5 Points to Fully Utilize RTK Accuracy on Site

Table of Contents

• Point 1: Stabilize positioning accuracy by optimizing satellite geometry

• Point 2: Ensure a good positioning environment by avoiding multipath and radio interference

• Point 3: Keep the distance to the base station short and use appropriate correction data

• Point 4: Proper installation and configuration of GNSS equipment

• Point 5: Appropriate measurement procedures and real-time accuracy checks

• Conclusion: Simple surveying with LRTK

• FAQ

RTK positioning (Real-Time Kinematic) is a crucial technology for obtaining centimeter-level high-precision position information in surveying and construction sites. If a high-precision Fix solution can be obtained, efficiency and reliability for tasks such as construction as-built control and infrastructure inspection improve dramatically. However, in actual field conditions, various factors such as multipath (signal reflections), poor satellite geometry, and communication delays can degrade RTK accuracy and make it difficult to obtain a reliable Fix solution.

This article explains five points to fully utilize RTK accuracy on site. Covering basics such as optimizing satellite geometry and countermeasures against multipath, as well as equipment settings and measurement procedures, it summarizes tips for consistently achieving centimeter accuracy in the field in an easy-to-understand way for beginners. At the end, we also introduce a new approach: simple surveying using LRTK. Now, let’s look at the points to maximize RTK accuracy one by one.

Point 1: Stabilize positioning accuracy by optimizing satellite geometry

One major factor that influences RTK positioning accuracy is the arrangement (geometry) of GNSS satellites. If the satellites visible in the sky are clustered in certain directions, the geometric integrity of the positioning calculations becomes weak and DOP values (dilution of precision) increase. When DOP is high (poor geometry), position errors grow and obtaining a Fix solution becomes more difficult. Conversely, when satellites are well distributed across the sky, the geometry is strong, DOP is kept low, and a more accurate solution is obtained.

Therefore, when choosing the time of day or location for RTK positioning, it is effective to check satellite geometry in advance with a GNSS planner and aim for time windows with low DOP values. Also, modern receivers support multiple GNSS constellations such as GLONASS, Galileo, and QZSS (Michibiki), so increasing the number of usable satellites by using multi-GNSS improves geometry. Additionally, do not set the elevation mask (the angle excluding low-elevation satellite signals) too high in receiver settings. If the elevation mask is too high, the number of usable satellites decreases and geometry worsens. Generally, using low-elevation satellites down to about 10–15° in a balanced way helps maintain good RTK horizontal accuracy (HDOP).

Point 2: Ensure a good positioning environment by avoiding multipath and radio interference

Countermeasures against multipath, one of the biggest enemies of RTK accuracy, are essential on site. In urban or mountainous areas, GNSS signals can reflect off building facades or rock surfaces and arrive later than the direct satellite signals, causing errors. In environments where errors from reflected waves are large, even high-performance receivers struggle to obtain an accurate Fix solution. As a countermeasure, choose measurement points with as much open sky as possible and avoid tall buildings, metal structures, large vehicles, and other objects that might reflect signals. If you must measure near a building, raising the antenna as high as possible reduces the effect of reflected waves. If a ground plane (metal plate) can be attached to the antenna, it can block reflections from below. Fundamentally, creating an environment where signals are less likely to reflect is most important. Additionally, appropriately adjusting the receiver’s elevation mask to exclude low-angle signals that are prone to reflection from the ground or buildings (for example, satellites below about 15°) can suppress the effects of multipath.

Next, avoid strong radio interference from nearby wireless sources. RTK relies on receiving very weak signals from satellites, so receivers near high-voltage power lines or strong electromagnetic sources such as wireless transceivers, Wi-Fi routers, or cellular base stations may suffer noise, reducing accuracy or destabilizing the Fix. Conduct measurements as far as possible from strong radio sources. It is wise to avoid being directly under high-voltage lines or near TV/radio broadcast antennas. If you must work in such locations, use a noise filter if the receiver supports it, turn off unnecessary built-in radio modules (such as Bluetooth), and keep other devices away from the antenna to minimize interference. Choosing a radio-clean environment is the quickest way to stably obtain RTK Fix solutions.

Point 3: Keep the distance to the base station short and use appropriate correction data

RTK achieves high accuracy by relative positioning between a reference station (base station) and a rover, so if the baseline length between them is too long, accuracy degrades. The farther the rover is from the base station, the more atmospheric delays and satellite orbit/clock errors differ between the two, and corrections cannot fully cancel them out. Generally, staying within 10 km is desirable; beyond that, obtaining a Fix may take longer and errors can expand to several centimeters or more. Ideally, set up your own base station near the work site if possible. If that is difficult, use correction data for nearby areas such as public continuously operating reference station data or virtual reference station (VRS) services from private providers to effectively shorten the baseline. Keeping the baseline short reduces error sources between the two stations and enables faster, more stable Fix solutions.

Also pay attention to the quality of correction data used. When using network RTK (e.g., Ntrip), confirm that the types of reference station data being distributed are compatible with your receiver. For example, use correction data for single-frequency receivers if you have a single-frequency GNSS receiver, and choose high-precision multi-frequency correction data (MSM4 or MSM7, etc.) if you have a multi-frequency receiver. If multiple correction services are available, choose one with stations closer to you or one with a proven track record for more stable accuracy. The communication environment for receiving corrections is also important. When connecting to Ntrip via mobile networks, do so where signal conditions are good and avoid communication delays or dropouts. If correction data delivery lags, RTK solutions may fall to Float or become unstable, so ensure corrections arrive in real time. Check the RTK status displayed by the receiver or app (for example, the correction reception latency in seconds) and flexibly switch to another mount point or take other actions as needed.

Point 4: Proper installation and configuration of GNSS equipment

To achieve high accuracy, correct installation and configuration of GNSS receivers and antennas are essential. First, mount the antenna firmly and level. If the antenna is tilted, the reception pattern from satellites becomes biased and, in the worst case, bias errors can mix into positioning results. When using a tripod or pole, check level with a bubble level and always keep the antenna face horizontal. Also be careful not to input the antenna height incorrectly. To ensure vertical accuracy, install the antenna sufficiently high above the ground (being too close to the ground increases shielding and ground reflection effects), measure the height from the measurement point to the antenna reference point accurately, and set it correctly in the receiver or app. When installing your own base station, accurate antenna height and base station coordinates are crucial. If wrong reference coordinates are broadcast as corrections, all coordinates obtained by the rover will have the same systematic error.

Review the receiver settings as well. Ensure the receiver is set to use all available GNSS constellations (if multi-GNSS capable, turn them all on), and if your receiver supports multi-frequency, use multi-frequency mode as much as possible. Utilizing multiple frequencies improves ionospheric error correction and can shorten time to Fix and improve accuracy. Also, if the receiver has built-in filter settings (such as moving average or smoothing), adjusting them to suit the field application can help reduce noise. Additionally, verify that firmware and position engine settings are up-to-date and stable before work. By optimizing both hardware and software aspects of equipment, you can maximize RTK potential.

Point 5: Appropriate measurement procedures and real-time accuracy checks

To reliably achieve centimeter-level accuracy on site, correct measurement procedures and real-time quality checks are important. When starting positioning, do not immediately begin measuring right after powering on the receiver or after moving to a new point; instead, remain stationary for several tens of seconds to allow satellites to be acquired and correction data to stabilize and confirm a Fix solution. If you start moving immediately after beginning, you may record positions while the solution is still in a Float state, resulting in lower-accuracy data. By moving and observing only after the first Fix is obtained, you can collect high-accuracy data. Even for single-point measurements, do not record immediately after a Fix is achieved; continue measuring for a short time to ensure the Fix does not drop out. Averaging measurements over several seconds, if necessary, can result in stable point data.

Also, get into the habit of continuously monitoring current solution and accuracy indicators during measurement. The receiver or app screen shows real-time information such as Fix/Float status, number of satellites in use, and HDOP values. Check these and monitor whether the solution has fallen to Float or the number of satellites has dropped dramatically. If HDOP suddenly worsens or correction data reception is interrupted, stop and investigate the cause. In some cases, moving slightly to improve sky view or reconnecting Ntrip can restore a Fix. If possible, measure a known point to verify error, or observe the same point multiple times at different times and compare results—these on-site accuracy checks are effective. Evaluating measurement data in real time on site and taking immediate countermeasures if problems arise prevents later discoveries that positions were off and allows you to make the most of RTK accuracy.

Conclusion: Simple surveying with LRTK

If you implement the five points above, you can fully utilize RTK’s high accuracy on site and greatly improve the efficiency and precision of surveying and construction management. However, mastering all the satellite awareness, equipment settings, and operational know-how described here may seem daunting for beginners. Also, high-precision RTK has traditionally required expensive professional GNSS equipment and a base station.

Enter LRTK, a new high-precision positioning system that uses a smartphone. LRTK combines a dedicated compact GNSS receiver with a smartphone app to enable centimeter-level positioning easily by a single person. For example, attaching an LRTK receiver to a smartphone and using a pole or monopod for surveying allows anyone to perform staking or as-built measurements that previously required specialized equipment and skilled operators. While regular smartphone GPS has errors of several meters (and often cannot measure height), LRTK can achieve horizontal ±1–2 cm (±0.4–0.8 in) and vertical ±3 cm (±1.2 in) accuracy. By averaging measurements for several seconds, you can further improve point accuracy to the millimeter level. This level of positioning accuracy rivals first-class surveying instruments while being simple to operate and compact.

By using solutions like LRTK, simple surveying can be carried out on site without specialized RTK knowledge, achieving both labor savings and higher-level work. If you need to quickly measure with minimal complex setup in environments that demand high accuracy, consider LRTK smart surveying.

FAQ

Q: What is RTK? A: RTK (Real-Time Kinematic) is a technique that uses two GNSS receivers—a reference station (base station) and a rover—to apply real-time corrections and achieve centimeter-level high-precision positioning. The base station and rover receive signals from the same satellites and cancel out common error sources (such as satellite clock errors and atmospheric errors) to compute high-precision relative positions. GPS alone can have meter-level errors in standalone positioning, but with RTK it can be pinpointed to centimeter-level accuracy, which is why RTK is widely used in surveying and civil engineering.

Q: What accuracy can RTK positioning achieve? A: In sufficiently good conditions with a Fix solution, RTK typically achieves about 1–3 cm (0.4–1.2 in) horizontal accuracy and several centimeters vertical accuracy. For example, roughly 2 cm horizontally and 3–5 cm in height is a common guideline. However, accuracy varies with base station distance, satellite geometry, and environmental conditions. This assumes an integer-fixed Fix solution; if the solution is a Float, accuracy can drop to several tens of centimeters. Maintaining a stable Fix solution is essential to consistently obtaining centimeter accuracy.

Q: What should I do if I cannot obtain a Fix on site? A: First, review the measurement environment. If there are tall buildings or obstructions nearby, move slightly to an open location to secure satellite visibility. Also check the number of usable satellites and DOP values, and consider changing the time of measurement if needed. If the base station is too far or corrections are not being received properly, Fix may fail. Check communication status and consider switching correction services or adding base stations. If radio interference is suspected, move away from strong signal sources. Restarting the receiver or resetting settings can sometimes help. As a last resort, abandon real-time positioning on-site and switch to static positioning or post-processing (PPK), but first systematically eliminate possible causes.

Q: Is high-precision RTK possible without expensive equipment? A: Yes. Recently, affordable equipment and services make RTK positioning feasible. Solutions like LRTK—a compact high-precision GNSS receiver that pairs with a smartphone—allow centimeter-level positioning without large surveying rigs. The accuracy that once required instruments costing hundreds of thousands is now accessible with compact receivers and communication services. With such new equipment, even non-specialists can perform high-precision positioning on site.