US Patent 10026287 Monitoring system

A monitoring system for deriving a measurement of a separation distance between a monitor and one or more tags, where each tag is adapted to be attached to or contained within an object to be monitored, comprises a monitor that is operable to trigger an event if the separation distance exceeds a set separation limit. A frequency of packet exchange between a tag and monitor is dynamically altered based on a comparison of one or more monitored parameters with a mode transition threshold.