| 摘要 |
An intrusion alarm system for monitoring a spacial zone to detect the occurrence of movement of an object within the zone consists of an oscillator providing R.F. signals from a radiating antenna coupled to the oscillator to propagate an R.F. field of signals within the zone being monitored, and a chassis having a portion shielded from the R.F. propagation of the antenna and disposed adjacent the antenna. The system further includes a receiving antenna adjacent the chassis for receiving the signals and modulations thereof caused by movement of an object within the field. A high gain amplifier, carried by the shielded portion of the chassis, amplifies the modulations of the received signals. Detecting means coupled to the amplifier provides an output signal in response to the amplified modulations. The output signal is adapted to activate means for manifesting occurrence of a moving object within the zone. Both local and remote alarms are actuated by the detecting system, the remote alarm being actuated only upon the occurrence of a predetermined number of detected movements.
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