Precision agriculture has become ever more essential in farming over recent decades. Farmers must maximise yields while minimising inputs due to increasing population pressures on limited arable land. A key technology that has allowed greater precision is real-time kinematic (RTK) guidance systems; these provide centimetre-level accuracy in positioning agricultural vehicles and implements over fields. We will discuss RTK guidance systems’ functionality and development in this article.
What Is RTK Guidance?
RTK guidance refers to a satellite navigation technique commonly employed in precision agriculture for providing accurate positioning data on vehicles and equipment in the field. RTK stands for real-time kinematic, which means this system provides real-time corrections as the equipment moves.
RTK guidance utilises a vehicle’s global navigation satellite system (GNSS) receiver and data from a fixed base station to deliver a pinpoint accuracy of 1-2 cm. The base station tracks satellites while tracking signal errors to calculate error corrections that it then transmits by radio to roaming vehicles. Rovers then use these corrections to pinpoint their locations within 2-3 cm accuracy precisely.
Positioning accuracy enables tractors, sprayers, planters and other machinery to follow precise routes without overlaps or gaps in their path. Guidance is displayed on a screen within each tractor cab so drivers can easily follow planned routes.
Evolution of RTK Guidance Systems
Beginnings With GPS
RTK guidance systems can be traced back to the introduction of NAVSTAR GPS in the 1980s. Civilian access enabled basic guidance systems using code GPS with 1-5 meters accuracy for straight lines and simple patterns. However, it needed greater precision for row crops due to limited accuracy from its 1-5 meter accuracy.
In the 1990s, differential GPS (DGPS) saw its next evolution through RTK systems such as differential GPS. DGPS uses stationary reference receivers to apply corrective factors to mobile receivers around the area, improving accuracy to 30-60 cm.
Network RTK Systems
Single base station RTK was limited by radio transmission distance restrictions to three and five kilometres, so manufacturers began developing GPS networks in the early 2000s as an expansion strategy. Network RTK utilises multiple permanent base stations transmitting corrections over radio towers positioned on the ground to increase coverage.
Global and Mobile Networks
The 2000s saw the introduction of satellite-delivered RTK correction services such as OmniSTAR in 1999 and StarFire from John Deere in 2001, providing global coverage with decimeter accuracy no matter their location.
The future is Already Here.
In the early days of GPS guidance, we laid the groundwork for modern precise systems. What started as meter-level accuracy has evolved rapidly into centimetre precision; RTK networks continue to expand to provide farmers with comprehensive area connectivity.
At the same time, RTK corrections are being integrated into farm equipment. John Deere receivers feature embedded modems to access global and regional networks, while Trimble provides an RTK correction service via cell connectivity.
The next phase in the evolution of RTK guidance will likely involve even greater automation, with machines using their ultra-precise RTK positioning to operate with minimal driver intervention or input. As the systems advance, we will see more devices capable of truly autonomous operation in the field, making decisions and navigating entirely based on RTK localisation. These ever-improving technologies will continue to advance precision agriculture into new realms; what started as simple steering assistance has since grown into fully optimised, self-directed field operations capable of running themselves from start to finish. The precision enabled by RTK allows machines to take over more and more tasks, taking automation to new levels. So, while RTK guidance began as a helpful aid for drivers, it will increasingly transition to an essential enabling technology for autonomous equipment over large areas. The future of farming will likely see fleets of driverless machines working the fields using RTK as their guide.
Conclusion
RTK guidance has come an incredibly long way in a relatively short period. A mere two decades ago, decimeter-level positioning accuracy seemed impossible – something that could only be dreamed about. The satellite and wireless technologies that enabled centimetre-level accuracy have yet to exist. But thanks to rapid advancements over a few short years, RTK systems went from aspirational to reality. What was once thought unachievable became not only possible but a crucial, indispensable tool for farmers across the globe. The progression from early code-based GPS to single base station RTK to far-reaching networks happened amazingly fast. Now, precision down to mere centimetres is essential to modern agriculture. RTK systems have evolved from fictional fantasy to fundamental necessity in just twenty years. The pace of innovation has been truly staggering, completely transforming the realm of possibility for agricultural positioning accuracy.
