Averaging Co-ordinates on your phone

Taking Co-ordinates for a geocache

One of the most important aspects when placing a geocache is getting accurate co-ordinates.

There is nothing worse than after the excitement of getting your geocache published, and the first logs come through saying “Great Location, Great container, but the co-ordinates were 10 metres out”

GPS co-ordinates are obtained from a range of satellites above us and how it works is a topic for a whole other discussion. But one key aspect to remember is that both the Earth and the satellites are constantly moving. The key to getting good co-ordinates is to get an “average”

Taking an instant co-ordinate reading means you will not necessarily get an accurate measurement of where you are. Many GPS units have a built in averaging tool and their instruction manuals will explain how to do this. But with the popularity of smart phones, more and more people are placing geocaches with them.

The native, or built in, apps that come with both iPhone and android phones, will give you an instant GPS location, but it may not be accurate. You will need to download an aftermarket GPS averaging tool to do this. Some of the paid geocaching apps (such as geosphere) offer this included. However, if you are not using one of these apps, you may wish to download an app such as GPS AVERAGING.

Check out our downloads page for links to the iPhone and Android versions.

Even with these tools, the key is to take your time and think about it. Many factors can affect your accuracy besides the Earth and GPS movement. Things such as cloud cover, and tree cover block your “line of sight” to the satellites. So if it’s a cloudy day, consider coming back again to confirm your co-ordinates. And if you are placing under a tree, take co-ordinates the same distance on both sides of the tree (away from the cover) and work out the middle.

To use the averaging apps, it’s pretty straight forward. I will explain it using the apple app but the android one is very similar.

Once you open the app, you will be presented with a map with a small dot representing your current location. Also on the map, there will be a +/- with a number of metres after it. Ideally, this should be 5.0metres. This is effectively indicating the amount of satellites you have a good line of site to. The more satellites, the small the number.

There will be an “averaging” icon. In the case of the iPhone version, it’s a small satellite icon. Once you tap this, a screen will appear with an icon to start averaging. Put your phone down and tap on the icon. You will see two sets of co-ordinates on your screen. One will be the “instant” co-ordinates, and the other will be the average. This app takes a reading every second and constantly averages them. The longer you leave it there, the more averaged the reading will be. I would suggest 5 minutes would be a good time. Once you are happy with the measuring, hit the stop icon and give the waypoint a name.

You will return to the map. To confirm the numbers, click on the satellite again, choose the waypoint you have just created, and you will see the co-ordinates. There will also be an option to email them to yourself.

From here, it’s time to create your listing and get your geocache published.

Good luck, and wait for those logs praising your placement.

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