GPS stands for Global Positioning System. This is a system used in a huge amount of modern technology in order to help identify geographical position and coordinates, which can in turn be used for navigation and a large number of other ends. If you are familiar with the term GPS, then chances are it’s because you use a satellite navigation device in order to find your way around roads. That said, almost all modern smartphones are also equipped with GPS, which allows us to not only use maps for navigation purposes, but also to benefit from location awareness in many apps in order to get access to useful featurers.
So how does this marvel of technology work? Well it's actually quite clever. Essentially, any GPS device works by sending a signal up which bounces off of a satellite. This signal will travel at a set speed unaffected by things like weather conditions and so by measuring the amount of time it takes to reach the destination it's possible to tell how far away you are from it. When the satellite receives your signal, it bounces it back to your device thus enabling it to do the basic math and work out how far away from it you are. The satellite of course is in 'geosynchronous' orbit which means it follows the Earth through it's rotation remaining at those precise coordinates at all times.
GPS is limited to some extent however. For instance, GPS signals struggle to make it through thick ceilings, which is why you will often lose your navigation systems when you go through an underground tunnel. Likewise, GPS cannot pinpoint your precise location within meters. It is generally agreed that GPS has an accuracy of around 7.8 meters, with a ‘95% confidence interval’.
All this means that there are some applications that cannot possibly utilize GPS. For instance, GPS cannot be used for indoor navigation – so it won’t be used to help you find your way around a mall any time soon and it can’t be used by military SWAT teams trying to coordinate movements around hostile buildings.
There are other systems that aim to make GPS more accurate. These include the likes of GLONASS, or Global Navigation Satellite System. GLONASS claims to have an accuracy of 4.5-7.4 meters. The main benefit of GLONASS when it is listed on phones for instance, is that it can provide a secondary ‘back up’ and a measure to help improve overall accuracy.