WGS84 vs ITRF Datums

The NovAtel receivers output position data based on the WGS84 ellipsiod when the receiver is running with the default datum settings. The WGS84 ellipsoid is now equivalent to the ITRF ellipsoid. As the parameters defining the ITRF ellipsoid change, the GPS system side is adjusted so that the WGS84 parameters are redefined and broadcast via almanac and ephemeris data. This means that as the GPS receiver tracks and decodes GPS data from the satellites, it is receiving the new information, and calculates the position with the latest version of the ellipsoid.