How to Connect Your LRTK Device and Smartphone App via Bluetooth
Pairing and connecting your LRTK device with your smartphone is straightforward. Below, we’ll walk you through each step—from preparing your hardware and configuring the app to completing the Bluetooth pairing.

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Equipment Preparation
First, prepare the LRTK device itself and your smartphone.

• Power On the LRTK Device: Press and hold the power button on the LRTK unit (whether it’s an LRTK Phone or LRTK Pro) until it powers up. Confirm that the status LEDs or other indicators light up, indicating the unit is operational. Also, check beforehand that the battery level is sufficient for your session.

• Enable Bluetooth on Your Smartphone: Next, turn on Bluetooth on your smartphone. On an iPhone, go to Settings > Bluetooth and toggle it on. On Android, open Settings > Connected devices > Bluetooth (or a similar menu) and enable it. Also make sure Location Services are turned on, as Android may require location permission to scan for Bluetooth devices.

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App Installation
Install the dedicated smartphone app for communicating with your LRTK device. The LRTK app is available for both iOS and Android and can be downloaded free of charge from the App Store or Google Play.

• Obtain from the App Store: If you are using an iPhone or iPad, open the App Store, search for “LRTK,” and install the official app provided by Reflexia Inc.

• Obtain from Google Play: On Android smartphones, open the Google Play Store, search for “LRTK,” and install the app.

After installing, open the app and complete the initial setup, including agreeing to the Terms of Use. The app supports Japanese and may display a brief tutorial on first launch. At this point, your smartphone is fully prepared.

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Bluetooth Pairing Procedure
Now, let’s connect your smartphone and the LRTK device via Bluetooth pairing. Please follow the steps below.

1. Detecting the Device on Your Smartphone: Open your smartphone’s Bluetooth settings screen and view the list of available devices. With the LRTK device powered on, you should see an entry like “LRTK XXXX” or the model name (e.g., “LRTK Phone” or “LRTK Pro”). The exact display name may vary by model or device ID, but look for a device name that includes “LRTK.”

2. Select the LRTK Device: Tap the detected LRTK device name in the list to start pairing. The first time you pair, your phone will display a “Pairing Request”—approve it to continue. If prompted for a PIN, enter the code shown in your LRTK manual (commonly 0000 or 1234).

3. Confirm Pairing Completion: In your phone’s Bluetooth settings, verify that the LRTK device is listed as “Connected” or “Paired.” For extra assurance, check the LRTK unit itself—many models change their LED color or blink pattern when a Bluetooth link is active. Once you see this confirmation, your smartphone and LRTK device are successfully connected and ready for wireless operation.

4. Verify Connection in the LRTK App: Next, launch the LRTK app you installed. The app should automatically detect the device, and once the connection is established, the connected LRTK device name will appear at the top of the screen—for example, “LRTK Phone (#XXXX) Connected.” You should also see satellite count and basic position information begin updating. If the app does not recognize your device, check the app’s settings menu for an option to manually select the Bluetooth connection.

With that, the Bluetooth pairing procedure between your smartphone and the LRTK device is complete. Once paired, simply launching the app will automatically connect to the device. This clears the preparation phase for RTK positioning, so next let’s move on to configuring the reception of the correction data necessary for high-precision measurements.

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Configuring Correction Data Reception
To achieve centimeter‐level accuracy with RTK positioning, it is essential to use correction information (error‐correction data) rather than standalone GPS. Correction information refers to the GNSS error data received at a base station (reference point) and transmitted to the rover (LRTK device) to enhance positioning accuracy.In this section, we will explain the types of correction data and how to obtain them, the steps for configuring them in the LRTK app, and methods for verifying that you have achieved an accurate positioning solution.

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Types of Correction Information
There are two main types of correction data used in RTK.One method is to use a public or commercial network RTK service (e.g., via the NTRIP protocol), and the other is to use correction data broadcast from your own base station (a local control point).

• Network RTK Corrections: This method connects over the Internet to a dedicated correction service (for example, the Geospatial Information Authority of Japan’s Continuously Operating Reference Stations network or a commercial RTK correction provider) to receive correction data broadcast from reference stations. By subscribing to a nationwide service, you can achieve high-precision positioning without setting up your own base station on site. Although a service contract is required, it offers the advantage of stable corrections over a wide area.

