| 摘要 |
Devices for acoustic remote control, remote alarm, remote recognition using, as a means of production and transmission, sound signals which are audible or otherwise. They comprise several types of transmitters including that of the drawing comprising a resonator 1 and a vibrating blade 2. The receiver includes a microresonator consisting of a miniature microphone 4 enclosed in a resonator 3; it is followed by an amplifier 5 followed by a filter; the main element is a phase-locked loop (PLL) 7; the control output 9 is taken on a relay or the mains; logic 8 carries out management, the supply of power 10 is by battery or mains. All the elements are tuned to the same adjustable frequency, which ensures great selectivity. Domestic and industrial applications. <IMAGE>
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