Results from tests of measurement errors indicate that the technique using PRO XR instruments and the Centimeter Option Phase Processor software will yield elevation measurements with an error approximating +/- 5cm for survey sites located up to10km from bench mark sites. The 5s minimum time interval between measurements will allow for 720 elevation measurements per hour.

Field evaluations, which included both static and Aon-the-fly@ elevation measurements, found the the GPS carrier-phase processing technique to be practical. Further, excellent replications of elevations were obtained when several measurements were taken in the same general area using different bench marks.