10-Item Checklist When RTK Isn't Delivering Accuracy

Table of Contents

• When RTK does not provide the required accuracy, determine which type of error it is.

• Is the positioning status a fixed solution?

• Is the correction information being received correctly?

• Is the connection unstable?

• Whether there are any problems with sky visibility and satellite configuration

• Are the antenna height, equipment height, and the pole's vertical alignment correct?

• Are the coordinate system, vertical datum, and known control points consistent?

• Are the initialization time and the relocalization procedures appropriate?

• Are you not observing in a location with strong reflections or shielding?

• Do the observation methods and verification procedures meet the on-site accuracy requirements?

• Whether there are any discrepancies between device settings and app settings

• Poor RTK accuracy can be improved not only by equipment performance but also through operational practices.

• When RTK does not provide accurate positioning, identify which type of error it is.

When you feel that RTK is not delivering the required accuracy, the first thing you should do is neither simply reboot nor immediately assume equipment failure. What you need to do first is determine the nature of the error that is occurring.

For example, if the positions are offset by the same amount in almost the same direction each time, the issue is more likely related to settings or references such as the coordinate system, antenna height, or base station coordinates. Conversely, if repeated measurements at the same location vary, suspected causes include the satellite reception environment, multipath, communication delays, or failure to achieve a fixed solution. Furthermore, when measurements are usually correct but occasionally exhibit large jumps, this is often related to communication loss, reinitialization, or the positioning state immediately after recovery from an obstruction.

RTK can provide high-precision positioning, but it delivers its intended performance only when several conditions—surrounding environment, observation procedures, correction information, and equipment settings—are all met. In other words, accuracy problems are not necessarily caused by a single factor; they often result from a combination of several small mistakes.

Therefore, when accuracy is lacking it is even more important not to make ad-hoc adjustments but to isolate causes in order. By checking the ten items introduced below from the top, you can identify the causes commonly encountered on site with a high probability. Whether for RTK-based surveying, as-built management, layout marking, assistance with point cloud alignment, or construction management, this way of thinking is the same.

1. Is the positioning status a fixed solution?

When verifying RTK accuracy, the first thing to check is whether the current solution is a fixed solution. In RTK, even when receiving correction information, you will not always get the same level of accuracy. In a float solution or standalone positioning state, errors of several centimeters or more are not unusual, and you may fail to meet the accuracy required in the field.

In practice, it's easy to be reassured simply because a position is displayed on the screen and to overlook the solution status. However, even if values are shown, if they are not a fixed solution you cannot use the intended point with confidence. First, it is important to clearly confirm on the app or controller whether the solution is a fixed solution, a float solution, or single-point positioning.

Possible causes for not achieving a fixed solution include an insufficient number of satellites, poor reception conditions, interruptions in correction data, inadequate initialization, and instability immediately after movement. In particular, on sites where work is rushed, operators may begin measuring immediately after powering on or moving and use values before the fixed solution has stabilized. This can later cause the results to not match known control points.

As countermeasures, it is effective to first wait in an open area until a fixed solution is obtained, to observe for several to a dozen seconds even immediately after the fixed solution to confirm the state is stable, and to verify once at a known point before beginning the actual work. It is also practical to observe the same point multiple times within a short period to see whether the values have settled.

When accuracy is lacking, confirm whether you are actually operating with a fixed solution before doubting the receiver's performance or the quality of the service. If you neglect this basic step, all subsequent assessments will be off.

2. Is the correction information being received correctly?

RTK is not a system that becomes highly accurate on its own; it can only improve accuracy when it receives correction information from a reference station or a distribution service. In other words, if the correction information is not received correctly, or if it is received but its contents are not appropriate, it is natural that the expected accuracy will not be achieved.

What you should first check is whether the reception of correction information itself is continuing. Check whether there is an indication that correction data is being received, whether reception updates have not stopped, and whether the correction delay is growing. If the update interval is unstable or the elapsed time since the last correction becomes long, it can become difficult to achieve a fixed solution, or the fixed solution may be unstable even if obtained.

When using your own reference station, it is also very important that the coordinates of the reference station itself are correct. If this is offset, all observed points will shift by a similar amount, resulting in a so‑called systematic error. On site, reception itself may appear normal and it can be hard to notice, but if the same pattern of shift appears against known points every time, you should suspect the reference station coordinates or the coordinate transformation settings.

Even when using network-based corrections, choosing the wrong connection or mismatched settings can result in correction conditions that differ from those originally intended. Be especially careful after changing settings, after replacing equipment, or after switching site-specific profiles. If accuracy is poor only at sites that differ from your usual locations, the cause may be not only the environment but also the way correction settings are being selected or used.

