Surveying has come a long way from compasses and chains. Today, surveyors rely heavily on advanced technology to collect accurate data—and one of the most powerful tools is GPS/GNSS. But just having the equipment isn’t enough. To get reliable results, you need to know how to use it right.
In this post, we’ll walk you through how GPS and GNSS systems work for surveying, what affects accuracy, and what you can do to get precise, consistent results every time.
Why Accuracy Matters in Surveying
Accuracy isn’t just a nice-to-have—it’s a must. In surveying, even small errors can lead to major problems. For example, imagine a misplaced boundary line or a construction error caused by inaccurate data. These mistakes can cost time, money, and lead to legal issues.
Using GPS/GNSS properly helps surveyors reach centimeter-level precision. This kind of accuracy is essential for land development, construction layout, infrastructure planning, and more.
GPS vs. GNSS: What’s the Difference?
Let’s clear up a common confusion.
- GPS stands for Global Positioning System, the satellite navigation system owned by the United States.
- GNSS is a broader term. It stands for Global Navigation Satellite System and includes GPS, as well as other systems like GLONASS (Russia), Galileo (Europe), and BeiDou (China).
If your equipment supports GNSS, you can access multiple satellite systems at once. This gives you more signals to work with, better reliability, and higher accuracy—especially in areas with obstructions or weak signals.
How GPS/GNSS Works in Surveys
Here’s a simplified version of how it all works:
- A GNSS receiver picks up signals from several satellites in orbit.
- It calculates the distance to each satellite based on how long the signal takes to arrive.
- Using trilateration, the receiver figures out your exact position on Earth.
- Corrections are applied to improve precision:
- SBAS (Satellite-Based Augmentation Systems) provide regional corrections.
- RTK (Real-Time Kinematic) uses a base and rover to correct position in real-time.
- PPK (Post-Processed Kinematic) corrects data after field collection.
- SBAS (Satellite-Based Augmentation Systems) provide regional corrections.
By combining hardware, software, and smart techniques, you can achieve incredible accuracy—even down to millimeters.
Key Factors That Affect Survey Accuracy
Even the best equipment can’t do all the work alone. Here are the most important factors that influence your final results:
1. Satellite Geometry (PDOP)
PDOP stands for Position Dilution of Precision. A low PDOP (preferably under 4) means satellites are well-spaced in the sky, giving you more accurate positioning.
2. Multipath Errors
Signals can bounce off reflective surfaces like buildings, vehicles, or water, creating errors. You can reduce these by avoiding reflective areas, using proper antennas, and elevating your equipment.
3. Signal Blockage
Tall buildings, trees, and hills can block signals. Surveying in open areas helps reduce this problem.
4. Interference
Radio signals and electronic interference from nearby devices or towers can cause problems. Stay alert to your environment and use equipment with interference-resistant features.
5. Atmospheric Conditions
Signal delays in the atmosphere (ionosphere and troposphere) can affect results. RTK and PPK help minimize these errors.
6. Equipment Quality
High-quality GNSS receivers, antennas, and updated firmware make a big difference. Always calibrate and maintain your gear.
7. Data Collection Habits
Collecting metadata (such as antenna height, observation duration, and environmental conditions) is just as important as collecting coordinates.
Field Best Practices for Reliable Results
Here are proven steps to follow on every project:
Scout the Site First
Look for obstructions, reflective surfaces, or potential interference. Use your planning tools to review satellite visibility before you start.
Use a Stable Base Station
Set it up over a known point. Level it, document the antenna model and firmware, and log the exact position and start/end time.
Measure Carefully with the Rover
Keep the antenna vertical, collect several shots per point, and document each observation.
Validate Your Data
Set a few checkpoints and compare results. Re-measure anything that looks off.
Post-Process When Possible
Even real-time RTK benefits from post-processing. This adds an extra layer of precision and peace of mind.
Pro Tips for High-Precision GNSS Surveys
If you’re aiming for the highest level of accuracy, keep these techniques in mind:
Use Dual-Frequency Receivers
They cancel out atmospheric delays and improve performance in challenging conditions.
Connect to Multiple Satellite Systems
The more constellations you track, the better. It reduces downtime and increases positional strength.
Extend Observation Time
For static control points, longer measurements (20–30+ minutes) increase precision and reduce noise.
Use a VRS or NTRIP Network
Virtual Reference Stations provide real-time corrections without a local base station. They work great for large jobs or remote areas.
Run Network Adjustments
Use least-squares adjustment methods for multi-point surveys. This makes your final data more consistent and defensible.
Log and Report Everything
Documenting the accuracy of your observations (in centimeters or millimeters) adds credibility and allows for future reference.
Recap: Key Components for GPS/GNSS Survey Accuracy
Here’s a clear checklist of what really matters in the field:
Use High-Quality GNSS Receivers
Dual-frequency units with support for GPS, GLONASS, Galileo, and BeiDou offer the best signal reliability.
Watch Satellite Geometry (PDOP)
Keep PDOP values below 4 to ensure a strong satellite configuration.
Avoid Signal Obstruction and Multipath
Stay clear of buildings, vehicles, and shiny surfaces. They reflect signals and reduce accuracy.
Set Up a Stable Base Station
Level your tripod, calibrate your antenna, and record all relevant setup info.
Collect Solid Rover Observations
Take multiple measurements per point and keep your gear steady and upright.
Verify with Check Points
Include known control points and double-check anything that looks off.
Post-Process When Needed
Use PPK or run network adjustments to enhance your data’s accuracy and consistency.
Document Everything
Record metadata like RMS errors, antenna specs, and environmental notes. This builds trust and traceability.
Why Work with ARC Surveyors?
At ARC Surveyors, we specialize in high-accuracy GNSS and traditional surveying. Our team uses the latest tools, software, and proven workflows to ensure every point we measure is both precise and reliable.
Whether you’re working on land development, utility mapping, or boundary surveys, our team has the expertise to deliver quality results with full documentation.
Explore our full range of surveying services here.
External Resource
Want to dive deeper into GNSS-based surveying standards? Visit the U.S. National Geodetic Survey for technical guides and best practices:
👉 U.S. NGS GNSS Guidelines
Final Thoughts
GPS/GNSS has changed the way we survey, but precision doesn’t come automatically. You need solid workflows, good equipment, and the right habits in the field.
By understanding how satellite systems work, minimizing common errors, and sticking to best practices, you’ll ensure your surveys are accurate, efficient, and defensible. Whether you’re mapping for design, construction, or compliance, it all starts with reliable positioning.
Need help planning your next survey project? Contact ARC Surveyors today—we’re ready to bring accuracy to your fieldwork.