10-Item Checklist for When RTK Fails to Achieve Accuracy

RTK is a convenient method for obtaining high-precision positioning information on-site in real time, but in actual operation there are often problems such as “it doesn’t achieve the expected accuracy,” “measurements taken at the same location don’t match,” and “the coordinates are unstable even though it shows Fix.” While RTK is convenient, simply turning on the equipment and receiving correction information does not always produce consistently stable results; only when multiple conditions are met—power status, communication conditions, satellite reception, handling of reference points, understanding of the coordinate system, entering the antenna height, and so on—does it demonstrate its true performance.

On site, if you single-mindedly attribute an accuracy issue to one cause, it can take a long time to recover. For example, if you assume "it's probably due to unstable communication," it's not uncommon that the real problem was a mistaken antenna height entry, or that even though you thought you had a fix, the coordinate system setting was actually off. In other words, when RTK is not delivering the expected accuracy, rather than responding by intuition, it's important to methodically identify and check the items that need verification in order.

This article organizes and explains 10 points to check in the field when RTK fails to deliver accurate results. Focusing on elements that are particularly easy to overlook on site—power, communications, Fix, satellites, reference points, coordinate systems, antenna height, known points, surrounding environment, and logging—it details where and how to look, why those factors affect accuracy, and the mindset to adopt during checks. Rather than panicking the moment a problem occurs, having reproducible procedures to narrow down the cause leads to more stable RTK operations.

Table of Contents

• Introduction

• Check 1 Is the power supply stable?

• Check 2: Is communication able to receive correction information without interruption?

• Do you correctly understand the status of Check 3 Fix?

• Check 4: Are there any problems with the number of satellites and reception status?

• Check 5 Are the conditions of the reference points and sources of correction appropriate?

• Check 6: Are the coordinate system and transformation settings correct?

• Check 7: Is there any error in the antenna height input?

• Check 8 Are you performing verification at known points?

• Check 9: Is the surrounding environment adversely affecting positioning?

• Check 10: Are measurement records and operational records being retained?

• Summary

Introduction

When RTK isn't delivering the expected accuracy, many sites tend to suspect the equipment itself first. However, in reality it is often an operational issue—such as settings, procedures, environmental conditions, or insufficient checks—rather than equipment failure. In particular, when the same operator continues using the same methods, confirmation steps can be omitted without anyone noticing, which delays detecting anomalies.

RTK accuracy is determined not by a single factor but by the accumulation of multiple conditions. If the power supply is weak, reception and communications become unstable, and if communications are disrupted, continuous reception of correction information is hindered. If satellite visibility is poor, it becomes difficult to obtain a fix, and even when a fix is obtained, if the coordinate systems differ the coordinates will not match the ones required. Furthermore, even a slight difference in the entered antenna height can manifest as a large error in the vertical direction. In other words, RTK accuracy problems are not necessarily resolved by fixing a single cause; it is essential to adopt the practice of checking multiple items in sequence.

In practice, when you encounter a situation where required accuracy cannot be achieved, simply knowing what to check first can greatly speed up recovery. Conversely, if verification items are not organized, people may repeatedly reboot, change measurement locations, or make different decisions depending on the operator, making it difficult to isolate the cause. Therefore, it is important for each site to have a common checklist and to verify items in the same order when anomalies occur.

From here, I will explain in order the ten items you should prioritize checking when RTK does not achieve the required accuracy, arranged with practical usability in mind. This is not mere theory; it is organized to include common on-site mistakes and key judgment points, so please use it to help develop your routine inspection procedures.

Check 1: Is the power supply stable?

The first thing to check is the power status, which is the most basic yet easily overlooked. If the power supply to any device involved in positioning—such as the RTK unit itself, the controller, a smartphone or tablet, or external communication equipment—is unstable, it can cause measurement variability and communication dropouts.

In the field, problems do not necessarily occur only when the battery level is nearly zero. Even if the battery level indicator still appears sufficient, a degraded battery can have its voltage become unstable the moment a load is applied, causing signal reception and communication performance to decline. Especially in environments with large temperature fluctuations, the displayed remaining charge often does not match actual runtime, and even if there are no problems in the morning, it can suddenly become unstable in the afternoon.

If you are using an external battery or a power cable, you should also check for poor contact and loose terminals. While moving, the cable can become partially disconnected or the connector may not be fully seated because the waterproof cap is pinched, which can make it seem to be working while it is actually experiencing repeated momentary outages. In this condition, reinitializations and repeated recalibration attempts occur frequently, and accuracy will not stabilize.

