NaviGadget

using TV signals for positioning

Feb 9, 2009 gps navigation, misc news

A company called Rosum has the ability to use TV signals to get a location fix where GPS signals can’t simply reach such as dense urban areas and indoors. There are many advantage to using TV signals instead of signals from GPS satellites.

First of these is power. Most of the time TV towers are about tens of miles from the device to be positioned so the signal ends up with approximately 40dB range – that is about ten thousand times stronger than GPS signals. (dB scale is logarithmic).

Second is the frequency. TV signals are at much lower frequency which allows for them to penetrate buildings. And a single TV tower can broadcast at multiple channels at once giving Rosum more options to choose from.

Last advantage would be the bandwith. In general, the wider the bandwidth of the signal, the more accurately one can resolve multipath. TV signals ranges from 6 MHz to 8MHz, however the bandwidth of the GPS satellite signal is 1MHz.

They have two different versions of their system. One of them is true TV-positioning and the other is TV + GPS Hybrid positioning. This second one takes the best part of each one. It relies on GPS signals in rural areas, and uses TV signals in urban and suburban areas.

We’re not sure who is using Rosum technology at the time but their site mentions that they’re focusing on mobile TV devices and home telecommunications.