A method, a device and a system for preventing false alarms in a theft-preventing system

摘要: The invention relates to a method, device and system for preventing false alarms in theft-preventing comprising magnetic field detecting at least one metal object first detection zone means determining time-difference; said method the steps of change parameter indicative zone; second time-difference between parameter; performing an action based on time-difference. In this way, due detector falsely example movement metal-doors may be reduced/eliminated. Additionally, opening and/or closing door with parts acting as active tag