The GPSTk is an open source C++ library for developing GPS applications.

The GPSTk suite consists of a core library, auxiliary libraries, and a set
of applications.  The GPSTk provides a wide array of functions that solve
processing problems associated with GNSS such as processing or using
standard formats such as RINEX.  The libraries are the basis for the more
advanced applications distributed as part of the GPSTk suite.

WWW: http://www.gpstk.org/