Real-Time Kinematic (RTK) GPS has revolutionized the way surveyors are working. RTK offers surveyors precise, real-time positioning to within a centimeter of accuracy. For those with experience in total stations, RTK GPS may feel challenging at first, but the technology brings significant benefits in accuracy, efficiency, and ease of use. This article provides an approachable overview of RTK GPS, covering its fundamentals, benefits, and applications to help you determine if RTK equipment is the right fit for you. Check out this video below to get an idea of what RTK is and how it works.
Benefits of RTK GPS in Land Surveying
Comparing RTK GPS with Traditional Surveying Methods (Total Stations)
Key Applications of RTK GPS in Land Surveying
Limitations and Challenges of RTK GPS
Future Trends in RTK and GNSS Technology
RTK GPS, or Real-Time Kinematic GPS, is a satellite-based positioning technique that provides highly accurate coordinates in real time. The GNSS technology inside of your phone typically offers accuracy within a few meters, but RTK improves this precision to a centimeter level in real-time by using differential data correction. This makes RTK a great replacement for a total station or robot, especially for those that need to do data pick-up a lot of points over a large area.
RTK GPS is distinguished by its real-time corrections, which deliver instantaneous, corrected positioning data, crucial for projects that require precision. RTK GPS achieves accuracy within a cm horizontally and 1-2 cm vertically. The technology relies on a combination of Global Navigation Satellite Systems (GNSS), such as GPS, GLONASS, Galileo, and BeiDou, enhancing its reliability and range of use. The real-time capability allows surveyors to bypass the delays associated with post-processing or data adjustments, resulting in more efficient fieldwork and greater productivity. For a great read up on RTK, check out RTK GPS by Richard Langely (1998) or NovaTel’s classic An Introduction to GNSS.
Understanding the how RTK GPS actually works is essential to ensure that you get the most out of RTK in the field. RTK GPS improves on conventional GPS accuracy through a method known as differential correction, which involves two key components: a Base Station and a Rover.
The Base Station is a stationary GPS receiver positioned over a known point. It collects raw satellite data and calculates any positional error by comparing the satellite-derived position with its known coordinates. The Rover, on the other hand, is the mobile receiver used by surveyors in the field. Both the base and rover connect to the same set of satellites to receive position and timing data. The base station calculates any errors and sends correction data to the rover through a radio signal, internet connection, or similar communication method. The rover then applies these corrections to its position readings, allowing the surveyor to achieve precise measurements immediately.
RTK GPS offers numerous benefits that are especially valuable for surveyors accustomed to traditional instruments like total stations. The most noticeable advantage is time efficiency. RTK eliminates the need for a line of sight to their instrument. There is no need to perform traverses to get your shots, which not only reduces the time required for each survey but also enables surveyors to survey must larger areas much faster. This makes RTK GPS highly suitable for projects that demand both speed and accuracy.
The precision of RTK GPS, which can achieve centimeter-level accuracy, is another significant benefit. This accuracy is invaluable for tasks like boundary surveys, construction site layouts, and topographic surveys, where even small deviations can have substantial consequences. Additionally, RTK GPS is highly versatile and allows surveyors to move freely across large areas without the need for constant line-of-sight between instruments, unlike total stations. This capability improves mobility and extends the range of possible survey locations. On top of this, unless you are already using a robotic total station, there are huge labour savings. While traditional manual surveying methods may require multiple personnel, an RTK GPS system can often be operated effectively by a single surveyor.In the mid-20th century, Electronic Distance Measurement (EDM) technology came along, which made things a little easier. Total Stations used lasers to measure distances more quickly and accurately than manual methods. However, surveyors still faced the same environmental challenges and had to manually process their data.
For surveyors who are familiar with total stations, understanding how RTK GPS differs can clarify when each technology is most useful. While both RTK and total stations provide precision under a centimetre, it is possible with a total station to achieve greater levels of accuracy with the proper technique. If you have a project with a 1-2 mm tolerance requirement, then a total station is a better fit for you. On the other hand, if you have a project with a tolerance of under a centimeter, an RTK system is a better fit. This difference in accuracy might influence the choice of equipment depending on project needs.
