Accuracy Estimates of Normal Heights Computed at GPS Sites

The dependence of accuracy of determining normal heights at GPS sites on the density of distribution of the sites within the GPS/levelling frame has been investigated. If the density amounts to one GPS/levelling site per 400 km ² , the accuracy of about ±11.5 cm in the central part of Europe. If the density is higher, e.g. one GPS/levelling site per 200 km ² , an accuracy of about ±5 cm can be achieved.