Correction information must be checked not only to see whether it has been received, but also to confirm that it continues to be usable under appropriate conditions. Many RTK accuracy problems can, in fact, be put on a path to resolution simply by carefully verifying how those corrections are being handled.

3. Is the connection unstable?

After confirming that the correction information is correct, the next step is to check the stability of the communication. In RTK, communication plays an important role in continuously receiving correction information. Especially in network RTK, accuracy and stability can degrade significantly if communication becomes intermittent.

In the field, it's easy to notice when communication is completely cut off, but what's troublesome is when the connection is weak. Even if the reception indicator remains and it looks like there is no problem, in reality data updates are delayed or interrupted, and as a result fixed solutions are more likely to be lost and positioning can become slightly unstable. This tends to occur especially in mountainous areas, on reclaimed or filled land, around structures near or below ground level, and at sites with many temporary enclosures.

Also, the connection between the receiver and the device should not be overlooked. If an external receiver is wirelessly connected to the device, that connection can become unstable, and even if the screen appears to be positioning, corrections and position updates may not be properly reflected. Power-saving settings on the device can also throttle communications, and in some cases the connection becomes unstable after resuming from sleep.

As countermeasures, the basics are to check the on-site communication quality before starting work, to try shifting the observation position slightly in areas with weak reception, to review the device’s power-saving settings and automatic sleep behavior, and, if a disconnection occurs, not to continue using it as is but to reconnect and then verify the known points.

When RTK isn't delivering the required accuracy, it's easy to focus only on satellites and coordinates, but in reality unstable communications are often the root cause. It's important to be aware that correction data is only meaningful if it continues to flow.

4. Are there any problems with sky visibility and satellite geometry?

Because RTK uses satellite signals, it is strongly affected by sky visibility. If high accuracy cannot be achieved, you need to check not only the sky directly above the observation point but also the openness of the sky in the surrounding area. If there are buildings, slopes, trees, elevated structures, cranes, or material storage yards, not only can the number of satellites received decrease, but the satellite geometry can become biased and accuracy can deteriorate.

What matters is not simply whether a small portion of the sky is visible, but whether there is enough sky visibility to ensure stable positioning. For example, in a location where only one side is open and the other side is blocked, the directions of receivable satellites become biased, which affects position stability. Even if there are enough satellites, poor satellite geometry can make positioning accuracy unstable.

Narrow roads in urban areas, beside structures, along forested areas, and near or under bridges are typical areas of concern. In such locations, reception can change with just a few steps even when using the same equipment. If measurements agree at known points but fail only next to a building, you should suspect line-of-sight conditions before attributing the issue to differences in equipment performance.

In practice, people sometimes insist on measuring the exact point they want and force the use of RTK at locations that are unsuitable for observation. However, there are indeed places that are not suitable for RTK. If necessary, it is important to occupy an auxiliary point in a slightly more open location and then transfer to the target by another method. Trying to complete every point using only RTK can actually reduce overall accuracy.

Even experienced operators tend to judge whether there is a problem with sky visibility by feel, but when accuracy degrades it is important to objectively check the direction of obstructions, changes by time of day, and whether relocating improves the situation. RTK is convenient, but the principle that it struggles to perform well without a clear view of the sky remains unchanged.

5. Are the antenna height, equipment height, and pole verticality correct?

A very common cause of RTK accuracy problems is actually incorrect entry of antenna height or instrument height, and a tilted pole. Because this can occur even when reception conditions are good, these issues are especially easy to overlook when there appear to be no problems with the surrounding environment.

For example, if you mix up the units when entering the pole height, use a previous setting that remained unchanged, or measure from a different reference point instead of from the tip, that error will be reflected directly in the results. Moreover, because it will be off by almost the same amount each time, there is a risk you will keep using it while mistakenly blaming the satellite or communications.

The verticality of the pole is also important. If you hurry the observation without checking the spirit level, even a slight tilt—especially with tall poles—will show up as a displacement of the tip position.

Because it affects not only the horizontal position but also the height, inconsistencies are likely to appear later when comparing with drawings or known points. On construction sites where people move around frequently, poor footing and soft ground can compound the problem, making it more difficult than expected to keep the pole vertical.

The same applies when using smartphone-connected or small RTK devices. While they are easy to use, if you operate them with ambiguous holding position, mounting position, or offset settings, you may end up measuring a different relative position each time. Even with highly mobile devices like LRTK, stable results are achieved only when correct mounting conditions and offset management are in place.

The measures are simple but important. Before starting work, always call out and confirm the entered instrument height, standardize the pole’s scale markings and locking position, verify at known points including the height, and when observing, pause for a breath to ensure true vertical. Poor RTK accuracy is not only caused by sophisticated factors; lapses in these basic procedures can make a big difference.

