초록 ▼

A sonic detector for security applications or the like includes a digital sampling circuit which converts sound waves into digital pulses and stores the pulses in a counter that is periodically reset by a timing circuit. If a predetermined number of pulses are accumulated in the counter before the c

A sonic detector for security applications or the like includes a digital sampling circuit which converts sound waves into digital pulses and stores the pulses in a counter that is periodically reset by a timing circuit. If a predetermined number of pulses are accumulated in the counter before the counter is reset, an alarm signal is generated to energize an alarm. The duration of the pulses may be altered to compensate for the effects of reflected sound which vary depending on the ambient acoustical environment. The number of pulses required to generate an alarm signal may be preprogrammed in accordance with the type of sounds to be detected. An anti-defeat circuit converts a continuous sound wave to the required number of digital pulses for generating an alarm.

대표청구항 ▼

An intrusion detection alarm device, comprising: a microphone; means for converting the output of said microphone into a plurality of electrical pulses; means for discretely counting said pulses; and means for producing an alarm when a prescribed number of said pulses have been counted by said count

An intrusion detection alarm device, comprising: a microphone; means for converting the output of said microphone into a plurality of electrical pulses; means for discretely counting said pulses; and means for producing an alarm when a prescribed number of said pulses have been counted by said counting means.