US Patent 8138918 Intrusion detection and tracking system

An intrusion detection and tracking system includes a plurality of nodes, a DP and a gateway. The nodes are disposed about an area and form a wireless network to be monitored, the nodes are configured to receive data and transmit data frames with a signal strength indicator and/or a link quality indicator in the frames. The DP is communicatively connected to the network and configured to analyze variations in the signal strength indicator and/or link quality indicator to detect and track disturbances to an electromagnetic field in the area. The gateway is configured to form a data link between the network and the DP.