Although many navigation applications are available on almost every mobile platform, they do not usually allow the user to understand how they work. This paper is an excellent opportunity to learn the principles on which these applications are based. Ibrahim, the author, designs, in an academic setting, a global positioning system (GPS) data logger device with a direct interface to Google Earth maps. He even suggests that the device can actually be built using off-the-shelf electronic components.

The paper first introduces the reader to GPS: what it is, its uses, error correction and data exchange techniques, related programming languages and standards, GPS-driven data logging, and storage. Then, it describes the actual data logger device, its hardware, and its software. The hardware part is composed of a low-cost GPS receiver, an interface to a secure digital (SD) memory card to store data, and a microcontroller. The software that drives all this acquires data, stores it in the Keyhole Markup Language (KML) file format on the SD card, and displays it directly on Google Earth maps, taking advantage of Google Earth’s application programming interface (API). This latter part is surely the most interesting and innovative, as it shows how to build on an existing application (in this case, Google Earth) to enhance its capabilities.

Although the scope of the paper is obviously academic, describing the different components of GPS data logging devices to the reader, it can also serve practical purposes, as it offers hints about building actual devices.