| 21. | The active sonar used in such operations is often of " mid-frequency ", approximately 3.5 kHz.
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| 22. | These large " active sonars " are used to search for submarines and are very powerful.
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| 23. | Passive detection is almost impossible and surface units are forced to use active sonar to search.
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| 24. | Modern military submarines rely almost entirely on a suite of passive and active sonars to locate targets.
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| 25. | Once at close range the Spearfish uses active sonar to classify and home in on its target.
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| 26. | The primary tactical active sonar of a submarine is usually in the bow, covered with a protective dome.
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| 27. | Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels.
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| 28. | Active sonar relies on an audible " ping " to generate echoes to reveal objects around the submarine.
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| 29. | The coauthor of the interim report stated that animals killed by active sonar of some Navy ships were injured.
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| 30. | It is a Low Frequency Active Sonar ( LFAS ) and consists of both active and passive sonar arrays.
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