Journal of the Korea Institute of Military Science and Technology (한국군사과학기술학회지)

The Korea Institute of Military Science and Technology (한국군사과학기술학회)
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Experimental Study on Estimation of Flight Trajectory Using Ground Reflection and Comparison of Spectrogram and Cepstrogram Methods

지면 반사효과를 이용한 비행 궤적 추정에 대한 실험적 연구와 스펙트로그램 및 캡스트로그램 방법 비교

  • Jung, Ookjin (Aerodynamics & Aeroacoustics Laboratory, Department of Aerospace Engineering, Chungnam National University) ;
  • Go, Yeong-Ju (Aerodynamics & Aeroacoustics Laboratory, Department of Aerospace Engineering, Chungnam National University) ;
  • Lee, Jaehyung (Aerodynamics & Aeroacoustics Laboratory, Department of Aerospace Engineering, Chungnam National University) ;
  • Choi, Jong-Soo (Aerodynamics & Aeroacoustics Laboratory, Department of Aerospace Engineering, Chungnam National University)
  • 정욱진 (충남대학교 항공우주공학과 공기역학 및 공력소음 실험실) ;
  • 고영주 (충남대학교 항공우주공학과 공기역학 및 공력소음 실험실) ;
  • 이재형 (충남대학교 항공우주공학과 공기역학 및 공력소음 실험실) ;
  • 최종수 (충남대학교 항공우주공학과 공기역학 및 공력소음 실험실)
  • Received : 2014.09.19
  • Accepted : 2015.02.27
  • Published : 2015.04.05
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Abstract

A methodology is proposed to estimate a trajectory of a flying target and its velocity using the time and frequency analysis of the acoustic signal. The measurement of sound emitted from a flying acoustic source with a microphone above a ground shall receive both direct and ground-reflected sound waves. For certain frequency contents, the destructive interference happens in received signal waveform reflected path lengths are in multiple integers of direct path length. This phenomenon is referred to as the acoustical mirror effect and it can be observed in a spectrogram plot. The spectrogram of acoustic measurement for a flying vehicle measurement shows several orders of destructive interference curves. The first or second order of curve is used to find the best approximate path by using nonlinear least-square method. Simulated acoustic signal is generated for the condition of known geometric of a sensor and a source in flight. The estimation based on cepstrogram analysis provides more accurate estimate than spectrogram.

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References

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