RTK Construction Site Implementation Guide: Key Points from Preparation to Operation

Table of Contents

• Introduction

• What Is RTK (Overview of High-Precision Positioning)

• Benefits of Introducing RTK on Construction Sites

• Equipment and Preparations Required for Implementation

• Own Base Station Approach vs. Network RTK Approach

• Costs of Implementation

• RTK Implementation Procedure (Step-by-Step)

• RTK Operation Tips (Practical Advice for the Field)

• Legal Requirements and Points to Note at Implementation

• Simple Surveying with LRTK (A New Approach)

• FAQ

Introduction

On construction sites and in civil surveying, positioning with conventional GPS can result in errors of several meters, failing to meet the accuracy required on site. RTK positioning is a technology attracting attention for addressing these issues. By using RTK (Real Time Kinematic), two GNSS receivers (a base station and a rover) perform real-time relative positioning to cancel error factors, enabling centimeter-level high-precision positioning. Obtaining high-precision position information on the spot greatly improves surveying efficiency and accuracy in construction management. With the Ministry of Land, Infrastructure, Transport and Tourism promoting smart construction (i-Construction), the use of RTK-GNSS as an ICT technology is accelerating in the construction industry.

This article is a comprehensive guide to introducing RTK on construction sites, covering the basic mechanism, required equipment, implementation steps, practical field usage tips, and legal points to note. In the latter part of the article, we also introduce LRTK, a new solution that can achieve high-precision positioning more easily than conventional methods. This content is intended to help those introducing RTK to a site for the first time and engineers interested in high-precision positioning form a concrete image of the process.

What Is RTK (Overview of High-Precision Positioning)

RTK stands for Real Time Kinematic, a positioning technique that can determine positions to centimeter-level accuracy by applying real-time corrections to GNSS (Global Navigation Satellite System) positioning errors. Standalone GPS positioning typically experiences errors of about 5–10 m (16.4–32.8 ft) due to atmospheric effects and satellite clock offsets. RTK achieves higher accuracy by using two GNSS receivers—a base station and a rover—and canceling common error components in the satellite signals received by both.

Specifically, a receiver installed at a known, accurate coordinate as a base station computes the error components from the received satellite signals and transmits them as correction information in real time. The rover receives and applies those corrections to its own positioning solution, resulting in a precise position with the errors removed. This method enables immediate positioning accuracy within a few centimeters that cannot be achieved by standalone positioning—truly a real-time differential positioning method.

Using RTK positioning is useful in many on-site scenarios, such as boundary and control point surveys, as-built control (post-construction shape verification), and machine guidance for heavy equipment (automatic control of construction machinery). High-precision GNSS receivers have long existed as surveying instruments, and large-scale civil works have used RTK-GNSS surveying, but recently miniaturization, cost reduction, and software advances have expanded usage to small and medium sites as well.

Benefits of Introducing RTK on Construction Sites

Here are the main benefits gained by introducing RTK on construction sites.

• Centimeter-level high accuracy: Traditionally, millimeter-level accuracy required long static observations or total station surveys. With RTK, however, you can secure equipment-level accuracy of a few centimeters within a short time. This is powerful in situations demanding high accuracy, such as boundary point surveys and as-built verification.

• Immediate position acquisition: Because corrections are applied in real time, simply bringing the rover to the point you want to survey yields coordinates instantly. There is no need to return to the office for post-processing, so you can confirm results on-site and reduce rework.

• Improved work efficiency and labor saving: RTK surveying generally does not require line-of-sight between points. Unlike total station surveys, you do not need to see between points, and as long as GNSS signals are receivable, positioning is possible even with obstacles. Therefore, surveying in complex terrains or around structures becomes easier for one person, enabling one-person surveying. This leads to reductions in personnel and shorter work times.

• Improved safety: Even when surveying points on roads or at heights, GNSS allows measurements from a safe, remote position. This reduces the need for personnel to enter hazardous areas and lowers risks of falls or collisions since there is no need to place reflective prisms at height.

• Easy digital integration: Coordinates collected by GNSS receivers or controllers (data collection terminals) are in formats that are easy to import directly into CAD software or GIS systems. This eliminates manual re-entry from field notebooks, reduces human error, and enables rapid drawing creation. Sharing field-acquired data via the cloud ties directly into ICT construction practices and contributes to digital construction management.

In summary, RTK introduction provides major advantages in accuracy, speed, and efficiency. The i-Construction policy driven by public administration is also a tailwind, and demand for high-precision GNSS surveying is expected to increase.

