| The Bearing Estimation of Narrowband Acoustic Signals Using DIFAR Beamforming Algorithm |
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| DIFAR 빔형성 알고리듬을 이용한 협대역 음향신호의 방향성 추정 |
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장덕홍, 박홍배, 정문섭, 김인수 |
1국방과학연구소 제2체계개발본부
2경북대학교 전자전기컴퓨터학부 |
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| Abstract |
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In order to extract bearing information from the directional sensors of DIFAR(directional frequency analysis and recording) that is a kind of passive sonobuoy, the cardioid beamforming algorithm applicable to DIFAR system was studied in the frequency domain. the algorithm uses narrow-band signals propagated though the media from the acoustic sources such as ship machineries. The proposed algorithm is expected to give signal to noise ratio of 6dB when it uses the maximum response axis(MRA) among the Cardioid beams. The estimated bearings agree very well with those from GPS data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1~$6.7^{circ}$ and 13.3~$43.6^{circ}$, respectively. Estimation errors are caused by SMR degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible. |
| Key Words:
Cardioid Beamforming, DIFAR, MRA |
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