• Local Base-Station Corrections: In this approach, you deploy your own base station on or near the site at a point with known coordinates, and broadcast correction data to your rover over a short-range radio link or local LAN. For example, you can run a second LRTK Pro in Base mode and transmit RTK corrections directly to your rover’s LRTK unit. Because all communications remain within the site, no Internet connection is required. The trade-off is that you must provide and set up your own base-station equipment and communications (for instance, using the L-Link radio feature available between LRTK Pro units).

In either case, once the rover’s LRTK unit receives the correction data, high-precision relative positioning (RTK) is achieved. In practice, network RTK (NTRIP) is most commonly used for its convenience, but in areas without cellular coverage—such as remote mountain regions—you can switch to a private base station plus radio link.

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Correction Data Settings in the App
In the LRTK app, configure how it receives correction data (e.g. your NTRIP connection). With your smartphone online, follow these steps:

1. Subscribe & Prepare Connection Details: If you’re using a network RTK service, sign up in advance and obtain the necessary connection details (NTRIP server address, port number, mount-point name, and login credentials). Various services are offered by local governments or private companies, so choose the one that best fits your needs. If you’re using your own local base station, verify how your rover will receive its correction data (e.g. via Bluetooth or Wi-Fi).

2. Open the correction settings screen in the LRTK app: On the app’s home screen, look for the “High-Precision Positioning Settings” section. You should see several icons or menu items such as “Network RTK,” “CLAS,” and “L-Link.” (*Note: CLAS refers to the centi­meter-level augmentation service from Japan’s Quasi-Zenith Satellite System and requires a compatible receiver.) To use a network RTK service, tap to open the “Network RTK” settings screen.

3. Enter your NTRIP connection details: In the Network RTK settings screen, input the NTRIP connection information provided by your service. Specifically, enter the correction-data server’s URL or IP address, the port number, the mount point name (i.e., the virtual reference-station identifier), and the user ID and password issued by your provider into the corresponding fields. Double-check for typos, then tap “Save” or “Connect” to activate the settings.

4. Start receiving correction data: Once your settings are correct, the smartphone app will connect over the Internet to fetch the correction stream and forward it in real time to your LRTK device via Bluetooth. The LRTK then uses those corrections to perform RTK calculations and compute high-precision position coordinates. You can usually monitor correction reception and satellite status in the app (for example, an indicator showing “Correction: Receiving”). With a good connection, you should see your position accuracy tighten up within a few seconds.

5. For Base-Station Mode: If you’re using your own local base station, switch the rover’s correction source in the app to “Local Base Station” or “L-Link.” For example, when two LRTK Pro2 units are linked via their built-in radio, turning on L-Link in the rover’s app will let it receive the wireless corrections broadcast from the base-station LRTK. You’ll also need to configure the base station itself (enter its known coordinates and start broadcasting), but we’ll omit those details here. The key point is simply to ensure the rover’s app is set to receive correction data by whatever method you’re using.

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How to Check Positioning Accuracy
Once the correction data is being received successfully, the LRTK unit will begin high-precision RTK positioning. Next, let’s verify the actual accuracy of the solution you’re getting. In RTK there are two types of computed solutions (or “modes”): the Float solution and the Fix solution.

• Float Solution (Floating Solution): This is a solution that has received correction data but has not yet resolved the integer ambiguities (the unknown whole-cycle phase differences between satellite signals). Its accuracy is typically on the order of tens of centimeters up to about one meter, and it represents the transitional phase after starting RTK positioning until a Fix solution is achieved. A Float solution may persist if there are too few satellites, poor satellite geometry, or unstable reception conditions. Because a Float solution does not yet offer full high precision, it is generally not used as the final positioning result; instead, you wait for the solution to converge to a Fix.

• Fix Solution (Fixed Solution): This is the solution state where the integer ambiguities between satellites have been resolved and the RTK calculations have stabilized. It guarantees centimeter-level accuracy, with actual positioning errors typically on the order of a few centimeters horizontally (about 5–20 mm) and within a few centimeters to a few tens of centimeters vertically. The ultimate goal of RTK positioning is to achieve a Fix solution. In the LRTK app, when the status changes to “Fix,” it confirms that high-precision positioning has been attained. Remember: only once a Fix solution is obtained is centimeter-level accuracy guaranteed.

