Real-Time Kinematic (RTK) Technique

Overview of RTK

• RTK enhances positioning accuracy of GNSS (Global Navigation Satellite System).
• Capable of centimeter-level accuracy.
• Essential for applications like land surveying.

GNSS Positioning Basics

• GNSS positioning affected by atmospheric layers, especially the ionosphere.
• Standalone GNSS receivers typically provide meter-level accuracy.

RTK Setup

• Components: Two GNSS receivers - Base and Rover.
  • Base Receiver: Static, placed over a known point.
  • Rover Receiver: Movable, used for data collection.
• Close proximity of receivers allows exclusion of common atmospheric errors.

Error Correction Process

• Base receiver transmits its position and satellite data to the rover.
• Rover uses this information to improve its positional estimates.
• Requires complex mathematical algorithms to achieve centimeter accuracy.

Measurement Techniques

1. Pseudo-Range Measurement:

   • Estimated range between satellite and receiver.
   • Based on signal transmission and reception times.
   • Not very accurate on its own.

2. Carrier Phase Measurement:

   • More advanced method to determine distance.
   • Involves counting the number of full cycles (wavelengths) in the sinusoidal waves of radio signals.
   • Each wavelength is approximately 20 centimeters.
   • Detailed computations in the rover estimate the number of wavelengths.

Field Application

• The rover collects data while moving, utilizing corrections from the base receiver.
• Information exchanged via internet or radio (called base corrections).
• Baseline: Distance between the base and rover.
  • Recommended maximum for single-band receivers: 10 km.
  • For multi-band receivers: 60 km.

Additional Information

• Not always necessary to own a base unit; local service providers may offer corrections via NTRIP technology.

Conclusion

• RTK is a vital technique for precise positioning, making it indispensable for surveying and other precision-required applications.