Physical perimeter security is an effective deterrent to intruders with metal fencing being very popular. A determined intruder can defeat most types of physical barrier, usually by cutting through or climbing over. Many electronic security systems focus on detecting intruders either before or after they have entered the property. This can result in either nuisance alarms from legitimate passers by or late alarms after an intruder has entered. Microphonic cable detects the act of entry by sensing vibration within the structure of the fence. Sophisticated algorithms can analyze the detection signal and annunciate alarm conditions.
Microphonic cable needs to be installed in a very specific way and cannot be installed to all fences. Fences need to be rigid or taut to avoid multiple false alarms. Adjoining fences or structures need to be isolated from the sensing fence to ensure that spurious vibrations are not introduced. Gates also need to be buffered to reduce nuisance activation.
The system is designed to detect all of the typical signals associated with attempts to climb, cut or lift the fence. Wind, heavy rain and hail can cause multiple activations. An anemometer can be fitted to alert the operator to the local wind conditions but this will not reduce the incoming alarms.