Equipment and Preparations Required for Implementation

To use RTK on site, several specialized pieces of equipment and preparatory actions are necessary. Below are the main items.

• GNSS receivers (for base and rover): Typically two GNSS receivers capable of high-precision RTK positioning are prepared. Both should be dual-frequency or better for RTK (supporting L1/L2 or L5 bands) and ideally receive multiple constellations such as GPS, GLONASS, Galileo, and QZSS. Prepare surveying antennas compatible with each receiver.

• Base station mounting hardware: The base station receiver must be firmly fixed in place. On site, set it on a tripod, dedicated pole, or a bracket attached to a building, and measure and record the antenna height (height from the ground to the antenna center) accurately. It is ideal to place the base station on a known point (a point with previously determined accurate coordinates) if possible.

• Rover carrying tools: The rover receiver is carried by an operator to survey each point. Generally, a GNSS antenna is mounted at the tip of a surveying pole about 2 m (6.6 ft) long, and a bubble level is attached near the bottom of the pole. When setting the antenna over a survey point, the pole must be held vertically, which is why a bubble level is used. Some modern receivers can correct pole inclination, but the basic principle is to maintain verticality while measuring.

• Communication methods (for transmitting correction information): A communication method is required to deliver the base station’s correction information to the rover in real time. Typical methods are radio modems or the Internet-based NTRIP method. When using radio, equipment such as low-power personal radio (920 MHz band) or UHF business radios is used to transmit directly between base and rover. For NTRIP, connect the base station to the Internet and stream correction data through an NTRIP caster server; the rover receives data via a cellular connection. If using network-based services, set up contracts and accounts with the correction data provider beforehand.

• Power and batteries: Ensure power for GNSS receivers and radio equipment. Portable batteries are commonly used on site. For long surveys, carry spare batteries to ensure sufficient capacity. If using tablets or smartphones on the rover, prepare chargers for those devices as well.

• Knowledge of known-point coordinates: It is important to know the exact coordinates (latitude, longitude, elevation) for the location where the base station will be installed. For public surveys, reference GNSS reference stations from the Geospatial Information Authority of Japan or existing triangulation points. If no known point exists on site, you can use network RTK to estimate base coordinates and later localize them; however, if the base station coordinates are inaccurate, all measured positions will be offset, so exercise caution.

With the above equipment and preparations, you have the foundation needed to start RTK surveying. Next, confirm that there are two major operational approaches for RTK in practice.

Own Base Station Approach vs. Network RTK Approach

There are two main operational choices for RTK positioning.

• Own base station operation (self-hosted RTK): Prepare your own base-station GNSS receiver and distribute correction information directly from the station installed on site. Advantages include operating independently without relying on external services and being able to position in areas without cellular coverage such as mountainous regions. There are no monthly service fees. Drawbacks include the extra cost of purchasing base-station equipment and the need for radio licensing and operational management if using radio communications. If you use the system at multiple sites, the time and effort to set up a base station each time should also be considered.

• Using an existing reference-network service (network RTK): Subscribe to correction data from the Geospatial Information Authority’s network of reference stations or a private GNSS correction service. You can start with only a rover receiver and no base station, lowering initial barriers. If cellular coverage is available, you can position nationwide and easily move between multiple sites. Disadvantages include ongoing service fees (typically a few thousand to several tens of thousands of yen per month) and difficulty using the service where mobile signals do not reach. Some services also require initial setup or coordinate system adjustments.

The own base station approach is suitable for places where real-time communication is difficult or for long-term projects, while network RTK is convenient for instant positioning over wide areas. Choose the approach that best fits site conditions and operating costs.

Costs of Implementation

Next, an overview of costs when introducing an RTK system. Costs vary widely depending on the chosen approach and equipment configuration.

• Initial equipment purchase: Traditional, high-precision surveying GNSS systems (sets of dual-frequency receivers from major manufacturers) can cost several million yen when equipping both a base and rover. Including high-performance antennas, dedicated controllers, and radio equipment makes the total very expensive. On the other hand, if you use network RTK and only prepare a rover, you may start from several hundred thousand yen up to around one million yen. Recently, low-cost GNSS chip–based receivers and smartphone-compatible RTK devices have appeared, significantly reducing initial cost.

• Running costs: With network RTK, subscription fees for correction data are recurring. Typical monthly fees range from several thousand to several tens of thousands of yen depending on coverage and guaranteed accuracy. With a self-hosted base station, there are no service fees, but there may be costs for radio license acquisition and maintenance (e.g., periodic calibration or battery replacement).

