiguity to detect effectively the low-level underwater targets. The port and starboard discrimination is performed by cardioid processing and the improvement of beamforming utilizes the cross correlation matrix of individual hydrophone pairs of linear array sensors. The sea test result shows that the system implemented is good for the detection of the low-level underwater targets.

Analysis of array invariant-based source-range estimation using a horizontal array (수평 배열을 이용한 배열 불변성 기반의 음원 거리 추정 성능 분석)

  • Gu, Hongju;Byun, Gihoon;Byun, Sung-Hoon;Kim, J.S.
    • The Journal of the Acoustical Society of Korea
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    • v.38 no.2
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    • pp.231-239
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    • 2019
  • In sonar systems, the passive ranging of a target is an active research area. This paper analyzed the performance of passive ranging based on an array invariant method for different environmental and sonar parameters. The array invariant developed for source range estimation in shallow water. The advantages of this method are that detailed environmental information is not required, and the real-time ranging is possible since the computational burden is very small. Simulation was performed to verify the algorithm. And this method is applied to sea-going experimental data in 2013 near Jinhae port. This study shows the performance of ranging for source orientation, transmission signal length, and length of a receiver through numerical simulation experiments. Also, the results using nested array and uniform line arrays are compared.

Own-ship noise cancelling method for towed line array sonars using a beam-formed reference signal (기준 빔 신호를 이용한 예인선배열 소나의 자함 소음 제거 기법)

  • Lee, Dan-Bi
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.6
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    • pp.559-567
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    • 2020
  • This paper proposes a noise cancelling algorithm to remove own-ship noise for a towed array sonar. Extra beamforming is performed using partial channels of the acoustic array to get a reference beam signal robust to the noise bearing. Frequency domain Adaptive Noise Cancelling (ANC) is applied based on Normalized Least Mean Square (NLMS) algorithm using the reference beam. The bearing of own-ship noise is estimated from the coherence between the reference beam and input beam signals. Own-ship noise level is calculated using a beampattern of the noise with estimated steering angle, which prevents loss of a target signal by determining whether to update a filter so that removed signal level does not exceed the estimated noise level. Simulation results show the proposed algorithm maintains its performance when the own-ship gets out off its bearing 40 % more than the conventional algorithm's limit and detects the target even when the frequency of the target signal is same with the frequency of the own-ship signal.