For Beginners: Procedure to Set Up an RTK Base Station

Table of Contents

• What is RTK?

• Role of an RTK Base Station (Reference Station)

• Benefits of Setting Up an RTK Base Station

• Required Equipment for an RTK Base Station

• Site Selection and Preparation for an RTK Base Station

• Procedure to Set Up an RTK Base Station

• Operation Tips for RTK Base Stations

• Simple Surveying Using LRTK

• FAQ

What is RTK?

In surveying for construction sites and infrastructure inspection, conventional GPS positioning can produce errors on the order of several meters, which may not meet required accuracy. The high-precision positioning technology that has attracted attention in recent years is RTK (Real Time Kinematic). With RTK, two GNSS receivers—a base station (reference) and a rover (mobile)—perform real-time relative positioning, enabling centimeter-level high-precision positioning.

Specifically, a base station is installed at a point whose coordinates are known accurately in advance. The base station computes the difference (error) between its measured GNSS-derived position and the known coordinate value. It then sends that correction information to the rover, which applies the correction to its positioning result in real time, reducing errors that would normally be several meters down to a few centimeters. Because both receivers observe signals from the same satellites, common error sources originating from the satellites or the atmosphere are canceled out, allowing high-precision relative positioning.

Such high-precision positioning data obtained with RTK greatly contributes to improving surveying efficiency and construction quality control. Recently, RTK technology has been increasingly applied in various fields—smart construction using ICT, aerial surveying with drones (UAVs), and autonomous tractors in agriculture, among others.

Role of an RTK Base Station (Reference Station)

In RTK positioning, a base station is a GNSS receiver that functions as a fixed reference point (sometimes called a "base"). The base station is set up at a location whose coordinates are known accurately in advance, and it calculates in real time the discrepancy between the GNSS positioning it receives and the preset known coordinate values. It then transmits that correction information to the rover, which applies the corrections to its positioning to achieve higher accuracy. In other words, the base station acts as a "stationary GNSS" and serves as the foundation for correcting the rover’s positioning.

If no base station is present in RTK, the rover alone performs normal GNSS positioning (single positioning), which results in errors of several meters. To obtain centimeter-level positioning accuracy, the presence of a base station is indispensable. Note that you can also perform RTK positioning by receiving base station data from public base station networks or commercial correction services, without installing your own base station (discussed later).

Benefits of Setting Up an RTK Base Station

Even in environments where network-based RTK (receiving corrections via the internet) is available, there are advantages to setting up your own RTK base station. Here are the main benefits of establishing your own base station.

• Usable even outside network coverage: In mountainous or remote areas where cellular signals do not reach, an in-house radio base station allows RTK positioning without internet connectivity.

• Centralized operation of multiple rovers: One base station can share the same correction information with multiple rovers, enabling all equipment on site to position consistently against a unified reference.

• Reduced running costs: By supplying correction information from your own base station without relying on external correction services, you can significantly reduce long-term costs.

• Stable accuracy: Keeping the distance between base and rover (baseline length) short reduces degradation of correction accuracy; within a few km, centimeter-level accuracy is easier to maintain stably.

• Independent operation in emergencies: If communications infrastructure is disrupted due to disasters, having a base station on site allows high-precision positioning to continue locally.

Required Equipment for an RTK Base Station

To build an RTK base station, the following equipment is required.

• High-precision GNSS receiver (for base station): The GNSS receiver unit that supports RTK. To achieve centimeter-level accuracy, a high-performance receiver that supports multiple frequencies (L1/L2, etc.) and multiple satellite constellations (GPS, GLONASS, Galileo, BeiDou, etc.) is desirable.

• GNSS antenna (for base station): Antenna to receive signals from satellites. Some models are integrated with the receiver, but for accuracy-focused setups, a high-sensitivity outdoor antenna (e.g., a large choke-ring antenna) should be used.

• GNSS receiver and antenna (for rover): To use RTK, a rover-side GNSS receiver and antenna separate from the base station are also required (this article focuses on constructing the base station, but positioning cannot be performed without rovers).

• Communication equipment (radio or internet connectivity): Means to transmit correction data from the base station to the rover. For radio transmission, a transmitter at the base and a receiver at the rover are needed (e.g., specific low-power radios or UHF data radios). For internet-based transmission, connect the base station to the internet (via built-in SIM cellular connection or an on-site Wi‑Fi router) and use an NTRIP server (caster) to distribute the data.

• Tripod, pole, and other mounting hardware: Survey tripods or poles to stably fix the base station antenna. For long-term operation, a mounting pole may be installed on a rooftop or similar location.

• Power supply: Batteries or power supplies to power the receiver and communication equipment. For extended outdoor operation, consider large-capacity batteries or solar panels.

• Configuration device: A device for configuring and checking the GNSS receiver. Many receivers connect via Bluetooth or USB and are configured and monitored using a dedicated smartphone app or PC software.

