Using ultra-wideband for real-time locating systems - Embedded.com

Using ultra-wideband for real-time locating systems

Real-time locating systems (RTLS) are used to automatically identify and track the location of objects or people in real time, usually within a building or other contained area.

The Global Positioning System (GPS) is often used in the case of outdoor RTLS deployments, but GPS signals use a frequency that does not pass easily through solid objects like ceilings and walls. When one attempts to use GPS inside a building, physical obstacles and other sources of interference make it difficult to determine locations with any level of useful accurately.

Other common wireless technologies — such as WiFi and Bluetooth — lack the speed and accuracy demanded by many applications. In this case, one solution is ultra-wideband (UWB), which employs very low energy for short-range, high-bandwidth communications over a large portion of the radio spectrum.

Early UWB systems tended to be physically large and to employ non-standard and/or expensive semiconductor technologies. More recently, it's proved possible to implement UWB using standard CMOS techniques. For example, the Irish fabless semiconductor company DecaWave has created a family of UWB parts called ScenSor based on TSMC's standard 90nm CMOS process.

We start with the ScenSor DW1000 IC, which is a complete, single-chip CMOS ultra-wideband IC based on the IEEE 802.15.4-2011 standard. This little scamp can enable tagged objects or people to be located both indoors and out to within 10 cm, even when they are moving at speeds of to 5m/s.


The ScenSor DW1000 IC (Source: DecaWave)

The DW1000 offers a communications range of up to 290m, plus it supports high data rate communications — up to 6.8Mb/s in Wireless Sensor Networks (WSNs).

Some users prefer to work directly with ScenSor DW1000 ICs and to differentiate their end products by designing and implementing their own antennas. Others prefer to use ScenSor DWM1000 modules with their integrated antennas, thereby facilitating simple product implementation with no RF design required.


The ScenSor DWM1000 Module (Source: DecaWave)

One example of the use of ScenSor technology is the Pixio robotic camera created by Move 'n See. The idea is to automatically track and film a person moving around a scene. The subject wears an armband and the camera pans, tilts, and zooms based on the armband's location. Move 'n See's armbands can also control the video, starting and stopping recording and switching the tracking between multiple people.

The folks at Move 'n See have developed some very innovative methods for producing top-quality video, including moving the camera in a smooth and comfortable manner and zooming in and out in an appropriate manner.

Move 'n See's first product employed GPS for location positioning and only worked only outdoors. By comparison, Move 'n See's latest product — the Pixio — uses DecaWave's UWB technology, which allows it to work indoors or out.

Another example of the use of ScenSor technology is provided by Agilion, which specializes in supplying turnkey wireless location solutions to factories, depots, warehouses, and other heavy industrial sites. Consider hand tools, which are often shared by a large number of workers on factory floors, and which are constantly being moved from one location to another. Tracking down a required tool often takes more time than the task for which it is required.

Key requirements for tracking technologies in this sort of deployment scenario are small size and weight, low power consumption, high accuracy, and fast response times. Furthermore, factories are often chaotic environments with a lot of moving metal and various radio devices that can interfere with location tracking solutions. RTLS systems used in these environments must work well in the presence of such interference without requiring “line of sight” to the items being tracked.

The reason I'm waffling on about all this is that Agilion recently selected DecaWave's ScenSor technology to implement their next generation of RTLS products because this technology outperformed competing UWB implementations and other technologies such as RFID and CSS. What can I say? I love this stuff!

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