» KSU Agricultural Research Center-Hays, Precision Ag.    The Agricultural Research Center¯Hays conducted a comparison of three DGPS correction sources (Coast Guard Beacon, FAA WAAS, and OmniSTAR) in both static and dynamic modes. Photos and results are published in a K-State Special Publication.    http://www.wkarc.org/Arch/Research/PrecisionAg/PrecisionAg.asp

» OmniSTAR    A commercial vendor that provides wide-area differential GPS service, using satellite broadcast techniques. Pricing, service and contact information.    http://www.omnistar.com

» U.S. Coast Guard Navigation Center    Maintained for the purpose of disseminating navigational status information for the GPS, DGPS, and LORAN radio navigation systems. Coverage plot map, DGPS status, discusses nationwide expansion, outages, and general information relevant to precision agric    http://www.navcen.uscg.gov/