Commuters, hikers, off-piste skiers and others regularly lose connectivity and usually don't have a satellite phone at hand in case of an emergency. Some people are concerned about radio wave pollution, or simply wish to spend a weekend completely offline and away from the temptation of their mobile phone. This is a project idea that should appeal to both.

Mockup of a mobile app that shows the promixity of the user to the nearest radio communication tower. This allows a user without reception to know in which direction to walk to get a signal, or for people trying to go as offline as possible to find the nearest “hole” in reception.

Note: signal quality varies strongly depending on the height difference and topography of the land, distance alone is not enough to paint an accurate picture of signal reception. This type of app may not be relied upon in an emergency.

Cell phone tower locations in Switzerland are provided by BAKOM (department of communications) on their old Web Geo site - see metadata records, and are in the process of being migrated into a layer on the GeoAdmin API. In the meantime, a subset of the data for the Canton of Geneva is available to us via the Geneva geoportal.

On this screenshot it can be seen that the further one goes from the center of town, the larger the average distance between radio transmitters.

Thanks to help from Adrian who presented SITG services at the Geneva #makeopendata camp, we have exported this data in shapefile format for processing. Using open source tool uDig GIS this data can be opened and re-exported as KML.

Finally, we imported the map data into a project powered by the Swiss GeoAdmin portal API. This allows us to use OpenLayers to display the points on a map, find the users' location using the HTML5 Geolocation API (also sample JSFiddle), and calculate distances, which is the essential function of this app.

Here is a screenshot of the app (the final app UI is not complete yet) running in a WebKit browser:

• loleg

• Source: https://github.com/loleg/swiss-tower-finder