Site Selection and Preparation for an RTK Base Station

When installing an RTK base station, it is important to place the antenna in as favorable an environment as possible. Choose an open site with no tall buildings, trees, or other obstructions so that the sky is visible. If obstructions are abundant, satellite signals can be blocked or reflected by buildings and walls (multipath), causing reduced positioning accuracy or longer times to obtain a fixed solution.

Also, ideally the base station should be located near the area where surveying will be performed (the area where rovers operate) and on stable ground. For example, on a construction site, set the tripod near the center of the site with a good view; for long-term use, fix the antenna to a firm, low-vibration location such as a building rooftop.

Next, preparing the coordinate values to set in the base station is important. The base station must have accurate coordinates of its installation position in advance. The most reliable method is to place the antenna over a reference point with known public coordinates (for example, triangulation points or permanent reference stations), but often such known points are not available on site. In that case, install the base station at an arbitrary point and later determine its coordinates with high precision. For example, conduct several hours or more of satellite observation (static surveying) at the base station and process the data later to compute precise coordinates. Another approach is to use a rover to survey nearby known points and adjust the base station coordinates to match those known points (localization). If you cannot obtain precise coordinates immediately, you can start operations using provisional coordinates determined by simple positioning at the base station and later apply a parallel shift correction to the collected survey data to align with known points—a method commonly used on sites.

Additionally, when installing the base station, accurately measure and record the antenna height (the vertical distance from the ground or reference point to the antenna phase center) and enter it into the receiver settings. This ensures proper height corrections in later survey data. At the initial setup stage, check settings such as the GNSS positioning mode and which satellites and frequency bands to track. If the receiver supports multi-GNSS, enable all satellite systems unless there is a specific reason not to, and set the RTK solution update rate as needed (for typical topographic surveying, 1Hz is sufficient; for machine guidance on heavy equipment, 5–10Hz may be used). After these preparations, proceed to the base station setup procedure described next.

Procedure to Set Up an RTK Base Station

Now let’s look at the concrete steps to set up an RTK base station. Here we assume a simple configuration of one base station + one rover, and explain the flow from base setup to starting rover positioning.

• Install the equipment: Securely mount the GNSS antenna used as the base station on a tripod or pole and connect it to the GNSS receiver unit. Keep the antenna level and install it in a stable position (a location with a wide sky view). Turn on the receiver and confirm that it begins receiving satellites normally.

• Measure and input antenna height: Measure the base station antenna height (vertical distance from the ground or reference point to the antenna phase center). Enter the measured antenna height later in the receiver’s settings so it is reflected in positioning calculations.

• Set base station coordinates: Enter the base station’s precise latitude, longitude, and height into the receiver. If installed over a known point, input those values; if unknown, use the receiver’s averaging function or similar observation-based method to calculate provisional coordinates and set them. Confirm the coordinate system (in Japan, for example, the JGD2011 geodetic system) and how ellipsoidal heights are handled according to the receiver’s specifications.

• Configure correction data distribution: Configure the receiver to broadcast correction information from the base station. For internet-based distribution, connect the receiver to the network and input the provided NTRIP caster address, port, mount point name, and login information. For radio transmission, configure the connected radio’s frequency channel and output so it pairs with the rover-side radio receiver.

• Start and verify the base station: Save the base station settings and start broadcasting correction data. Verify on the receiver display or app that the status shows “Broadcasting” or similar, and confirm that the number of satellites and DOP values are good. If the base station is stably sending data, it will wait for connections from rovers.

• Configure rover reception: Set up the rover GNSS receiver to receive correction data from the base station. For NTRIP, enter the same caster information to start the client connection; for radio, set the rover radio to the same frequency and put it in receive mode. When the rover receives correction information, its solution will transition from “Single” to “Float” and then to “Fixed.”

• Verify positioning accuracy: Once the rover obtains an RTK fixed solution, check the achieved accuracy. Monitor whether the rover’s current coordinates in the fixed state remain stable within a few centimeters; if possible, measure a known point and compare the error against its known coordinates. If horizontal errors are within a few centimeters and vertical errors within several tens of centimeters, the base station setup is successful.

Operation Tips for RTK Base Stations

When operating an RTK base station, pay attention to several points to maintain stable, high accuracy. Key items are summarized below.

• Ensure sky visibility: Place both base and rover in as open a view of the sky as possible. Insufficient satellite tracking leads to degraded accuracy and increased time to obtain a fixed solution. Watch for environmental changes (cranes being erected during construction, seasonal foliage growth, etc.) and maintain satellite visibility.

• Manage baseline distance: The greater the distance between base and rover (baseline length), the more the effectiveness of corrections diminishes and accuracy becomes unstable. Practically, aim for up to about 10 km. Place base stations near the surveying area when possible, and consider multiple base stations to cover wide areas.

• Choose communication methods appropriately: Select correction data communication methods according to radio conditions. NTRIP using cellular networks is convenient for urban areas and for operating multiple units over wide areas, but may be out of range in mountainous areas. Radio transmission offers excellent real-time performance within line-of-sight, but low-power radios typically have a practical range of about 1 km. Consider relays or higher-power digital radios (which may require a license) if needed.

