The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
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Simulation of time-domain bottom reverberation signal using energy-flux model

에너지 플럭스 모델을 활용한 해저 잔향음 신호 모의

  • 정영철 (서울대학교 조선해양공학과) ;
  • 이근화 (세종대학교 국방시스템공학과) ;
  • 성우제 (서울대학교 조선해양공학과) ;
  • 김성일 (국방과학연구소 제 6기술연구본부)
  • Received : 2018.10.22
  • Accepted : 2019.01.23
  • Published : 2019.01.31
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Abstract

Ocean reverberation is the most limiting factor in designing realistic and real-time system for sonar simulator. The simulation for an ocean reverberation requires a lot of computational loads, so it is hard to embed program and generate real-time signal in the sonar simulator. In this study, we simulate a time-domain bottom reverberation signal based on Harrison's energy-flux bottom reverberation model by applying Doppler effects as ship maneuvering and autoregressive model. Finally, the bottom reverberation signal with realistic characteristics could be generated for the simulation of ONR reverberation modeling workshop-I problem XI and East Sea ocean environments.

능동소나 시뮬레이터에서 실제와 유사하고 실시간 운용 가능토록 설계하는데 가장 제한적인 요소는 잔향음이다. 잔향음 모의는 계산시간이 많이 소요되어 시뮬레이터에 반영하고 실시간으로 신호를 생성하는데 한계가 있었다. 본 연구에서는 Harrison의 에너지 플럭스 해저 잔향음 모델을 기반으로 함정 기동에 따른 도플러 효과와 자기회귀 모델을 적용하여 해저 잔향음 시계열 신호를 모의하였다. 최종적으로 해군연구국 잔향음 워크숍-I 11번 문제와 동해 해양환경을 토대로 모의 한 결과, 실제와 유사한 특징의 해저 잔향음 신호를 생성할 수 있었다.

Keywords

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Fig. 1. Ocean reverberation for general case.[3]

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Fig. 2. Geometry of bistatic closed-form reverberation and scattering area.[12]

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Fig. 3. Geometry of reverberation Doppler shift.[13]

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Fig. 4. The flow chart for the generation of ocean bottom reverberation signal.

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Fig. 5. The ocean environments of RMW-I problem XI.

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Fig. 6. Comparision of closed-form reverberation level with RMW-I problem XI results.[15]

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Fig. 7. Simulated result of reverberation time series for a RMW-I problem XI.

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Fig. 8. Comparison of ensemble average result with 100 iterations with closed-form reverberation level.

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Fig. 9. Spectrogram of CW reverberation signal for a RMW-I problem XI.

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Fig. 10. Ship GPS position for the simulation in the East Sea and GEBCO bahtymetry is applied.

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Fig. 11. The ocean environments of simulation.

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Fig. 12. Simulated result of total reverberation time series for a CW signal.

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Fig. 13. Simulated result of total reverberation time series for a LFM signal.

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Fig. 14. Spectrogram of total CW reverberation.

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Fig. 15. Spectrogram of total LFM reverberation.

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Fig. 16. Polar plot of a CW reverberation intensity.

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Fig. 17. Polar plot of a LFM reverberation intensity.

Table 1. Sonar system parameter for simulation.

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