To achieve near-perfect accuracy in surveying operations is no simple feat. As the planet is constantly moving through space, in a persistent rotation, determining the exact three-dimensional position of an object or location is not as simple as using a measuring tape. Instead, we must use multiple reference points, complex mathematical calculations and skilled professionals to get the desired results.
Like most technology, however, surveying equipment has improved over time. We have talked previously about the dumpy level and how things have changed since its heyday. Still, the dumpy level is relatively low-tech compared to the cloud-serviced, satellite-positioned options we have available today.
Now that digital surveying equipment has become the mainstay for construction, astronomy, agriculture and most other surveying operations, it is important to know the differences between electronic systems. Today, we look at GNSS receivers, RTK GPS and DGPS to determine how they have evolved from previous technologies and what the differences between them are.
GNSS Receivers
The most basic option for digital surveying is a single Global Navigation Satellite System (GNSS) receiver. This is often a component of the more complex DGPS and RTK GPS systems, but it is basic in the sense that it does not do any corrections. It simply measures the distance between the rover and the base station and calls it a day.
DGPS
Differential Global Positioning Systems (DGPS) are like an upgrade to GNSS receivers. They still measure the distance between the rover and base station, but they then communicate with land-based stations within range and satellite-based systems also. These stations perform real-time corrections to their position and, when used in conjunction with the data from the DGPS, they can improve the accuracy to within 40 cm.
RTK GPS
Finally, we have the most advanced version of surveying equipment, namely Real-time Kinematic Global Positioning Systems (RTK GPS). These devices perform the same functions as GNSS receivers and DGPS, but they also have additional computations during the data processing stage. They use additional formulas for correcting the ionospheric delay and satellite clock errors that are present with DGPS alternatives.
| Feature | DGPS | RTK |
| Correction type | Differential code-based corrections | Carrier-phase corrections |
| Typical accuracy | Often sub-meter to meter-level, depending on system and conditions | Centimeter-level when properly configured |
| Equipment | GNSS receiver plus correction source | Base and rover or network RTK rover |
| Real-time use | Yes | Yes |
| Best for | GIS mapping, navigation, agriculture, asset location, lower-precision work | Surveying, construction staking, machine control, boundary work, topographic surveys |
| Main limitation | Not precise enough for many professional survey tasks | Requires stronger setup, reliable corrections, and proper field checks |
| Typical user | GIS teams, marine users, agriculture users, mapping crews | Surveyors, engineers, contractors, construction crews |
The biggest difference between RTK and DGPS is the level of accuracy each system can achieve. DGPS improves standard GPS/GNSS positioning by applying correction data from a reference source. Depending on the equipment, correction service, and field conditions, DGPS typically provides sub-meter or meter-level accuracy.
RTK is more precise because it uses real-time carrier-phase corrections from a base station or RTK network. When properly configured, RTK can deliver centimeter-level accuracy in real time. This makes RTK the preferred choice for professional surveying, construction layout, machine control, and other applications where small positioning errors can affect the final result.
In general, DGPS is suitable for improved positioning, while RTK is used when survey-grade accuracy is required.
The main difference between RTK and DGPS is accuracy. DGPS improves standard GPS/GNSS positioning with differential corrections, usually providing sub-meter or meter-level accuracy depending on the correction source and field conditions.
RTK provides a higher level of precision by using real-time carrier-phase corrections from a base station or RTK network. This allows RTK systems to achieve centimeter-level accuracy, making them the better choice for land surveying, construction layout, machine control, and other high-precision applications.
In short, DGPS is useful for improved positioning, while RTK is the preferred solution when survey-grade accuracy is required.
Hopefully, you have found this information about GNSS receivers, DGPS and RTK GPS informative and helpful. If you would like to learn more about the systems utilizing this technology and how they help you, contact us! We look forward to hearing from you!
Bench Mark Equipment & Supplies is your team to trust with all your surveying equipment. We have been providing high-quality surveying equipment to land surveyors, engineers, construction, airborne and resource professionals since 2002. This helps establish ourselves as the go-to team in Calgary, Canada, and the USA. Plus, we provide a wide selection of equipment, including global navigation satellite systems, RTK GPS equipment, GNSS receivers, and more. We strive to provide the highest level of customer care and service for everyone. To speak to one of our team today, call us at 403-286-0333 or email us [email protected]
