RTK GNSS Operational Tips: On-site Know-how to Maximize Accuracy

Table of Contents

• Introduction

• What is RTK GNSS

• Optimize satellite geometry (keep DOP low)

• Thorough multipath mitigation (avoid reflections and blockage)

• Keep an appropriate baseline distance between base and rover (short-baseline positioning)

• Verify NTRIP correction quality (correct data format and communication)

• Avoid radio interference (steer clear of strong noise sources)

• Improve receiver installation (antenna leveling and height adjustment)

• Operate with correct measurement procedures (initial Fix and kinematic positioning tips)

• Optimize device and software settings (coordinate system and mask settings check)

• Check accuracy during measurement (monitor HDOP and Fix/Float)

• Troubleshooting (what to do when you can’t get a Fix)

• Simple surveying with LRTK

• FAQ

Introduction

RTK GNSS (Real-Time Kinematic GNSS) is an innovative technology that enables position measurement with centimeter-level accuracy (half-inch accuracy) for surveying and construction sites. Traditional standalone positioning (standalone GPS) produced errors on the order of meters, but using RTK, correction information from a base station can cancel errors in real time and achieve high-precision positioning within a few centimeters. As a result, work efficiency and reliability in construction management and infrastructure inspection are dramatically improved.

However, to consistently obtain a high-precision fixed solution (Fix) on site, you must pay attention to several points. For example, RTK accuracy can be degraded by radio reflections from buildings or walls (multipath), satellite geometry, unstable communications, and other factors, potentially causing situations where a stable Fix is hard to obtain. Also, to use RTK effectively you should understand the difference between “Fix” and “Float,” always verify that a Fix is maintained, and ensure you do not confuse global geodetic coordinates with local coordinate systems when setting up devices.

This article summarizes on-site know-how to maximize accuracy with RTK GNSS and clearly presents operational tips. We cover basics such as optimizing satellite geometry and multipath mitigation, base-station operation points, measurement-procedure cautions, and even simple surveying methods using our portable GNSS receiver LRTK. The explanations are organized to be easy for beginners to understand, so please use this as a practical guide for high-precision RTK GNSS field operations.

What is RTK GNSS

RTK GNSS (Real Time Kinematic GNSS) is a positioning method that uses two GNSS receivers: one installed at a known coordinate point as a base station, and the other operating as a rover that moves while receiving real-time corrections. The base station measures its own position, computes the error components, and transmits that correction information to the rover via radio or the Internet. The rover immediately applies the received corrections to its own positioning, reducing errors that would be several meters in standalone positioning down to a few centimeters. Even within Japan’s geodetic systems, RTK can provide geodetic coordinates in the World Geodetic System with centimeter-level accuracy (half-inch accuracy) on-site.

RTK positioning requires a communication link between the base and rover to transmit correction data. Common methods include direct radio transmission from base to rover in the UHF band, or using Internet-based distribution services called NTRIP for network RTK (e.g., VRS). In the latter case, you can use public continuously operating reference station networks as virtual reference stations, avoiding the need to set up your own base station. Note, however, that real-time methods stop providing positioning if communications are interrupted, so ensuring a stable communication environment on site is important. Also, the farther you are from the base station (baseline length), the less effective the corrections become and the larger the error tends to be; in practice, RTK positioning is preferably performed within an area of a few km.

Based on the above, the following sections explain specific tips to extract maximum accuracy from RTK GNSS positioning.

Optimize satellite geometry (keep DOP low)

One major factor affecting RTK positioning accuracy is the geometry of GNSS satellites in the sky. The indicator calculated from satellite geometry is the DOP (Dilution of Precision), which reflects the quality of the satellite geometry. If satellites are clustered to one side of the sky, the geometry is weak and the GDOP becomes large, degrading accuracy. When GDOP is high (biased satellite geometry), the observation errors are harder to cancel and a stable Fix is difficult to obtain. Conversely, if satellites are evenly distributed across the sky, the geometry is strong and GDOP remains low, resulting in smaller positioning errors and stable RTK.

Countermeasure: During planning of survey date/time and location, use a GNSS planning tool (satellite prediction software) to check the satellite geometry at the planned observation times. Start measurements at times when DOP values are as low as possible. Many modern GNSS receivers support multiple GNSS constellations—GPS, GLONASS, Galileo, and QZSS (Michibiki)—and increasing the number of usable satellites improves geometry. Also avoid setting the mask angle (elevation cutoff) excessively high in receiver settings. Although very low-elevation satellites tend to have larger errors, using satellites down to about a 15° elevation in balance can distribute satellites across the sky and keep horizontal DOP (HDOP) favorable. Optimizing satellite geometry and keeping DOP values low is the first step toward high-precision RTK positioning.

Thorough multipath mitigation (avoid reflections and blockage)

In urban and mountainous areas, reflected satellite signals from surrounding buildings, cliffs, and other surfaces—known as multipath—occur frequently. Reflected waves arrive slightly later than direct signals from the satellite, causing overestimation of distances and errors in position calculations. In high-rise downtown areas, satellite signals can even be blocked entirely (satellite blockage). Multipath and blockage are RTK’s enemies, so take every possible countermeasure on site.

Countermeasure: Choose measurement points with a wide open view of the sky whenever possible. An environment without nearby high-rise buildings, metal structures, or large vehicles (reflection sources or blockages) is ideal. In urban canyons, where reflections and blockage occur easily, try to move away from buildings to a spot with a clear sky view. If you must measure near buildings, install the antenna as high as possible to reduce influence from ground or structure-reflected waves. If available, attach a ground plane (metal plate) to the antenna; it can block unwanted reflections from directly under the antenna and mitigate multipath. High-performance GNSS antennas and receivers may include multipath mitigation functions, but the basic approach is to create an environment that avoids reflections and blockage. Reviewing receiver mask settings to exclude low-elevation satellites that are likely to reflect off the ground or buildings (for example, set elevation mask to about 15°–20°) is also effective. Thorough multipath mitigation helps obtain a more stable Fix and greatly reduces the risk of RTK accuracy degradation.

Keep an appropriate baseline distance between base and rover (short-baseline positioning)

RTK achieves high accuracy by relative positioning between a base station (fixed) and a rover (mobile). Therefore, if the base and rover are too far apart (long baseline length), accuracy deteriorates. This happens because error factors in received satellite signals (ionospheric delay, satellite clock errors, etc.) vary with distance and cannot be fully corrected by the base station’s corrections. In general practice, it is desirable to keep the baseline length within 10 km. Beyond that, it may take longer to obtain a Fix, or the positional error may increase to several centimeters or more.

Countermeasure: If the work area is large, install the base station as close to the site as possible. For example, on a large construction site where you can operate your own base station, choose a reference point as centrally as possible in the survey area. This keeps the baseline short, reducing differential ionospheric and tropospheric errors and allowing a faster, more stable Fix. Also be sure to set the base station’s coordinates accurately. Either install on a point with known coordinates or determine the base coordinates precisely by static surveying after setup so the position used for corrections is well calibrated. Any error in the base station coordinates will directly affect the absolute accuracy of rover measurements, so handle reference coordinates carefully. If setting up your own base is difficult, consider using network RTK services (VRS, etc.) that utilize national or private continuously operating reference station data. Using NTRIP to generate a virtual reference station near you effectively keeps the baseline short, making it easier to maintain accuracy over a wide area.

Verify NTRIP correction quality (correct data format and communication)

When using Internet-based network RTK (NTRIP), the quality of the reference station data you receive—correction information—directly affects positioning accuracy. Correction quality means whether the content matches the rover receiver and whether it arrives without delay in real time.

Countermeasure: First, confirm that the correction format and type provided are compatible with your receiver. For example, if the rover is a single-frequency (L1-only) GNSS receiver, the NTRIP service must provide a data stream for single-frequency use (e.g., MSM4 format). If the rover supports multi-frequency, selecting higher-precision formats such as MSM7 or correction data that includes all GNSS constellations will extract better performance. NTRIP services often provide several mount points (different data types or reference networks), so choose correction data for a base network close to your work area or a service with a reliable track record.

Also manage communication latency. If you connect to NTRIP over a mobile network or pocket Wi-Fi, perform measurements in areas with good signal and avoid data lags or drops. Large delays in correction data cause corrections to be applied using outdated information, making Fix unstable or reverting to Float. If your receiver or app can display RTK status (e.g., Differential Age or received message counts), monitor these indicators to ensure corrections are arriving in real time. If you observe interruptions or delays in correction data, switch to another mount point, change communication methods (use a backup line), or take other measures to maintain an environment where you always receive high-quality correction data.

Avoid radio interference (steer clear of strong noise sources)

RTK positioning receives very weak satellite signals, so you must also be careful about interference (jamming) from strong nearby radio signals. For example, high-voltage power lines can induce strong electromagnetic fields and add noise to GNSS reception. On construction sites, work radios, Wi‑Fi routers, and cellular base stations may emit signals that mix into the receiver and degrade positioning accuracy.

Countermeasure: Conduct positioning away from strong radio noise sources whenever possible. Avoid locations directly beneath high-voltage lines or near TV/radio transmission antennas where strong electromagnetic fields are present. If you must work nearby, consider using any line filters supplied with your receiver (antenna-line filters, etc.). Also reduce interference by changing receiver settings—for instance, disable unused wireless modules (turn off built-in UHF transmitter or Bluetooth if not in use) and keep other electronic devices at a reasonable distance. In Japan, CLAS signals from the QZSS are used in some RTK environments on the L6 band; these also benefit from being free of strong interference. Choosing a radio-clean environment is a quick route to obtaining a stable Fix.

Improve receiver installation (antenna leveling and height adjustment)

The way a GNSS receiver and antenna are installed can affect RTK accuracy. Pay careful attention to installation on site and eliminate error sources.

Countermeasure: First, install the antenna as level as possible and avoid tilting. A tilted antenna biases reception toward certain sky directions and can introduce systematic error in positioning. When mounted on a tripod or pole, use the built-in bubble level to ensure it is truly level.

Next, antenna height is important. Placing the antenna just above ground makes it susceptible to reflected waves and blockage from nearby obstacles. It is common practice to mount the antenna on a pole about 1.5–2 m (4.9–6.6 ft) high to improve visibility. However, if an antenna mounted at the top of a pole swings significantly in the wind, it can adversely affect positioning, so secure it firmly with clamps. In strong winds, avoid using an unnecessarily long pole and instead install at a lower height as appropriate.

Also, when installing your own base station, be sure to measure and record the antenna height. The antenna height (from the antenna phase center to the ground reference point) is needed for post-processing or comparing with other survey results, so measure it accurately to the centimeter level (half-inch accuracy). As noted earlier, calibrate the base station coordinates at a known point when possible. Careful antenna installation and reference point handling eliminate unnecessary errors and maintain RTK’s high accuracy.

Operate with correct measurement procedures (initial Fix and kinematic positioning tips)

To reliably obtain a stable Fix, correct measurement procedures and operational habits are essential. The initial actions when starting RTK and behavior while moving greatly affect data quality.

Countermeasure: After starting positioning, do not move immediately—remain still for several tens of seconds until the first Fix is obtained. When powering up and beginning, satellite acquisition and reception of correction data may be unstable for several seconds, and the solution may be in a Float state. If you move during this stage, you will only obtain unstable position data. Wait with the antenna fixed until the receiver has captured a sufficient number of satellites, correction data is flowing, and the status shows “FIX.” After obtaining the initial Fix, if you are performing static surveying, maintain the Fix on site for a while and average multiple position readings to improve accuracy.

For kinematic surveys while moving, if the Fix is lost even once and reverts to Float, the data during that period will not meet centimeter accuracy. Therefore, even during mobile surveys, make a habit of stopping at key locations to allow the receiver to regain Fix before recording points. For example, on a long survey, stop at regular intervals to check satellite status and, if necessary, wait a few seconds for Fix recovery before continuing.

As a preparatory measure, warm up the receiver sufficiently before measurement. Operating the device for a while after power-up lets internal clocks and temperatures stabilize, often improving accuracy. If satellite reception deteriorates during measurement, try slightly moving the antenna position; small adjustments sometimes improve reception. If Fix remains unstable, resetting the positioning session (re-acquiring corrections or restarting the receiver) can help. Sometimes restarting from scratch gets you back to Fix more quickly than continuing in a fragmented state.

By recording only data when a stable Fix is maintained, you can fully extract RTK GNSS’s potential on site.

Optimize device and software settings (coordinate system and mask settings check)

To maximize RTK GNSS performance, optimize the settings of your devices and software (apps). Receivers and smartphones have many configurable options; adjust the ones that affect positioning accuracy and operation.

Countermeasure: First, check the coordinate system settings that underlie your positioning results. If you want to match public survey coordinate systems in Japan, set the device’s geodetic system to JGD2011 or JGD2022 and enable geoid-based height correction if needed. For height, apps may offer geoid height data (e.g., GSIGEO2011) to convert GNSS ellipsoid height to conventional orthometric height; some apps (our LRTK app included) can automatically correct using the Geospatial Information Authority of Japan’s correction API. Confusing world geodetic coordinates with local systems causes coordinate offsets, so always select the coordinate system appropriate for your surveying purpose.

Next, check receiver and app positioning mode settings. When operating in RTK mode, make sure to select the correct base/rover mode, ensure Bluetooth or serial connections between devices are stable, and attend to basic connectivity. If you use software for NTRIP, pre-enter server address, port, mount point name, and login credentials accurately and perform a connection test.

Use positioning data recording features in apps or receivers. For static points, an average positioning mode that averages values over a set time is effective; for example, averaging multiple Fix readings over 10 seconds yields a more stable result than a single reading. For mobile surveying, some devices have high-frequency logging functionality; logging continuous position data at 5–10 Hz, for example, allows post-analysis of trajectories and detection or filtering of moments when a solution dropped to Float. Refer to manuals and Q&A from your device or software vendor and prepare optimal setting profiles in advance so field operations run smoothly.

Check accuracy during measurement (monitor HDOP and Fix/Float)

In field RTK operations, the ability to judge positioning accuracy in real time is important. It’s too late if you return to the office only to discover part of your data is inaccurate. Evaluate the quality of current position information on site and avoid recording uncertain data.

Countermeasure: Primarily, check the solution status displayed by the receiver or app. “FIX” on the display is a prerequisite for high accuracy, but also monitor HDOP and estimated position error indicators. HDOP reflects satellite geometry and typically an HDOP in the 1–2 range is ideal, 3–4 is generally acceptable for practical use, but above 5 it indicates accuracy degradation. If HDOP worsens, pause measurements and wait for geometry to improve or consider changing the environment.

Also constantly check whether the solution has fallen to “Float” or “DGPS” etc. If it becomes Float, the points recorded during that period cannot be guaranteed for precision and should be re-measured if necessary. If you are logging continuously, note the times when Float occurred so you can exclude those segments during post-processing.

Modern RTK apps often show the number of satellites used, per-satellite signal strengths, and correction reception status. Indicators such as “used/visible satellites” help judge whether enough satellites are available, and a single weak satellite may hint at nearby obstacles. Monitor correction latency and base link status indicators as well, and continually ask yourself whether the current position data can be trusted—this mindset is key to high-precision work.

Troubleshooting (what to do when you can’t get a Fix)

Even with thorough preparation, you may encounter situations on site where you cannot obtain or maintain a Fix. Prepare a checklist for isolating causes and remedies so you can respond calmly.

Possible causes and countermeasures:

• Insufficient satellites or poor geometry: Check the environment—if the sky view is obstructed, move to a location with a clearer view. If satellite geometry is poor at that time, wait a while. Use a GNSS planner to check upcoming satellite conditions and judge whether improvement is likely.

• Multipath or blockage: Recheck for reflection or blockage sources near the antenna. If necessary, change the antenna position, raise it, add a ground plane, or apply other mitigation measures described earlier.

• Baseline over limit or base inconsistency: Confirm that the distance from the base station is not too great. For network RTK, check whether the selected reference service is appropriate and, if possible, switch to correction data from a closer source. If operating your own base, verify that the base coordinates were entered correctly (no data-entry errors).

• Correction data not being received: Check NTRIP connection or radio communication. For mobile networks, move to an area with better signal or restart the communication device. Also consider server-side issues—test other mount points or check the service provider’s status information.

• Receiver or app malfunction: Sometimes the GNSS receiver or software becomes unstable and cannot produce a Fix. In that case, reset positioning: disconnect and reconnect NTRIP, power-cycle the receiver, or restart the app. After restart, reacquire satellites and begin again; this often restores Fix.

If these checks do not resolve the issue, consider hardware failure or configuration mistakes. Prepare spare batteries, alternative communication means, and manuals in advance. By calmly working through possible causes, you can usually restore a Fix.

Simple surveying with LRTK

Our company offers a portable GNSS receiver called LRTK as a practical solution to use high-precision RTK positioning on site. LRTK is a small device that pairs with a smartphone or tablet and serves as an intuitive “all-purpose surveying tool” for field technicians. RTK positioning, which formerly required specialty equipment and experience, can be started easily with LRTK even without expert knowledge.

One feature of LRTK is flexible switching of positioning methods according to the communication environment. Normally, it connects to network RTK (NTRIP) via the smartphone’s Internet and obtains corrections on-site to achieve centimeter-level positioning (half-inch accuracy). In areas without cellular coverage, LRTK can also use the QZSS-provided centimeter-level augmentation service CLAS. Using a dedicated L6-band antenna, LRTK can perform real-time high-precision positioning even where the Internet is unavailable.

LRTK also offers robust cloud-based data management. Positioned points and photos taken on-site with LRTK are automatically plotted on a cloud map and can be shared with the team in real time. For infrastructure inspection, photos taken with a smartphone connected to LRTK are immediately tagged with accurate coordinates and shared with office staff, streamlining reporting workflows and improving coordination.

By using LRTK, you can greatly improve productivity and accuracy on surveying sites. The compact receiver is easily operated with one hand, and complex device configuration is unnecessary, increasing field mobility. As a solution that supports the Ministry of Land, Infrastructure, Transport and Tourism’s DX initiatives for construction sites, LRTK has already been adopted at many sites. Developed under the concept “Make high-precision positioning easier and more accessible,” LRTK will change future surveying styles. If you want to practice high-precision RTK positioning easily on site, consider simple surveying with LRTK.

FAQ

Q1. I can’t seem to get a Fix in RTK positioning—what could be the cause and how should I respond? A. Causes for not obtaining a Fix include insufficient satellites or poor geometry, surrounding multipath environment, too great a distance from the base station, or lack of correction data reception. Remedies are detailed in the Troubleshooting section above, but begin by clearing the sky view to increase satellite count, avoid reflections and blockage, shorten the baseline (or use VRS services), and improve communication. If the problem persists, restart the receiver or app. By eliminating causes one by one, you can usually regain a Fix.

Q2. What positioning accuracy can RTK-GNSS actually provide? A. Under good conditions and proper operation, RTK can achieve about 1–2 cm (0.4–0.8 in) horizontally and about 2–5 cm (0.8–2.0 in) vertically. Typical high-performance RTK-GNSS receiver specifications show values such as horizontal accuracy: ±(1 cm (0.4 in) + 1 ppm), vertical accuracy: ±(2 cm (0.8 in) + 1 ppm). For example, with a 10 km baseline, horizontal ±1 cm + 10 ppm (= ±1 cm + ±1 cm) yields roughly ±2 cm; vertical ±2 cm + ±2 cm yields about ±4 cm. Shorter baselines further reduce errors. Note that satellite conditions and the environment can temporarily worsen accuracy, so continuously monitor conditions as described above.

Q3. How far from the base station can I position? A. The shorter the baseline distance to the base station, the more favorable for accuracy and Fix stability. Ideally remain within a few km up to 10 km; beyond 10 km, correction effectiveness decreases and it takes longer to obtain a Fix or accuracy degrades. At 20–30 km distances, even if you obtain a Fix, errors often exceed several centimeters and maintaining Fix may be unstable due to signal delays. For wide-area surveys, use network RTK in VRS mode that leverages national reference stations; VRS sets up a virtual base near the user so you effectively measure with a baseline of a few km and more easily maintain high accuracy.

Q4. What is the difference between a “Fix” and a “Float”? A. A Fix is a solution in which the integer ambiguities of carrier-phase measurements are resolved, yielding centimeter-level accuracy and a reliable position. It is the target solution for RTK. A Float solution is computed while the integer ambiguities remain unresolved and typically has accuracy in the decimeter to submeter range. During RTK initialization or when radio conditions are poor, solutions are often Float and converge to Fix when conditions improve. In practice, only measurements taken while in Fix should be used to guarantee high accuracy; data recorded during Float should generally not be used for final deliverables.

Q5. Is there an easy way to start RTK surveying without specialized equipment or advanced knowledge? A. Yes. One option is to use a portable GNSS receiver like LRTK. LRTK is a palm-sized RTK-GNSS receiver that connects to a smartphone, designed to provide centimeter-level positioning in real time without requiring complicated setup. It supports network correction services (NTRIP) and can also receive QZSS CLAS signals where cellular coverage is absent, allowing immediate surveying on site. LRTK is easy for first-time RTK users and is recommended as a tool to access high-precision positioning without specialized gear or expertise. Combining LRTK with the operational tips in this article will help anyone achieve more stable, high-precision positioning.

Q6. What is the difference between RTK and PPK? A. RTK (Real-Time Kinematic) receives corrections from a base station in real time and computes high-precision positions on the spot, providing immediacy but requiring communications in the field. PPK (Post-Processed Kinematic) records base and rover data in the field and combines them later for correction in post-processing. PPK—also called post-processing—does not require field communications and can provide robust results by synchronizing base data and rover logs later, which is useful for drone surveys, filling gaps due to satellite loss, or obtaining stable positioning over long distances. However, results are generated after returning from the field. The key difference is whether you prioritize real-time results (RTK) or post-processed stability and flexibility (PPK). Choose according to field conditions—RTK is common for terrestrial surveying where immediate results are needed, while PPK is used when communications are difficult or for moving platforms like drones.