The continuous improvement of OmniSTAR's DGNSS (Differential Global Navigation Satellite Systems) means that greater accuracies are now possible at longer distances from reference stations than ever before. OmniSTAR, operates a global network of reference stations; to maintain consistency, all the stations in the network are coordinated with reference to the International Terrestrial Reference Frame (ITRF).

The current datum for the OmniSTAR reference station network is  ITRF2005 which was introduced in February 2008, an incremental change from ITRF2000. 

For more information about datums, click on the arrows next to the topics below.

In any differential system the coordinates of the mobile or rover are in the same coordinate reference frame as that of the reference site(s), whether these are fixed sites on land or satellites in orbit. Because we use the ITRF, we need to regularly update the coordinates of the reference stations to compensate for the centimetre-level movements of the various tectonic plates on which they lie.

 
Although the reference stations move continually, the site positions are surveyed and updated every few months. This frequency keeps the reference stations positions with in a couple of centimetres of their true coordinates.