RTK

RTK (Real-Time Kinematic) is a high-precision satellite navigation and positioning technology based on carrier phase observations. Unlike conventional standard GPS, which relies purely on direct satellite ranging (where civilian accuracy is typically within several metres), RTK introduces fixed ground base stations to deliver real-time differential corrections for systematic errors such as satellite orbit errors, clock drift, as well as ionospheric and tropospheric delays. By achieving centimetre-level spatial positioning resolution, RTK directly enhances the real-time 3D spatial coordinate accuracy of mobile terminals (including smart vehicles, autonomous agricultural machinery, and surveying instruments) to within 1 to 2 centimetres, serving as an indispensable core positioning foundation for advanced autonomous driving, high-definition (HD) mapping, and precision agriculture automation.

Core Technical Architecture and Operating Principles

The technical architecture of an RTK system primarily comprises a Base Station, a Rover (the receiver mounted on a vehicle or equipment), and a wireless data communication link:

Base Station Error Observation and Differential Data Broadcast:

Positioned at precise, pre-surveyed geographical coordinates, the base station continuously tracks signals from Global Navigation Satellite Systems (GNSS). Because its physical position is fixed, it computes the comprehensive spatial propagation errors of current satellite signals in real time and broadcasts these differential correction data to nearby rovers via cellular networks (using the 4G/5G NTRIP protocol) or radio transmission.

Carrier Phase Double-Difference Resolution and Centimetre-Level Positioning: 

While capturing raw satellite signals, the rover (such as an autonomous vehicle equipped with a high-precision GNSS receiver) simultaneously receives differential correction data transmitted by the base station over the wireless network. The on-board RTK algorithm chip resolves the carrier phase double-difference integer ambiguity to eliminate the vast majority of errors, instantly calculating the vehicle's precise 3D centimetre-level spatial position within the Earth coordinate system.

Safety Guidelines and Physical Constraints

Strictly avoid relying solely on RTK for high-precision autonomous navigation in areas with severe satellite signal obstruction, such as long underground tunnels, dense high-rise urban canyons, enclosed multi-storey car parks, or zones with strong electromagnetic interference (Prohibiting Sole Reliance on RTK for High-Precision Navigation in Heavily Obstructed Environments):

RTK precision depends heavily on clear, line-of-sight multi-frequency satellite signals. Never place blind trust in the autonomous driving system's spatial positioning if satellite reception drops (commonly known as losing the RTK fixed solution or losing satellite lock). The driver must intervene and take over manual control immediately to prevent lane departure and potential collisions caused by positioning drift or sudden coordinate jumps.

Never ignore system downgrade alerts or attempt to force-engage advanced autonomous driving functions during base station communication outages, RTK differential service server downtime, or excessive network latency (Prohibiting the Override of System Downgrade Warnings When RTK Data Links Fail): 

Once the network differential link is severed, the RTK system instantly degrades to standard single-point positioning, causing accuracy to plummet from centimetre-level to several metres. Warnings indicating positioning accuracy degradation must never be ignored; at this point, the spatial reference underpinning vehicle perception and localisation is severely compromised, and relying on HD maps for lateral and longitudinal control poses severe safety risks.