Also, not only the receiver but the terminal that handles correction data must have its power-saving settings taken into account. If the terminal restricts background communications or suppresses app activity when the screen turns off, reception of correction data may be interrupted. When accuracy is lacking, you should not only check power-cycling the device, but also verify the battery charge level, battery degradation, power delivery path, connection status, and the terminal’s power-saving settings.

On-site measures include not only checking remaining battery level before starting work, but also managing the charge status of replacement batteries in a list and making it standard practice to always take a spare before long-duration tasks. Furthermore, recording the relationship between the time accuracy issues occur and the battery level makes it easier to determine later whether a particular power supply system is faulty. Power is a basic matter, but if it remains unstable you cannot correctly isolate causes even if you check other factors.

Check 2 Is communication uninterrupted and receiving correction information?

RTK assumes that the mobile station is stably receiving correction information. Therefore, when accuracy is not achieved, you must always check the stability of the communication. It is important to assess not just whether it is simply "connected", but whether the necessary corrections are being delivered continuously and without delay.

On site, people can be reassured just because a connectivity icon is displayed. However, in areas with weak signals or congested network conditions, even if the connection itself is maintained, correction data may arrive late or be intermittently missing. This can make maintaining a Fix difficult, slow the convergence of coordinates, and cause observations to become unstable.

A point to pay particular attention to is that a deterioration in communication quality does not always manifest itself in an obvious way. A complete disconnection is easy to notice, but delays on the order of a few seconds or brief dropouts can be difficult for operators to recognize on the spot. As a result, even when "Fix" is displayed, values may not be stable, and re-observations may differ slightly.

When checking communications, start by looking at the device's network status. Make clear whether it is using cellular, an external router, or tethering, and identify which path is being used to receive correction information. Then, not only check the antenna indicator but also verify within the communications app and the positioning app the time of correction reception, the update interval, and the status of the connection endpoint. Even if you can connect to the correction source, you need to examine the overall connection conditions, because the mount point settings may be incorrect or the authentication credentials may have expired.

In mountainous areas, cuttings, under bridges, under elevated structures, and areas with dense structures, communication quality can change drastically while moving. In such sites, the connection may become unstable only after arriving at the measurement point, so checking connectivity only around the office before work is insufficient. It is important to verify at the measurement location itself whether corrections can be received continuously.

In practice, when communication problems are suspected, rather than immediately rebooting, checking the connection endpoint, reception time, update interval, line type, and location-specific trends makes it easier to trace the cause. Communication is a hard-to-observe factor, but it is a very important prerequisite that affects RTK accuracy.

Check 3: Can you correctly understand the state of the Fix?

A common misconception when verifying RTK accuracy is the belief that "if it’s Fix, you’re safe." While Fix is indeed an important state indicating that high-precision positioning has been achieved, relying solely on the Fix indicator to proceed with work is risky. When the required accuracy is not being obtained, you should recheck what Fix actually means and how stable that state is.

First, it should be understood that Fix merely indicates that the integer ambiguities of the carrier phase have been resolved, and that alone does not guarantee the correctness of the measurement. For example, even when Fix is displayed, if the coordinate system is set incorrectly the resulting coordinate values will not match the ones you expect, and if the antenna height is different it will introduce an error in height. Furthermore, if you record immediately after a Fix while the solution has not yet fully stabilized, reproducibility may be low.

In practice, there are cases where observations are taken immediately the moment a Float changes to a Fix, but this should be approached with caution. Especially right after arriving on site, after restarting equipment, or after reestablishing communication, a Fix indication may appear even though the internal state has not yet stabilized. It is important to wait a short time to see if the values settle, and, if necessary, verify consistency by reobserving multiple times.

Also, depending on the device or app, in addition to Fix, Float, and Single, displays such as DGPS, applying corrections, or converging may appear, and operators who are not familiar with them can misinterpret them. Rather than judging it’s okay just because the display is green, you should check the current solution type, estimated accuracy, correction reception status, continuous Fix duration, and so on.

When accuracy is poor, we also reexamine the Fix rate itself. Look for trends such as whether it’s taking longer than usual to achieve a Fix today, whether a Fix quickly reverts to Float, or whether Fix hold times are extremely short in certain locations — these can point to other issues like communications or the satellite environment. Fix should be understood not as a result but as a state, and it is necessary to judge it including stability and reproducibility.

