Patent Document ID: 9240113
Application ID: 13270444
Patent Status: 1

Claim One:
1. A low-power security and monitoring system based on variation measurement of a sound transfer characteristic, the system comprising: a sound source generating device that outputs a sound wave of an audible frequency band having a predetermined frequency band within a predetermined monitoring space; and a sound measuring device that: calculates an acoustic wave transfer function, which is a unique characteristic value of the monitoring space and based on the sound wave outputted from the sound source generating device; and determines an intrusion into the monitoring space based on a comparison of an acoustic wave transfer function based on the sound wave and measured in a monitoring mode with an acoustic wave transfer function based on the sound wave and measured in an initial setting mode; and wherein, when the sound measuring device determines no intrusion into the monitoring space, the monitoring mode of the sound source generating device switches to a low power mode in which the sound source generating device outputs the sound wave having a lowest voltage level to be able to detect variation in the acoustic wave transfer function, and wherein, when the sound measuring device determines the intrusion into the monitoring space, the monitoring mode of the sound source generating device switches to a high reliability mode in which the sound source generating device outputs the sound wave by increasing a voltage level of the sound wave in a stepwise manner.