Introduction
TTNmapper (http://www.ttnmapper.org/) is a great tool to measure network coverage. Since many nodes do not have any possibility to be location-aware, you need to use a clever trick to be able to use every possible node for performing measurements. TTNmapper does.
The basic idea is that your smartphone and a node that was selected in the smartphone app are both close each other. This allows TTNmapper to measure the node's signal strength and combine this with the smart phone's location. It's available for both android and iOS. This recipe shows how to setup the android version.
Special thanks goes to jpmeijers who is the creator of the tool!
Download the app
Download the app in the playstore

Link a device
Once the app is installed you need to link a device. This is the device which will be used to measure the signal strength from. Unlike older ttnmapper versions it's now possible to use your ttn account to simply select a device, which is a big improvement.


Then continue by selecting the application and device you'd like to use.


As a result the chosen device is 'linked'

Mapping
That's it! Slide the 'mapping' switch to the right to start mapping. When walking around the app will notice that the message send by the LoRa node were received by the TTN backend. It will then combine it with your phone's location and map the location together with signal strength and gateway ID.

Experiment mode
Most options in the app explain themselves. There is one thing however that may need some additional explanation, and that is the 'experiment' concept. Although it may sound attractive to get huge unrealistic lines on the map by using e.g. air balloons, the main aim of the app is to to provide a realistic coverage map. This means that the contributions are filtered and exceptional measurements are suppressed because it's likely that under normal circumstances they cannot be reproduced.
Still it's possible that you are going to do some uncommon stuff and in such occasions it makes sense to want to log the results anyway. For these occasions the experiment mode was introduced. By using an experiment you can keep your results in a separate result set while not polluting the general map.

The result
Results are shown on the website http://ttnmapper.org . Note that there may be a delay because merging of the new data and the existing data files is done as a batch job, so it may take a day or so before data is shown.
Happy mapping!
