What are the differences between RTK and DGPS? 4 perspectives to consider when prioritizing accuracy

Table of Contents

• First, clarify the differences between RTK and DGPS

• Viewpoint 1: Compare based on differences in accuracy

• Viewpoint 2: Compare the positioning mechanism and stability

• Perspective 3: Compare in terms of ease of on-site operations

• Perspective 4: Compare by intended use and deliverables

• Which should you choose: RTK or DGPS?

• Summary

First, summarize the differences between RTK and DGPS

In practical fields that handle positioning information, what matters is not simply "whether positioning is possible" but "how accurate," "how stable," and "under what conditions" it can be used. In particular, in areas such as surveying, construction, maintenance, as-built verification, position guidance, and asset management, there are situations where deviations of several meters (several ft) are acceptable, and situations where differences of several centimeters (several in) determine the quality of the work. Therefore, if the differences between RTK and DGPS are understood vaguely, it can easily lead to problems such as failing to achieve the expected accuracy after deployment, incompatible operations, or inability to meet the quality requirements of deliverables.

RTK and DGPS are both approaches for correcting satellite positioning errors and aiming for higher accuracy than standalone positioning. At first glance they may seem like similar technologies based on their commonalities, but in practice there are major differences in how corrections are applied, the accuracy achieved, the need for initialization, operational procedures, and the applications they are suited for. Simply put, DGPS is a method for obtaining better accuracy than standalone positioning that is relatively easy to use, while RTK is a method for achieving even higher accuracy. However, because higher accuracy tends to impose stricter operational requirements, RTK is not always the correct choice.

First, DGPS is a method in which a reference receiver installed at a known point calculates the errors of satellite signals and sends that correction information to the rover, thereby reducing the errors of standalone positioning. Standalone positioning can produce offsets on the order of several meters (several ft), but with DGPS those errors can be kept smaller more easily. In a broad sense, any positioning that uses differential corrections includes the DGPS idea, but in practice DGPS is often treated as "differential corrections centered on code-based positioning aiming for meter-level (ft-level) to sub-meter-level (sub-ft-level) accuracy."

RTK, on the other hand, is a method that improves accuracy by using the phase information of the carrier wave contained in the satellite signals. Because it deals with much finer information than code-based corrections, it can achieve centimeter-level positioning when conditions are favorable. However, RTK does not function simply by receiving correction information; it only reliably delivers high accuracy when multiple conditions are met, such as integer ambiguity resolution and initialization, satellite tracking status, continuity of communications, and the influence of the surrounding environment. In other words, it is easy to understand if you think of DGPS as a relatively easy-to-deploy correction-based positioning method, and RTK as a correction-based positioning method that is highly accurate but requires careful management of conditions.

If you leave this difference vague and conclude, "Isn't it the same if corrections are applied?", on-site expectations will be misaligned. For example, DGPS may be sufficient for vehicle management and wide-area patrol records, but in situations where cm-level (half-inch-level) reliability is required—such as assisting boundary verification, as-built management, stakeout, or obtaining precise coordinates around structures—DGPS may not be enough. Conversely, assuming RTK for tasks that are adequate at the meter-level (ft-level) or sub-meter-level (sub-ft-level) can unnecessarily increase operational burden.

In this article, we organize the differences between RTK and DGPS from four accuracy-focused perspectives to make it easier for practitioners to judge. Rather than simply explaining terminology, we clearly explain what to look for when selecting a system on-site, why those differences affect operations, and which option to choose. For those who wonder, "RTK seems to be more accurate, but how different is it?" or "Where is the boundary between tasks for which DGPS is sufficient and those that require RTK?", this article provides clear criteria to guide adoption decisions.

Perspective 1: Compare by differences in accuracy

When comparing RTK and DGPS, the primary factor to consider is accuracy. This is because many of the reasons for implementing corrected positioning are to secure a level of positional accuracy that standalone positioning cannot provide. RTK and DGPS differ significantly in their approach to accuracy.

DGPS corrects some of the errors that occur in standalone positioning—such as satellite orbit errors, clock errors, and effects from the ionosphere and troposphere—based on error information observed at a reference station. This reduces the error compared with standalone positioning, but in general it is often assumed to achieve meter-level to sub-meter-level accuracy. Of course the results vary depending on the reception environment, the quality of the corrections, and the receiver’s performance, but it is not realistic to expect centimeter-level reproducibility from DGPS from the outset. In other words, DGPS is a technology that “improves position considerably,” but it is somewhat different in character from a technology that “matches fine coordinates precisely.”

