Understanding RTK accuracy
Cut to the chase: RTK accuracy fades with distance. Think of it like a radio signal – the further you are from the source, the weaker it gets. This happens at a predictable rate, and knowing this helps you get the most out of your RTK system.
Ever wondered how RTK systems achieve centimeter-level accuracy? And why that accuracy seems to change the further you get from the base station? The truth is, it's not some kind of sorcery. It all boils down to simple math.
Let's break it down.
A quick refresher on RTK
Real-Time Kinematic (RTK) is like a turbocharger for satellite navigation. It takes the already impressive accuracy of GPS and similar systems and makes it 100 times more accurate. We're talking about pinpointing locations down to the centimeter. This incredible precision makes RTK essential for applications where every millimeter counts, from precision agriculture and construction surveying to autonomous vehicle navigation.
How distance impacts RTK accuracy
One of the most common questions about RTK is how accuracy is affected by the distance between the rover (the device receiving the corrections) and the base station (the fixed reference point).
Think of it like a radio signal. The further you are from the source, the weaker the signal gets, and the more likely it is to be affected by interference. Similarly, in RTK, the further the rover is from the base station, the more challenging it becomes to maintain that ultra-high accuracy.
But why?
The answer lies in something called Parts Per Million (PPM). PPM is a unit of measurement used to describe the accuracy degradation in RTK positioning systems as the distance from the base station increases. In the context of RTK accuracy, 1 ppm equates to an error of 1 millimeter per kilometer.
This means if a system has a horizontal accuracy degradation of 0.5 ppm, every kilometer the rover moves away from the base station, an additional error of 0.5 millimeters is introduced.
OK, But how does this translate to your specific rover?
Let's take the Septentrio Mosaic-X5 receiver as an example. Its specifications tell us:
The formulas provided in the image allow us to calculate these variations:
- Horizontal Accuracy: Accuracy = 0.6 cm + 0.5 ppm × Distance
- Vertical Accuracy: Accuracy = 1.0 cm + 1.0 ppm × Distance
Horizontal Accuracy Analysis
The horizontal accuracy of RTK starts at 0.6 cm when the distance from the base station is zero. This base accuracy increases linearly with the distance due to the 0.5 ppm factor. For instance, at a distance of 10 km (10,000 meters), the additional error is 0.5ppm × 10KM = .5cm, making the total horizontal accuracy 0.6cm + 0.5cm = 1.1 cm.
Vertical Accuracy Analysis
Similarly, the vertical accuracy starts at 1.0 cm and increases by 1.0 ppm per kilometer. At the same distance of 10 km, the additional error is 1ppm X 10KM = 1cm, resulting in a total vertical accuracy of 1.0cm + 1.0cm = 2.0 cm.
Graphical Representation
To illustrate these accuracy changes, we plotted the accuracy against distances up to 50 km:
The graph shows how both horizontal and vertical accuracies degrade with increasing distance. The horizontal accuracy remains better than the vertical accuracy, but both follow a similar trend of linear degradation.
What This Means for You
Understanding the relationship between distance and RTK accuracy is crucial for getting the most out of your RTK system.
The degradation in accuracy with distance implies that RTK systems are most effective when the rover is relatively close to the base station. For applications requiring extremely high precision in the 1cm range such as construction and high-precision agriculture, it is crucial to maintain a shorter distance from the base station, typically around 10km. For applications requiring high precision in the 2-3cm range, this distance can be extended to 50km.
To sum it all up, understanding the relationship between distance and RTK accuracy is essential for optimizing the use of RTK systems in various applications.
By keeping these distance considerations in mind, you can ensure that your RTK system delivers the precision you need, no matter the application.
Want to learn more about optimizing your RTK setup? Contact Sales