Check 4 Are there any problems with the number of satellites and reception status

The accuracy of RTK is greatly influenced not only by how many satellites are being received but also by their geometry. Therefore, when accuracy is lacking, you should not be reassured by the satellite count alone; it is important to check the overall reception conditions.

On site, people tend to assume "it's fine because there are many satellites," but in reality, if the satellites in view are clustered in one part of the sky or mostly at low elevation angles, the geometric conditions worsen and position stability can deteriorate. Also, even if the number of satellites is sufficient, if some signal quality is poor or signals are affected by multipath, it can become difficult to obtain a fix, or even if a fix is obtained the values may not be stable.

When checking satellite reception, first look at the current number of satellites being received and the number of satellites in use. Because there are cases where a satellite is being received but not sufficiently used in the calculations, it is important to focus not just on the simple counts but on whether they are contributing to the positioning calculation. In addition, checking the reception status for each GNSS type makes it easier to notice abnormalities such as a particular signal being weak or instability in a specific satellite system.

Even more important is how open the sky is. If there are trees, slopes, buildings, retaining walls, vehicles, or large heavy machinery nearby, satellite visibility will be limited. If the low-elevation directions are heavily obstructed, positioning conditions can suddenly deteriorate. Some sites experience different reception in the morning and afternoon, so accuracy can vary at the same location depending on the time of day.

If your positioning app lets you view the satellite layout and signal strength, it’s useful to check those as well. Even with many satellites, accuracy can be unstable if their placement is biased, and if signal strength is variable you should suspect environmental effects. When satellite conditions are poor, rather than forcing observation at that spot, you need to make decisions such as moving slightly, initializing in an open area with a clear view of the sky, or waiting for reception to stabilize.

Satellites are a factor you cannot increase yourself, but you can choose conditions that make reception easier. That is precisely why, when accuracy is lacking, the ability to correctly read the current satellite conditions is important.

Check 5 Are the conditions of the reference points and correction sources appropriate?

In RTK, accuracy depends not only on the rover but also directly on the conditions at the correction reference. Therefore, when accuracy degrades, you must check not only the area around the rover but also which reference point, which correction information, and which method are being used.

When using your own reference station, the installation conditions of the reference station itself are critically important. If the reference station’s antenna position is unstable, the installation point coordinates are inaccurate, there are reflective sources nearby, or the antenna height setting is incorrect, those errors will directly affect the rover. No matter how much you review only the rover, if there are problems with the reference station the accuracy will not be stable.

Even when using a network-based correction service, it is necessary to understand which areas and what kinds of corrections are being provided. In areas outside the correction service coverage, near boundaries, or in regions with significant communication delays, the expected accuracy may not be achieved. It is also important to review whether the method being used matches the field conditions and whether the receiver settings conform to the correction service specifications.

In practice, it’s easy to feel reassured simply because corrections are being received, but what matters is the quality of those corrections. When the correction source switches, the reference station changes, the service undergoes maintenance, or distribution settings are modified, behavior different from usual can occur. If accuracy is poor only on specific days, or another site has no problem, you should suspect the reference point or the conditions of the correction source.

Also, the concept of baseline length cannot be ignored. In general, the longer the distance to the correction reference, the more the measurement is affected by error sources, and accuracy tends to differ particularly on days when atmospheric conditions are unstable. Network-based systems have measures to suppress this influence, but even so they can become unstable under certain conditions.

In the field, recording the name of the correction source being used, the connection destination, the method, and the reference conditions makes later comparisons easier. When accuracy is lacking, it is important not to look only at the mobile station, but to adopt the perspective of inspecting the correction infrastructure itself.

Check 6: Are the coordinate system and transformation settings correct?

One of the most common problems with RTK is that, although positioning itself is possible, the obtained coordinates do not match the desired ones. The first thing to suspect in this case is the coordinate system and transformation settings. If these are misaligned, even when the equipment is in good condition and the Fix is stable, the resulting coordinates will be unusable on site.

Mistakes in the coordinate system appear as differences ranging from several centimeters (several in) to several meters (several ft), and in some cases even more. Moreover, because they can look like correct measurements at first glance, they are difficult to notice in the initial stages. When an operator thinks, "For some reason everything is slightly shifted today," they often suspect positioning accuracy first, but in many cases the issue can actually be explained by differences in settings.

