Using GPS for asset tracking
Introduction
Real-time Location Systems (from English Real-time locating system or RTLS) are systems that automatically identify and track the location of objects or people in real time, usually within a building or other closed area. Wireless RTLS tags are attached to objects or carried by people, and in most RTLS, there are fixed reference points that receive wireless signals from the tags to determine their position.
The physical layer of RTLS technology is usually some form of radio frequency (RF) communication, although some systems use optical (usually infrared) or acoustic (usually ultrasound) technologies alternatively or in addition to RF. Tags and fixed reference points can be transmitters, receivers or both, resulting in numerous possible technological combinations.
RTLS are a form of local positioning systems, and do not usually refer to GPS or cell phone tracking. Position information usually does not include speed, direction, or spatial orientation.
Origin
The term RTLS was coined in 1998 at the ID EXPO trade show by Tim Harrington (WhereNet), Jay Werb (Pinpoint), and Bert Moore (Automatic Identification Manufacturers, Inc.(AIM)). It was created to describe and differentiate an emerging technology that not only provided automatic identification capabilities of active RFID tags, but also added the ability to view the location on a computer screen. At this show, commercial products based on RTLS by PinPoint and WhereNet were shown for the first time. Even though this functionality was previously used by government and military agencies, the technology was too expensive for commercial use. In the early 1990s, the first commercial RTLS were installed in three health care facilities in the United States, and were based on the transmission and decoding of infrared signals from actively transmitting tags. Since then, new technology has appeared that allows RTLS to be enabled also on passive devices.
Location concepts
Contenido
RTLS son generalmente usados en áreas internas y/o confinadas, como edificios, y no proveen cobertura global como GPS. Los tags RTLS son fijados a elementos móviles que quieren ser rastreados o gestionados. Los puntos de referencia RTLS, los cuales pueden ser transmisores o receptores, están espaciados a lo largo de un edificio para proveer la cobertura deseada. En la mayoría de los casos, mientras más puntos de referencia se instalen, mayor precisión en la localización se logrará, hasta alcanzar las limitaciones de la tecnología.