So what you're saying is speed cameras ARE picked up by satellite?

All I know is I have never had to download any data onto mine (I've had it for a year) and it works perfectly for me.

I suppose it doesn't really matter anyway; many people find them immensely useful and so they treat themselves to one, while other people stick to a map. I know I'd hate to be without mine now as it's nigh impossible on getting lost; you can avoid traffic jams; and you don't have to keep looking at a map whilst driving - or pulling over to take a look because you've missed a turning. If something makes life that bit easier for you then that's a good thing is it not?

I know that nearly everyone I know has one these days, and I imagine they will soon become as common as mobile phones.

Strawberry

NOTHING is picked up by the satellites - not even your car. There are several of them (I think it's a couple of dozen) in geo-stationary orbit over the equator. Wherever you are on the planet you ought to be able to "see" a few of them although being near big buildings may spoil that. Your GPS device knows where they are so when it picks some up it can calculate it's own position (like navigating by stars but hopefully more accurate). Data updates are done by other means depending on make, anything from a CD in the post to a download over a mobile phone connection is theoretically possible but downloading via the inetrent and copying to the flashcard is the most common. Depending on supplier amongst the data are the coordinates of various landmarks such as cashpoints, petrol stations and known cameras. So if your set knows where it is it can compare that with its known landmarks and display them on the screen. The catch is that if the set loses it's position (say in the City of London where there is a high concentration of tall buildings) it might not show a camera even if it is in the data. And if it has loaded Visa's database of coordinates of cashpoints you could end up driving across fields trying to find one!!!

The GPS and Route Planning functions are seperate parts of any system. GPS just tells you where you are and you can get it on it's own to use with ordinary maps.

GPS is actually a system developed by the US military and given their record of accuracy it may be a relief to know that the rival European system Gallileo took another step forward this week with the launch of a prototype satellite. If all goes to plan in a few years time you'll have a choice of satellite provider.

But GPS' still WORK by satellite! They pick up the signals form a satellite (4 satellites actually!)

Incidentally, I drive through the City of London on a regular basis (maybe 4 times a week) and I have never once lost my signal on my TomTom. As for it not picking up speed cameras there due to the high buildings - I don't know how familiar you are with the City of London - but there are very few speed cameras in that square mile as it's almost impossible to exceed the speed limit due to the road layout and traffic. The few they do have dotted about are always picked up by my sat nav (which is picking up signals from 4 satellites) - so I must have bought a good one.

You wrote: "The GPS and Route Planning functions are seperate parts of any system. GPS just tells you where you are and you can get it on it's own to use with ordinary maps."

I really can't understand what you mean by saying "the GPS tells you where you are and you can get it on its own to use with ordinary maps" - what would be the pont of having TWO maps? The GPS has an inbuilt map already in it! Why would you use another one too?

By the way, as you are going to such pains to try and be precise it would help if you spelt the word 'separate' correctly - for a moment I thought 'seperate' was some technological function of a GPS.

As for a GPS telling you to drive across a field: would YOU do that to try and find a cashtill????

It sounds to me as though should stick to your maps - you obviously aren't at ease with all this new technology.

Stawberry

Oooooops...typo correction. I left out the 'i' in point - hence the word 'pont'.

I agree withe Steve. Gps just gives co-ordinates in lat and long. Used in aviation it just gives a string of points from A to B; there is no topographical information. For "in car" navigation the gps calculatrd position is overlayed on a prestored map. It is rather like calculating your position and putting a cross on a map but it is being done continuously.This is the reason why the ToTom is region specific. Points interest are preloaded as are speed cameras and, because fixed cameras don't change much, they don't need updating that often. However, the more regularly you update the more accurate the information should be providing the provider of the database is doing their job correctly. The number of satellites that a gps receiver can lock onto determines the accuracy of the positional fix.

Time for a lock. We're getting into technical stuff about Sat Navs and an atmosphere is brewing in here.

MarkJ HT Mod