Estimated reading time: 6 minutes
Table of contents
- Introduction
- Key Takeaways
- Understanding RTK positioning: Why the environment matters
- RTK multipath: Errors from reflections, trees, and terrain
- Urban canyon: What goes wrong in cities, forests, and mountains
- Mitigation strategies for multipath interference
- RTK multipath: A checklist for robust accuracy
- FAQ
Introduction
RTK multipath is one of the most common reasons an RTK fix suddenly disappears or becomes inaccurate in real-world jobs. RTK (Real-Time Kinematic) positioning is all about centimeter-level accuracy, but in urban environments or under dense tree canopy, multipath errors can show up fast. In an urban canyon (tight street corridors) or in thick forest, the signal gets disturbed.
Often, the receiver isn’t the problem, the environment is: reflections, signal blockage, vegetation, and terrain. And that gets expensive: wrong points create rework on construction sites, in surveying, or in machine control.
Key Takeaways
- RTK multipath is common and often causes lost or inaccurate RTK fixes in the field.
- Urban environments, forests, and terrain shielding increase multipath errors and degrade satellite geometry.
- RTK relies on a very sensitive carrier phase, so site selection, clean setup, and a clear measurement routine matter.
- Mitigation starts at the job site: clear sky view, distance from reflective surfaces, suitable antennas, and quality checks.
- Typical symptoms include no fix, long float times, sudden jumps, or a “good-looking” fix that is still wrong.
Understanding RTK positioning: Why the environment matters
Understanding RTK (Real-Time Kinematic) positioning means knowing that NTRIP RTK uses carrier-phase measurements plus correction data from reference stations to compute very precise positions. That same carrier phase is extremely sensitive.
RTK multipath and terrain effects on RTK accuracy can delay a fix or make it unstable. That’s why good mitigation strategies for multipath interference don’t start only in software as they start at the measurement location: open sky, a clean setup, and a consistent field routine.
Get started with RTKdata
Access stable NTRIP correction data for challenging environments through RTKdata’s global network of reference stations.
RTK multipath: Errors from reflections, trees, and terrain
RTK multipath means the GNSS signal arrives not only via the direct path, but also as reflected copies for example off glass, concrete, cars, water, or the ground. Those copies create multipath errors that can shift positions from centimeters to even meters. This happens especially often in urban city environments.
Then there’s signal blockage: fewer satellites, worse geometry, more terrain effects on RTK accuracy.
The impact of trees and foliage on GNSS signals can be severe too: leaves attenuate signals, tree canopies scatter and reflect them, and the receiver sees a noisier, less stable signal set.
Common symptoms:
- no RTK fix
- RTK float solution that won’t resolve
- sudden position jumps
- a RTK fix that “looks good” but is actually wrong
Urban canyon: What goes wrong in cities, forests, and mountains
Cities are where multipath errors occur becomes most obvious. In an urban canyon, building facades bounce signals back, and cranes or moving vehicles constantly change the reflective landscape.
In forests, the impact of trees and foliage on GNSS signals shows up as slow fix times, jitter, and instability especially under dense canopy.
In mountains, terrain effects on RTK accuracy get worse because slopes block satellites while rock faces and water surfaces create strong reflections.
Mitigation strategies for multipath interference: Setup, checks, and corrections
Good mitigation strategies for multipath interference start with site choice and antenna setup:
- mount the antenna high and stable
- keep distance from metal, glass, and water
- avoid reflective surfaces and tight corridors when possible
To reduce RTK multipath, antennas with a ground plane or choke ring can help, along with multi-GNSS / multi-frequency receivers.
Understanding RTK (Real-Time Kinematic) positioning also means doing quality control:
- verify Fix vs Float
- set sensible DOP limits
- run check measurements / control points
For stable correction data in difficult areas, you can use rtkdata.com, and if needed, book a meeting to review your setup. We have a phenomenal support team that can help you with all your needs.
Check your setup and protect the project
Discuss site selection, antenna setup, and quality checks to reduce multipath errors in challenging environments.
RTK multipath: A checklist for robust accuracy
Most field issues come from RTK multipath — not the receiver. Use these points as a quick guide:
- Place the antenna with clear sky view, high, and securely mounted
- Keep distance from reflective surfaces (a key way to reduce how multipath errors occur in urban environments)
- In forests, account for the impact of trees and foliage on GPS signals: prefer clearings/edges and measure longer
- Choose the measurement site so mitigation strategies for multipath interference can work (360° view + checks)
- For difficult projects, test corrections via rtkdata.com (30-day free trial) and re-check measurements if unsure
Test corrections in the field
Try stable real-time correction data in your critical scenarios like forests, mountains, or an urban canyon.
Frequently asked questions
What is RTK multipath and why does the fix drop out?
RTK multipath means that reflected copies of the GNSS signal arrive in addition to the direct signal (e.g., via glass, concrete, cars, water, or the ground). These multipath errors disrupt the sensitive carrier phase, delaying the fix or making it unstable and inaccurate and often occur in cities.
How do cities, forests, and terrain affect RTK accuracy?
In an urban canyon, facades, cranes, and vehicles reflect signals. In forests, canopy attenuates and scatters signals. In mountainous terrain, slopes block satellites while rock and water surfaces reflect signals. This degrades geometry and increases terrain effects on RTK accuracy.
How can I tell when a measurement is problematic?
Typical signs include no fix, persistent float, position jumps, or a fix that “looks good” but is actually wrong.
What measures help reduce multipath errors?
Optimize site and antenna setup: mount high and stable, and keep distance from metal, glass, and water. Use antennas with a ground plane or choke ring and multi-GNSS/multi-frequency receivers. Add quality checks with Fix/Float verification, DOP thresholds, and control measurements.
How does rtkdata.com provide support in difficult areas?
You can use stable correction data and, if necessary, book a meeting to check the setup; this allows you to improve measurement routines and setup in a targeted manner. We have a phenomenal support team that can help you with all your needs.