Here we go again.
Like mp3 encoders before LAME, RTK GPS based on inexpensive GPS receivers & software has long been a dream that no-one has been able to get working.
For years, a Japanese team has used a discontinued uBlox module that costs just as much as a commercial RTK GPS solution. Now the latest hobbyist movement is to use just the GPS front end & do all the baseband processing in software. Unfortunately, we have no idea what to do with baseband GPS data to convert it into RTK corrected information.
For years, Maxim has had a GPS front end available for $11 but only now has anyone tried doing anything with it. http://unreasonablerocket.blogspot.com/2011/02/gps-progress.html
It doesn't look like he's going to have enough time to finish it.
There are some notes on using a laptop for baseband processing but no actual sourcecode.
The only remaining step is really getting data into the format RTKLIB needs. This is really a movement worth getting behind, since RTK GPS would eliminate the pressure sensors, sonar, pitot tubes, & guesswork VTOL flyers have become familiar with. Well, unless you're in the business of selling pressure sensors, sonar, & pitot tubes.