Table of Contents

• What is an RTK base station?

• What is NTRIP?

• Advantages and disadvantages of setting up your own RTK base station

• Advantages and disadvantages of using NTRIP

• Cost comparison between RTK base station and NTRIP

• Which should you choose?

• Simple surveying and using LRTK

• FAQ

In recent years, the adoption of a high-precision positioning technology called RTK (Real Time Kinematic) has progressed in construction and surveying. The centimeter-level positioning accuracy (cm level accuracy (half-inch accuracy)) provided by RTK delivers major advantages that standalone GPS positioning could not, improving the efficiency of surveying tasks and enabling autonomous operation of construction machinery. At the same time, many technicians face the dilemma of whether to install and operate a "base station" (reference station) themselves or to use an internet-based network RTK service (NTRIP). In this article, we explain the basics and role of an RTK base station and compare the costs, advantages, and disadvantages of operating your own base station versus using an NTRIP service. We hope this helps you decide which option best suits your company’s needs.

What is an RTK base station?

An RTK base station (reference station) is a fixed station that serves as the reference for error corrections in RTK positioning. RTK positioning typically uses two GNSS receivers simultaneously: a base station and a rover (mobile station). The base station is installed at a point whose coordinates are accurately known in advance, and it calculates errors by comparing the positioning result from received GNSS satellite signals with the known coordinates. The base station then sends that correction data to the rover in real time. By applying the correction information received from the base station to its own GNSS positioning, the rover can reduce positioning errors that were several meters down to several centimeters. In other words, the base station functions as a reference point that enables the rover to obtain high-precision positions.

Traditionally, dedicated radios such as UHF bands have been used to transmit correction data from the base station to the rover. For short distances, radios can communicate directly and pass differential data in real time. More recently, however, a networked RTK approach that distributes correction information via internet connections has become widespread. This uses a mechanism called NTRIP (described below), allowing base station data to be sent and received without physical dedicated radios.

What is NTRIP?

NTRIP (Networked Transport of RTCM via Internet Protocol) is a protocol for distributing GNSS correction data over the Internet. Simply put, it is a mechanism for receiving remote reference station data via mobile networks or other internet links. If an RTK-capable receiver (the rover) can access the Internet via mobile data or Wi‑Fi, it can obtain real-time correction information from an NTRIP-compatible distribution server (NTRIP caster).

In Japan, there are networks of electronic reference points maintained by the Geospatial Information Authority (about 1,300 stations) as well as GNSS reference station networks run by private companies, and real-time correction services that leverage these networks are available. For example, SoftBank’s “ichimill” operates more than 3,300 proprietary reference stations nationwide and distributes centimeter-level correction information (cm level accuracy (half-inch accuracy)) to subscribers. By using NTRIP, users can achieve high-precision RTK positioning without installing their own base stations. However, NTRIP requires a communication environment: the worksite must be within mobile coverage. In areas without radio reception, the traditional method of using a privately owned base station plus radio communication to exchange correction data remains effective.

From the next chapter, let’s look at the pros and cons and cost differences of operating your own RTK base station versus using an NTRIP service.

Advantages and Disadvantages of Setting Up Your Own RTK Base Station

Advantages

• Lower running costs: Once you have installed the base station equipment, you do not incur monthly fees for using correction data. Over the long term, operating your own base station can be more economical than continuously paying service fees in some cases.

• Ability to operate multiple rovers simultaneously: One privately owned base station can share the same correction data with multiple rovers. For example, on a site where several workers use multiple GNSS receivers or machines, everyone can use the base station’s radio or network distribution without needing separate contracts for each device.

• Operation possible outside communication coverage: Even at remote mountain sites, islands, or offshore locations where mobile signals do not reach, real-time positioning is possible by connecting a privately owned base station and rovers via radio. Because you are not dependent on external services, you can achieve high-precision positioning regardless of location.

• No service dependency risk: By managing the base station in-house, you can control risks such as suspension of correction information or service downtime. You are not affected by external providers’ system maintenance or outages, which provides operational reassurance.

Disadvantages

• High initial installation cost: Purchasing a high-precision GNSS receiver and antenna for a base station is not inexpensive, and installation work also costs money. Antenna installation in a clear, elevated outdoor location, poles and mounting hardware, lightning protection and waterproof cases—all require a substantial investment. This initial cost can be a major hurdle for small and medium-sized businesses.

• Maintenance and management burden: Operating your own base station entails equipment maintenance, regular operation checks, firmware updates, and possibly radio station license applications/renewals, creating various management tasks. You must also handle repairs, theft prevention, and damage protection yourself, which places personnel demands on your organization.

• Limited coverage area: The effective range of a base station’s correction data is generally said to be on the order of a few kilometers to several tens of kilometers in radius. A fixed base station cannot serve sites that are far away, so you may need to add or relocate base stations for each new site. This becomes impractical if your sites move widely and frequently.

• Environmental requirements and risk mitigation: High-precision base station operation typically requires antenna placement in an open sky area free from sources of signal interference, and you must protect equipment from lightning, strong winds, and extreme temperature changes. Securing suitable installation environments and taking responsibility for risk management are all tasks your company must handle.

Advantages and Disadvantages of Using NTRIP

Advantages

• Low initial barrier: When using a networked RTK service, you do not need to prepare expensive base station equipment yourself. As long as you have a rover GNSS receiver, you can subscribe and immediately receive correction data. This ease of introduction is a major advantage.

• Usable nationwide: Private RTK correction services use mobile networks and cover almost all of Japan. Even if your sites are scattered across different regions, you do not need to install new base stations in each location, and you can obtain consistent positioning accuracy anywhere within the service area. This is suitable when you want to cover a wide area flexibly.

• Maintains accuracy over long distances: Corrections based on multiple reference stations (e.g., VRS methods) can maintain stable accuracy even at locations tens of kilometers away where a single base station’s accuracy tends to degrade. This ability to suppress errors at remote sites is a unique benefit of networked services.

• Less operational burden: Since service providers generate and distribute the correction information, users can operate without being concerned with complex technical operations. Base station maintenance and calibration are not required, reducing daily operational workload.

Disadvantages

• Ongoing usage fees: Networked services require monthly or annual subscription fees. Fees are often relatively inexpensive at a few thousand yen, but long-term cumulative costs can be significant. For example, even a 5,000 yen per month plan amounts to 300,000 yen over five years, comparable to equipment purchase costs.

• Costs increase with number of users: When multiple devices use RTK, subscriptions are usually required per device. Where a privately owned base station can serve multiple rovers with one unit, networked services require per-device contracts, causing costs to increase proportionally with the number of terminals (major services may offer discounted multi-ID plans, but cost increases tied to device count remain unavoidable).

• Dependence on communication environment: Because reception of correction data always requires a communication link, the service cannot be used where mobile reception is unavailable. In tunnels, deep mountains, or other areas outside communication coverage, networked RTK will not function; in such cases, the traditional method of a private base station plus radio is required.

• Dependent on service provision status: The correction data you use is provided by the service operator, so you are affected by their system maintenance or temporary suspensions. The data format and content are also determined by the service, limiting fine-grained control or customization by your company. However, for typical positioning applications, these limitations are rarely problematic.

Cost Comparison between RTK Base Station and NTRIP

As noted above, the cost structures of operating your own base station and using a network service differ greatly. Comparing the main items yields the following:

From this comparison, the cost advantage of RTK operation depends on the usage pattern. If you want to minimize initial investment and use the service only when needed, networked services are advantageous; but if you plan continuous, long-term use, operating your own base station may ultimately be cheaper.

Which should you choose?

