Local Area Warning of Optical Fiber Intrusion

Abstract

Disclosed is a method and apparatus which provides for alerting of potential fiber optic cable intrusion. A stress detector located at a fiber optic cable termination point detects stress on the fiber optic cable and generates an alarm signal in response to the stress detection. The alarm signal is transmitted to remote alarm units along the fiber optic right of way via a conductive metallic portion of the fiber optic cable (e.g., the fiber optic cable sheath). In response to receipt of an alarm signal, the alarm units initiate a perceptible (e.g., audible and/or visible) alarm. The stress detector may also determine a location of the stress, and generate an alarm signal addressed to a particular one or more alarm units in the vicinity of the stress location.

1 - 30 . (canceled) 
     
     
         31 . An alarm unit comprising:
 an antenna for receiving signals radiated by a conductive metallic portion of a fiber optic cable;   means for detecting an alarm signal comprising alarm configuration information, said alarm signal generated by a stress detection mechanism and transmitted via said conductive metallic portion; and   means for initiating an alarm in response to receipt of said alarm signal.   
     
     
         32 . The alarm unit of  claim 31  wherein alarm signals associated with said alarm unit, as well as alarm signals associated with other alarm units, are transmitted via said conductive metallic portion, said alarm unit further comprising:
 means for recognizing an alarm signal associated with said alarm unit as distinguished from an alarm signal associated with said other alarm units; and   wherein said means for initiating an alarm is responsive to receipt of an alarm signal associated with said alarm unit.   
     
     
         33 . The alarm unit of  claim 32  wherein said means for recognizing an alarm signal associated with said alarm unit further comprises means for recognizing based on a particular frequency associated with said alarm unit. 
     
     
         34 . The alarm unit of  claim 32  wherein said means for recognizing an alarm signal associated with said alarm unit further comprises means for recognizing based on an indicia associated with said alarm unit contained in said alarm signal. 
     
     
         35 . The alarm unit of  claim 34  further comprising means for generating a visible alarm. 
     
     
         36 . The alarm unit of  claim 34  further comprising means for generating an audible alarm. 
     
     
         37 . The alarm unit of  claim 31  wherein said conductive metallic portion is a metallic sheath. 
     
     
         38 . The alarm unit of  claim 31  wherein said alarm configuration information specifies a type of alarm said at least one alarm unit is to initiate. 
     
     
         39 . The alarm unit of  claim 31  wherein said alarm configuration information specifies a duration of alarm said at least one alarm unit is to initiate.