6. Are the coordinate system, vertical datum, and known points consistent?

When people on site say "RTK doesn't match," the issue is often not the positioning accuracy itself but how the coordinates are being handled. This is a very important distinction to make. Even if the receiver is providing a high-precision position, if that value is expressed in a different coordinate system or the elevation is referenced to a different datum, it obviously will not match the drawings or existing results.

A common case is when the planar coordinate system does not match the site drawings. If one site assumes a plane rectangular coordinate system but the output is produced with different settings or transformation conditions, the numbers may look plausible while the positions differ significantly. Also, with elevation, if you handle ellipsoidal height and orthometric height without understanding the difference, you can end up with discrepancies in elevation alone. When the horizontal coordinates more or less agree but the heights do not, you should suspect a difference in the reference systems.

Furthermore, there may be cases where site-specific local coordinates or custom handling of past survey results remain in place. If RTK is introduced while it is still unclear which geodetic realization the control points on the drawings are based on, the issue is not "poor accuracy" but rather that "the objects being compared are different." Adjusting the equipment repeatedly without detecting this will not improve the situation.

That is why verifying known points before beginning this work is important. If they agree at the known points, you can conclude that at least the coordinate system and transformation settings are not significantly off. Conversely, if the known points show the same shift in a consistent direction, you should prioritize reviewing systematic factors such as the coordinate system, vertical transformation, reference point information, and antenna height input.

A common pitfall when introducing RTK is focusing solely on observation accuracy and postponing verification of the consistency of the resulting coordinates. No matter how good the positioning, if the underlying coordinate framework is different it cannot be used in practice. If you feel the accuracy is lacking, you need to check not only whether the numbers are correct but also what they are being compared against.

7. Are the initialization time and re-acquisition procedures appropriate?

In RTK, accepting values as-is immediately after powering on, or immediately after recovering from signal obstruction, can lead to poor accuracy. This is caused more by insufficient initialization or re-fix procedures than by a faulty receiver.

A fixed solution is not something you can consider permanently reliable once it is displayed. In situations such as passing under trees during work, entering the shadow of a vehicle, passing under an overpass, or a temporary interruption of the terminal connection, the status of the solution may change. Values observed immediately afterward may appear to be fine but can be unstable.

What tends to happen in the field is an operation where multiple points are quickly recorded while moving. Although this lets work proceed at a good pace, if observations are finalized without sufficiently checking the status at each point, values taken immediately after reinitialization or unstable values just after recovery of a fixed solution can be included in the results. When reviewed later, this appears as a few points that jump unnaturally.

As a countermeasure, make it a habit to check the status not only at the start of work but also after the reception environment changes. When you move from an obstructed location to an open area, do not take the next point immediately; instead, confirm that the fixed solution is stable. If necessary, return to a known point or the immediately previous point and recheck. Check whether the elevations and horizontal positions are continuous and plausible. Simply having these procedures in place can greatly reduce the inclusion of outlier measurements.

RTK's appeal is fast positioning, but prioritizing speed too much can actually cost you time later in rework. When accuracy isn't being achieved, it's important to review whether you've shortened the waiting time required for initialization or re-acquisition, or whether you're too readily accepting values immediately after reacquisition.

8. Are you observing in locations with strong reflections or obstructions?

One cause of RTK accuracy degradation that cannot be overlooked is the effect of reflections known as multipath. This phenomenon occurs when satellite signals are reflected off buildings, metal, guardrails, vehicles, retaining walls, water surfaces, and the like, and the mixing of direct and reflected waves disrupts positioning. Even when the sky appears open, strong surrounding reflectors can keep accuracy from stabilizing.

Particular attention should be paid to locations such as the edges of buildings, near material storage yards, around steel frames and heavy machinery, along temporary fences, in narrow passages, and around bridges. In these places, measuring the same point several times can produce slightly different values or fluctuate by several centimeters (several in). Although it may appear normal at first because there are enough satellites, instability becomes apparent when you look at differences from known points or at repeatability.

What makes reflections troublesome is that they do not produce a clear warning like a communication outage. Even when a fixed solution has been obtained, the surrounding environment can cause the result to fail to meet the expected accuracy. Therefore, observers must judge the conditions of the location rather than rely solely on the on-screen status.

As a countermeasure, first put even a little distance between you and the reflective object. Moving just tens of centimeters (several in) to several meters (several ft) can sometimes improve the situation. If you absolutely must measure on the spot, you need to change the observation method itself — for example, take multiple observations and check the differences; take auxiliary points at a nearby safe position and process them indirectly; or use another method in combination.

