Real-time kinematic positioning

Real-time kinematic positioning (RTK) is the application of surveying to correct for common errors in current satellite navigation (GNSS) systems.

[1] It uses measurements of the phase of the signal's carrier wave in addition to the information content of the signal and relies on a single reference station or interpolated virtual station to provide real-time corrections, providing up to centimetre-level accuracy (see DGPS).

The accuracy of the resulting range measurement is essentially a function of the ability of the receiver's electronics to accurately process signals from the satellite, and additional error sources such as non-mitigated ionospheric and tropospheric delays, multipath, satellite clock and ephemeris errors.

[5] In practice, RTK systems use a single base-station receiver and a number of mobile units.

The most popular way to achieve real-time, low-cost signal transmission is to use a radio modem, typically in the UHF Band.

With network RTK, accuracy of 8mm + 0.5ppm horizontal and 15mm + 0.5 ppm vertical relative to the nearest station can be achieved, depending on the device.

[7] For example, with a base station 16 km (slightly less than 10 miles) away, relative horizontal error would be 8mm + 8mm = 16mm (roughly 5/8 of an inch).

A typical CORS setup consists of a single reference station from which the raw data (or corrections) are sent to the rover receiver (i.e., the user).

More specifically, a GNSS network decreases the dependence of the error budget on the distance of nearest antenna.