RTK Positioning Glossary – High-Precision Positioning Using RTK in Surveying

What is RTK Positioning?

RTK (Real-Time Kinematic) Positioning is an advanced satellite navigation technique delivering centimeter-level accuracy in real time. Unlike conventional GNSS receivers, which achieve only meter-level accuracy, RTK uses a combination of carrier-phase measurements and real-time corrections from a fixed, surveyed base station. The base station—placed on a geodetically known point—receives GNSS signals, calculates errors caused by atmospheric interference and satellite imperfections, and transmits these corrections to a mobile receiver (rover). The rover applies these corrections to its own GNSS data, resulting in positions accurate to just a few centimeters.

RTK’s real-time accuracy is crucial in surveying, mapping, construction, precision agriculture, and UAV/drone navigation. By integrating the global reach of satellite navigation with terrestrial correction data, RTK has redefined geospatial workflows and enabled new levels of automation and reliability across industries.

How is RTK Used in Surveying?

RTK is the gold standard for field operations requiring high-precision, real-time positioning. Surveyors deploy a base station on a known reference point and use a rover receiver to collect points across the site. The rover receives both satellite data and real-time corrections from the base, ensuring every position is accurate and legally defensible.

• Boundary Surveys: RTK ensures property markers are placed with minimal deviation from legal coordinates, reducing disputes and complying with regulatory standards.
• Topographic Mapping: Accurate 3D data is collected for digital terrain models, crucial for engineering, flood risk assessment, and resource management.
• Construction Layout: Surveyors stake out design coordinates in the real world, guiding placement of structures, roads, and utilities with confidence.
• As-Built Documentation: RTK records the precise locations of constructed features for compliance and future asset management.
• Network RTK: Many professionals use region-wide correction services (via NTRIP) to eliminate the need for a local base and expand coverage.

RTK’s combination of accuracy, speed, and reliability makes it a cornerstone technology in geospatial professions.

Technical Principles of RTK

Base Station and Rover

RTK systems use a two-part architecture:

• The base station sits on a known, surveyed point, receives GNSS signals, and computes real-time corrections for errors.
• The rover is mobile, collecting the same GNSS signals as the base and receiving corrections via radio, cellular (NTRIP), or satellite link.

Robust communication between base and rover is essential. If the link is lost, the rover reverts to less accurate modes. Modern systems support multi-constellation (GPS, GLONASS, Galileo, BeiDou) and multi-frequency tracking, increasing reliability even in obstructed environments.

Carrier-phase ambiguity resolution is the mathematical core of RTK, enabling centimeter results by resolving the integer number of carrier wavelengths between receivers and satellites.

Satellite Signals and Corrections

RTK leverages carrier-phase measurements, using the oscillations of the GNSS carrier wave rather than just the code phase. This allows distances to be measured with millimeter precision but requires resolving the integer ambiguity.

Both base and rover observe the same satellites. The base, knowing its true position, calculates errors and transmits corrections (typically in RTCM format) to the rover. The rover applies these corrections, effectively eliminating shared errors.

Multi-frequency, multi-constellation receivers are now standard, improving accuracy and reducing initialization times, especially in challenging environments.

Error Sources and Correction Methods

Key error sources in GNSS positioning include:

• Atmospheric Delays: Ionospheric and tropospheric effects slow GNSS signals.
• Satellite Orbit Errors: Imperfections in predicted satellite positions.
• Multipath: Signal reflection from surfaces causes errors.
• Receiver & Satellite Clock Errors: Minute timing errors affect calculations.

RTK mitigates these by using real-time corrections from the base, which shares nearly identical error conditions with the rover (within 10–20 km range). Errors unique to one receiver (multipath, local interference) are harder to remove but can be minimized with good antenna placement and modern signal processing.

RTK Communication Modes

RTK requires a low-latency link to transmit corrections:

• Radio: Reliable for remote areas but limited to 10–20 km and requires line-of-sight.
• NTRIP (Internet): Uses cellular networks for wide-area service and is scalable for multiple rovers.
• L-Band Satellite: Delivers corrections to remote or offshore locations, suitable for global coverage.

Hybrid receivers can switch seamlessly between communication methods for maximum uptime and flexibility.

Accuracy, Precision, and Real-Time Corrections

• Accuracy is how close a measured position is to its true value.
• Precision is the repeatability of measurements.

RTK delivers both, providing positions that are both correct and consistent—critical for legal surveys, engineering, and high-value agriculture.

RTK achieves centimeter-level results through carrier-phase tracking and real-time differential corrections. Modern systems use multi-frequency, multi-constellation data for reliability and fast initialization. For ranges beyond 20 km, network RTK techniques (including Virtual Reference Stations) extend high-precision positioning.

Types of RTK Systems

Single-Base RTK

A single base station serves one or more rovers via radio or cellular. It offers high accuracy within 10–20 km but requires careful setup and maintenance of the base station.

Network RTK

Multiple permanent reference stations feed data to a central server, which models spatially varying errors and delivers corrections via NTRIP or similar protocols. This approach:

• Extends coverage
• Enhances reliability through redundancy
• Reduces the need for local base setup

National and commercial networks offer subscription-based access to network RTK corrections.

RTK Correction Delivery Methods

• NTRIP: Internet-based delivery via cellular modem or WiFi. Ideal for urban and semi-urban areas.
• Radio: UHF/VHF, for remote locations without internet.
• L-Band Satellite: Subscription-based, for global or regional coverage.

Receivers often support all methods, allowing flexible operation and maximum uptime.

Key Applications and Use Cases

• Surveying & Mapping: Accurate boundary and topographic surveys, construction layout, and as-built documentation.
• Construction: Real-time stakeout, machine control, and validation of infrastructure placement.
• Precision Agriculture: Automated steering, variable-rate application, and yield mapping for resource optimization.
• UAV/Drone Navigation: Precise flight control, mapping, and georeferencing.
• Asset Management: Accurate utility, pipeline, and infrastructure mapping for long-term planning.

RTK in the Future

RTK is expanding with the growth of GNSS constellations, better communication infrastructure, and integration with cloud and IoT technologies. The rise of affordable multi-frequency, multi-constellation receivers and increased availability of network RTK services make high-accuracy positioning accessible for more sectors, including autonomous vehicles, robotics, and smart cities.

Summary

RTK Positioning is a cornerstone technology for any application demanding real-time, centimeter-level accuracy. By integrating carrier-phase GNSS measurements with real-time correction data from a known reference, RTK empowers surveyors, engineers, farmers, and drone operators to achieve reliable, legal, and repeatable results—no matter the scale or environment.

For more information or to see RTK in action for your next project, contact us or schedule a demo .