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How does the RTK system solve the GPS positioning error? How accurate can it be?
With the popularization of the global satellite navigation system (GNSS), positioning accuracy has attracted more and more attention. However, satellite signals such as GPS are often affected by various factors during the transmission process, resulting in a decrease in their positioning accuracy. At this time, the real-time dynamic positioning system (RTK) becomes an important tool to solve positioning errors.
What is an RTK system?
RTK is an application that uses satellite navigation technology to perform measurements and correct common errors in current satellite navigation systems. The system measures the signal's carrier phase, combines it with information about the signal's content, and relies on a fixed base station or interpolated virtual base stations to provide real-time corrections, providing centimeter-level accuracy.
RTK systems send correction data via fixed base stations, allowing mobile units to be more accurately positioned.
How RTK system works
The basic concept of RTK is to use the carrier waveform of the satellite signal as the signal source and ignore the information content in the signal. The base station transmits its observed carrier phase, and the mobile compares its own phase measurement with the data received from the base station. In this process, the calculated distance depends mainly on the product of the carrier wavelength and the integer number of revolutions between the satellite and the mobile device, and the addition of the phase difference.
Application Areas
RTK systems are widely used in land surveying, hydrological surveying, and drone navigation. By using RTK technology, professionals in these fields can obtain high-precision measurement results, thereby ensuring the effective execution of projects.
Precision and Limitations
Depending on the RTK system settings, if a single base station is used, the vertical accuracy can reach 15mm and the horizontal accuracy can reach 8mm + 1ppm. This means that if the base station is 16 kilometers away, the horizontal error may reach 24mm. While such errors may limit their usefulness in general navigation, they can enable extremely high accuracy in surveying or autonomous driving systems.
RTK's accuracy performance benefits from precise base station selection, correct measurement environment and advanced signal processing technology.
Network RTK and CORS
In order to expand the application scope of RTK system, network RTK technology was born. This technology is based on a network consisting of multiple base stations, which can further improve the reliability and accuracy of the system. The Continuously Operating Reference Station (CORS) broadcasts correction information via the Internet to help users obtain more accurate positioning information.
ConclusionThe RTK system is undoubtedly a powerful tool that not only significantly improves the positioning accuracy of GPS, but also expands its application range, demonstrating its irreplaceable value from surveying to agriculture. As technology continues to advance, we can’t help but wonder what future positioning technology will look like. Can it break the current precision limits to achieve higher accuracy?
