Monitoring Device, Carrier Device and Method Involving Monitoring Device and a Carrier Device

摘要

A method for monitoring the presence of a monitored item. A poll signal is transmitted from a monitoring device arranged in a mobile telephone or similar, to a carrier device arranged on the monitored item. The poll signal has predetermined characteristics identifying the monitoring device and the carrier device. A response signal is transmitted from the carrier device to the monitoring device in response to the poll signal the response signal enables the monitoring device to identify and determine the position of the carrier device. Action is taken if it is determined that the distance between the monitoring device and the carrier device is greater than a predetermined threshold distance. Theft or loss of valuable items can be detected if they are provided with carrier devices according to the present invention.