RTLS are used to automatically identify and track the location of objects or people in real time, usually within a building or a delimited area. The fixed reference points receive wireless signals from RTLS tags to determine their location.
Examples of real-time locating systems are:
- Tracking automobiles through an assembly line
- Locating pallets of merchandise in a warehouse
- Identification of people for security and safety reasons
- Finding medical equipment in a hospital
The physical layer of RTLS technology is usually some form of radio frequency (RF) communication, like BLE (Bluetooth 4.0), UWB (Ultra Wide Band ) or propietary systems, etc. Tags and fixed reference points can be transmitters, receivers, or both, resulting in numerous possible technology combinations.
RTLS are a form of local positioning system, and do not usually refer to GPS, mobile phone tracking. Location information usually does not include speed, direction, or spatial orientation. Instead they are very cost effective, need minimal batteries, work indoor and outdoor, do not need a mobile telecom operator and use open protocols.
Technologies in Real-Time Location Systems RTLS
There is a wide variety of technologies on which RTLS can be based:
- Infrared (IR). They require a clear line of sight for labels and sensors to communicate, so if a board is covered by a blanket or flips, the system may not work properly.
- Ultrasound. Ultrasound, as a communications protocol, is slower (with longer wavelengths) than the infrared, so it generally can not match the performance of other technologies
- Wi-Fi. Although Wi-Fi infrastructure is often preexisting in the performance environment, accuracy is limited to up to 9 meters, which makes its value as a tool for locating the location is uncertain.
- RFID. There are two types of RFID technologies to consider, active and passive. Passive RFID technology works only in the proximity of specialized RFID readers, providing a ‘point-in-time’ location. As an example, let’s think of a fashion store where the reader sends a radio signal to a labeled item of clothing and an alarm is triggered only when the label is detected very close to the designated control point. With active RFID, it has tags that send the signal to a reader every few seconds (similar to a cell phone and a tower) and triangulation software or other methods are used to calculate the position of the marked object.
- UWB. The advantage of UWB technology is the high level of transmission safety. The UWB signal is difficult to detect and localize, because the spectral power density is below background noise. It can reach an accuracy of 10 centimeters at measuring distances of up to 100 m.
- BLE. The Bluetooth Low Energy (or BLE) appears from the specification in version 4.0. It is aimed at very low power applications powered by a button cell. It has a data transfer rate of 32Mb / s. It operates on frequencies of 2.4 GHz and was created for marketing reasons for smartphone and tablet devices. Important advantages of this technology are that it’s based on a universal standard, and is immediately available on mobile devices without hardware need.
Comparison of Different Technology Tags for RTLS: