초록 ▼

A perimeter monitoring system is arranged to detect passage across a perimeter of an area. The system primarily includes an emitter, a retroreflector, a detector and an alarm. The emitter provides a modulated visible laser beam. The retroreflector is arranged to direct the beam along a segment of th

A perimeter monitoring system is arranged to detect passage across a perimeter of an area. The system primarily includes an emitter, a retroreflector, a detector and an alarm. The emitter provides a modulated visible laser beam. The retroreflector is arranged to direct the beam along a segment of the perimeter and return the beam along the segment. The detector includes a device that blocks reception of light outside an angle of less than 5 degrees. One or more local or remote alarms are activated in response to the signal. For example, a remote alarm is located on the inside of a residence window where it is activated by another visible laser beam. Alignment of the peripheral monitoring system is less costly and false alarms are less likely than with known systems.

대표청구항 ▼

[ What is claimed is:] [1.]1. A perimeter monitoring system comprising:a. a reflector positioned to receive a beam of light along a segment of a perimeter of an area to be monitored and to provide a returned beam;b. a monitor comprising:(1) an emitter that provides the beam of light;(2) a detector t

[ What is claimed is:] [1.]1. A perimeter monitoring system comprising:a. a reflector positioned to receive a beam of light along a segment of a perimeter of an area to be monitored and to provide a returned beam;b. a monitor comprising:(1) an emitter that provides the beam of light;(2) a detector that provides a first signal when an interruption of the returned beam is detected;(3) an alarm; and(4) a controller comprising a timer that, when activated, reverts to being inactive after lapse of a period of time, wherein:(a) the controller activates the alarm to provide a first warning when the timer is active; and(b) the controller activates the alarm to provide a second warning in response to the first signal when the timer is inactive; and(c) the controller activates the timer in response to a second signal; andc. a receiver that provides the second signal.