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How GPS devices use postcodes to find your destination

As technology develops and we become more reliant on machines and screens to provide us with the information we need, good old-fashioned maps are becoming obsolete in everyday use. If you don’t own a Sat Nav, chances are you have at least a basic form of GPS on your phone or tablet.


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Unless you simply need directing to a city or large town, it is more than likely that you will be using a postcode to search for the shop, restaurant or friend’s house that you’re visiting. For the times when you are unsure, our Postcode Finder can help you track down the postcode for the location you need.

In the beginning

GPS, or Global Positioning System, has been around since 1957, when the first man-made satellite was sent into space. Initially, GPS was invented by the US Department of Defence for military use only, but in 1983 after a Korean plane on a commercial flight strayed off course into USSR territory and all passengers were killed, the US President was spurred into proposing that GPS should be available for civilian use. Since then, GPS has developed from something only used by spacecraft and large forms of transportation such as planes, to a household object used by millions of us each day.

The science behind GPS

There are currently 27 GPS satellites in space, which each orbit the Earth twice a day. A GPS device then has to locate at least four of these satellites, measuring the distance between them, in order to calculate your exact location on Earth.

The device measures your distance from the satellites by analysing radio signals and how quickly they have travelled from the satellite. By plotting the spheres around each satellite in which you could be, the device can find your whereabouts at the point where all four spheres cross.

Introducing postcodes

The majority of UK postcodes are specific, down to the street or road on which the building or landmark is located. Your GPS device will know the location of your destination postcode in relation to satellites, and will consequently be able to direct you there by working out the difference between your current location and your destination.

And whilst your GPS device is doing all this scientific work and processing the complex mathematical calculations, all you have to do is follow the simple map or verbal directions.

Technical difficulties

As with any type of technology, GPS isn’t completely foolproof. There are a few ways in which GPS signals can be broken, for example a lack of reception or even tall trees and buildings may disrupt the signals.

When it comes to routes the device gives you, there may also be restrictions down certain roads that the device isn’t aware of (e.g. if you’re in a large vehicle the device may not know that a certain bridge on your route is unsuitable), and of course the device will not have knowledge of any temporary road closures.

If you are travelling in extreme rural areas there may also be some minor roads that the device has no data for, in which case a paper map of the local area would be preferable. Another problem could arise if the place you wish to visit is yet to be postal registered. In this case it is also advisable to use a postcode as close to this location as possible to help you find the right way.

GPS devices are fast becoming one of the world’s most popular pieces of technology, yet we would be nowhere without knowing the postcode of our destination. Why not use our Postcode Finder to double check the location before you enter it into your device? The last thing you want is to find yourself miles away from your destination because of one misread digit!