[Rolebama]

Read this: http://www.rac.co.uk/know-how/motori...more-accurate/
Any GPS system can only work to within the accuracy of the satellite system, which is currently quoted as two metres (Your actual location -/+ one metre.) My RAC200 will occasionally put me within this if I get enough satellite signals. As to comments about blind people, a metre can be far enough out to cause serious problems.

[Snowball]

When reading the claimed capabilities of items such as satnavs, I can't help wondering just how much is intended to be taken as a feature for practical use.

Electronic signals can be "bent" by the influence of magnetic fields due to features of the surrounding landscape (artificial and natural), so what really is the practical minium reliable distance?

[wagolynn]

Originally Posted by Snowball

When reading the claimed capabilities of items such as satnavs, I can't help wondering just how much is intended to be taken as a feature for practical use.

Electronic signals can be "bent" by the influence of magnetic fields due to features of the surrounding landscape (artificial and natural), so what really is the practical minium reliable distance?

For anyone interested there are some interesting facts at: http://en.wikipedia.org/wiki/Global_...me_measurement
The maths can get a bit heavy but the explanations are good without the maths.
Hope that helps.

[smudger]

I am only chuffed with the fact that mine gets me from A to B without getting me lost;)

[Rolebama]

I regularly get between 7 and 11 satellites, and I find mine very accurate. (I use it on foot as well in strange places.) When I set off from my daughters houses, I sometimes only have 3 satellites, and the 'plot' can put me up to 100metres in any direction of my actual location, but as more satellites come into play, I can watch it moving closer to my actual location. (Hope that makes sense.)

[mills705]

As GPS was designed for the military its got to be accurate!
Some bombs etc are sent via GPS co ordinates so that must tell you how good it is.
I will admit the more satellities it has to calculate your position the better as the triangulation improves!
Also with car sat navs it puts you on a road. With my tomtom it guesses where u are if it doesnt like the fact your not on a marked road.

[Watcher]

Gps

Originally Posted by mills705

As GPS was designed for the military its got to be accurate!
Some bombs etc are sent via GPS co ordinates so that must tell you how good it is.
I will admit the more satellities it has to calculate your position the better as the triangulation improves!
Also with car sat navs it puts you on a road. With my tomtom it guesses where u are if it doesnt like the fact your not on a marked road.

GPS was indeed set up for military use, which is why there is a timing error deliberately built-in for civil use.

There is a system that uses fixed base points to broadcast signals that correct the error to a degree, but still not to military standard (which might well be less than plus or minus a few centimetres - the actual figure is classified).

If you were to see the hardware used for very, very accurate GPS (not to mention the costs) you would soon realise why the units available to oiks like us cannot possibly be that accurate!

[wagolynn]

Originally Posted by Watcher

GPS was indeed set up for military use, which is why there is a timing error deliberately built-in for civil use.

The random timing error was reduced to zero in 2000. There is, in effect, a separate system for the military or say surveyors but you need to purchase a key and you have to be a ‘friend’ to America to have one. More details at the link in post #3 in this thread.

[Airbag]

The cynic in me thinks the most significant bit about this article is in the heading "..benefits including automatic road tolling systems...".

Is this what the EU commisioner means when he says "What we are doing opens the door for European businesses and citizens to benefit from the myriad of better applications and new opportunities made possible by more precise navigation signals"?