Things to check include the zone number of the plane rectangular coordinate system, the geodetic reference system in use, the required transformation parameters, geoid corrections, and how elevations are treated. Always verify that the design coordinates shared on site and the coordinate system of existing drawings match the output settings of receivers and apps. In particular, when moving between multiple sites, previous site settings can remain and be used at the next site.

In the vertical direction, people sometimes assume there is an error because they do not understand the difference between ellipsoidal height and elevation. Even if you look only at the numbers and judge them to be "too high," they will of course not agree if a different type of height is being output. It is necessary to be clear whether what is required on site is elevation, ellipsoidal height, or some other converted value.

Also, because settings can be reset after controllers or apps are updated, you can't be sure things are fine just because you've configured them once. If multiple people are responsible, it's important to standardize the settings so they are the same no matter who uses them. Be aware that some issues that appear to be poor accuracy are actually due to coordinate interpretation rather than positioning accuracy.

Check 7: Are there any errors in the antenna height input?

Errors in antenna height are a very common source of error in RTK operations. In particular, when the vertical (height) value doesn't match, you should first suspect the antenna height input. Moreover, because this problem can occur even when the positioning itself is functioning normally, it is more likely to be overlooked the more stable the communications and RTK fix are.

There are standards for antenna height that define from where to where it is measured. If you do not correctly understand whether the height refers to the antenna phase center, the bottom of the equipment, or the tip of the pole, the same numerical input can mean different things. Because the reference point can vary between devices, it is risky to rely solely on past experience.

At job sites, mistakes such as changing the pole length but not updating the input value, assuming a pole was fixed when it actually telescoped partway, or entering the wrong unit while thinking you had remeasured occur frequently. Especially on busy sites, workers often continue working trusting the values once set, and only notice a large discrepancy during the final check against known points.

Also, antenna height is an item that tends to vary depending on the person measuring it. If the way the tape measure is placed, the reading point, and how the instrument is held are not standardized, differences of several centimeters (a few in) can arise. Because this has a greater impact on height than on planar position, particular care is required for as-built verification and height management.

As a countermeasure, standardize measurement criteria for each piece of equipment with photos, and implement an operation in which staff always call out and confirm before entering data. In addition, record antenna height at the start of work and when changing poles, and include it in daily reports and observation logs so that later verification becomes easier. When you feel accuracy is lacking, reviewing the antenna height is quick to do and has a large impact, so it is worth checking at an early stage.

Check 8: Are you performing matching at known points?

To reliably ensure accuracy in RTK operations, verification at known points is indispensable. No matter how good the instrument’s display may look, you cannot determine whether the coordinates are truly correct unless you confirm that the measured values agree at known points. Whether accuracy is lacking or not, making a habit of routinely verifying against known points directly leads to early detection of problems.

The purpose of checking against known points is not just to verify the condition of the equipment. A major advantage is that it allows you to verify several elements together, such as coordinate system settings, correction reception, antenna height input, and observation procedures. In other words, if results do not agree at known points, there is a high likelihood that something is wrong somewhere. Conversely, if results consistently agree at known points, it becomes easier to judge that the operating conditions at that time are generally good.

The important thing is not to take a single measurement and be done. Cross-check at multiple times—immediately on arrival, during work, and before finishing—because doing so makes it easier to notice variations that occur over time or mistakes from configuration changes made along the way. If measurements were correct in the morning but start to drift in the afternoon, suspect changes in communication status, device reconnections, or configuration errors after battery replacement.

Choosing known points is also important. Use points with clear, reproducible markers and choose reference locations where the surrounding environment is unlikely to change significantly. Ambiguous points or points that are difficult to sight will reduce the reliability of the matching results themselves. Known points should not merely exist; it is essential that anyone measuring them can reproduce the same position.

In practice, you may be tempted to skip checking known points to save time. However, if that later causes you to doubt all the data, it will lead to much greater rework. You should incorporate known-point checks not only as a response when RTK fails to produce the required accuracy, but also as a basic procedure to detect anomalies early.

Check 9: Is the surrounding environment adversely affecting positioning?

RTK tends to perform well in open-sky conditions but is strongly affected by the surrounding environment. Therefore, when accuracy is insufficient, you need to check not only the equipment and settings but also whether the environment at your current location is unfavorable for positioning.

Typical examples are obstruction and reflection caused by buildings, trees, overpasses, signs, retaining walls, metal fences, vehicles, heavy machinery, and the like. When signals from satellites do not arrive directly and instead reflected signals from the surroundings are received, the positioning solution can be adversely affected. This is called multipath. In locations with poor visibility, even if there are enough satellites, observation quality can be poor and coordinates may fluctuate.

