Mapping, GPS and 4G: what you need to know

Why does my tablet sometimes become inoperable as soon as I leave home? Why can't I see a map on the screen when GPS is active? Here are some tips to help you understand these situations.

GPS

To begin with, a few details about GPS: this system, made up of satellites managed by the US military, enables you to determine your geographical position with an accuracy of 1 to 3 meters, provided you have an appropriate receiver. GPS is part of a global positioning system (GNSS) that also includes the Russian GLONASS, Chinese BEIDOU and, more recently, European GALILEO systems. It's important to note that GPS only provides longitude and latitude coordinates; it doesn't replace a map, but rather indicates our position on it. It is therefore essential that you also have a map of the area in question.

Other positioning methods

GPS is not the only positioning system: in urban areas, it is possible to obtain a fairly precise location using triangulation techniques, thanks to 3G/4G cell phone antennas or Wi-Fi hotspots. The advantage is that the signal is acquired much faster in these dense areas than that of GPS satellites. So, although the majority of tablets and almost all smartphones are equipped with a GPS receiver, these devices also use Wi-Fi and mobile telephony to complement GPS, particularly in urban "canyons". This is handy because, being connected via these technologies, they can download the map of the area at the same time as the location.

However, this method doesn't work outside areas covered by the network, i.e. in most places where we practice outdoor activities (sea, mountains, aviation, desert...). In these places, without GPS, it's impossible to locate yourself!

Map: essential download before you set off!

GPS alone is not enough: you also need a map. For a tablet to display a map, it must be loaded into its memory. If you've preloaded the map, you'll be able to access it. If not, ...

A quality map is rarely offered free of charge. It's a small price to pay for security. Some applications allow you to plan your itinerary in advance by downloading free maps in temporary memory. Although these applications are operational in the field, there is a risk of finding yourself without a map, particularly if you stray from the planned area or if the device's memory management suddenly deletes this data to make room.

Losing access to a card can have serious consequences. It is therefore preferable to use an application that downloads real maps into the device's memory.

In conclusion

To use our tablets and smartphones effectively for positioning and tracking, we need :

a device with an authentic GPS receiver,
an application that allows you to download and display maps adapted to your sporting activity (topographic, marine, aerial, etc.),
and to download a detailed map of the area in question.