Safety Monitor: only alert on multiple sensors

To avoid false alarms, I feel it could be constructive to allow a restriction on alerts generated by intrusion sensors. Along the lines of...

Only alert if x number of sensors are triggered within y seconds.

Rationale is that a single sensor event is often a false alarm (e.g. air draft triggering a PIR sensor) where a couple of sensors triggered within a close timeframe is very telling (given sufficient sensors).