The Role of a Base Station in RTK and Your Deployment Options

RTK (Real Time Kinematic) positioning is a surveying method that uses two GNSS receivers simultaneously: a stationary reference unit (base station) installed on the ground, and a mobile unit (rover) that determines its position while moving around the work site.By comparing the sets of satellite signals received at the base and rover in real time, the base station calculates correction data and transmits it to the rover. This reduces the positioning error—from several meters with stand-alone GNSS—to just a few centimeters. Given that ordinary GPS/GNSS stand-alone fixes are typically accurate to only 5–10 m, RTK is drawing attention as a technology that can boost positioning accuracy by roughly two orders of magnitude.

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In RTK positioning the base station plays a critical role. It is installed at a precisely surveyed, known coordinate and, by comparing that fixed coordinate with the GNSS signals it receives, it estimates error components in real time—such as satellite clock drift and atmospheric effects. The base station then transmits the resulting correction data to the rover, which applies the corrections to its own observations to compute highly accurate positions. In other words, the base station functions as the reference point that enables the rover to perform centimeter-level relative positioning.

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Correction data can be passed from the base station to the rover in two main ways: through a direct radio link—such as low-power license-free radios or UHF radios—or via an Internet connection, typically an Ntrip-enabled cellular network. Although the classic RTK setup used a dedicated radio channel between the base and rover, “network RTK,” which streams corrections over the Internet, has become increasingly common. In a network-RTK workflow, the user no longer installs a personal base station; instead, the rover retrieves corrections from a service provider’s virtual reference station (VRS) network through the mobile network. In Japan, well-known services include SoftBank’s ichimill, NTT DOCOMO’s High-Precision GNSS Correction Service, and KDDI (au)’s RTK correction service.

On the other hand, users can also purchase their own equipment and set up and operate a local base station. So, how do the up-front investment, ongoing costs, and operational pros and cons differ between running your own base station and using a network-based RTK correction service? Let’s look at the specifics.

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Cost Analysis for Deploying and Operating Your Own RTK Base Station

When you set up and operate an in-house RTK base station—whether at a job site or within your company—there are many factors to consider, from the initial capital outlay to day-to-day operating expenses and the requirements for a suitable installation environment.
In this section we break down the cost components of the self-hosted base-station model, highlight key operational considerations, and summarize the unique advantages and disadvantages of running a base station yourself.

• Up-front costs:
  The first—and often largest—barrier is the capital outlay. Purchasing a high-precision GNSS receiver for use as a base station, together with a survey-grade antenna, typically runs from several hundred thousand to several million yen (tens of thousands to hundreds of thousands of US dollars). A fixed base-station package from a Japanese survey-instrument manufacturer, for example, can easily cost several million yen, so establishing an RTK base station generally requires a significant investment.Installation expenses must also be factored in. You need a clear, elevated outdoor location and must supply the pole or mast and mounting hardware to secure the antenna, pay for installation labor, provide lightning protection, and house the electronics in a weather-proof enclosure. Depending on the site, additional work—such as roof access arrangements or cable routing—may be required, adding further construction costs. Taken together, these items mean that building and deploying your own base station demands a substantial initial investment.

• Operating costs: Running your own base station generally involves lower ongoing expenses than relying on a network-RTK service. Most recurring costs are limited to equipment maintenance, power supply, and data-communication charges for the station itself.Costs differ depending on the communication method. For instance, if you distribute correction data via the internet, the base station must have its own connection—whether wired broadband or an LTE line—and you’ll pay the associated subscription and data fees. When the station uses a SIM card to send data to an Ntrip server, expect an additional monthly data charge of several thousand yen.By contrast, when the base station communicates directly with the rover over a dedicated radio link, the operating costs for data transmission are minimal, although you must factor in the administrative work of obtaining a license and scheduling periodic inspections of the radio equipment. As for power, electricity fees are negligible if the site has access to a constant commercial supply; however, if you plan to run the station on a standalone system such as solar panels with batteries, the expense of that setup must be included in the initial capital outlay.Overall, running your own base station entails only relatively modest ongoing expenses—primarily telecommunications charges and electricity—without the fixed subscription fees that accompany network-based RTK services.

