Importance

Loading Importance Indicators...

Abstract

An acoustic signaling system comprises a transmitter, which has frequency stability to create sounds which can reliably be received and which is loud enough to be heard by a receiver. The receiver includes an electret microphone, a limiting amplifier which has high gain, high frequency roll off and produces a maximum output for any input above a minimum value and a Schmitt trigger circuit to square up the output of the limiting amplifier and function as a zero cross detector. A micro-controller measures the times of the zero crossings and performs the detection and decoding algorithms to determine what code is being received. Each code consists of an anonymous repeating sequence of tones, which are transmitted for a certain duration followed by a silence, which allows room echoes to decay. The system creates acoustic sound codes, which are pleasant, sounding, can reliably be received and convey sufficient information to activate toys or dolls.

Loading the Abstract Image...

First Claim