What Is RTK Correction?

Real‑Time Kinematic (RTK) is a differential GNSS technique that uses a reference station at a known location to compute satellite signal errors and transmits corrections to a rover receiver, achieving centimeter‑levelpositioning in real time.

While standalone GNSS provides 1–5 meter accuracy, RTK leveragescarrier‑phase measurements and real‑time differencingto push accuracy to 1–3 cm, widely used in surveying, construction, agriculture, and GIS asset mapping.

Why Traditional GNSS Cannot Reach Centimeter Level?

A GNSS receiver calculates its position from multiple constellations (GPS, BeiDou, GLONASS, Galileo). However, signals are affected by several error sources:

• Satellite orbit errors – small deviations between predicted and actual satellite positions.
• Atmospheric delays – ionospheric and tropospheric effects slow signal propagation.
• Multipath interference – signals reflected off buildings, trees, or terrain degrade accuracy.

How RTK Works: Base Station + Rover

A typical RTK system comprises three core components:

• Base Station – fixed at a precisely known location, continuously tracks satellites, computes error corrections.
• Rover – mobile receiver that applies corrections to compute a high‑precision coordinate.
• Communication Link – UHF radio, 4G/5G, Wi‑Fi, or NTRIP over internet.

The base station covers a service radius of roughly 10–20 km, within which the rover can achieve stable centimeter‑level accuracy.

The Role of Carrier‑Phase Measurements

The key to RTK’s high precision lies in carrier‑phase measurement. GNSS receivers measure two signal types:

• Code (pseudorange) – meter‑level accuracy, used for coarse positioning.
• Carrier‑phase – measures the phase of the carrier wave, achieving centimeter‑level accuracy.

The L1 carrier wavelength is 19 cm, whereas the code wavelength is ~300 m, making carrier‑phase significantly more precise. RTK resolves theinteger ambiguity to determine the exact number of wavelengths, enabling centimeter‑level fixes.

How RTK Correction Data Is Delivered

Method 1: Radio RTK

The base station broadcasts corrections via UHF radio to the rover. No cellular network required — ideal for mining, construction sites, and remote agriculture.

Method 2: NTRIP Correction

NTRIP (Networked Transport of RTCM via Internet Protocol) streams corrections over the internet. The rover connects to an NTRIP server, receiving differential data from a CORS network — no local base station needed, suitable for urban surveying and large‑area operations.

What Is a CORS Network?

CORS (Continuously Operating Reference Station) is a network of permanent GNSS stations that collect satellite data 24/7 and provide real‑time correction services via NTRIP.

• Wide coverage — no need to deploy a local base station
• Lower equipment costs and easy deployment
• Widely used by surveying firms, government agencies, and construction companies

Why Multi‑Frequency GNSS Improves RTK Performance

Modern RTK receivers support multiple constellations (GPS + BeiDou + GLONASS + Galileo) and multiple frequencies (L1 / L2 / L5), which:

• Reduce atmospheric errors
• Improve initialization speed and reliability in challenging environments
• Enhance robustness against signal obstruction and multipath

Multi‑constellation, multi‑frequency capability has become the standard for professional RTK receivers, ensuring consistent centimeter‑level performance.