Whether your company needs to know where their valuable assets are at any point in time (be they transport and their drivers or stock), or as a parent you want to know where your child is, location based services have moved beyond the scope of only FTSE100 companies or police forces. A few years ago I experimented with a program called CellTrack which detected which cell tower your mobile phone was closest to, and then relayed that information to a central server. Sadly the project appears to have stopped development; however, TruePosition appear to have picked up the baton, and taken the concept a great deal further with their U-TDOA technology.
As an example, the last time I used such location tracking services (CID based I believe), you were only able to detected in which approximate area the phone was in. Now, thanks to clever use of existing technologies, accuracy has increased a great deal. If any of my English readers watch ‘The Bill’ you will already have a rough idea of how the phones are tracked, with triangulation from any three cell towers being the most basic mode of operation. However, there are circumstances where three reference points (in this case, cell towers) are not available. If you were to travel through a remote area, on a motorway, you may well find that the cell towers are positioned in a straight line running alongside the road. This obviously makes traditional triangulation an issue, however with the use of Angle Of Arrival calculations, only two transmitters are required.
Of course, there are times when you may either need higher accuracy, or when only one cellular tower is in range of the phone being used to track your valuable asset. In these circumstances, a Global Positioning System comes into play. As you may have noticed from my Amsterdam posts, I already play with a GPS unit with my PDA and SmartPhone. The versatility is quite impressive, and the ability to achieve a 3D fix with just 4 satellites in view mean that you can be reassured that the quoted location is very accurate.
To get the best of both worlds, a Hybrid solution is required. In cities with many tall buildings, obtaining a reliable GPS fix can be an issue, so this is where the aforementioned U-TDOA and similar approaches (check the link for a comprehensive guide to just how it all works) come into play. When you need higher accuracy, or mobile phone towers are not in such abundance, GPS can really help track your assets down. When you combine the two systems together, you end up with a higher accuracy and coverage service. Personally, I like the idea of being able to use technology your child already has (a mobile) to make sure they are safe, and where they are supposed to be. I would not like to use the service without the child’s consent, but I can see it helping keep children safe, and parents reassured.
