Why Your RTK GPS Isn't Always Accurate: 7 Environmental Factors That Affect Precision (And How to Fix Them)

Real-Time Kinematic (RTK) GPS technology is a cornerstone for industries like drone surveying or mapping, inspection, construction, and accident reconstruction. With RTK GPS receivers, drone pilots can achieve centimeter-level accuracy, making them essential for tasks like mapping accident scenes, inspecting infrastructure, or guiding drones with precision. But even the most advanced RTK GPS receivers can deliver inconsistent results if environmental factors interfere. If you’ve noticed your drone surveying solutions producing unexpected errors, you’re not alone. Understanding why your RTK GPS isn’t always accurate is the key to unlocking its full potential.

At Robota, we’ve worked with drone pilots, inspection teams, and accident reconstruction companies to overcome environmental challenges that impact RTK GPS performance. In this blog post, we’ll explore seven common environmental factors that affect RTK GPS accuracy and share practical solutions to address them. Whether you’re a drone pilot mapping a site or an accident reconstruction specialist recreating a scene, these tips will help you ensure your RTK GPS receivers deliver the precision you need. Let’s dive into the factors and solutions, guided by questions we hear from our customers.

What Are the Factors That Could Affect the Accuracy of Your RTK GPS Positions?

RTK GPS receivers rely on satellite signals and correction data to provide high-precision positioning. However, environmental conditions can disrupt these signals, leading to errors that impact drone surveying solutions. Here are seven key factors that can reduce the accuracy of your RTK GPS positions for drone pilots:

1. Multipath Interference: GPS signals reflecting off surfaces like buildings, vehicles, or water arrive at the receiver with delays, causing position errors. This is common in urban areas where inspection and accident reconstruction often occur.

2. Obstructed Sky View: Trees, tall buildings, or bridges can block satellite signals, reducing the number of satellites your RTK GPS receiver can track, which affects drone pilots working in complex environments.

3. Ionospheric and Tropospheric Delays: Atmospheric layers can slow GPS signals, introducing errors. These effects are more pronounced during solar activity or humid conditions, impacting drone surveying solutions.

4. Poor Satellite Geometry: When satellites are clustered closely in the sky (high Dilution of Precision, or DOP), positioning accuracy decreases, challenging inspection teams needing precise measurements.

5. Electromagnetic Interference (EMI): Power lines, radio towers, or electronic devices can disrupt GPS signals, affecting the performance of Bluetooth and Wi-Fi RTK GPS receivers used by drone pilots.

6. Baseline Distance Issues: In RTK systems, long distances between the base station and rover (baseline) can introduce errors due to atmospheric differences, critical for accident reconstruction accuracy.

7. Vegetation and Terrain: Dense foliage or uneven terrain can weaken signals, especially in rural or forested areas where drone pilots and inspection teams operate.

   
   

These factors can degrade the performance of your RTK GPS receivers, but understanding their impact is the first step to overcoming them. Let’s explore how to improve accuracy.

How to Improve RTK GPS Receiver Accuracy?

Improving the accuracy of your RTK GPS receivers is achievable with the right strategies, ensuring reliable results for drone pilots, inspection teams, and accident reconstruction companies. Here’s how to address environmental challenges and optimize your setup for drone surveying solutions:

Minimize Multipath Interference:

1. Position your receiver away from reflective surfaces like glass buildings or vehicles, common in urban inspection and accident reconstruction sites.

2. Use antennas designed to reject multipath signals, such as the helical antennas featured in Robota’s Bluetooth RTK GPS receivers.

3. Elevate the receiver on a tripod to reduce ground reflections during drone operations.

Ensure a Clear Sky View:

1. Choose survey locations with minimal obstructions, like open areas, for optimal satellite visibility during inspections.

2. Plan missions during peak satellite availability using mission planning software, critical for drone pilots in obstructed environments.

Correct Atmospheric Delays:

1. Use correction services like RTK networks (e.g., NTRIP) or a local base station, such as Robota’s RoboDot, to account for ionospheric and tropospheric errors.

2. Opt for Post-Processed Kinematic (PPK) workflows for drone surveying solutions to correct atmospheric errors post-mission.

Optimize Satellite Geometry:

1. Set an elevation mask (e.g., 15°) on your RTK GPS receiver to exclude low-elevation satellites prone to errors.

2. Monitor DOP values in real-time using RoboDot’s touchscreen display or web UI, and pause surveys when satellite geometry is poor to ensure accuracy for accident reconstruction.