• Other costs: Additional expenses include surveying poles, tripods, cables, and data communication contracts (SIM cards). If you plan to link survey software or CAD, include license fees. For first-time implementations, budget for training and trial operation periods for staff.

RTK implementation costs depend on purpose and scale. While low-cost equipment options have lowered barriers, selecting the optimal combination for your needs is important. A cheap system may suffice in some cases, while high-reliability projects may require more robust equipment.

RTK Implementation Procedure (Step-by-Step)

Below is a step-by-step outline for implementing RTK and beginning operation. Details vary by equipment and environment, but this provides an overview.

• Base station installation and setup: Install the base-station GNSS receiver at a control point on site. Ideally, use a point with known accurate coordinates (triangulation point, reference station, or an existing site control point). Secure the antenna on a tripod or similar, measure the antenna height, and enter it into the receiver or software. Set the receiver to base-station mode and register the coordinate value for that location. If the global geodetic coordinates are unknown, you can temporarily set a local coordinate and later correct for offsets. If connecting the base station to the Internet, use a SIM card or pocket Wi‑Fi and enter the NTRIP caster information (server address, port, mount point, login ID/PW) to start streaming correction data. For radio transmission, configure the transmitter frequency and power so the rover can receive. Check that the base station is receiving satellites stably (monitor the number of satellites and DOP values).

• Rover startup and connection: Power on the rover GNSS receiver and configure it to receive corrections from the base station. Mount the rover antenna on the pole and enter the antenna height if required. For NTRIP, set the same caster information on the rover client. For radio, power on the radio receiver on the rover and tune it to the same channel or frequency as the base. If configured correctly, the rover will begin receiving correction data from the base station.

• Confirming a high-precision solution (Fixed solution): After correction data reception begins, check the solution status on the rover. Initially, without corrections the solution is Single, then it moves to Float, and finally converges to Fixed. A Fixed solution indicates that carrier phase integer ambiguities have been resolved and centimeter-level accuracy has been achieved. In open-sky environments, Fix is typically achieved within several tens of seconds to a few minutes after power-up. Confirm that the rover displays “FIX” and that position quality indicators are sufficiently small. Stable maintenance of the Fixed state indicates RTK is functioning properly.

• Surveying points: Once Fixed is achieved and high-precision positioning is available, survey the target points. Move the rover (antenna on the pole) to each point and record coordinates. Place the pole tip over the point, hold it still for several seconds until values stabilize, and press the observation button on the data collector or app to record the coordinates. Many devices offer modes that average several seconds of position or record instantaneous positions. In all cases, keep the pole vertical (even with tilt-compensation receivers, verticality is the basic principle). When surveying multiple points, prepare a list of point names or numbers in advance and assign names during recording to simplify post-processing. Some apps allow importing a point list and selecting points while surveying to avoid mistakes.

• Verification and saving results: After surveying all required points, verify and save the collected data. If possible, re-measure a known control point on site and compare the obtained coordinates with the known accurate values. Performing check measurements on known points at the start or end of work verifies the overall system accuracy (errors within a few centimeters are acceptable). Large discrepancies may indicate incorrect base-station coordinate input or datum setting errors, which should be corrected. If no issues are found, back up all survey point data. Sync coordinate lists stored in the data collector or smartphone to the cloud and copy to external storage for redundancy. Finally, power down and pack equipment. After fieldwork, charge batteries and clean and inspect equipment.

These steps outline the typical flow from RTK implementation to actual measurement. First-time users may encounter uncertainties in each step, but understanding the basic sequence will help handle situations calmly on site.

RTK Operation Tips (Practical Advice for the Field)

Here are several points and cautions to remember for smooth RTK operation on site. To maintain high accuracy and prevent trouble, pay attention to the following.

• Ensure satellite reception environment: Open-sky visibility is the foundation of GNSS accuracy. In areas with tall buildings or dense trees, the number of visible satellites may decrease and multipath errors from signal reflection may increase. Operate both base and rover in locations with as much visibility as possible. If surveying in obstructed environments, choose times with favorable satellite geometry or slightly relocate measurement positions to stabilize accuracy. Vertical accuracy is especially sensitive, so plan observations with sufficient margin.

• Unify equipment settings and datums: The coordinate system entered at the base station must match the coordinate system used on the rover. In Japan, the World Geodetic System (JGD2011) is typically used, but if you use a local coordinate system on site, you will need to convert it later in the office. Align settings with the final deliverable coordinate system in mind. Also double-check communication settings (frequency and NTRIP info) and antenna height entries to avoid input errors.

• Stable radio communication: When using radio in a self-hosted base station setup, ensure the radio signal reliably reaches the rover by considering antenna placement and height. Low-power personal radios have an approximate line-of-sight range of 100 m (328.1 ft), so consider mounting the base station higher or using a repeater if necessary. When using higher-power radios, comply with radio laws and choose frequencies with minimal interference. In urban areas, surrounding radio interference may destabilize communication.

• Battery management: Monitor battery levels so receivers and communication devices do not run out during surveys. Carry spare batteries and swap them at appropriate intervals for long tasks. Note that battery performance drops in cold climates. Charge batteries after daily work and replace degraded batteries promptly.

• Data backup: Always back up coordinates collected on site the same day. Upload to cloud storage or internal servers when possible to guard against device failure or loss. Recording key point values in a field notebook is also useful. Raw data and project files are critical deliverables for design and construction, so store them in multiple locations for risk mitigation.

• Regular verification and calibration: Long-term operation may see changes in equipment characteristics or the surrounding environment that affect accuracy. Periodically measure known points to check errors and send equipment for manufacturer calibration when necessary. Keep an eye on firmware and software update notices and use the latest stable versions when possible.

Following these points will help you use RTK surveying reliably. Even with high-precision equipment, performance depends on environment and settings, so careful operation based on fundamentals is required.

Legal Requirements and Points to Note at Implementation

When introducing and operating RTK on construction sites, pay attention to related laws and regulations. Main points are summarized below.

• Surveying Act and public surveys: In Japan, surveying is regulated under the Surveying Act. Private in-house surveys for company use do not normally require special permission, but for public surveys—such as cadastral surveys or public construction as-built surveys—registration as a surveying business, placement of qualified personnel, and adherence to work procedures are required. For GNSS-based public surveys, follow Geospatial Information Authority guidelines and as a rule use GNSS equipment certified by the Director-General of the GSI as “Class 1 GNSS surveying instruments” for high-assurance public surveys. This standard applies to public surveys, and ordinary construction surveys or in-house as-built checks do not always require Class 1 equipment. The important point is to ensure sufficient accuracy and reliability for the intended purpose. For official boundary determination and other legal procedures, conduct surveys under the supervision of licensed surveyors.

• Compliance with the Radio Law: If correction information is transmitted by radio from the base to the rover, ensure the radio equipment complies with the Radio Law. In Japan, low-power personal radios (920 MHz band, output ≤10 mW) require no license but have limited range. Using higher-power radios (e.g., simple radios in the 351 MHz band or 1 W UHF radios) requires applying for a radio station license from the Ministry of Internal Affairs and Communications. License acquisition may require personnel with radio operator qualifications, so if your company lacks that expertise, opt for communication methods that do not require a license (cellular or low-power radio). Choose devices with technical conformity certification (Giteki) to avoid operating illegal radio stations.

• Handling of survey results: When using RTK data for public purposes (e.g., land registration or deliverables for public works), verify that the results meet the required accuracy. For example, cadastral surveys or boundary determinations may demand millimeter-level accuracy, so it is common to validate RTK results with total station measurements. For electronic deliverables, organize coordinates in required data formats (such as GSI’s SIMA format). Even with RTK, traditional surveying knowledge and legal requirements remain important; apply new technologies within established practices.

• Equipment certification and scope of use: As with Class 1 GNSS surveying instruments, uncertified devices may not be allowed for official surveys. New smartphone-linked, simplified RTK devices may offer high accuracy but lack formal certification. Lack of certification does not necessarily indicate poor performance; manufacturers may forgo certification for cost or market reasons. Some uncertified devices have shown performance comparable to Class 1 instruments in internal verification. However, for public surveys, certified models are generally required, so take care when using uncertified devices for official purposes. For routine construction surveys and as-built checks, uncertified devices can be useful if you perform prior internal accuracy verification.

In short, RTK implementation requires attention to legal and institutional issues as well as technical matters. In most cases, common-sense precautions allow smooth operation, and consulting surveying professionals can reduce risks.

Simple Surveying with LRTK (A New Approach)

So far we described the two conventional methods for RTK: installing your own base station or subscribing to an external network RTK service. Recently, however, a new approach has emerged to further reduce the effort and cost of those methods and make centimeter-level positioning easier. One such system is called LRTK. LRTK is a high-precision positioning solution that pairs with smartphones and minimizes the need for specialized surveying equipment and complex settings, aiming to make high-precision positioning accessible to anyone.

LRTK realizes RTK-equivalent precise positioning with a remarkably simple workflow by combining a compact dedicated GNSS receiver and a smartphone app. For example, attach a receiver to a smartphone, hold it in one hand, and tap a button on the app at the point to be measured to obtain high-precision coordinates. It also enables height-direction positioning that standalone GPS cannot achieve, reaching professional surveying levels of accuracy—about ±1–2 cm (±0.4–0.8 in) horizontally and within a few centimeters vertically—while remaining very intuitive to operate. Unlike conventional RTK equipment, LRTK avoids complex field adjustments and requires little specialized knowledge.

Unlike traditional RTK, LRTK users do not need to provide their own base station or contract with external correction services. Proprietary algorithms that use cloud correction data and positioning information from multiple points enable centimeter-level accuracy with a single receiver. Acquired coordinates are automatically converted to Japan’s geodetic reference frame on the map, so datum conversion and data management are handled by the cloud service. In short, with a smartphone and an LRTK device, even non-surveyors can perform precise surveying easily.

LRTK can be seen as a third option that resolves the complexities of both self-hosted base stations and network RTK. The required equipment is compact and portable, and you do not need to set up your own communications. On site, simply pressing the positioning button yields results—an ease of use unmatched by conventional methods. Depending on site conditions and required accuracy, the optimal positioning method may vary, but for those who want to try high-precision surveying more casually or need accurate positioning despite not being specialists, LRTK is a strong candidate. Advances in technology are making centimeter-level positioning more accessible than ever.

FAQ

Q1. What is the difference between RTK and ordinary GPS positioning? A1. Standalone GPS (GNSS) positioning calculates position using only satellite signals and typically yields errors of about 5–10 m (16.4–32.8 ft). RTK, on the other hand, uses correction information from a base station to cancel error factors in real time, enabling position determination within a few centimeters. In short, RTK dramatically improves positioning accuracy in real time compared with ordinary GPS.

Q2. What level of accuracy can RTK surveying achieve? A2. In favorable conditions, RTK surveying typically achieves about ±1–3 cm (±0.4–1.2 in) horizontally and ±3–5 cm (±1.2–2.0 in) vertically. However, accuracy depends on distance from the base station and satellite reception conditions; errors increase with distance from the base and in environments with many obstructions. In open-sky conditions near the base station, errors around 2 cm (0.8 in) are common. Using multi-GNSS and multi-frequency receivers helps maintain stable high accuracy.

Q3. How much does it cost to introduce an RTK system? A3. Implementation costs vary by approach and equipment. A high-performance surveying GNSS set for both base and rover can reach several million yen in initial cost. Conversely, purchasing only a rover and using network RTK may start from a few hundred thousand yen. Low-cost smartphone-based RTK options are also available. For network RTK, monthly fees of several thousand to several tens of thousands of yen are typical. With a self-hosted base, there are no service fees, but budget for radio licensing and equipment maintenance. Choose the method that fits your usage and budget.

Q4. What is needed to use network RTK? A4. For network RTK, the essentials are an RTK-capable GNSS receiver (rover) and a communication method. Specifically, you need the receiver and antenna plus an Internet connection (embedded SIM or smartphone tethering) to connect to a correction data service. Pre-contract with a correction service and configure the receiver or app with server and account information. On site, power on the receiver and communication device and connect to the service to start receiving corrections. In short, a single rover and network access are sufficient to operate network RTK.

Q5. Are licenses or qualifications required to use RTK? A5. Qualifications are not strictly required to perform RTK surveying itself, but certain permissions and certifications may be relevant depending on the operation. If you run your own base station using high-power radio, a radio station license is required and the license application must usually be handled by personnel with radio operator qualifications. Low-power personal radios generally do not require a license. If undertaking public surveying work, registration as a surveying business and work by licensed surveyors or supervised staff is required. For typical construction companies using RTK on their own sites, these licenses and qualifications are not necessary for basic use, but ensure legal requirements are met when using survey results for official purposes.

Q6. Can someone without surveying experience use RTK effectively? A6. Traditional RTK equipment sometimes required specialist knowledge, but user-friendly devices and support apps have made operation easier for newcomers. Smartphone-linked RTK solutions (such as LRTK) are designed for intuitive operation while providing high-precision positioning. Nonetheless, understanding GNSS fundamentals is recommended to ensure accuracy and troubleshoot issues. For critical survey outputs, support from experienced surveyors and double-checks provide assurance.