One of the most significant distinctions between total stations and RTK is that RTK GPS does not require line-of-sight between the base and rover, making it more suitable for large, wooded, hilly or urban areas. In contrast, total stations rely on direct line-of-sight, which can limit their effective range in certain settings with lots of obstacles.
RTK GPS also has a broader operational range, allowing surveyors to work across several kilometers, while total stations are limited by line-of-sight requirements. This extended range gives RTK GPS a substantial advantage for larger projects. RTK GPS often requires less setup time as well, enabling surveyors to start data collection faster compared to the detailed setup process required for each new position with a total station. However, for settings where maximum precision is required, such as certain construction or engineering applications, the millimeter accuracy of a total station may be preferable.
The accuracy, efficiency, and mobility provided by RTK GPS make it well-suited to a variety of land surveying applications. One of the most common uses is in topographic surveys, where surveyors need to gather extensive data over large areas quickly. RTK GPS allows them to move from one location to another without requiring repeated setups, making it an ideal tool for generating topographic maps efficiently. With the use of tools like Auto Recording, you can drive or walk your area and the points will be recorded automatically.
In construction, RTK GPS is commonly used for layout and stakeout tasks. The ability to accurately position construction elements such as foundations, utilities, and road alignments is crucial, and RTK GPS provides the precision needed to execute these tasks effectively. With software like MicroSurvey’s FieldGenius and the Hemisphere S631 you can stakeout in double the time.
Another common application for RTK GPS is boundary surveys, where it can provide the precision necessary for delineating property lines—a requirement for both legal and zoning purposes. With 7th Generation RTK you can survey under trees and near buildings, helping reduce the need for a total station. Check out our video here, where we compared two seventh generation receivers, the Hemisphere S631 and GS18: Hemisphere S631 Head to Head with the Leica GS18.
Additionally, RTK GPS is frequently used in Geographic Information System (GIS) data collection, particularly when mapping assets like utility lines or water infrastructure where precise positioning data is required for accurate record-keeping and maintenance.
Despite its advantages, RTK GPS has some limitations that surveyors should keep in mind. One constraint is its dependency on a base station. In areas where an NTRIP network is unavailable, surveyors may need to set up their own, which adds setup time and requires a known point for positioning. Another challenge is the need for a clear line of sight to the sky; RTK GPS may struggle in areas with dense forest cover, steep valleys, or tall urban structures that block satellite signals. If you do not have a receiver with the ability to use the latest signals, it will struggle in these environments.
RTK GPS also relies on stable communication between the base and rover to transmit correction data in real time. If the signal is lost or interfered with, the rover’s accuracy can be affected, potentially causing delays. Power and battery requirements are another factor, as both the base station and rover require sufficient battery life for field sessions, so surveyors must plan accordingly. For a better idea of the things that can influence RTK performance, check out this article: Factors Affecting RTK Performance: An In-Depth Guide for Surveyors.
For those new to RTK GPS, transitioning from total stations can be made easier by familiarizing oneself with the equipment and practicing the basics. Surveyors should spend time learning about their specific RTK GPS system, as different configurations may require unique steps. Practicing the setup of the base station, connecting the rover, and ensuring that real-time corrections are functioning is essential for getting comfortable with the equipment.
Data management is also an important aspect of RTK GPS, particularly if integrating with GIS software, which often has different requirements from total station data. Testing RTK GPS in various environments, from open fields to areas with potential signal obstructions, will provide a realistic understanding of how it performs under different conditions.
Here at Bench-Mark we developed the Survey-Assistant.com website to make the transition from total stations to RTK as easy as possible. We have guides on how to setup the equipment, perform stakeouts, do data pickup and more. Check out the below video to see what kind of RTK setup is best for you.
As RTK GPS technology continues to advance, with new trends enhancing its capabilities and expanding its applications. One significant development is the widespread availability of NTRIP RTK networks. Many states now offer free RTK networks that you can work with. Through the use of a network of base stations the available working area of network rovers can extend correction coverage, allowing for greater accuracy and reliability over larger areas. Additionally, as more satellite systems and frequencies become available, multi-constellation and multi-frequency GNSS are making RTK GPS more resilient to signal issues and environmental interference.