Reduce Electromagnetic Interference:

1. Avoid placing receivers near power lines or radio towers, which are common near infrastructure inspection sites.

2. Use high-quality RTK GPS receivers with filtered antennas, like RoboDot, to minimize EMI (electromagnetic interference) effects. In many applications, such as those using RoboDot, external cables aren’t required, further reducing potential EMI sources for drone pilots.

Manage Baseline Distances:

1. For precise accident scene mapping, control the baseline using a local base station like RoboDot and keep it under 20 km to minimize atmospheric discrepancies during RTK surveys.

2. Before relying on correction networks for long-distance drone surveying, study the network to understand the baselines to your scene; longer baselines can affect accuracy, so proper evaluation is key.

Account for Vegetation and Terrain:

1. In forested areas, use multi-constellation receivers (GPS, GLONASS, Galileo, BeiDou) to track more satellites for inspection tasks.

2. Deploy base stations on elevated terrain to improve signal reach for both drone pilots and rovers.

By applying these solutions, you can enhance the performance of your RTK GPS receivers, ensuring precise data for inspection, accident reconstruction, and drone piloting tasks. But what specific challenges arise from multipath interference?

Why Does Multipath Interference Cause Such Big Problems for RTK GPS?

Multipath interference is a major issue for RTK GPS accuracy, especially in urban settings where drone pilots and inspection teams operate. When GPS signals reflect off buildings, vehicles, or other surfaces, they travel a longer path to your Bluetooth RTK GPS receiver and rover, causing miscalculated distances. This can lead to errors of several centimeters, which is unacceptable for construction or infrastructure inspections requiring pinpoint accuracy.

Robota’s RTK GPS receivers are designed to minimize multipath effects, making them a reliable choice for challenging inspection and reconstruction scenarios. But how do atmospheric conditions come into play?

How Do Atmospheric Conditions Affect RTK GPS Accuracy?

Atmospheric conditions significantly impact RTK GPS performance. The ionosphere and troposphere can delay GPS signals due to charged particles or weather factors like humidity. These delays can cause errors of up to several meters if uncorrected, affecting drone surveying solutions used by inspection teams and accident reconstruction specialists.

To mitigate atmospheric effects:

1. Use real-time correction data from a nearby base station or RTK network to adjust for delays.

2. Leverage PPK processing for post-survey corrections, ensuring high accuracy for drone pilots.

3. Schedule surveys during stable weather to minimize tropospheric interference.

By addressing atmospheric challenges, you can ensure your RTK GPS receivers perform reliably, even in variable conditions.

What Role Does Satellite Availability Play in RTK GPS Precision?

Satellite availability and geometry are critical for RTK GPS accuracy. Your receiver needs at least four satellites for a 3D position, but more satellites and better geometry (satellites spread across the sky) improve precision. Poor geometry, or high DOP, can degrade accuracy, impacting drone pilots and inspection teams who rely on centimeter-level precision.

To optimize satellite availability:

• Plan surveys using GNSS mission planning software to identify peak satellite availability.

• Avoid surveying under dense tree canopies or near tall structures, common in inspection and reconstruction sites.

Robota’s Bluetooth RTK GPS receivers support multiple constellations for robust field performance. For added flexibility, consider enabling repeater mode, this lets you place the base station in an ideal location while operating both the rover and receiver freely in an open area using the repeated signal.

How Can You Test and Verify RTK GPS Accuracy?

Verifying the accuracy of your RTK GPS receivers is essential for reliable results in drone piloting, inspection, and accident reconstruction. Here’s how to test your system:

• Conduct Known Point Tests: Survey a point with known coordinates and compare your RTK results to reference values.

• Use Check Shots: Collect multiple measurements at the same point to assess consistency, critical for accident reconstruction.

• Monitor RTK Status: Ensure your receiver is in “Fixed” mode for centimeter-level accuracy, rather than “Float” or “DGPS”.

• Review Log Files: Analyze raw data logs to identify issues like multipath or poor satellite geometry.

Regular testing helps you catch environmental issues early and maintain confidence in your drone surveying solutions.

Take Control of Your RTK GPS Accuracy with Robota

Environmental factors like multipath, atmospheric delays, and poor satellite geometry can compromise the accuracy of your RTK GPS receivers, but they don’t have to. By understanding these challenges and applying the solutions outlined above, drone pilots, inspection teams, and accident reconstruction companies can achieve centimeter-level precision. Robota’s advanced Bluetooth RTK GPS receivers are built to perform in demanding conditions, ensuring reliable results for your projects.

Ready to elevate your surveying accuracy? Explore our RoboDot Touch RTK GPS Base/Rover. Contact our team today to find the perfect tools for your next inspection, construction, drone surveying or mapping project and experience precision like never before.