On the other hand, RTK uses carrier-phase measurements to capture very small changes in the distance from the satellite to the receiver. Therefore, when the integer ambiguities are correctly resolved and a Fix solution is obtained, horizontal accuracy of a few cm (a few in) and relatively high vertical accuracy can be achieved. This is the fundamental difference between DGPS and RTK. If DGPS is a technology that improves the errors of standalone positioning to a practical level, RTK is a technology intended to address operational situations that demand strong coordinate consistency and reproducibility.

In practice, this difference in accuracy directly translates into differences in the range of tasks that can be performed. For example, for rough location awareness over a wide area, patrol records, coarse determination of an object's presence, or approximate placement on a map, DGPS accuracy may be sufficient. However, when it comes to checking as-built conditions, laying out positions near structures, verifying clearances from existing facilities, comparing with design values, or acquiring data that will later be aligned by coordinates in subsequent processes, meter-level deviations (ft-level deviations) cannot be ignored. At that point, RTK's cm-level accuracy (half-inch accuracy) makes a difference.

What matters even more than a one-off error is repeatability. On site, it’s important how well a point measured today matches the point measured next week within the same coordinate system. DGPS is useful for reliably capturing the approximate position, but for reproducing the same point multiple times with high consistency, RTK is more suitable. In tasks that overlay data from different times—such as drawings, construction management, integration with point clouds and photogrammetry, and time-series comparisons of maintenance data—this difference in repeatability becomes a difference in the quality of the deliverables.

However, what must not be misunderstood here is to simply assume that "RTK is always cm-level" and "DGPS is always meter-level." RTK delivers high accuracy only when conditions are right. In situations such as poor reception, a restricted sky view, unstable communications, failed initialization, or strong multipath, you cannot maintain the expected Fix. In those cases, accuracy degrades. In other words, RTK has high potential accuracy but requires strict operational conditions to realize that performance.

On the other hand, DGPS, even if it does not reach cm level accuracy (half-inch accuracy), can have advantages in situations where operational conditions are relatively benign and ease of use is important. This is not a matter of “inferior because of lower accuracy,” but of whether it is sufficient for the required accuracy. For example, for tasks such as identifying an object's location and linking it to a register, recording abnormal points along a patrol route, or roughly organizing the positions of wide-area assets, DGPS can still provide sufficient operational value. A realistic approach is to choose RTK only where high precision is necessary, or to use them selectively or in stages.

If you are making a judgment based on accuracy, the first step is to clarify "what degree of error is acceptable for that task." Whether being off by 1 m (3.3 ft) is acceptable, whether you want to keep it within 30 cm (11.8 in), or whether you need to match within a few centimeters (a few in) will greatly change your choice. The difference between RTK and DGPS is not a difference in technical terminology, but a difference in how far they can meet the allowable error. Clarifying this without ambiguity is the most important starting point to prevent implementation failures.

Perspective 2: Compare the positioning mechanism and stability

The next perspective to consider is the positioning mechanism and its stability. If you choose a technology based solely on differences in accuracy, you may find in actual field use that it is "harder to use than expected" or "unstable in situations where stopping causes problems." Because higher-precision methods require more delicate condition management, it is important to understand usability and stability in the field as well.

DGPS is primarily based on the idea of applying differential corrections to code-based positioning. In other words, a reference station determines the errors in the satellite signals and conveys those offsets to the mobile receiver to improve positioning. This mechanism is relatively simple and does not require the complex initialization that RTK does. Therefore, in environments where correction information can be received, it tends to provide position improvements relatively smoothly. It is suitable for tasks that do not demand high repeatability but want results reliably better than standalone positioning.

On the other hand, RTK improves positioning accuracy by using the difference in carrier-phase. What becomes important here is the process of resolving the ambiguity. While the carrier phase can capture very fine changes, the challenge is how to determine the integer number of whole-wave cycles of offset. If this is successfully resolved and a Fix solution is obtained, centimeter-level accuracy (cm level accuracy (half-inch accuracy)) can be achieved. However, reaching that point requires a sufficient number of satellites, a good reception environment, continuous correction information, and observations with low noise. In other words, because RTK is an advanced mechanism, it is susceptible to the effects when conditions deteriorate.

What practitioners often care about is "which is less likely to fail/stall" and "which is easier to handle in the field." From this standpoint, DGPS can be relatively stable and easy to use in many situations. Of course, accuracy deteriorates in poor reception conditions, but the burden is generally smaller than with RTK—such as the fix dropping, requiring reinitialization, or having to constantly monitor the solution status. This ease of use is a major advantage, particularly for applications that record approximate positions while in motion.