• Installation Environment and Precautions: When running your own base station, the surrounding conditions are critical. The antenna must be placed where the sky is wide open. Ideally, you need an “open-sky” environment—no roofs or trees overhead and no buildings, cliffs, or other obstructions on the horizon.

• It is also crucial that there are no strong sources of electromagnetic noise—such as high-voltage power lines or radio towers—near the antenna, as they can disrupt signals. For permanent installations, mount the antenna securely on a pole or bracket and shield all equipment from wind, rain, and lightning. Install proper grounding for lightning protection, add fall-prevention measures when mounting at height, and give full attention to safety. In addition, the enclosure that houses the base-station receiver and communication devices should be ventilated and de-humidified to keep the internal temperature within an appropriate range. Only after these environmental preparations and precautions are in place can a self-owned base station continuously deliver stable correction data.

• Benefits of running your own base station:
  While a self-owned base station requires a larger up-front investment and installation effort, it delivers several clear advantages. Most importantly, it eliminates the recurring subscription fees charged by network RTK services, so your ongoing costs for correction data drop dramatically and long-term savings accumulate. If you need to operate multiple rovers at the same time, one in-house base station can stream corrections to all of them. For example, on a site running five survey instruments or machine-control units, a single base—or its Ntrip stream—can serve every unit, whereas a network service would normally require a separate subscription for each device. A proprietary base station also gives you RTK capability in cellular dead zones or areas outside a service provider’s coverage; as long as radio communication between the base and rovers is maintained, you can achieve centimetre-level accuracy even in remote mountains or offshore projects. Finally, because you control the base, you control uptime: you are not exposed to service outages, maintenance windows, or other disruptions on a third-party network, giving you greater operational security and peace of mind.

• Drawbacks of running your own base station:
  Operating a private base is not without downsides and obligations. The biggest obstacle is the substantial upfront outlay: purchasing a high-accuracy receiver, antenna, mounting hardware, power and communications equipment can be prohibitively expensive for small and mid-size contractors. Once installed, the base also demands ongoing care—troubleshooting hardware failures, performing regular calibration and validation, applying firmware updates, and so forth—all of which consume staff time and expertise. Because a fixed base station only supplies reliable corrections within a limited radius (typically a few to 20 km), your jobsites must lie inside that footprint; work farther afield requires relocating the base or installing a new one. In addition, you alone must mitigate risks such as weather damage, natural disasters, theft, or vandalism.Taken together, a self-owned base station makes most sense for large operations that use RTK continuously over a wide area, or for projects in regions with little or no cellular coverage—scenarios in which long-term savings outweigh the startup cost. Otherwise, the high entry barrier and maintenance burden can offset the financial advantages.

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Cost Comparison When Using a Network-RTK Service (e.g., Ichimill)

Next, let’s examine the costs and key characteristics of using network-based RTK services supplied by carriers such as SoftBank or NTT Docomo. With network RTK (an Ntrip correction service), you can achieve centimeter-level positioning without deploying your own base station—the service provider streams the correction data directly to your rover. This section summarizes the pricing structures and coverage areas of the main services, the equipment you still need, and the principal advantages and disadvantages of the network-RTK approach.

• Service fees: When you opt for a network-based RTK service, you sign a subscription agreement with the provider and pay a monthly (or annual) fee. SoftBank’s high-precision positioning service ichimill, for example, delivers centimetre-level accuracy for only a few thousand yen per month—remarkably inexpensive for this level of performance. The ability to receive nationwide correction data for a flat rate is one of the key advantages of the network-RTK model. Contract terms vary by provider, but many services offer discounted annual plans that can lower the cost even further for long-term users.

• Some providers also offer short-term options—daily or monthly “pay-as-you-go” plans—and even free trial periods. To use such a service you still need a GNSS rover receiver and a device with mobile-data connectivity; acquiring this hardware is the user’s responsibility (the outlay for the high-precision GNSS receiver is the same as in the self-hosted-base-station model).

• Major Network-RTK Services in Japan: Available network-RTK options include SoftBank’s ichimill, NTT DOCOMO’s “DOCOMO High-Accuracy GNSS Correction-Information Service” (a corporate offering provided through NTT Communications), and KDDI (au)’s RTK correction service. In addition, several alternatives have emerged that draw on the Geospatial Information Authority of Japan’s CORS network or deliver wide-area corrections via independent providers such as ALES and NTT Geospace.SoftBank’s ichimill is notable for operating its own nationwide array of more than 3,300 reference stations. Corrections generated from this dense network are streamed to users, enabling consistent positioning accuracy on the order of ±5 cm anywhere in Japan.

• Moreover, by leveraging the mobile-network infrastructure to place reference stations at a very high density, the correction stream remains stable even while the rover is in motion, allowing centimeter-level accuracy to be maintained continuously over large work areas.

• NTT DOCOMO and au offer comparable solutions, streaming data from their own or affiliated reference-station networks and covering nearly all regions of Japan. Pricing across the services is broadly similar, but differences exist in the equipment makers they partner with and in the bundled extras—such as support programs or proprietary software—so it is wise to compare them and choose the one that best fits your needs and workflow.

• Service Area and Communication Environment: Before you can use a network-based RTK service, two conditions must be met: (1) your work site must lie within the provider’s coverage area, and (2) the rover must have a reliable data link to the service. Most Japanese providers now cover the entire country, yet service may still be restricted in sparsely served mountain regions or on remote islands where telecom infrastructure is limited.In practice, major carrier-backed services such as ichimill can be used almost anywhere a mobile-phone signal is available; even rural mountain sites that receive a 4G/LTE signal can receive the correction stream without difficulty. Conversely, any location that falls outside cellular coverage—inside tunnels or deep forest, for example—cannot use a network-based service. In such cases you would switch to a locally installed base station that transmits corrections by radio, as discussed earlier.On the rover side you need an Ntrip-capable data link. The most common approach is to insert a SIM card into the tablet or data controller connected to the rover GNSS receiver and connect to the correction server over a mobile network. Tethering through a smartphone works as well. The key requirement is a stable connection; although RTK corrections amount to only a few hundred bytes to a few kilobytes per second, they must stream continuously in real time. A standard 4G line is more than sufficient, but in mountainous terrain you may need to mount the antenna higher or use repeaters to maintain coverage.

• Benefits of Network-Based RTK Services: The greatest advantage of using a network-based RTK service is its low barrier to entry. Because you do not have to purchase an expensive base-station receiver or carry out complex installation work, you can start centimeter-level positioning as soon as you have a rover-side GNSS receiver. Up-front costs are therefore limited to the price of the rover instrument; for corrections you simply pay a monthly subscription and tap into the provider’s nationwide reference-station network.Wide-area coverage is another major benefit. If your job sites are scattered across the country or change frequently, a network service lets you work anywhere without having to install a new base station at each location; you enjoy the same RTK environment everywhere. Operationally, you are freed from maintaining and managing base-station hardware, so you can focus solely on positioning tasks. Many providers monitor their systems around the clock and handle troubleshooting for you, giving peace of mind that reliable correction data will always be available. In addition, the service automatically keeps pace with the latest correction techniques and standards, sparing you the work of updating your own system.

• Drawbacks of Network-Based RTK Services: There are, however, several caveats when you rely on a subscription service. First, a recurring running cost is unavoidable. Even if the fee is only a few thousand yen per month, the cumulative expense becomes significant over time. For example, a ¥5,000 monthly plan adds up to roughly ¥300,000 over five years—an amount comparable to purchasing hardware outright. In addition, costs scale with the number of units in use. If you need RTK for several crews or machines, you must pay a subscription for each rover, whereas a single in-house base station could serve them all. (Many major carriers do offer discounted multi-ID plans, so the impact can be mitigated depending on your fleet size.)

• Another drawback is the dependence on the communications environment. As noted earlier, in areas where the cellular signal is unstable, the system cannot maintain RTK-level accuracy and work may have to be paused. Moreover—although it is rare—server maintenance or outages on the provider’s side can temporarily interrupt the delivery of correction data, forcing users to fall back to stand-alone GPS or to operate with reduced accuracy until service is restored.

• Finally, because you do not own the reference station yourself, there are certain limitations on the data you can obtain. For instance, you cannot use the raw reference-station observations for your own verification or run proprietary correction algorithms; you must work within the formats and outputs defined by the service provider. In ordinary positioning tasks this restriction is rarely an issue, but it is worth noting. All things considered, network-based RTK services are an excellent choice for companies that want to adopt centimeter-level positioning quickly and with minimal up-front investment, or for field operations that require flexible, wide-area surveying capability.

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In-house Base Station vs. Network-based RTK Service

The table below summarizes the key differences between running your own reference station and subscribing to a network-RTK service. It highlights, at a glance, how each option stacks up in terms of cost structure, convenience, and operational flexibility. Use it as a guide when deciding which model best fits your site conditions and company workflow policies.

Which set-up suits which field conditions and workflows?

As a rule of thumb, if your surveying or construction work is concentrated in one area for an extended period—or if a large site runs many RTK-guided machines at the same time—installing and operating your own base station pays off. On a multi-year earth-moving project, for example, the initial capital outlay is quickly recovered and the system delivers stable, low-cost positioning throughout the job. Likewise, on remote mountain or offshore sites that lie outside mobile-network coverage, a self-owned base station paired with local radio links is often the only practical RTK solution.

Conversely, for surveying firms that move from site to site or for small contractors adopting RTK for the first time, the network-service model is attractive because it is simple to start and requires almost no upfront hardware. For short-term jobs or occasional use, a monthly subscription is cheaper than buying a base-station outfit, and for infrastructure-inspection work that spans long corridors—highways, railways, pipelines, etc.—a network service eliminates the need to relocate and re-survey a base each time the crew moves.

In practice, the best strategy is to choose the approach that matches a project’s specific requirements and constraints. Some organisations even run both systems in parallel: they rely on their own base station under normal conditions but keep a network RTK subscription as a backup, ensuring continuity if the base goes offline or the team moves beyond its coverage.

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Introducing LRTK

Finally, let us highlight LRTK, an RTK-GNSS device that fits seamlessly with either deployment model—dedicated base-station operation or network-based service use. Developed by our company, LRTK is an ultra-compact, lightweight receiver that can function just as easily as a fixed base station or as a mobile rover, giving you maximum flexibility on site.

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LRTK Phone – a clip-on RTK-GNSS module for your smartphone. Despite its ultra-compact size, LRTK Phone delivers centimeter-level positioning accuracy, making it a true grab-and-go solution for the field. The unit belongs to Refixia’s LRTK series—products engineered to bring RTK surveying within everyone’s reach.

The model shown here is a smartphone-integrated RTK receiver: an extra-slim GNSS unit (≈ 125 g, 13 mm thick) that snaps onto the back of an iPhone or other handset and instantly turns it into a pocket-sized, all-purpose surveying instrument. With nothing more than one phone and one LRTK device you can handle control-point surveys, 3-D point-cloud acquisition, layout/setting-out tasks, and even AR-assisted construction management. All data collected can be synced to the cloud in real time.

In short, it is a field-ready DX tool built around the concept of “one RTK surveyor for every person.”

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LRTK units are engineered with the flexibility to operate in either base-station or rover mode. With two devices, for example, you can fix one on an established control point as an ad-hoc base station while using the second as a rover in the field. That setup preserves the classic advantages of a self-owned base—operation in cellular dead zones and simultaneous corrections for multiple machines—yet in a package that is dramatically smaller and lighter than conventional gear.

Conversely, a single LRTK device can just as easily act as a rover that connects to a network-RTK service. Each unit is a tri-frequency GNSS receiver that supports Japan’s QZSS “Michibiki” CLAS signal, delivers rapid integer-fixed (FIX) convergence, and features automatic tilt compensation. The dedicated LRTK App lets you switch correction sources or positioning modes with a tap, so you can alternate seamlessly between “leave it as a base” and “carry it as a rover.” In short, LRTK enables a hybrid workflow that combines the best of self-owned base stations and network RTK services in one pocket-sized package.