Another promising area is the integration of RTK GPS with unmanned aerial vehicles (UAVs) or drones, enabling high-precision mapping over vast or challenging terrains. This combination is particularly valuable for projects that require comprehensive, high-resolution topographic data, as UAVs equipped with RTK can provide detailed mapping that would be difficult or impossible to gather from the ground.
RTK GPS offers land surveyors a powerful tool that combines precision, speed, and mobility, distinguishing it from traditional surveying methods. While learning RTK GPS may initially seem challenging, its efficiency and accuracy make it a valuable addition to any surveyor’s toolkit. As RTK GPS technology continues to evolve, surveyors who master its fundamentals will be well-equipped to stay competitive in a rapidly advancing industry, embracing both traditional skills and modern tools to meet the needs of diverse projects.
RTK GPS, or Real-Time Kinematic GPS, is a satellite-based positioning system that delivers centimeter-level accuracy by using a method known as differential correction. Traditional GPS offers positional accuracy within a few meters, but RTK GPS reduces this error to within 1-2 centimeters by incorporating real-time correction data. A base station with a known position collects raw data from satellites, calculates any positional errors, and then transmits corrections to a rover unit used in the field. The rover applies these corrections instantly, providing highly accurate real-time coordinates, which makes RTK GPS ideal for precision surveying applications.
While both RTK GPS and total stations offer high levels of accuracy, they operate differently and are suited to different tasks. RTK GPS does not require line-of-sight between its base and rover units, which makes it ideal for surveying large or obstructed areas like forests, hilly regions, or urban spaces with tall buildings. In contrast, total stations require a clear line-of-sight to measure distances and angles, limiting their use to open areas or places with few obstacles. RTK GPS also typically requires less setup time and enables surveyors to cover large areas more quickly, whereas total stations might require precise positioning and more detailed setups for each new measurement point.
RTK GPS is widely used in topographic surveys, where surveyors need to gather data over large areas quickly and accurately. The technology is also commonly used in construction layout and stakeout, enabling surveyors to accurately position key construction elements like foundations, utilities, and road alignments. Boundary surveys also benefit from RTK GPS, as its precision helps to delineate property lines accurately for legal and zoning purposes. RTK GPS is also integral to Geographic Information System (GIS) data collection, especially for mapping utilities and infrastructure with precise location data for record-keeping and maintenance.
RTK GPS has some limitations, particularly in its dependency on a base station. In areas where a networked RTK (NTRIP) system is unavailable, surveyors may need to set up their own base station over a known point, which adds to setup time. Additionally, RTK GPS requires a clear view of the sky to maintain a satellite connection, which means it can be less effective in areas with dense forest cover, valleys, or near tall buildings. Stable communication between the base and rover is also necessary for transmitting correction data in real time; if this connection is interrupted, accuracy may decrease. Power and battery management is also a factor since both the base and rover units require reliable power sources for extended field sessions.
Surveyors transitioning to RTK GPS should start by becoming familiar with their specific RTK equipment and practicing basic setup and operational techniques. Learning to set up the base station, connect the rover, and ensure that real-time corrections are working smoothly is essential for successful fieldwork. Understanding RTK data management is also crucial, especially when integrating with GIS software, as it may have unique requirements compared to total station data. Testing RTK GPS in various environments, such as open fields or areas with potential signal obstructions, will help new users understand how RTK GPS performs under different conditions and improve their confidence in using the technology.
Bench Mark Equipment & Supplies is your team to trust with all your surveying equipment. We have been providing high-quality surveying equipment to land surveyors, engineers, construction, airborne and resource professionals since 2002. This helps establish ourselves as the go-to team in Calgary, Canada, and the USA. Plus, we provide a wide selection of equipment, including global navigation satellite systems, RTK GPS equipment, GNSS receivers, and more. We strive to provide the highest level of customer care and service for everyone. To speak to one of our team today, call us at 403-286-0333 or email us at [email protected].
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