Patent ID: 7215785
Filing Date: 2007-05-08
Classification: A63H,G01S

Abstract:
1. A passive sound telemetry system for measuring an angle θ and a distance R with respect to an acoustic generation source, the passive sound telemetry system comprising: first through third acoustic receivers disposed at three of four vertices of a square each side of which has a predetermined length L, for receiving first through third acoustic signals having an arrival time difference from the acoustic generation source, the predetermined length of the acoustic receivers being set to be within a wavelength of a sound being measured; first through third low-pass filters respectively coupled to the first through third acoustic receivers for amplifying the corresponding first through third acoustic signals and filtering noise and high frequency signals therefrom having a frequency greater than an audible frequency; first through third zero crossing detectors respectively coupled to the first through third low-pass filters for converting the first through third acoustic signals into a pulse signal for every period based on a zero electrical potential, to thereby generate first through third pulse signals; earliest reception signal detector means coupled to the first through third zero crossing detectors for detecting a pulse signal having the earliest phase among the first through third pulse signals; first through third arrival time difference calculator means coupled to the earliest reception signal detector means for calculating an arrival time difference between the pulse signal of the earliest phase and the first through third pulse signal, respectively; and a signal processor coupled to the first through third arrival time difference calculator means for reading the first through third arrival time differences generated from the first through third arrival time difference calculator means in response to a counting end signal of the arrival time difference calculator means, and obtaining an angle and distance between a center of the square having first through third acoustic receivers at vertices thereof and the acoustic generation source, based on the second minimum arrival time difference value and the third minimum arrival time difference value.