While RTK offers high accuracy, you need to understand the solution state when using it. If you use it without knowing whether you are currently in Fix, Float, or a standalone solution, you may misjudge the reliability of the coordinates you obtain. For example, even if you have high accuracy while Fix is maintained, if in an area with many obstructions it temporarily falls to Float and you record without noticing, the coordinates may later become inconsistent. If you choose RTK, you should not simply introduce the equipment; you need operational understanding based on state monitoring.

Also, the continuity of communications is directly linked to stability. RTK requires continuous reception of correction data, and if communications are interrupted it can become difficult to maintain a solution. DGPS also requires correction information, but in terms of operational sensitivity RTK tends to be more affected by communication quality. If the site is in mountainous areas, around structures, focused on mobile platforms, or in locations with unstable communications, this difference cannot be ignored. Even if RTK is implemented to achieve high precision, it may struggle to demonstrate its capabilities at sites where communications are not stable.

Moreover, the impact of the surrounding environment cannot be overlooked. In environments with buildings, trees, slopes, metal structures, vehicles, and the like, satellite signal reflections and obstructions occur, degrading positioning quality. DGPS is also affected, but RTK is more sensitive to such environmental factors because it handles phase information precisely. Before accuracy itself, it is particularly important in RTK operations to confirm: "Does this site have sufficient sky visibility?", "Is the site free from strong reflections?", and "Can satellites be tracked continuously while moving?"

In terms of stability, DGPS is easier to use under relatively mild conditions, while RTK provides higher accuracy but is more susceptible to operational conditions. It’s not about which is superior; you should consider the balance between the accuracy the site requires and the operational burden the site can tolerate. If centimeter-level accuracy is always required and you can operate it including status monitoring and communications management, RTK is appropriate. On the other hand, if some error is tolerable but you need to record consistently, DGPS may be the more realistic option.

Even when prioritizing accuracy, accuracy is not determined by theoretical values alone. It is only when it can be stably reproduced in the field that it can be called practical accuracy. In this sense, the difference between RTK and DGPS should be understood not only as a difference in numbers but as a difference in field stability arising from differences in their mechanisms.

Perspective 3: Compare ease of on-site operations

One aspect that is often overlooked when selecting technology is the ease of on-site operation. If you choose based only on the accuracy listed in the catalog, after deployment you are likely to encounter problems such as "each preparation takes a lot of time," "accuracy varies depending on the person in charge," and "checking the calibration environment becomes a hassle." In actual practice, it is extremely important not only that accuracy is high, but also that the system can be operated to deliver consistent quality no matter who uses it.

DGPS is a method that is relatively simple to operate and therefore easy to implement. If you want to improve accuracy over standalone positioning but do not want to manage detailed aspects such as the initialization state each time or the solution fix status, it offers ease of use. On sites with multiple workers, or in operations where recording location information is the primary purpose, simple operation directly translates into productivity. In the field, conditions are not always ideal: weather, movement, working time, and communication conditions are constantly changing. For that reason, the ability to be used with only a few decision points is itself a significant advantage.

RTK needs to be considered all the way through to operational design after deployment. For example, you need rules for things like how long to wait before starting positioning, whether to record data unless a Fix has been obtained, whether to check for reinitialization after entering a shielded environment, and what the conditions for resuming after a communication loss should be. If these points are left ambiguous when deployed in the field, data quality can vary by operator even when using the same equipment. The performance of high-precision technology depends greatly on the users’ understanding and on having well-defined operational rules.

Time efficiency on site is also important. RTK can provide very efficient, high-precision positioning when conditions are right, but if waiting for initialization or a re-fix occurs, it can disrupt the work rhythm. For tasks that require collecting many points in quick succession, these stoppages can be a surprisingly large burden. While DGPS does not match RTK in terms of accuracy, the burden of checking the system status each time is comparatively small, making it easier in some situations to maintain a steady tempo of work. Which is more efficient should be judged by the overall workflow rather than by simple positioning speed.

Furthermore, the difference in training costs cannot be ignored. To use RTK properly, an understanding of satellite positioning basics, the concept of corrections, solution status, error factors, and the influence of field conditions is necessary. Of course, you do not need to grasp everything at an expert level, but at the very least a superficial understanding such as “I’m safe because a high-precision readout is displayed” is insufficient. It is important that field personnel can judge why they should trust that coordinate and under what conditions a re-measurement is required. In contrast, DGPS tends to be able to keep the burden of operational training comparatively low.

