GPS RTK

GPS RTK (real-time kinematic) is a carrier-phase GNSS technique that delivers centimeter-level position in real time by resolving the integer carrier-phase ambiguities. A fixed base station on a known point streams corrections to a roving receiver over radio or cellular link; differencing cancels most atmospheric and orbit error. Horizontal accuracy reaches 1 to 2 cm and vertical 2 to 4 cm within roughly 10 to 20 km of the base. In hydrography, RTK fixes vessel position and, through RTK tide, gives the ellipsoidal height of the sounding datum directly, removing the need for a separate tide gauge where a geoid model is available.