Drawing with RTK

The most spectacular show of RTK positioning? Of course drawing!

RTK antenna in a (slight) movement

We put our small but powerful RTK kit to a difficult test. We used the antenna to draw a drawing on the ground, on the pavement in front of the building. What does this mean for satellite positioning? Significant terrain barriers were preventing or significantly hindering the signal reception from some satellites. The corrections were provided to our “drawing rover” by a nearby base station, created by us ourselves from the components included in the U-blox GNSS RTK C94 – M8P evaluation kit.

What were we drawing? Of course, our nice logo. How big? Look at the photo. Yes, the height of the logo is two ordinary paving stones. One is 6 cm wide!

Sketch on paving stones with visible GNSS RTK receiver antenna and visualization of its movement along the edges of the drawing, achieved in real time, in the u-center software.

Static positioning

We checked the positioning accuracy of a single point by placing two identical GNSS antennas next to each other. One of the receivers received RTK corrections from our base station, the other used standard GNSS. We have marked the deviations from the average recorded position on the chart below. Green is GNSS. It is not bad, it is only about + -2 m, with moderate visibility of the satellites (except for a few points with significant error, at the very beginning of the registration). What can we say about RTK? With the scale used, it is simply one point. We need to zoom this chart.

GNSS antennas
Recorded position deviations from the mean value in meters: green – GNSS, red – RTK.
Recorded position deviations from the RTK average in meters .

The accuracy of determining the position in real time reached the order of 1 cm. In our opinion, this is a fantastic result. The absolute positioning accuracy depends on the accuracy of the base station positioning. More on that soon.

The possibilities of using these techniques are huge: hydrographic and geodetic measurements, positioning of drones, autonomous vehicles, unmanned units or agricultural tractors. Wherever accurate positioning is necessary, and it is not possible to set up your own base station, specialized services, e.g. state-owned ASG-EUPOS in Poland, transmitting corrections come to the rescue. For everyone who would like to learn more about the techniques used here, a great guide on RTK and RTN systems is available here (in Polish): http://www.asgeupos.pl/webpg/graph/standards/Poradnik%20ASG-EUPOS%202014.pdf.