All Perimeter Intrusion Detection Systems (PIDS) are susceptible to false alarms and it is critical that all PID manufacturers continuously strive to lower these false alarm rates. Microwave PID Systems have a low false alarm rate in comparison to other systems, however to make microwave a suitable PID system for a wide range of sites (over water, very close to fences, areas of dense foliage etc.) it is imperative to continuously strive to reduce false alarm rates.

Microwave PIDS work by analysing changes in the received signal between a transmitter and a receiver. From a historical point of view they have suffered from an inability to discriminate between a human target and false alarm events from animals, weather and the movement of trees and foliage. False perimeter alarms create considerable additional effort and headache for operators to manage. Even a very low Nuisance Alarm Rate (NAR) has a severe effect on perimeter security system performance.

This report provides an analysis of how to reduce false alarm rates in Microwave PID systems. The three attributes of a PID system (Operating frequency, antenna and digital signal processing of the data) are investigated to analyse their potential to decrease the false alarm rates caused by the three sources mentioned above.

What's inside?

• Cause of false alarms
• Microwave PID system attributes
• Operating frequency of microwaves
• Antenna design in microwave PID systems
• Main frequency components caused by various perimeter security events