On the other hand, RTK also has operational strengths. At sites where procedures are standardized and staff are trained, it can acquire high-quality data with minimal need to backtrack, reducing the effort required for re-surveys and corrections. In other words, while DGPS may have the edge in ease of use during the early stages of implementation, RTK can lead to long-term efficiency improvements if a high-quality operational framework can be established. The important thing is to choose according to the maturity of the site.

From the perspective of ease of field operation, the following questions are important. Is it sufficient to know a rough position in the field, or will the data be used later overlaid with drawings and other data for precise use? Can the operator check the status each time? Is it necessary to continue work even if communications deteriorate? Do you need to collect many points in a short time, or prioritize high accuracy even with fewer points? Depending on these conditions, the practical ease of use of RTK and DGPS can be reversed.

In other words, ease of operation is not just about "whether the operation is simple." It is a perspective on whether a system can run smoothly without undue strain, taking into account required accuracy, site conditions, training programs, and quality control methods. Even in comparisons that emphasize accuracy, methods whose operation collapses will eventually fall out of use. This operational perspective is indispensable for turning the differences between RTK and DGPS into meaningful on-site decisions.

Perspective 4: Comparing Suitable Use Cases and Deliverables

The difference between RTK and DGPS ultimately manifests in which applications they are suited for. This is not merely a matter of equipment preference, but a difference in the accuracy and repeatability required of deliverables. Even for the same positional information, the approach to take changes depending on whether it is sufficient to know an approximate location on a map, or whether it is necessary to overlay it with design values or existing data with high precision.

DGPS is primarily suited to grasping and recording approximate positions. For example, in tasks such as managing target positions across large sites or long routes, recording the locations of anomalies during patrols, or organizing equipment and assets on a map, DGPS can be sufficient. In such applications, although positions must not be off by several meters (several ft), centimeter-level precision (half-inch accuracy) is often not required. Rather, the ability to stably cover a wide area, ease of operation, and the ability to record without stopping work are more important.

Also, DGPS can be well suited for use on moving platforms or for continuous recording. For example, in applications that record position histories during driving or walking, record wide-area survey routes, or organize the locations of targets, maintaining stable continuous reception is prioritized over having excessively high accuracy. In such operations, RTK's cm-level accuracy (half-inch accuracy) may not be fully utilized.

On the other hand, RTK is suited to applications where the coordinate accuracy of the deliverables themselves determines work quality. In surveying, construction management, as-built verification, stakeout, assisting in boundary confirmation, alignment with point clouds and image data, time-series displacement comparisons, and detailed positioning around structures, cm-level accuracy (half-inch accuracy) is valuable. In these tasks, merely knowing a position is not enough; it is important to know exactly where something is and how little it deviates. To reconcile with design values or existing data, DGPS is often inadequate, making the introduction of RTK highly worthwhile.

In terms of deliverables, DGPS is suitable for "records with location information," but it has limitations for tasks where "high-precision coordinate data itself" is the primary deliverable. Conversely, RTK is suited to deliverables where the question is whether those coordinates can be used in downstream processes. For example, in situations such as overlaying multiple measurement datasets to the same reference, re-measuring and comparing across days, or using positional offsets directly for quality assessment, RTK is more appropriate.

What's important here is not to assume that "higher accuracy is always better." RTK can provide high accuracy, but you should determine whether that level of accuracy is truly necessary for the deliverable. For some tasks, it may be better overall to secure sufficient accuracy with DGPS while prioritizing operational stability and work efficiency. Conversely, if RTK is required for the deliverable but you settle for DGPS, the data may be unusable in later stages, and you may end up having to redo the work.

To make it easier for operational staff to decide, if location information is mainly for recording and management and some positional deviation does not undermine the essence of the work, DGPS is a sensible option to consider. Conversely, if the position itself determines the quality of the deliverable and reproducibility and consistency are important, RTK should be prioritized. This difference may be hard to see at the moment of measurement on site, but it becomes a significant factor in later stages such as drafting, analysis, updating management ledgers, maintenance, and design comparisons.

Especially recently, there has been an increase in situations where location information is handled not on its own but linked with photos, point clouds, drawings, registers, construction data, and the like. If such data integration is assumed, coordinate consistency becomes more important than before. In that context, it is necessary to more clearly delineate which tasks can be adequately handled with DGPS and which are better predicated on RTK. Anticipating how deliverables will be used at the implementation stage leads to a choice that is unlikely to fail.

Which should you choose: RTK or DGPS?

