Theft detection device

Abstract

A theft detection device, for warning a property owner that a item of property such as an automobile, a child, or a personal item has been brought beyond a predetermined acceptable distance, comprising a plurality of transmitters and a receiver. Each transmitter continuously transmits a unique signal. The receiver monitors the signals from the transmitters, and determines when the signal strength therefrom drops below a predetermined threshold level or is missing altogether. When the property is moved from the owner beyond an acceptable distance, the signal strength will drop below the threshold level and will not be detected, indicating an alert condition. Once an alert condition is established by the receiver, a beeping unit is activated to provide an audible warning to the owner that the property has been stolen, so that the authorities can be immediately notified.

What is claimed is:  
     
         1 . A theft detection system, for preventing the theft of a plurality of items of property from an owner, comprising: 
 a plurality of distinct transmitters, each transmitter associated with one of the items of property, each transmitter having a unique signal and a predetermined acceptable distance that the receiver should not exceed from the transmitter; and    a receiver, for separately monitoring and detecting the unique signals from each of the transmitters and assuring that each unique signal exceeds a threshold level, and for visually and audibly indicating when one of the unique signals is not detected above the threshold level which indicates that the transmitter has exceeded the acceptable distance, the receiver has distinct visual indicators for each of the transmitters for indicating to the owner which of the transmitter has exceeded its acceptable distance, wherein the acceptable distance for each transmitter is separately settable.    
     
     
         2 . The theft detection system as recited in  claim 1 , wherein each transmitter transmits its unique signal at a constant interval.  
     
     
         3 . The theft detection system as recited in  claim 2 , wherein the acceptable distance for each transmitter is set by a distinct sensitivity control which determines the threshold beneath which the unique signal from that transmitter will not be detected.