Companies began to rely on the Russian system, and the United States has responded to the economic realities for U.S. companies. DGPS is generally used in circumstances when the receiver will be moving, such as in maritime applications that track merchant vessels or vehicle-mounted systems. With nondifferential GPS you can get readings accurate enough to tell which block a vehicle is on. But we can get location readings that are accurate to within two centimeters, so DGPS is not for us. Because Evans' land survey team in Scottsdale doesn't need to track movement, but only to capture a precise location, it finds the Trimble 4000 system works fine.
Surveyors press a button and get an on-point reading.
Cost is not as much an issue as is getting the proper technology for our needs. You can use one to find your location or the location of key terrain features. With it, you can plot a vessel's waypoint to within 49 feet. The system can hold up to 500 waypoints to help chart courses for ocean-going craft. The U.S. Geological Survey is using a combination of GPS devices to monitor activities on Hawaiian volcanoes.