Here's some additional information on Surveying and GPS from the Army Corp of Engineers manual titled Engineering and Design - Control and Topographic Surveying. Chapter 9 is titled GPS Real Time Kinematic Topographic Survey Procedures.
http://www.usace.army.mil/publications/eng-manuals/em1110-1-1005/
It may help explain how surveyors use GPS system.
There's also a detailed manual titled Engineering and Design - NAVSTAR Global Positioning System Surveying
http://www.usace.army.mil/publications/eng-manuals/em1110-1-1003/toc.htm
Enjoy -- Justin