Taking the four perspectives we've examined so far into account, choosing between RTK and DGPS becomes much easier to determine. In short, the criterion for selection is not "which is higher-performing" but "which best matches the accuracy required and the operational conditions of the task." This way of thinking is critically important in practical work.

First, for tasks that require accuracy on the order of several cm (a few in), or for operations where strict coordinate consistency is required in downstream processes, it is highly worthwhile to choose RTK. For example, in positioning, as-built management, detailed coordinate recording, overlaying multiple data sets, or operations close to construction or surveying, RTK’s high accuracy directly becomes the reliability of the deliverables. In such cases, the decision to adopt RTK should include consideration of RTK-specific management such as initialization, communications, sky visibility, and status monitoring.

On the other hand, for use cases such as broadly managing locations, practically recording the positions of assets or anomalies, or keeping a history of patrol operations, DGPS is realistic. If meter-class (ft-class) to sub-meter-class (sub-ft-class) accuracy is sufficient for the task, it is easier to achieve results without assuming the strict operational requirements of RTK. In other words, DGPS is suited to tasks that aim to secure the necessary-and-sufficient level of accuracy relatively stably.

The decisions that are easy to get wrong are those cases where RTK is adopted solely because of the term “high accuracy.” Indeed, RTK is attractive, but if field conditions are poor, that accuracy cannot be maintained. Also, if the person responsible does not understand the solution status, there is a risk they will record low‑reliability coordinates while believing them to be high‑accuracy. Conversely, choosing RTK for tasks where DGPS is sufficient can make it hard to perceive benefits relative to the operational burden.

When selecting, it's easier to organize your thinking by following this order. First, determine the allowable error; next, consider whether communications and reception can be ensured on-site; and then confirm that the responsible personnel's operational understanding and the management system are feasible. Following this order makes it clearer whether RTK is required for the work or DGPS is sufficient. Conversely, if these three points are left vague, you can encounter two extreme failures after implementation: "insufficient accuracy" and "accuracy is achievable but operation cannot be sustained."

Also, it's important not to confine tasks to a single approach but to consider each use case. At some sites, understanding approximate positions with a DGPS-equivalent approach is sufficient, and acquiring only the critical points with RTK at high precision can be more efficient. You don't need to process everything to the same precision level; in practice, adopting the idea of using different accuracy levels according to the importance of the deliverables is effective.

What matters for practitioners is not memorizing technical names but determining which accuracy range their work requires. RTK and DGPS both enable the use of positioning information one step beyond standalone positioning, but they differ in the target accuracy ranges and in operational burden. As a basic guideline, choose RTK when high accuracy is required and DGPS when you want stable, practical position improvements, while making the final decision based on site conditions and deliverable requirements.

Summary

The difference between RTK and DGPS is not simply a difference in correction method. It is a difference in the accuracy achievable for the task, the operational management required, on-site stability, and the types of deliverables they are suited to. If you choose with accuracy as the priority, there are four points to grasp first. The first is whether the required accuracy is on the order of meters (m, ≈3.3 ft) or centimeters (cm, ≈0.39 in). The second is whether there is a system that can consistently deliver that accuracy on site. The third is whether operations can be carried out without undue burden on the personnel and site conditions. The fourth is how that positioning information will ultimately be used as a deliverable.

DGPS is an effective method that improves accuracy compared to standalone positioning while remaining relatively easy to use. It provides sufficient value for managing approximate positions, patrol records, and asset location tracking. On the other hand, RTK can achieve cm-level accuracy (half-inch accuracy) under the right conditions and is suitable for tasks where coordinate precision is important, such as surveying, construction, staking out, as-built management, and data overlay. It is not a matter of which is superior, but which better meets the operational requirements.

For practitioners gathering information on "rtk", it's easy to focus on RTK's high accuracy. However, what you should really look at is not just the accuracy figures, but whether that accuracy can be consistently translated into operational value. If it cannot be used reliably on site, high accuracy is of no use, and unnecessary precision can only increase the operational burden. Conversely, if RTK is used correctly where needed, location information becomes more than a mere record—it becomes a foundation for improving the quality of construction and management.

If you are considering introducing RTK in practical work and want to leverage high-precision positioning with the simplest possible operation, it can be effective to consider an iPhone-mounted GNSS high-precision positioning device like LRTK. On site, not only accuracy but also portability, ease of getting started, and ease of integrating into daily operations are important. Understanding the differences between RTK and DGPS, identifying the accuracy range that your company's operations truly require, and smoothly transitioning to high-precision operations without undue strain will become increasingly important for future use of location information.