This section of the ActivityWorkshop is intended to house a variety of information about GPS units and their applications. I guess we're going to have to start calling them GNSS systems soon, especially when Galileo gets online, but in the meantime I think we can safely use "GPS" to refer to all satellite navigation systems.
GpsPrune is a java application from the activity workshop for viewing, editing and converting coordinate data from GPS systems. You can find more details about this free program in the software section, along with other free GPS-related tools like the Mkgmap gui and the Osm wrangler.
Firstly there is a section on GPS maps detailing how to load free maps from openstreetmap onto the memory card of a Garmin GPS receiver like the eTrex series. You can also convert maps, create your own from the openstreetmap data, and combine different maps into files for transfer to your GPS receiver.
In a series of experiments using Garmin GPS receivers, there's a comparison of the measurements from a Garmin Etrex Vista with a Garmin Etrex Vista HCx to analyse receiver precision under different conditions. Higher sensitivity apparently doesn't always mean better data.
Plus there's another experiment on receiver sensitivity using screengrabs from the two Garmin receivers to analyze which satellites are visible, how they track across the sky, and which receiver manages to lock on to more satellites when there's a tree in the way.
Thirdly there's a look at satellite motion using both measurements from the Garmin receivers and broadcasted satellite positions to see the sky coverage of the satellites.
The GPS links page provides a variety of links including free software applications and useful websites for getting the most out of your GPS.
In order to find out how many contributors OpenStreetMap has (and why it's nowhere near the 1.3 million they claim), there is some analysis on OpenStreetMap stats.
Several of the sections in the activity workshop relate to places in Switzerland. The Swiss places page provides an alphabetical list of Swiss places mentioned in this website and suggests activities based in each area.