WatchIt. A fully supervised identification, location and tracking system

Radio frequency (RF) based systems have been successfully deployed in personnel identification and access control applications where the tag read ranges are usually less than one meter. Such technology has also been used in the identification of assets such as raw and finished goods inventory. These assets are well controlled so that one meter or less read ranges are adequate. Attempts to apply RF technology to the problems of location, identification and control of assets and/or people within a facility have exposed the limitations of RF over longer read ranges. The tag to reader path is no longer homogeneous because walls, furnishings, and equipment introduce impairments to the simple direct propagation of RF energy, so that the presence of an RF signal at a receiver cannot be used as a reliable indication of location. This paper describes the WatchIt system which combines the transmission power of radio frequency with the containment control of infrared to accurately locate and track assets and personnel within facilities