Acoustic homing
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Acoustic homing is a system which utilizes sound to guide a moving object, such as a torpedo. Acoustic homing can be either Passive or Active in nature. Using Passive, the system is designed to move either toward or away from a sound, and may also be designed to move only toward certain types of sounds to the exclusion of others. While Active is a true Sonar. The system emits a sound pulse, that reflects off objects and then back to the system. Where the system processes the echos to determine the proper response.
[edit] Method
An object can be equipped with two or more acoustic transducers, which function as speakers and microphones. If a transducer receives a sound louder than that received by the other transducer, the object turns in the transducer's direction. If the object is to manoeuvre in three-dimensional space, more than two transducers are needed. Typically, more than three transducers are used, and arrays of over 100 are not unknown. A large number of transducers allows for more accurate steering.
[edit] Uses
Acoustic homing is useful in weapons, specifically torpedoes. Torpedoes can be made to move toward ships using acoustic homing.