The dependence of detection system performance on fence construction and detector location

There is little published data to show how intruder detection system performance is affected by the construction of the fence or by the position the sensor is mounted on the fence. We compare false alarm data for sensors mounted either on a double welded-mesh fabric or single welded-mesh clad with a steel sheet. Each fence construction is used on the Prison estate for England and Wales. We study false alarm data taken over a 6 month period for four different detection systems. We consider how false alarm rates are affected by wind and the presence of wildlife; and look at time between alarms, and the percentage of alarm free days for each fence. We also analyse data from two detection systems each installed at both the bottom and top of each fence with a view to identifying: whether the positioning of detection systems both at the top and bottom are necessary to detect cutting and climbing attacks; whether mounting the upper sensor in the coil is effective in detecting attacks; and whether the top or bottom of the fence is more susceptible to false alarms.