ANDing alarm systems

Summary form only given. This paper discusses a means by which perimeter alarm systems can be combined to reduce the Nuisance Alarm Rate or False Alarm Rate (FAR) without compromising the Detection Rate (DR). Alarm systems operate on different principles and so have different strengths and weaknesses. Here we report work the Police Scientific Development Branch (PSDB) has conducted on combining complementary systems to reduce the FAR that would result from using either system on its own. We have ANDed a Video Motion Detection (VMD) System and a fence mounted microphonic Perimeter Intrusion Detection System. If each simultaneously goes into alarm, an operator is alerted. ANDing is not a new concept and has been used before, but not as far as we know to combine a Video Motion Detector (VMD) with a Fence Mounted System (FMS) at a real problem site. This paper reports and discusses the results from several operational trials of this combination of detectors. It gives a view on the practical value of ANDing such systems