NCJ Number
28612
Date Published
1975
Length
6 pages
Annotation
SYNOPSIS OF THE TESTING OF A LOW-LEVEL SHOCK DETECTION UNIT FOR PERIMETER-CONTROL FENCES TO DETERMINE IF IT WOULD DETECT ALL PHYSICAL ATTEMPTS TO BREECH THE PROTECTED FENCE WITHOUT CREATING NUISANCE ALARMS.
Abstract
THE DESIGN AND INSTALLATION OF THE UNIT ARE DESCRIBED, AS ARE THE DIFFERENT TESTS PERFORMED. THIS SENSOR SYSTEM EXPERIENCED NO FALSE ALARMS AND THE NUISANCE ALARMS (BIRDS, WIND, AND RUBBING) OCCURRED ONLY AS A RESULT OF EXTREME ACTION. NO ALARMS WERE GENERATED AS A RESULT OF NEARBY VEHICULAR TRAFFIC. RESEARCHERS CONCLUDED THAT THE 'FENCE GARD II' UNIT HAD A HIGH PROBABILITY OF DETECTION WITH LOW (NIL) FALSE ALARM RATE. HOWEVER, IT WAS POINTED OUT THAT IF THE INTRUDER WAS AWARE OF THE SENSORED CONDITION (NOT AN UNLIKELY CIRCUMSTANCE, SINCE THE INDIVIDUAL SENSORS WERE EASILY OBSERVABLE) THE FENCE COULD BE BRIDGED WITH A STEP LADDER, PROVIDING THE LADDER DOES NOT MAKE CONTACT WITH THE FENCE, THEREBY DEFEATING THE SENSOR SYSTEM OPTIONS FOR MAKING THE SENSOR UNITS UNDETECTABLE BY OBSERVERS ARE DISCUSSED.