Assessing the Performance of Omni-Directional Receivers for Passive Acoustic Detection of Vocalizing Odontocetes
Acoustic detection and localization of marine mammals will assist mitigation efforts for various Naval and scientific missions that may impact protected species. This study sought to experimentally quantify the sonar performance of omni-directional receivers as a means to passively detect vocalizing...
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| Format: | Text |
| Language: | English |
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2004
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| Online Access: | http://www.dtic.mil/docs/citations/ADA424911 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA424911 |
| Summary: | Acoustic detection and localization of marine mammals will assist mitigation efforts for various Naval and scientific missions that may impact protected species. This study sought to experimentally quantify the sonar performance of omni-directional receivers as a means to passively detect vocalizing Odontocetes in coastal waters. To accomplish this objective control led experiments using a calibrated mid-frequency sound source were conducted on the San Clemente Island Underwater Range (SCIUR) in July 2002. Six Odontocete signals were selected for transmission based upon availability and quality of archived recordings: 2 orca and 2 pilot whale whistles and sperm whale and Risso's dolphin clicks. Several hundred iterations of each signal were broadcast from R/V Point Sur at stations 300 m to 12,000 m from the range's moored three-element array. Statistical analyses were performed on the output of an energy and matched filter detector to quantify detection probability and range limits as a function of false alarm rate signal type and signal to noise ratio. The matched filter generally outperformed the energy detector with respect to the required signal to noise ratios and maximum detection range for given probabilities of detection P(D) and false alarm rate P(FA). The matched filter detected the orca2 and pilot1 whistles beyond 5000 m with a 90% P(D), 1% P(FA) and source level (SL) of 140 dB re 1 muPa. For the same conditions the orca1 and sperm whale calls were detected at 1500 m but the pilot2 and Risso's dolphin signals were not detected at the peak realized SNR of -2 dB. The energy detector had no detections with a 90% P(D) and 1% P(FA) at this -2 dB SNR, but all signals except one orca whistle were detectable beyond 1000 m with a 50% P(D) and 1% P(FA). The sperm whale was the exceptional energy detector performer with detection ranges exceeding 7 km (140 dB re 1 muPa SL) at the 50% P(D) and 1% P(FA). The original document contains color images. |
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