On site, there are many situations where "if we can't measure here, it's a problem," but forcing a one-time measurement in an environment unfavorable to RTK will undermine the reliability of the results. When you can't achieve sufficient accuracy, it's important not only to check the instrument's settings screen but also to take a step back and verify what surrounds the observation point.

9. Do the observation methods and verification procedures meet the on-site accuracy requirements?

One reason people feel RTK does not deliver accuracy is that the observation method itself does not match the required accuracy specifications. This is not a problem with the equipment but an operational issue. For example, while it may be sufficient for a rough overview, the observation procedures as-is can be insufficient for tasks that require precise as-built verification or high reproducibility.

A common practice is to observe only once for a short time and then finalize the result. While RTK’s strength is that it can quickly capture multiple points while moving, when high accuracy is required it is necessary to perform repeated observations of the same point, ensure sufficient observation time, compare with known points, and verify from different directions. It is not appropriate to evaluate it as “doesn’t match despite being RTK” while omitting these steps.

Also, it is important to note that the level of verification required varies by site. Errors that are acceptable for provisional plans or rough position checks may be unacceptable for applications close to final inspection. In other words, whether an accuracy shortfall is problematic must be judged not only by the absolute value but also in relation to the intended purpose.

In practice, setting rules such as confirming known control points first thing in the morning, reconfirming at milestones, observing important points at least twice, and remeasuring any abnormal values on the spot will reduce the number of situations you have to worry about later. Furthermore, if you reconcile measurements with drawings and perform back-calculation checks on the same day, you can avoid taking problems home.

Introducing RTK improves work efficiency, but if you cut back on the verification processes, concerns about accuracy increase. When you feel the accuracy is insufficient, you need to review not only the instrument readings but also whether the observation procedures themselves are appropriate for the task.

10. Ensure there are no discrepancies between device settings and app settings

Finally, what I want to confirm is the consistency between device settings and app settings. In RTK, not only the receiver itself but also the terminal app, output format, coordinate transformation, antenna offset, update interval, and other settings interact and affect the results. If even one of these is mismatched, it will show up in the field as "it somehow doesn't match."

For example, even if the receiver computes correct positions, if the app's coordinate settings differ the values displayed will not match the site reference. If the conditions for height correction differ, only the elevation may be offset. On devices that use tilt compensation, results can vary depending on whether that function is enabled and on its calibration status. Settings left over from a previous site, different templates for each operator, or a reset to default values after an update—these kinds of causes are very common in practice.

Also, depending on the output update interval and how values are rounded for display, observers may be misled into thinking it is stable. Because the internal state may be changing even when the numbers look clean, it is important to check the settings themselves, not just the appearance.

An effective countermeasure is to standardize the settings for each site. Consolidate the coordinate system to be used, the handling of elevation, offset values, observation acceptance criteria, and the procedure for verifying known points into a single operational procedure so that anyone who uses it will achieve similar results. This is especially important when it is used by multiple people, because leaving decisions to individual judgment reduces reproducibility.

Even when introducing easy-to-use equipment like LRTK, it's important not to oversimplify operations based solely on convenience. Easy connectivity and portability are major advantages, but what ultimately determines the final outcome is the standardization of settings and thorough verification procedures. To reduce accuracy issues, aligning settings is as important as selecting the equipment.

RTK accuracy problems can be improved not only by equipment performance but also by operational practices

When RTK fails to deliver the expected accuracy, it's easy to assume "this device must be inaccurate." However, in reality it is often a combination of factors such as insufficient confirmation of a fixed solution, incomplete correction information, unstable communications, poor reception environment, mistakes in entering antenna height, discrepancies in coordinate systems, observations made immediately after re-fixing, the effects of reflections (multipath), inappropriate observation methods, and variability in settings.

In other words, in practical terms it is often better to think of many accuracy problems not as the instrument having reached its limits, but as the instrument not being in the conditions required to deliver its intended performance. That is why, when a problem occurs, it is important to isolate factors one by one. Check at known points, check the status display, change the observation environment, and review the settings. Simply repeating these basic steps will considerably reduce concerns about accuracy.

RTK used in the field offers the appeal of being fast, convenient, and highly accurate. To maximize that value, you need to organize the entire operation—not just the receiver’s performance but also communications, apps, coordinate settings, and observation rules. Even when using compact, easy-to-handle equipment like LRTK, field reproducibility improves only when known points are verified and settings are standardized.

When accuracy is poor, it's especially important not to hastily assume a single cause. To clarify what you should review on the site today, first go through these 10 items in order from the top. RTK accuracy becomes more stable the better you can correctly isolate the issue.