What is LRTK?
By using an RTK-compatible receiver, it is possible to achieve centimeter-level accuracy that cannot be obtained with standalone positioning. RTK (Real-Time Kinematic) is a positioning method in which multiple GNSS receivers—one at a base station and another at a rover—simultaneously perform GNSS observations to precisely calculate the positional relationship (vector) between them.

Compared to standalone positioning (using only a single receiver), RTK performs relative positioning with a reference station, allowing for error correction and dramatically improving positioning accuracy.

Traditionally, commercially available RTK receivers with integrated antennas and batteries were large and expensive. This led to strong demand from the civil engineering and construction industries for a smaller, more user-friendly, and cost-effective solution—prompting the development of LRTK.

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High-Precision Positioning with CLAS Support
One of the major advancements in the LRTK Pro2 is its support for Japan’s Centimeter Level Augmentation Service (CLAS), provided by the Quasi-Zenith Satellite System (QZSS “Michibiki”). CLAS is a technology that enhances positioning accuracy to within a few centimeters by generating correction signals based on error data from the Geospatial Information Authority of Japan’s electronic reference stations and transmitting those signals via QZSS satellites.

One of the key advantages of CLAS is that, as long as you have a compatible receiver, you can receive the correction data broadcast from satellites free of charge—without needing an internet connection or base station.

How High-Precision Positioning with QZSS/CLAS Works
Correction data generated at ground control stations is transmitted via the "Michibiki" satellites to the LRTK receiver (user device), enabling real-time error correction and achieving centimeter-level positioning accuracy. With CLAS support, LRTK can provide high-precision positioning even in remote mountainous areas or offshore locations where mobile network coverage is unavailable.

There are no limitations based on the distance from a reference station—if the correction signal from Michibiki, which covers nearly all of Japan, can be received, centimeter-level positioning is possible. This is a major advantage compared to traditional network-based RTK methods, such as the VRS system, which require a connection to a mobile communication network.

For example, at the site of the Noto Peninsula earthquake that occurred in 2024, LRTK played an active role in surveying under conditions where communication infrastructure had been disrupted, contributing to immediate high-precision positioning. In this way, CLAS support enables LRTK to provide stable, high-accuracy GNSS positioning even in areas lacking infrastructure or during disaster situations.

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Enhanced Positioning Stability with Triple-Frequency GNSS Reception
Another key technical feature of LRTK is its support for triple-frequency GNSS reception. One of the major sources of positioning error is ionospheric delay, but this can be mitigated by using signals on multiple frequencies. Additionally, by utilizing the carrier phase measurements of multiple frequencies, LRTK can resolve integer ambiguities—essential for high-precision positioning—more quickly and reliably.

By receiving signals on multiple frequencies from several satellites simultaneously, the system becomes less susceptible to obstructions and multipath interference, allowing for stable centimeter-level positioning even under challenging conditions.

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Role of the Tilt Compensation Function
The LRTK Pro2 is equipped with a tilt compensation function that accurately calculates the coordinates of the positioning point (the ground point directly below the tip of the pole), even when the receiver is tilted.

In general, GNSS surveying captures the point directly beneath the antenna, so if the pole is not held vertically, the measured position will be offset from the intended point.

Even when obstacles or elevation differences prevent the pole from being held vertically over the target point, the pole can be inserted at an angle to accurately obtain the coordinates of the intended location.

This tilt compensation function was developed in response to on-site users' requests to enable measurements even if the pole is not held perfectly vertical.

The device also offers excellent dust and water resistance, with an enclosure rated at IP67 to withstand sudden rain and harsh outdoor conditions. Careful attention has been given to the hardware design to ensure durability and stable positioning performance even in the most demanding field environments.

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Compact Design and Long Battery Life Technology
LRTK houses all components necessary for high-precision positioning within a compact body measuring approximately 10 cm in diameter and 5 cm in thickness. With its all-in-one design—integrating both antenna and receiver—there is no need for cable connections between separate devices as in traditional systems. This single unit alone enables centimeter-level positioning.

In terms of power, the device is designed with features that enable long-duration operation on-site.

In remote job sites without internet access, LRTK can be used in a standalone setup with one unit serving as the base station and another as the rover. Additionally, LRTK connects via Bluetooth to a dedicated smartphone app. By installing the free LRTK app on a smartphone or tablet, users can intuitively perform positioning tasks and record data directly in the field.

The location data recorded on-site can be synchronized with the cloud service "LRTK Cloud," allowing users to verify points against maps through a web browser on a PC. From hardware to software to the cloud, LRTK is a fully integrated positioning tool—refined with a field-first approach.

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RTK Utilization with LRTK
As we have seen, the LRTK compact RTK receiver is a product that successfully combines high-precision, stable positioning with excellent adaptability to on-site conditions.

Thanks to Japan’s unique CLAS satellite augmentation system, LRTK enables centimeter-level high-precision GNSS positioning even in areas without cellular coverage. Its triple-frequency multi-GNSS reception ensures continued stable positioning even under challenging conditions. The tilt compensation function allows users to obtain accurate positioning points with a single tap, even in scenarios that were previously difficult, dramatically improving on-site work efficiency.

In addition, its compact all-in-one design, long-lasting battery, and rugged, waterproof construction offer exceptional ease of use and reliability as a surveying instrument. Combining all these design principles, LRTK stands as the optimal RTK positioning solution for a wide range of users—from major contractors and small civil engineering firms to surveyors and infrastructure maintenance professionals.

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If you are interested in introducing LRTK, we invite you to request our free information materials. We have prepared detailed documentation covering product specifications and real-world application examples. Discover the value that the high-precision GNSS solution "LRTK" can bring to your projects—available now through our downloadable materials.