One thing to pay particular attention to is that environmental effects can change suddenly depending on the location. Even within the same site, moving only a short distance can change how open the sky is and can greatly affect the ease of getting a fix and the stability of coordinates. For example, conditions that are unstable along slope faces, at the tree line, next to buildings, or near heavy machinery may improve just a few meters away. If you do not understand these characteristics, it is easy to mistake them for equipment malfunction.

Also, the effects of weather and nearby work should not be overlooked. More than the rain itself, reception conditions can change due to wet structures, shifts in heavy-equipment placement, and the movement of people or vehicles around the site. There have been cases where accuracy dropped after temporary scaffolding or materials were added. If it was fine yesterday but unstable today, checking whether the surrounding environment has changed can provide a clue.

When checking the environment, simply confirming that the sky is visible overhead is not sufficient. You should comprehensively assess which directions are blocked, whether there are nearby objects that are prone to causing reflections, and whether the location is disadvantaged for communications, including radio waves. If you can shift the observation point slightly, it is also effective in practice to move to a position with better conditions.

RTK is a technology with high on-site adaptability, but that does not mean the influence of the environment can be ignored. When accuracy is lacking, it is all the more necessary to calmly consider whether you should really measure at that location and whether the conditions can be improved.

Check 10 Are measurement records and operational records being kept?

Finally, what I want to check are the measurement records and the operational records. These may not seem like direct factors for improving accuracy on the spot, but they are actually very important for preventing recurrence and identifying causes. At sites where records are not kept, when accuracy problems occur it becomes impossible to know "what was different," and the same troubles tend to be repeated.

Items to be recorded include the measurement date and time, observation point name, operator, equipment used, correction connection destination, Fix status, satellite status, antenna height, result of comparison with known points, weather, surrounding conditions, whether any abnormalities occurred, and so on. You do not need to write down every detail, but you should leave at least the minimum information that allows later comparison. In particular, when a problem occurs, even a brief record of the situation makes it easier to isolate the cause.

For example, even if a particular site shows a continuing tendency for accuracy to worsen in the afternoons, without records it will be written off as nothing more than a hunch. However, if communication status, number of satellites, location, and time are retained, you can suspect environmental changes or a deterioration in link quality during specific time periods. In other words, records are not merely reporting documents but materials for improving operational quality.

In addition, keeping records makes differences between personnel easier to see. If operational differences are discovered — for example, one operator consistently skips known-point checks, antenna height records are often missing, or the number of re-observations is low — these can be addressed through training and procedural improvements. Past records also carry significant weight when comparing accuracy trends before and after equipment updates or app changes.

In practice, you may find record-keeping tedious and want to skip it. However, precisely because RTK is a condition-dependent technology, the presence or absence of records becomes a difference in on-site capability. To avoid leaving accuracy problems to ad hoc fixes, measurement records and operational records should be positioned not at the end of a checklist but as the foundation of daily operations.

Summary

When RTK is not achieving the expected accuracy, it is important not to focus solely on the poor numbers but to check, in order, which conditions have broken down. The ten items introduced here are factors that have a particularly large impact in the field and are easily overlooked. Check whether the power supply is stable, whether communications are being maintained, whether you correctly interpret the Fix, whether satellite reception is good, whether there are problems with reference points or correction sources, whether the coordinate system settings are correct, whether there are errors in antenna height, whether you are performing checks against known points, whether the surrounding environment is causing any issues, and whether records are being kept. By checking in this order, you can more easily narrow down the causes of many accuracy problems.

The important thing is not to look at just one item, but to view the whole systemically. RTK problems often involve multiple overlapping factors; for example, communications might be slightly unstable while the antenna height input was also entered incorrectly. That is precisely why, instead of relying solely on intuition and experience, formalizing checks into a checklist that allows anyone to arrive at the same conclusion is effective.

Also, rather than panicking and checking only when accuracy falls short, making a routine of pre-start inspections, known-point verification, settings checks, and record keeping will make problems less likely to occur. RTK is a high-precision, efficient technology, but to reliably realize its performance it is essential to carefully and consistently carry out the basic procedures for each site.

Accuracy problems are troubles you want to avoid, but viewed differently they can also be an opportunity to improve operations. If you organize these ten items as on-site check procedures and make them usable before work, during anomalies, and after work, the reproducibility and reliability of RTK operations will surely improve.