Both stand-alone GPS (Global Positioning System) devices, and smart phones with GPS technology, work by detecting the position and signals from a series of satellites. The devices calculate their position by reference to these satellites.
There are a number of GPS devices and Smartphone apps that have widely different functionality. At the more basic end, the GPS device or app may give you your current grid reference so you can then use this to help to navigate with your paper map.
Many devices will let you pre-plot a route using mapping software on your PC (such as Memory Map etc.), or download a prepared route from elsewhere. The line of the pre-planned route is then often shown on the screen.
At the top of the range are GPS devices such as Satmap or Garmin Oregon, and Smartphone apps such as Viewranger and several others, that allow you to purchase full Ordnance Survey maps (1:25 000 or 1:50 000) which are then stored so they can be shown on your device (overlaid with any pre-planned route), with your current position marked.
No. There is some confusion in that, if a mobile signal is available to them, Smartphones may use something called Assisted GPS to gain the approximate location from the phone signal. The mobile signal is then used to speed up the calculation of the position fix from the GPS satellites. The availability of a phone signal has no effect on the eventual accuracy of GPS readings once a device has fixed its position; the purpose is simply to get a fix faster when the GPS functionality is switched on.
There are some cheap apps that do require an internet signal to show mapping, and so are not likely to work in wild areas. However, the better quality Smartphone apps store any mapping legally on your phone so that it is always available.
More recent devices and smart phones tend to now use High Sensitivity GPS which is much more effective in forestry, and can be accurate to around 4m once the device has completed a fix.
Occasionally GPS signals are jammed by the military. We are often informed of when this is scheduled to happen and include a news story on the Mountaineering Scotland/Walkhighlands websites if the jamming is likely to affect hill walkers, though there are also GPS jamming exercises which are not announced.
No! Everyone heading into the hills needs to learn how to read a map, and to be able to navigate effectively with a paper map and compass.
Why? Firstly, even if you have a Smartphone or GPS with full detailed OS mapping, it can't read and interpret the map for you! All it can do is show your position - being able to actually interpret the map correctly remains an essential skill.
Heading into the hills means you need to be able to understand from the map what the terrain will be like, choose suitable routes from it and be able to make decisions about changing your route if you need to. For example, in the winter, there may be a dangerous cornice where a summer route runs close to the edge of the cliffs above a corrie; you need to be a skilled navigator here to be able to understand that you may need to take a route further back from the edge than the shown summer route, to avoid the risk of falling through the cornice.
A Smartphone, GPS, or indeed a paper map cannot tell you this - itís the skills of the map reader that are needed. Plans may also change, the weather may close in, heavy rain might mean that a burn won't be crossable, there may be an accident. So everyone needs to be able to look at the map and work out the best way to adjust any route to deal with changing situations.
Secondly, even if you are a skilled navigator who can read a map well, and are happy using a Smartphone or GPS to navigate, batteries could run down and, although you can carry spares or a charger, there is still a chance your phone or GPS could break or malfunction. So it's essential to at least have a paper map and compass as a reserve.
As mentioned above, even a Smartphone/GPS user navigating effectively should be using their map reading skills at all times. However, if using a Smartphone or GPS as your primary means of navigation, your compass skills could become rusty. If this applies to you, it's a good idea to practice regularly to ensure you can remember how to use a compass effectively if and when the need arises.
This varies greatly. Generally, dedicated GPS devices have had longer battery life than smart phones. With smart phones it also depends on what other apps you are running, and what calls etc. you make.
You can conserve battery further by switching off the mobile signal (though note that on iPhones specifically, airline mode also switches off the GPS). Some smart phones can be switched on, recording a GPS track for up to 14 hours or so; others may drain much, much faster.
When buying a Smartphone, it's worth checking the battery capacity; also, a larger screen is likely to drain the battery faster. With many models it is also possible to get a spare battery, or to carry a portable charging device.
If using Smartphone or GPS navigation, take the time to learn how to use it well and understand how it works and its limitations.
Most dedicated GPS devices are of rugged construction and are reasonably waterproof. Smartphones can be much more fragile, though waterproof cases are available and they can be used with care. Some smart phones are 'rugged' models which may be waterproof and better able to stand up to knocks - probably a good choice for those wanting to take them into the outdoors.
The root cause of getting lost is usually a lack of adequate navigation skills, no matter what technology is being used. In many cases, walkers do not have the skills to read a map or navigate effectively. Some mistakenly think that carrying a Smartphone or GPS means that they do not need these skills, which is a recipe for disaster, for all the reasons given above.
Every hill and mountain walker needs to learn how to interpret a map, and to navigate effectively using a map and compass, including in poor visibility. Check out for more information on these essential skills. For those less sure of their abilities, we have excellent courses available on basic navigation.
The information on this page was kindly prepared by Paul & Helen Webster from WalkHighland