For the two hundred eighty-first edition of the GeoGearHeads fills us in about the technology behind the GPS system. Some of the reference material he used in he research was; "" by Mohinder S. Grewal, Lawrence R. Weill, and Angus P. Andrews "" by Greg Milner "" by Hiawatha Bray The live video session from this Google+ Hangout On Air can be found on . Subscribe to the feed: Social Media: Email: