How to View RTK Logs? Explaining 5 Items You Should Check

When using RTK in the field, you may find that although everything appeared fine during positioning, later checks of the coordinates reveal unexpected scatter or lower-than-expected accuracy. In such cases, the RTK log is invaluable. The log is not just a record; it is an important resource for later verification of what the reception conditions were at that time, whether the correction information was stable, and whether the quality of the coordinates was sufficient.

On the other hand, in practice, even when logs are kept, there are many cases where they are not fully utilized because people don't know where to look. With so many recorded items and numbers that appear technical, trying to track everything in detail can actually make decision-making harder. In reality, however, the checkpoints that directly affect on-site decisions are fairly limited. You don't need to understand every item perfectly from the start; just looking at the five key items in order will let you catch most anomalies and oversights.

In this article, we clearly organize five items that field personnel should check first when reviewing RTK logs, presented in an easy-to-understand way from a field perspective. By checking in the order of positioning status, satellite reception status, correction data and communications, accuracy indicators, and configuration settings, it becomes easier to logically understand why that positioning result occurred. This content is useful not only for those who have just introduced RTK, but also for those who already use it daily and want to make re-measurement decisions and quality checks more reliable.

Table of Contents

• Key concepts to grasp before checking RTK logs

• Check, by examining the changes in the positioning state, whether a stable solution was obtained.

• Determine whether the observation conditions were reasonable by examining the number of satellites and the reception environment.

• Verify the conditions for maintaining a fixed solution by examining correction data and communication status.

• Evaluate the reliability of the coordinates by examining accuracy metrics and variability.

• Verify that the overall assumptions of the log are correct by reviewing the timestamps and configuration settings

• Summary

Key Concepts to Understand Before Reviewing RTK Logs

When looking at RTK logs, the first thing to keep in mind is not to judge quality based on a single number. For example, even if a fixed solution is achieved at a certain moment, if it frequently switches to a float solution before and after that moment, you should be cautious about coordinate stability. Conversely, if a value looks slightly poor at a particular instant but the overall record is stable, it may still be usable in practice. It is important to consider logs not as something to inspect at a single point, but as material for seeing how the state changed over time.

Also, clarifying the purpose of checking the logs makes judgment easier. The weight given to items to focus on changes depending on whether the purpose is deciding whether re-measurement is necessary, verifying the quality of the results, or isolating communication problems. For example, if the decision is about re-measurement, coordinate variability and the continuity of fixed solutions are particularly important, whereas if you suspect a communication problem you should pay attention to the intervals at which correction data is received and whether there are any gaps. Rather than casually scanning the logs, decide what you are trying to judge before you begin checking, and you will find it easier to pick up the information you need.

In practice, when you see a single bad value in the log, you may be tempted to dismiss the entire positioning result because of that alone. However, RTK positioning depends on multiple factors—satellite geometry, sky visibility, communications, equipment settings, work procedures, and so on. Therefore, the cause of an anomaly is not necessarily a single issue. The positioning may have been unstable because there were few satellites, or because the correction data experienced large delays. Alternatively, errors in antenna height or coordinate system settings can cause the output to be offset even when the numbers themselves appear stable. That is precisely why it is important to interpret multiple items in relation to one another.

Furthermore, checking logs should not be done only when problems occur. Rather, by making a habit of reviewing logs during normal operations, you can notice signs of anomalies earlier. If you routinely understand the time to reach a fixed solution, trends in the number of satellites at each site, the status of correction reception, and the stable ranges of accuracy indicators, you will more readily sense when something is different. When an experienced operator can quickly make a judgment on site, it is not just special intuition but also familiarity with these routine records.

Reviewing RTK logs is less a difficult analytical task than a reading task to reconstruct the situation on site afterward. By tracing when, where, in what condition, and to what extent the quality was, you can reach practical judgments without overcomplicating things. From here, I will explain, in order, the five items you should prioritize in practical work.

Confirm whether a stable solution was obtained by examining the progression of the positioning state

The first thing you should check in an RTK log is how the positioning status evolved. When assessing the reliability of coordinates on site, the basic information to look at first is whether the solution at that time was a fixed solution, a float solution, or a state close to single‑point positioning. If you look only at other numerical values without confirming this, you are likely to make incorrect judgments. This is because even if similar coordinate values are recorded, values obtained from a fixed solution and those obtained from a float solution are handled completely differently in practice.

The important thing is not whether it became a fixed solution for a single instant, but how long the fixed solution persisted. Right after positioning begins the state can be unstable and may alternate between fixed and float solutions. If you accept points obtained at this stage as-is, coordinate differences are likely to appear when you recheck them later. By checking the time of the switch to a fixed solution in the log and then tracking how stably the fixed solution was maintained afterward, it becomes easier to judge whether to adopt that observation.

For example, even if a fixed solution appears immediately after you start observing, if it soon reverts to a float solution, the surrounding environment or communication conditions may have been unstable. Conversely, even if it takes a little time to transition to a fixed solution, if it then remains stable and continuous, the positioning result can be considered sufficiently reliable. On-site, people tend to simplistically assume “it’s fine because it became a fixed solution,” but when reviewing logs it is important to focus on the continuity of the fixed solution rather than its initial attainment.

Also, the number of times the positioning state switches is important. If state transitions occur repeatedly within a short period, you should assume there is some problem with the positioning environment. Background factors vary: obstructed sky view, nearby structures that cause reflections, intermittent interruptions in correction communications, and so on. Such instability may be hard to notice on site, but when you review the logs it appears clearly as changes in state. In particular, for points that will be retained as deliverables or points near control points that greatly affect downstream processes, you should carefully check whether these state transitions occurred.

Also, when assessing the positioning state, you should be mindful of its relationship to the length of the observation time. If you only have short-duration observations, you may merely be capturing a temporarily stable state, and sufficient reproducibility may not be guaranteed. Conversely, if a stable fixed solution persists throughout a sustained observation period, it is easier to conclude that the positioning was well conditioned rather than a coincidental result. In practice, work efficiency is important, but observations so short that stability cannot be confirmed from the logs can result in re-measurements or rework.

The progression of positioning status is the foundational information for reading RTK logs. If this is unstable, you should make cautious judgments even if the number of satellites and accuracy indicators you look at later appear good. Conversely, if this is stable, it becomes easier to interpret the other items consistently. First, make it a habit to check three basic points—when a fixed solution was achieved, how long it was maintained, and whether the status degraded at any point—to make log reading much more practical.

Judge whether the observation conditions were unreasonable by checking the number of satellites and the reception environment

Next, you should check the number of satellites and the reception environment. RTK determines positions based on signals from satellites, so if you cannot stably receive a sufficient number of satellites in the first place, you cannot expect high accuracy. Logs often record information on the number of satellites used, the number being tracked, and the satellite configuration, and by checking these you can infer whether the observation conditions at that time were severe.

When looking at the number of satellites, it’s important to note that simply having more is not necessarily better. Of course it is important that a certain minimum number of satellites are continuously available, but you also need to check whether the satellite geometry is uneven. In environments where satellites are concentrated overhead or only visible in certain directions, positional stability can degrade even if the count appears sufficient. If logs include geometric indicators, check those as well to confirm the satellite distribution was reasonable.

In actual field sites, there are many conditions unfavorable to satellite reception, such as near buildings, at the edge of slopes, under trees, and around heavy machinery or temporary structures. In such locations, reception can also change depending on the time of day. If the logged satellite count fluctuates significantly, it may indicate that line-of-sight conditions changed during the work or that surrounding obstructions affected reception. It becomes particularly easy to isolate the cause when unstable positioning and a decrease in satellite count coincide in the same time period.

Also, even when a sufficient number of satellites are visible, quality can degrade if signals are affected by reflections. This is the so‑called multipath problem. It is not easy to conclusively diagnose multipath from logs alone, but when signs coincide—such as a sudden deterioration in precision indicators despite an unobstructed sky view, fixed solutions becoming unstable, or coordinates fluctuating subtly—it is worth suspecting a reflective environment. It is more likely to occur where metal surfaces, walls, water surfaces, or vehicles are nearby, and checking site photos and work notes together with the logs improves diagnostic accuracy.

The number of satellites can be used for on-site judgment before observations begin, but when checking logs it plays a larger role in post-event evaluation. In other words, when considering "why that point was off," it serves as material to verify whether the reception conditions at the time were sufficient. If the satellite count was low and fluctuated greatly, it's safer to treat that point as a candidate for re-measurement. Conversely, if the satellite count was stable and the positioning solution remained continuously fixed, it is more likely that the cause lies elsewhere.

What’s important here is not to evaluate the number of satellites in isolation. By looking at it together with positioning status, accuracy indicators, and the reception status of correction data, you can determine whether the instability was caused by a lack of satellites or whether there were enough satellites but quality dropped due to another factor. If you’re not yet familiar with RTK logs, it’s sufficient at first to simply look at the trend in satellite count and check whether it decreased during the period when the anomaly occurred. Even that alone will let you catch many problems caused by site conditions.

Verify the conditions for maintaining a fixed solution by checking correction data and communication status.

In RTK, it is important not only to receive satellite signals but also to receive correction data reliably. Therefore, when checking logs you should always verify the reception status of the correction data and the stability of the communication link. On site, people tend to focus on the receiver itself and the number of satellites, but if corrections are not being delivered properly, the fixed solution will not be stable. In fact, many of the causes for an inability to maintain a fixed solution are hidden in issues related to the correction data.

The first step in verification is to check whether correction data was being received continuously. Logs may record the reception times of correction information, update intervals, and delay times. If reception intervals are unnaturally long or delays become large, the positioning solution can become unstable. On site it may appear that communication is working, but in reality it can be intermittent and corrections may not arrive in time when needed. By examining the logs you can confirm those subtle instabilities that are hard to detect from appearances.

Problems with correction data are closely related to the communication environment. When communication quality degrades due to working while moving, communication outages caused by terrain, or the influence of surrounding structures, the delivery of corrections becomes unstable. If the time in the logs when the solution switched from a fixed solution to a float solution coincides with abnormalities in correction data updates, the likelihood that the cause lies on the communications side increases. Being able to confirm such a correlation prevents you from simply concluding that “the accuracy was poor” and makes it easier to link the issue to “instability in correction reception” and take appropriate next measures.

Also, even if correction data has been received, you need to be careful when an old correction is still being carried over. Delayed corrections can make it appear that positioning is possible momentarily, but they will cause a decline in quality. If the log records indicators such as correction elapsed time or correction age, it is important to check that those values are not large. In particular, these values tend to become unstable immediately after moving into an area with weak communication or right after starting work, so they should be checked together with the timing of adopting observations.

What is often overlooked in practice is that not only a complete loss of communication, but also a weak connection can be dangerous. A complete outage is easy to notice in the field, but intermittent delays or momentary dropouts tend to go unnoticed while observations continue. As a result, when you later look at the logs you may find that fixed solutions lasted only for short periods, or that there are large differences in quality between observation points. Communication problems should be verified not by intuition but by the time stamps in the logs.

When checking this item, you should also determine whether the anomaly in the correction data was temporary or persisted across the entire site. If it was temporary, you may only need to remeasure specific points. However, if it was unstable overall, you should review that day's observational conditions themselves. Operational improvements may be necessary, such as antenna placement, workflow, communication methods, and the order of observations.

