DGPS vs RTK: Understanding Precision in GNSS for Mining and Environmental Surveys

Surveying ground control for accurate georeferencing of drone surveys

Accurate positioning is essential in industries where centimetres—or even millimetres—matter. In sectors like mining and environmental consulting, two major GNSS (Global Navigation Satellite System) technologies dominate: Differential GPS (DGPS) and Real-Time Kinematic (RTK). Understanding their differences—and the recent advances in GNSS technology—can make or break the success of a project.

What is DGPS?

Differential GPS (DGPS) enhances the standard GPS signal by using a fixed ground-based reference station. This station knows its exact location and continuously compares it with the position calculated from satellite signals. It then broadcasts correction data, which roving receivers use to correct their positions in real-time or in post-processing.

Typical DGPS accuracy is around 0.5 to 5 metres, depending on the system and environmental conditions.

Example in Mining:

In open-pit mines, DGPS can guide haul trucks and excavators. Although sub-metre precision is not sufficient for fine grading or drilling operations, it’s perfectly acceptable for tracking vehicle paths, managing stockpiles, and performing general topographic mapping.

Example in Environmental Work:

For environmental baseline surveys, such as vegetation mapping or installing transects or quadrats, DGPS provides a fast, efficient method of recording data points without requiring ultra-fine precision. It balances accuracy and operational speed, critical for covering ground and getting the job done in field campaigns.

What is RTK?

Real-Time Kinematic (RTK) GNSS improves accuracy far beyond DGPS, typically achieving 1–2 centimetres horizontally and 2–4 centimetres vertically. RTK works by measuring the phase of the signal’s carrier wave, not just the information transmitted. Corrections are transmitted via a radio or cellular network from a base station or a network of base stations (RTK networks).

Example in Mining:

RTK is indispensable in mine site survey control, blast design, and machine guidance systems. For example, when setting out drill patterns for blast holes, centimetre-level precision ensures optimal fragmentation and minimal environmental impact. RTK also supports autonomous dozers and graders that must maintain exact blade positions.

Example in Environmental Work:

RTK shines in environmental rehabilitation and monitoring projects where precise transects or quadrats must be mapped and revisited accurately over time. For example, in restoration ecology, setting up 10 m × 10 m monitoring quadrats or 20 m linear transects and relocating them year after year with centimetre-level repeatability improves the integrity of long-term data sets.

Advances in GNSS Accuracy: Closing the Gap

Historically, RTK required a local base station within 10–20 km. However, several innovations are transforming the landscape:

1. RTK Networks: Commercial RTK correction services (like Trimble VRS Now, TopNETlive) provide corrections over the internet, eliminating the need to set up a local base station.

2. PPP (Precise Point Positioning): Services like Trimble CenterPoint RTX and NovAtel’s TerraStar-X offer global corrections without a local base, achieving sub-10 cm accuracy anywhere in the world, albeit with a slight convergence time (up to several minutes).

3. Multi-Constellation GNSS: Newer receivers tap into not just GPS but also GLONASS, Galileo, and BeiDou satellites, dramatically improving reliability and reducing downtime under challenging conditions like forest canopies or open-cut pit walls.

4. L-band Corrections: Some services broadcast corrections via L-band satellites, allowing near-RTK accuracy without internet or UHF radio—ideal for remote mining or environmental sites where connectivity is sparse.

5. Hybrid Systems: Some systems combine PPP and RTK for the best of both worlds—global availability and local, real-time accuracy—critical in operations moving across wide areas without consistent cellular coverage.

Conclusion

Both DGPS and RTK have their place depending on the required accuracy, cost, and project needs. In mining, where centimetre precision drives efficiency and safety, RTK is non-negotiable for tasks like blast hole drilling or autonomous machine control. In environmental surveying, where large areas must be covered quickly and moderate precision suffices, DGPS still holds value.

However, GNSS technology continues to evolve, making high-precision positioning more accessible, even in remote areas. Understanding these technologies helps mining and environmental professionals choose the right tool for the job—and avoid costly mistakes in the field.

Multi Scan is a distributor for both South Instruments GNSS and STEC Precision GNSS systems in Australia. Contact us for DGPS and RTK hire and sales.