| 摘要 |
<p>An ultrasonic intrusion detection system having means for transmitting and receiving ultrasonic energy within a protected zone and generating an alarm when a moving object is present in the protected zone is supplemented to provide multiple independent response zones utilizing the same transmitter for all zones but individual receiver modules which can be added to the existing transmitter-receiver system to provide protection for additional independent zones with associated indicators for selectively indicating those zones which have been triggered by the presence of an intruder or other moving object.</p> |
