Originally Posted by
Icare9
Is there really a need for more Sat Nav systems?
I can understand that some satellites may reach their life expectancy or orbit decay, but what we have now isn't instantly up to date for every new road, either in the UK, Europe or elsewhere....
as for in car systems, you usually pay through the nose for "updates" which aren't current, simply the latest possibly months old) updates.
Currently, there are several manufacturers each with a range of models, some with better clarity, size of screen or specialised for HGV's motor bikes etc....
Do they get their mapping from different satellites?
The mapping does NOT come from the satellites. The satellites, and the local receiver, give a position in space--latitude and longitude, and height above some calculated datum. The maps that translate that into a position on the road, or wherever, are held on the device, and the frequency of their updating (and their accuracy) depends on the map supplier. This is why, on the whole, Google maps wins, because you download a map pretty much every time you use it, and they keep their maps up to date.
Another set of satellites won't affect this situation, nor is it being proposed for the convenience of motorists.