US Patent 8937539 Method and apparatus for automatically disarming a security system

A security system comprises a system control panel for arming and disarming the security system. A door sensing unit comprises a first transceiver interconnected with the system control panel over a network. The first transceiver is mounted proximate to a door that defines at least a portion of a perimeter around an area to be monitored by the security system. The first transceiver has an detection field proximate to the door. A disarm device comprises a second transceiver that automatically transmits a disarm device packet. The first transceiver receives the disarm device packet when the second transceiver is within the detection field. The first transceiver sends a disarm message to the system control panel over the network to disarm the security system based on at least the disarm device packet.