TomTom GO GPS - Manual (Page 88)

How Does Navigation Work? 22.
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How Does Navigation Work?
Global Positioning System (GPS)
In order to navigate you to your destination, your TomTom GO must know
where you are now. To find your current position, your GO uses the Global
Positioning System (GPS). GPS is available for free and without subscription.
GPS uses satellites to transmit signals to GPS receivers. Your TomTom GO
has a built-in GPS receiver. Using the GPS signal, your GO can work out where
you are and how fast you are going. GPS signals work in all weather,
anywhere in the world.
Note: Your TomTom GO does not transmit your position, so others cannot use
it to track you while you are driving. You can however send your position to
TomTom Buddies. For more information, visit www.TomTom.com/plus
Finding your position faster
If you use your TomTom GO in combination with TomTom HOME, your GO
will download information about where the GPS satellites are going to be for
the next 7 days.
With this information, your GO will be able to find your current position very
quickly when it is first switched on.
Maps
Once your TomTom GO knows where you are and you have told it where you
want to go, it uses the digital map on the memory card or hard disk to work
out the best route to your destination.