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On the LRTK app, the current solution status is displayed. For example, when the status indicator changes from “Float” to “Fix,” it’s a sign that high-precision positioning has been achieved. You can also view the HDOP value (Horizontal Dilution of Precision) in the app. HDOP reflects the satellite geometry’s impact on accuracy—values below 1.0 are considered excellent, while values above 2.0 indicate degraded precision. During surveying, be sure to monitor that the HDOP remains low and stable.

How to Utilize the LRTK Device with the Smartphone App
When paired via Bluetooth with your smartphone, the LRTK device can be put to many different uses in the field. In this section, we’ll cover concrete on-site use cases, methods for leveraging your survey data, and troubleshooting tips in case the connection doesn’t work as expected.

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Field Use Cases
High-precision GNSS via smartphone + LRTK is revolutionizing a wide range of on-site operations—from construction and civil engineering to infrastructure maintenance and inspection. Below are some representative examples.

• Layout and Surveying on Construction Sites:
  By using LRTK for setting out (layout) based on design plans, tasks that once required total stations can now be performed more easily with fewer people. For example, you can pre-register your target point coordinates in the LRTK Cloud, then simply follow the smartphone’s guidance on site to reach each point with centimeter-level accuracy. The app’s on-screen guidance and AR overlay allow crew members to intuitively mark batter boards or fixture locations, dramatically improving both efficiency and precision. In surveying operations, equipping each team member with their own LRTK means they can independently measure and record the coordinates of all required points, enabling parallel work and faster completion.

• Infrastructure Inspection & Maintenance: For roadways, railways, and highways, managing inspection photos alongside their precise locations is critical. The LRTK app’s “photo positioning” feature allows you to tag site photographs taken with your smartphone with centimeter-accurate coordinates from the LRTK device. Using this, when documenting bridge cracks or track equipment conditions, you can store images in the cloud complete with exact latitude/longitude. You can then compare past and present inspection photos on a map to accurately assess deterioration over time. In disaster response scenarios, teams can instantly share photos of damage along with their locations, greatly aiding recovery planning.

• Point Cloud Surveying & 3D Documentation: By combining a device like the LRTK Phone with an iPhone’s LiDAR, you can geo‐reference 3D point clouds obtained via photogrammetry or quick scans. For example, using the high-precision coordinates from LRTK as your reference, you scan surrounding structures with your smartphone and embed public-coordinate positioning into the field-captured point cloud. This enables highly accurate as-built verification and post-construction documentation. Because both the point cloud and positioning data can be uploaded to the cloud in real time, you can even review the site’s 3D conditions remotely from the office.

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Data Logging & Cloud Sync
All positioning data captured with the LRTK app is automatically saved on your smartphone and can be synced to the LRTK Cloud as needed. LRTK Cloud is a web service provided by Reflexia that centralizes your survey coordinates, photos, point-cloud data, and more in an online platform. Its core features are free—anyone can get started simply by registering. With a single tap of the “Sync” button in the app, all collected coordinate data and images up to that moment are instantly uploaded to the cloud. From the office, you can log into LRTK Cloud via a web browser to view and download the latest field data in real time.

On the cloud platform, you can view a list of your survey points plotted on a map along with their attribute details, and share the data with your team. For example, if a field engineer attaches notes and photos to a measured point and saves it to the cloud, stakeholders back in the office can immediately access that information and understand the situation. The system also offers a shareable URL feature, allowing you to grant external parties access to the positioning data as needed. By leveraging cloud synchronization, information flows seamlessly between the field and the office, boosting operational efficiency and the productivity of your entire team.

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Troubleshooting (Handling Connection Issues)
If Bluetooth pairing or correction‐data settings aren’t working correctly, please check the following points:

• Unable to Pair: If your smartphone cannot find the LRTK device, first make sure the device is powered on, then toggle Bluetooth off and on and try scanning again. If it still doesn’t appear, restart the LRTK device or attempt detection with a different phone to rule out a device fault. If the LRTK is already paired with another device, it may be invisible to new phones—reset any old pairing records if needed. If a pairing request is sent but the connection still fails, check for a mistyped PIN or Bluetooth interference. Verify that you’re using the correct PIN as shown in the device manual, and, if there are strong radio sources nearby, move away from them and try again.

