| 摘要 |
An alarm device including an acoustic pressure sensor (10) delivering an analog signal to first amplifying means (12) and to second amplifying means (14), a first comparator (34) where the positive input is connected to the output of the second amplifying means and where the output delivers a warning signal to alarm means (26, 28) when there is a break-in or an attempt at breaking in, and self-adjusting means including a microprocessor (26) programmed to deliver a digital signal at the negative input of the first comparator where the pulses have a variable width which increases in accordance with the duration and the importance of the atmospheric disturbance so as to automatically increase the alarm device triggering threshold and reduce its sensitivity when the acoustic sensor detects an atmospheric disturbance such as wind.
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