positioning


Location, location, location…..


Alun Lewis looks into the widening range of position-finding technologies which will soon be supplementing conventional GPS in mission-critical radio applications


W


hen it comes to finding out where people and assets are, the average man in the street could be forgiven for thinking that we already have


all the answers. Global Navigation Satellite Systems (GNSS) technologies – specifically, so far, the US’s Global Positioning System (GPS) – have plummeted in price over the past ten years and have become incorporated into cellular phones, cars and cameras. Further advances in location-based services and applications such as Google Earth and Google Street View continue to shrink the planet even further. While GPS-based location services have grown into a


multi-billion dollar industry for the cellular sector in just a few years – and continue to grow at around 50 per cent each year - the mission-critical nature of the environments where most TETRA systems operate mean that things are nowhere near as simple or straightforward. A wide – and growing – range of factors mean that there’s


no ‘one-size-fits-all’ location solution for TETRA, especially where actual positioning technologies to find and track


resources are involved. Fortunately, an increasing number of other technologies – RFID, Bluetooth, eLORAN, Wi-Fi and UltraWideband (UWB) radio can be brought into play to either enhance GPS or replace it entirely in some situations.


More satellites In terms of generic GPS activity, things are going to be getting increasingly crowded in space over the next few years with a number of new satellite systems going up or expanding their areas of coverage. After numerous delays, budget problems and the inevitable


politicking, Europe’s own Galileo project is hoped to go live around 2015 – though there still may be some coverage problems, given the small number of satellites initially. Both free and commercial positioning services will be available with reported accuracies ranging from one metre down to centimetres, while a short messaging function will allow limited communication functions with some terminals to confirm that help is on its way. Meanwhile, the Russians have been busy expanding


For many mission- critical radio applications,


position-finding and


tracking technologies have become an essential part of the package. Now undergoing testing


are novel positioning technologies


designed to support


firefighters in difficult locations such as apartment blocks and underground car parks (picture: Cassidian Systems)


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GLONASS, their own system, which is expected to reach out beyond their borders in the next year or two as more satellites are launched. Commercialization of the services is lagging far behind the US’s GPS, but the compatibility between the two technologies means that dual-purpose chipsets are now available and the two systems are expected to work together to provide increased accuracy – especially in the far northern hemisphere and in the inevitable ‘urban canyons’ in downtown cities.


...and more GNSS Meanwhile, other GNSSs – both global and regional – are also in development by a range of countries, including India (IRNSS), China (BeiDou) and Japan (QZSS). For Chris Muir, director of sales at the GPS antenna design


specialists Sarantel, there are a number of caveats to add about the current performance of GPSs – especially in TETRA systems. “While GPS has been a huge consumer success story, many of these implementations have failed to really exploit the real power and accuracy out there and lowered the market’s expectations”, he says. “Tere are a whole range


TE TRA TODAY Issue 3 May 2011


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