한국음향학회지 (The Journal of the Acoustical Society of Korea)

  • 제38권1호
  • /
  • Pages.114-119
  • /
  • 2019
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  • 1225-4428(pISSN)
  • /
  • 2287-3775(eISSN)
한국음향학회 (The Acoustical Society of Korea)
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수중 음향 통신에 있어서 변형된 파형 정형 필터의 성능 평가

Performance evaluation of a modified waveform shaping filter for the underwater acoustic communication

  • Park, Kyu-Chil (Department of Information and Communications Engineering, Pukyong National University) ;
  • Jeong, Hyunsoo (Department of Information and Communications Engineering, Pukyong National University) ;
  • Park, Jihyun (Department of Information and Communications Engineering, Pukyong National University)
  • 투고 : 2018.11.08
  • 심사 : 2019.01.23
  • 발행 : 2019.01.31
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초록

천해에서 전송되어진 음향 신호는 해수면 및 바닥과 같은 경계로부터의 다중 반사파에 의해 많은 영향을 받는다. 경계로부터의 매우 큰 반사 신호는 심볼 간 간섭을 일으켜 수중 음향 통신의 성능을 저하시키는 요인이 된다. 일반적으로 이러한 종류의 음향 채널에서 반사된 신호를 방지하기 위해 파형 정형 필터를 사용되고 있다. 특히 상승 코사인 필터가 널리 사용되며, 이 필터는 전송 신호의 대역폭을 제한하는 데에도 사용된다. 본 연구에서는 천해에서 영상 데이터 전송을 위한 상승 코사인 필터를 평가하며, 이를 바탕으로 새로운 수정된 상승 코사인 필터를 제안하고 평가 하였다. 수중 음향 통신 시뮬레이션에 사용된 통신 시스템은 직교 위상천이변조(Quadrature Phase Shift Keying, QPSK) 시스템이고, 송수신 거리와 심볼율을 달리하여 수행한 결과, 최저 1.0 %에서 최고 32 %의 에러 감소율을 보였다.

The transmitted acoustic signals are severely influenced by multiply reflected signals from boundaries, such as sea surface and bottom in the shallow water. Very large reflection signals from boundaries cause inter-symbol interference so that the performance of the underwater acoustic communication is degraded. Usually, the waveform shaping filters are used to prevent the reflected signals under this kind of acoustic channel. Especially, the raised cosine filter is widely used, which can also be used to restrict the bandwidth of the transmitted signal. In this study, we evaluate the raised cosine filter for image data transmission in the shallow water, and propose a new modified raised cosine filter. The QPSK (Quadrature Phase Shift Keying) system is used for the underwater acoustic communication simulations with different distances and symbol rates. As a result, the bit error rate was reduced from the minimum 1.0 % to the maximum 32 %.

키워드

GOHHBH_2019_v38n1_114_f0001.png 이미지

Fig. 1. QPSK system, (a) modulation system, (b) demo-dulation system, and (c) its scatter plot.

GOHHBH_2019_v38n1_114_f0002.png 이미지

Fig. 2. Raised cosine filter according to the roll-offf actor, (a) time signal and (b) frequency response.

GOHHBH_2019_v38n1_114_f0003.png 이미지

Fig. 3. Experimental configuration.

GOHHBH_2019_v38n1_114_f0004.png 이미지

Fig. 4. Experimental configuration, (a) impulse response at 100 m, (b) impulse response at 400 m.

GOHHBH_2019_v38n1_114_f0005.png 이미지

Fig. 5. Results of simulations according to roll-off factor, (a) Rcos (0.0), (b) Rcos (0.5), (c) Rcos (1.0), and (d) Rect+Rcos (0.5).

Table 1. Simulation and experimental parameters.

GOHHBH_2019_v38n1_114_t0001.png 이미지

Table 2. Simulation results.

GOHHBH_2019_v38n1_114_t0002.png 이미지

참고문헌

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  8. Raised Cosine Filtering, https://kr.mathworks.com/help/comm/examples/raised-cosine-filtering.html.
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