Chapter 7Real-Time Kinematics Relative Positioning

Real-time kinematics (RTK) is a high-precision positioning technique that uses carrier phase and pseudorange measurements in real time. The high-precision position calculations are performed at the rate of measurements at the rover station. The base station, which is located at a known position, transmits its raw data, appropriately formatted, through a data communication channel. Ultra high frequency (UHF), cellular Global System for Mobile Communications (GSM), Long Term Evolution (LTE), WiFi, or Internet channels can be used for data transmission. Usually the data is transmitted one way, from the base to the rover. One or several rovers can listen to a certain base station and difference their raw measurements with raw measurements from the base station to correct the position.

There are several formats in use for data transmission of full raw measurements or differential corrections. All formats compact the transmission of information that is necessary to cancel GNSS errors. Errors that do not depend on the position of a station, or are nearly independent of location, tend to vary slightly with position and have almost equal effects on the measurements of both stations. These include satellite clock errors, satellite ephemerides errors, and atmospheric delays. The rover, having available its own measurements and the measurements from the base station, is able to form across-receiver differences to calculate the high-precision ...

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