I did include a description, but buried it. I was hoping people would be intrigued and Google it. Here's is the description (from http://www.gaiagps.com/acknow

I did include a description, but buried it. I was hoping people would be intrigued and Google it. Here's is the description (from http://www.gaiagps.com/acknowledgments http://www.gaiagps.com/acknowledgments) Kevin Lacker's Kalman Filter - Underneath the hood, Gaia GPS uses a "Kalman Filter" to get more accuracy from the iPhone GPS. The Kalman Filter code was written by Kevin Lacker, a technical advisor to the Gaia GPS team, and egineer at Google. The Kalman Filter code is now open source and available for anyone to use. You can read more about Kalman Filters on Wikipedia, and you can download the source code on GitHub.