• Plan for communication interruptions: Many receivers can maintain accuracy using internal prediction for several tens of seconds if correction data is temporarily interrupted. Do not panic for short outages of a few seconds to a dozen seconds—wait and check whether the fixed solution quickly recovers after reconnection. If interruptions are frequent, raise the radio antenna, move the rover to a location with better cellular reception, or take other measures.

• Base station coordinate accuracy: Errors in the base station coordinates translate directly to the rover’s coordinates. When high accuracy in a public coordinate system is required, place the base station on as accurate a known point as possible or correct the base station coordinates beforehand (or perform post-processing adjustments). Even if you start with provisional coordinates, be sure to later verify corrections using known points and adjust the resulting coordinates.

• Equipment maintenance: Because base station equipment often runs outdoors continuously, implement waterproofing, dust protection, and theft prevention. For long-term use, regularly inspect antenna mounting, cable integrity, and battery levels to ensure stable operation.

Simple Surveying Using LRTK

As explained so far, building an RTK base station requires preparing equipment and performing various settings. For beginners, some parts may seem somewhat challenging. One solution that greatly simplifies these procedures is LRTK. LRTK is a system that combines a compact high-precision GNSS receiver with a smartphone app, enabling RTK surveying to be completed with just an iPhone.

With LRTK, simply selecting base station mode in the dedicated smartphone app and tapping a button automatically starts everything from network RTK settings to correction data distribution. You do not need to handle cumbersome NTRIP connection settings or adjust radio frequencies manually. Positioning status checks and data recording are all intuitively operable on the smartphone screen, so workers without specialized training can use the system after a brief explanation.

Additionally, LRTK receivers are rugged with industrial-grade waterproof and dustproof designs (compliant with IP standards) and can be used reliably in harsh outdoor environments. They also offer extensibility such as enabling 3D scanning and AR-assisted stakeout workflows using just an iPhone. Even beginners who are hesitant to adopt RTK can start smart surveying easily by using LRTK.

FAQ

Q: What is the difference between RTK and regular GPS positioning? A: Regular GPS (single positioning) determines position with a single receiver and typically has errors on the order of several meters. RTK uses two receivers—a base station and a rover—and uses correction information from the base station to cancel errors, achieving centimeter-level accuracy. In short, RTK is “GPS positioning improved with help from a base station,” and the improvement in positioning accuracy is substantial.

Q: Do I have to install an RTK base station myself? A: Not necessarily. You can perform RTK positioning by receiving correction information from national or commercial GNSS base station networks without installing your own base station (network RTK). However, there are significant benefits to setting up your own base station, such as operation in areas without network coverage and cost savings for continued use. As described in this article, setting up your own base station can provide stable accuracy and operational flexibility depending on the use case.

Q: How should I determine the coordinates to set for the base station? A: The most reliable method is to place the antenna over an established reference point with known coordinates (such as a Geospatial Information Authority of Japan control point) and use that value. If known coordinates are not available, you must compute the base station coordinates by long-duration observation with static processing or by surveying other known points with a rover and adjusting the base coordinates accordingly. If you cannot immediately obtain precise coordinates, you can start operations with provisional coordinates and later correct the survey results to match known points.

Q: What is NTRIP? How is it different from sending corrections by radio? A: NTRIP is a protocol for sending and receiving RTK correction data over the internet. A base station publishes correction information to an NTRIP server (caster), and rovers receive that data over the internet via cellular connections. Unlike direct radio transmission, NTRIP allows rovers to receive corrections even tens of kilometers away as long as cellular service is available. In environments where internet connectivity is difficult, such as mountainous regions, traditional radio communication for correction transmission remains effective.

Q: How accurate is RTK positioning? A: Depending on operating conditions, RTK can typically measure positions within a few centimeters of error. For example, with the base station within a few km and good satellite reception, horizontal accuracy of about 2–3 cm and vertical accuracy of around 5 cm can be achieved. However, if there are many obstructions nearby or the distance is large, it can be more difficult to obtain a fixed solution and accuracy may deteriorate.

Q: Do I need qualifications or licenses to use RTK? A: No specific qualifications are required to use RTK positioning itself. Anyone with the appropriate equipment can perform RTK surveying. However, for radio-based correction transmission, some radios may require radio operator licenses or a radio station registration (for example, when using high-power professional radios). Also, when using RTK surveying results for public surveying purposes, the work may need to be conducted under the supervision of a licensed surveyor, so be mindful of applicable operational rules.

Q: What is LRTK? A: LRTK is the name of the compact RTK-GNSS solution provided by our company. By attaching a small receiver to an iPhone and using a dedicated app, you can easily perform centimeter-class positioning. The system allows what used to be complex base and rover setup to be completed with a single tap. Its ease of use without requiring specialized knowledge is a key feature, significantly improving efficiency for on-site positioning tasks.