How Do Sat Navs Work?

Without doubt, sat navs are an essential part of driving today: for many of us, finding new places and following unfamiliar routes would be incredibly difficult without a GPS device leading the way – perhaps even impossible.

If you’re looking to get your hands on a new sat nav device, you’ve probably realised just how huge the range available is: numerous manufacturers offer a variety of designs, with different features and prices to suit most budgets. Whether you have a good idea of the sat nav you want or are starting with a blank slate, you may well find yourself asking a common question – how do sat navs even work, anyway?

GPS Explained 

What is GPS? You’re sure to have seen this on your smartphone, tablet, or other gadget, but what does it mean? Well, GPS refers to the Global Positioning System – a network of satellites orbiting Earth at fixed points, which beam signals to anyone using a receiver. Within these signals, time codes and geographical data are transmitted, allowing you to pinpoint your exact location.

This network is maintained by the USA’s Department of Defence, and consists of between 24 and 32 satellites: these orbit at a minimum of 20,000 km outside the earth’s surface. The GPS system was created in the 1970s, and has been in full operation since 1994 – it’s free to use, and ensures a high level of accuracy, giving you a reliable pinpoint to within a few metres (while it is capable of even tighter accuracy, only the military has the authorisation to use it at this level).The more satellites used in the system, the greater your GPS accuracy will be – sat navs feature a GPS receiver tuned to their frequency, picking signals up and displaying their data on your screen.

These satellites circle Earth twice each day – in a precise pattern – and receivers use the information contained within the signal to triangulate your position: it compares the time at which the signal was sent to the time it was received. This difference in time informs the receiver how distant the satellite is, which is used in conjunction with similar measurements from other satellites, which gives the reading you’ll use to navigate to your destination.

It’s a complex process, for sure, though the end results appear fairly simple: the maps you read as you drive may look pretty basic (for clarity’s sake), yet satellite navigation is anything but. Occasionally, certain factors may affect your GPS signal, and, as a result, the accuracy of your sat nav itself: delays may be caused as the signal passes through Earth’s atmosphere; the signal might reflect off high buildings, natural formations, and other large objects before reaching your receiver; and the clock within the receiver may be less accurate than those aboard the satellites, causing slight errors in timing.

You’ll need to update your maps from time to time – this may be free depending on the device you buy, or you may be required to pay. We’ll explore this in another guide, but for now, we hope this has helped you to understand how GPS works!

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