One proven validation method is to use your equipment, field procedures and processing software to obtain positions of points with known coordinates such as those of calibration baselines and basenets. The degree of care in doing such calibration is, of course, dependent on the required accuracy and intended use of the estimated positions.

Plots depicting expected positioning accuracy as a function of time for dual-frequency GPS observations are available here ( static / kinematic ). Carrier phase ambiguity estimation is the main factor affecting the convergence seen in the accuracy plots. Resolved ambiguities are key in benefiting from the full positioning accuracy provided by the carrier phase measurements.

The kinematic processing plot was obtained by processing in kinematic mode (position estimated independently at each observation epochs) data that was collected in static mode. As such it represents a best-case scenario by neglecting some of the real-word effects of observations collected from a moving receiver.