| 摘要 |
A wireless acoustic communicator is disclosed which permits a remotely-located operator to monitor and control a central vacuum cleaner. The acoustic communicator does not need problematic batteries, airflow blockers, or special wiring networks but uses only low-frequency acoustic signals that are transmitted through the pipe system of the vacuum cleaner. Command signals are effectively transmitted, even while air is flowing through the pipe system, by using a continuous multi-frequency signal, a resonant physical structure, and an adaptive signal detector. A preferred embodiment uses a powerful reed to generate a continuous acoustic signal. The reed is manually plucked by a slide switch to start vibration, which is then continued by the airflow through the pipe system caused by the running vacuum motor. The vacuum motor runs only if the signal is present. The acoustic communicator includes a resonant detection tube that filters the signal before it reaches a microphone. The adaptive signal detector reacts to noise and airflow sensed with a microphone by tracking signal phase, altering detection criteria, and sampling independently in time, frequency, and space. In addition, the wave form of the acoustic signal can be changed to create a control signal for other central vacuum cleaner functions, such as motor speed control. The acoustic communicator can also be used to monitor the central vacuum cleaner; for example, it can report a full condition of the dust filter.
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