Precision GPS means achieving position accuracies of centimeters instead of the more typical meter results of standard consumer-grade GPS. This is done by taking advantage of the carrier phase information from the reciever in addition to the pseudorange measurements. Traditionally this kind of accuracy has only been available from survey-grade receivers costing many thousands or tens of thousands of dollars. With recent technology improvements, however, this capability has started to become possible using receivers costing less than $100 and in some cases, less than $50. Uses for high accuracy positioning include surveying, mapping, drones, precision agriculture, marine navigation, construction, open-sky warehouse management and sports feedback.
RTKLIB is an open source software package written by Tomaji Takasu from the Tokyo University of Marine Science and Technology. Using GNSS raw data, it is possible to do real-time and post-processing to accurately determine a position, using differential information from two receivers. The software supports all major satellite constellations (GPS, GLONASS, Galileo, BeiDou, SBAS, QZSS) and major file exchange formats. The toolkit runs with a GUI on Windows and commandline tools on Linux.

There are only a few companies offering low-cost GPS receivers with access to the raw measurements necessary for calculating precision solutions. My work has all been done with U-blox receivers. They are a well established company that also provides easy-to-use free evaluation tools useful for configuration and testing of their receivers and complete documentation. There latest Generation 8 hardware includes both the NEO-M8T intended for precision GPS and the less expensive NEO-M8N intended for consumer applications but also capable of providing the information necessary for precision GPS.

There are other good options out there ... I'm hoping others will contribute more information about them in the community section of this website.

This site offers information, resources, and tutorials for those just getting started in the world of low cost precsion GPS. For those with more experience, it provides a place to share information about their projects, learn about what other people are doing, and to ask and answer questions. For those of you familiar with my "rtklibexplorer" blog, this site is intended to be an extension to the blog that allows better organization of the information, more user interaction, and easier upload and download capabilities. It's still a work in progress, but I hope to get more information and capabilities posted soon. At the moment much of the information, especially for more advanced users, is still available only on the original blog which can be accessed from the main menu.