RTK logs are useful not only for checking the coordinate results but also for verifying how reliably the correction data was being delivered. When a fixed solution cannot be maintained, many people first suspect satellite reception, but in reality problems with communications and receiving correction data are often the hidden cause. By making a habit of comparing changes in positioning status with the recorded correction data, isolating the cause becomes much easier.

Evaluate the reliability of coordinates by examining accuracy metrics and variability

The purpose of examining an RTK log is ultimately to judge how much you can trust the resulting coordinates. Therefore, checking the accuracy indicators and variability is indispensable. Even if the positioning status shows a fixed solution and the number of satellites and correction reception appear fine at first glance, it is risky to accept the coordinates as-is if the accuracy indicators are unstable. Conversely, if this aspect is stable, you can be fairly confident in the quality of the observation results.

Accuracy metrics recorded in logs are expressed differently depending on the instrument and settings, but generally horizontal and vertical estimation errors, dispersion indicators such as standard deviation, and position solution quality metrics are useful references. What is important here is not to look only at absolute values, but to examine temporal changes. Even if a good value appears at a single point in time, if it fluctuates greatly before and after, it is difficult to call the observation stable. Checking whether it remains within a similar range throughout the observation makes it easier to judge the reliability of the results.

What you need to pay special attention to is when horizontal and vertical tendencies differ. In RTK, the vertical (height) direction is generally more prone to instability, so even if the planar position is stable, the height alone can fluctuate. The points you need to check change depending on whether the required on-site deliverable is focused on planar position or whether strict height control is also necessary. For example, it is not uncommon for staking out positions to be fine while height management requires rechecking. When reviewing logs, don’t be reassured by looking only at the horizontal plane; you should also properly check the quality in the vertical direction.

Also, if there are records of observing the same point multiple times, the differences between those observations are an important factor for assessment. If measurements taken at the same location at different times show large coordinate differences, it suggests the presence of some instability. Conversely, if the differences remain small even at different times, the point can be evaluated as having high repeatability. On site, measurements sometimes end after a single observation, but for important points, combining multiple observations with log checks greatly improves the accuracy of quality verification.

When examining variability, attention is also needed for measurements taken immediately after movement. Immediately after stopping a moving object, or when the observation attitude has not yet stabilized, values can fluctuate for several to about ten seconds. If a record is taken in the log before that fluctuation has settled, then—even if the positioning state is a fixed solution—it remains a point of concern in practice. It is important to check whether there was sufficient time from the start of observation to taking the measurement, and whether the recording was made after the values had stabilized.

Furthermore, if the accuracy indicators are consistently good but only the differences from known points are large, you should suspect an error in the configuration settings. In other words, even if the accuracy indicators show internal stability, if the coordinate system or antenna height is set incorrectly, you may obtain consistently shifted values. Therefore, good accuracy indicators are a necessary but not sufficient condition. Read them only as information indicating that the solution was stable under those conditions, and ultimately make a judgment in combination with checks against known points and verification of the settings.

For practitioners, what matters is not to regard accuracy indicators as difficult technical values but to use them as material for deciding whether a re-measurement is necessary. Along with a stable fixed solution, a sufficient number of satellites, and correct reception of corrections, the trend of the accuracy indicators should also be stable. If these four conditions are met, the reliability of that observation can be considered quite high. Conversely, if even one of them is unstable, the observation should be treated with caution. Making the purpose of checking the logs clear will make the accuracy indicators feel less daunting than they otherwise would.

Verify that the overall assumptions of the log are correct by checking the timestamps and settings

Finally, what you should check are the time and configuration settings. This may seem unremarkable at first glance, but it is extremely important in practice. Even if the positioning status and accuracy indicators appear clean, if there are errors in assumptions such as time settings, the coordinate system, or antenna height, the final results will not be correct. Moreover, this kind of mistake is hard to notice in the field and is often only discovered when reviewing logs later, so it is something you should make a habit of always checking.