• App won’t recognize the device: If your phone shows the LRTK as paired but the LRTK app still won’t connect, check the app’s Bluetooth and Location permissions in your phone’s settings. If the app isn’t allowed to use Bluetooth or access location data, the device may be blocked from discovery. Grant those permissions, then restart the app—if it still fails, reboot your phone and try again. Occasionally another app (for example, a music controller) may be occupying the Bluetooth link in the background, so closing any such apps can also resolve the issue.

• Cannot receive correction data / Won’t achieve Fix: If you’re connected to your correction service but never get a Fix solution, first verify your phone’s Internet connection (mobile data or Wi-Fi) to ensure the stream isn’t dropping. Next, double-check your NTRIP settings—URL, port, username, and password—being careful to avoid full-width/half-width character mistakes or stray spaces. For paid services, also confirm your subscription is still valid and that you’re not logged in on another device simultaneously.Satellite reception matters, too: tall buildings or dense trees can leave you stuck in Float mode. Move to a more open area or simply wait a bit for the satellite geometry (GDOP) to improve. If you still can’t get a Fix, try reloading the correction stream in the app and reboot your LRTK device before reconnecting.

• Position jumps despite a Fix solution: If you have a Fix but notice occasional large jumps in your coordinates, radio interference or multipath (reflected satellite signals) may be to blame. Under power lines, between tall buildings, or near reflective surfaces, signals can become erratic—try moving to a different spot and re-measuring.When using your LRTK device handheld, avoid blocking the antenna, keep the unit as level as possible (even if your model offers tilt compensation, excessive angles reduce accuracy), and consider using the app’s averaging feature to smooth out any remaining noise.

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If none of the above steps resolves the issue, reach out to the manufacturer or your sales agent’s support team. Although the LRTK series is relatively new, user communities and FAQ resources are continually expanding. By calmly isolating and addressing the root cause, you’ll find that most problems can be resolved.

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Utilizing LRTK and Benefits of Adoption
Finally, we’ll summarize the benefits of adopting the LRTK terminal. Let’s explore why field engineers choose LRTK over other RTK-GNSS devices, and then briefly touch on future prospects while reviewing real-world implementation examples.

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●Compact, Lightweight & Highly Portable: The LRTK terminals are designed to be extremely compact and lightweight. For example, the LRTK Phone snaps onto your smartphone and fits in your pocket—no bulky, stationary GNSS receivers required. Its ease of transport makes it possible to perform high-precision positioning anywhere, anytime.

●Effortless Smartphone Integration: You don’t need a dedicated controller—your everyday smartphone becomes a precision surveying device. The intuitive mobile app lets even untrained staff operate the system confidently on day one. The clear UI and real-time positioning display minimize confusion for first-time RTK users.

●High Accuracy & Reliability: Achieve centimeter-level accuracy with RTK, and take advantage of advanced features such as multi-band support and tilt compensation in higher-end models like the LRTK Pro2. Some models even receive direct correction signals (e.g., QZSS CLAS), enabling precise positioning in remote, cellular-dead zones. These technical advantages ensure stable, reliable data in any environment.

●Seamless Data & Cloud Integration: Positioning data syncs instantly via LRTK Cloud, enabling smooth information sharing between field and office. This streamlines report generation and data consolidation, boosting overall project productivity. The core cloud functionality is free to use, offering added cost-efficiency.

●Exceptional Cost Performance: Despite its advanced capabilities, the LRTK series is affordably priced, making it practical to equip each team member with their own unit without blowing the budget. Its strong cost-performance profile has driven adoption across large general-contractor sites and smaller projects alike, positioning LRTK as a key tool for on-site digital transformation (DX).

●Proven in the Field & Future Outlook: Users report dramatic gains in efficiency and confidence in their survey results after adopting LRTK. For instance, a highway maintenance contractor deployed LRTK Phone units for bridge inspections, pairing high-precision location tags with photos to elevate the quality of their records. A railway operator trialed LRTK for trackside patrols and accurately logged previously hard-to-pinpoint anomalies. In 2023, LRTK played a vital role in earthquake damage assessments in the Noto region, helping teams rapidly document critical infrastructure conditions. As the “1 cm-precision smartphone survey” becomes the new standard, LRTK’s use is set to expand across ever more applications.