A device for detecting and locating sources of wireless data packets exhibiting selected, defined behaviour of interest. The device monitors an environment and populates a queue of packets dependent on a selected detection template which carries algorithms to packets to detect the behaviour of interest. The device extracts identifier data from packets in the queue to identify sources of detected behaviour. Information on signal strength of wireless data packets received by an antenna from identified, detected sources is displayed at a user interface. The interface is responsive to selections of template, selection of source devices detected and adjustments to the orientation and/or proximity of an antenna relative to selected, detected source devices to provide an interface for detection and location of source devices exhibiting selected behaviour of interest.