First, timestamps are essential for cross-referencing with other records. When reconciling work reports, photos, known-point observations, records from other devices, the times of communication failures, and so on, analysis of causes becomes difficult if the log timestamps are off. For example, even if there is a record that a communication failure occurred at a certain time, if the log’s clock is incorrect, it cannot be correlated with anomalies in correction reception. Time consistency is especially important when multiple personnel are involved on site or when a third party reviews the records later.

Next to check are the coordinate system and datum settings. Even if RTK is internally stable, if the adopted coordinate system or transformation parameters do not match the intended purpose, discrepancies with known points and inconsistencies with other results will occur. Even when logs show no problems with position quality, if the delivered results appear shifted you should suspect these settings. This is especially true in operations where multiple sites or multiple result streams coexist, because mistakes in carrying over settings are likely and checking the logs becomes especially valuable.

Setting the antenna height and instrument height is also important. If the difference in the vertical direction is offset by a constant amount, this configuration item should be the first suspect. If the method of entering height or the interpretation of the reference position is incorrect, the observations themselves may be stable while only the resulting values are systematically biased. Moreover, this bias is hard to detect in accuracy indicators, so it’s easy to miss unless you check the settings section of the log. If vertical-direction errors repeatedly occur in the field, it can often be faster to inspect the configuration settings than to examine the reception environment.

Additionally, the logging interval and the conditions under which data were saved should also be checked. If you do not know whether the measurements were point observations or continuous recordings, or at what timing values were saved, you may misinterpret temporal changes. For example, a short-term instability may actually have occurred but been missed because the save interval was coarse. Conversely, if data were recorded at fine intervals, it becomes easier to detect even temporary anomalies. Logs alone are not sufficient; only by understanding the conditions under which the records were kept can you make a correct evaluation.

What matters in this item is not the quality of the numerical values, but whether the assumptions for the entire log are correct. Positioning status, number of satellites, receipt of corrections, and accuracy indicators are, so to speak, information that shows the quality during the observation. On the other hand, time and configuration settings are the foundation that determines whether that quality information can be used correctly as results. If there is an error here, no matter how clean the log is, the reliability of the results will collapse. That is why, as the final check item, it should not be taken lightly and should always be reviewed.

In practice, when coordinates don’t match, people tend to suspect the reception environment or communications first, but there are many cases where the actual cause was simply insufficient verification of configuration settings. When making log checks a routine, it’s important to review both the items that assess quality and the items that check preconditions together. Doing so speeds up isolating the cause and makes it easier to minimize the scope of re-measurements and rework.

Summary

RTK logs are not something to be saved and forgotten; they are important records for later verifying the reliability of positioning results. It may seem difficult if you don’t know where to look, but in practice, by checking just five items—changes in positioning status, the number of satellites and the reception environment, correction data and communication status, accuracy indicators and their variability, and the times and configuration conditions—you can make quite practical judgments.

What's particularly important is not to decide success or failure based on a single number. Look not only at whether it was a fixed solution but whether that condition was sustained. Read not only whether there were many satellites but also how that number changed over time. Check not only whether the accuracy indicators look good but also whether there are any mistakes in the configuration settings. Once you can adopt this way of looking, RTK logs become more than mere machine records; they serve as useful material for reviewing the site.

Also, checking logs becomes more valuable when done routinely, not only when trouble occurs. If you know, for a typical site, how long fixed solutions are maintained, how the satellite count typically varies, and what ranges of accuracy indicators are considered stable, you can detect anomalies more quickly. To use RTK reliably in practice, you need not only the skill to measure but also the ability to read the records after measuring.

If you want to operate RTK in a form that is easier to handle in daily work, including checking logs like these, interoperability with the devices used on site and the ease of verifying positioning results also become important. In practice, choosing tools not only for accuracy but also for ease of verification, ease of handling records, and maneuverability on site leads to stable operation. For those who want to make RTK more accessible and more practical, considering an iPhone-mounted GNSS high-precision positioning device like LRTK can help streamline the flow from positioning to verification.