Based on the above, whether a privately owned base station or an NTRIP service is more suitable depends on the user’s situation. Generally, it is advisable to first consider the easy-to-start networked RTK services. For first-time RTK surveying introductions or operations with sites scattered across many locations, NTRIP is realistic and cost-effective because there is no need to prepare base station equipment. For small businesses or short-term projects, the ability to contract only for the required period makes network services an attractive option.

On the other hand, if your company has large construction sites that remain in the same area for extended periods, or if you need RTK in environments far from communication infrastructure such as mountainous regions or islands, installing your own base station can be worthwhile. Although the initial investment is large, there are benefits such as no additional costs for operating multiple machines simultaneously and independent positioning even outside communication coverage. For large-scale projects used for many years, the initial cost can be recovered and the investment highly profitable.

In summary, as a guideline: choose NTRIP if you want wide-ranging, flexible use and to keep initial costs down; choose a privately owned base station if you intend continuous use in a fixed area or if communication environments are unstable. However, networked services have been improving rapidly, and in many cases you can operate without a private base station. It is wise to first verify the availability of correction services, and consider installing your own base station only if necessary.

Simple surveying and using LRTK

“I don’t want the hassle of setting up a private base station—I want to use RTK more easily.” Solutions that meet this need have recently appeared in the form of the LRTK series. LRTK is a small GNSS receiver device developed to make RTK positioning more accessible; it links with smartphones and tablets to enable simple centimeter-level positioning (cm level accuracy (half-inch accuracy)). For example, a product called the “LRTK Phone” is a dedicated ultra-thin GNSS unit that weighs about 125g and is about 13 mm (0.51 in) thick; by attaching it to the back of an iPhone, the smartphone instantly becomes a versatile surveying instrument capable of high-precision positioning. No complicated operations are required: you simply launch the dedicated app and press a button to measure reference points or set out positions, allowing non-specialist personnel to operate it easily.

Because LRTK terminals can obtain real-time correction information via a smartphone’s communications, they can of course connect to existing networked RTK services such as NTRIP and perform high-precision standalone positioning. At the same time, combining LRTK units makes it possible to build a simple private base station. For example, with two LRTK devices, you can place one on a known point at the site as a mini base station and use the other as a rover; this enables traditional RTK surveying even at sites outside communication coverage or in areas not supported by services. In other words, LRTK allows you to switch between the convenience of networked RTK services and the independence of a privately operated base station depending on the situation.

Moreover, LRTK is a multi-GNSS, multi-frequency receiver that supports the centimeter-level augmentation service (CLAS) provided by Japan’s quasi-zenith satellite system “Michibiki.” Because it can receive CLAS signals, it maintains high-precision positioning from satellite-based corrections even where mobile communications do not reach. Functionally, it also features a high-performance RTK engine that obtains a fixed solution (Fix) quickly after start-up and automatic pole-tilt compensation, enhancing usability in the field. The dedicated LRTK app provides intuitive switching of correction sources (network or CLAS) and positioning mode settings, so anyone can operate it without confusion.

By using LRTK, centimeter-level positioning that once required bulky equipment and specialist knowledge can be achieved with “one smartphone + a small device.” If each field worker can carry their own high-precision positioning tool, surveying and construction management workflows will be dramatically more efficient. LRTK also lowers introduction costs compared to traditional surveying instruments, making it easier for small and medium-sized companies to adopt. If you are interested in simple RTK surveying, check the details of LRTK; it may enable a new surveying style that balances ease of use and high precision at your site.

FAQ

Q: What is required to install my own RTK base station? A: You need a high-precision GNSS receiver and antenna for the base station, a secured installation location (a stable spot with good line-of-sight), power and communications. You should also prepare a pole and mounting hardware for the antenna, waterproof cases, lightning protection, and other equipment. If you plan to distribute correction data via communications, you will need an internet connection or radios and may also need to apply for or renew radio licenses as required.

Q: How can I use correction services via NTRIP? A: If you have an NTRIP-compatible RTK receiver (rover) and an internet connection, you can use NTRIP. First, subscribe to a correction service offered by a private provider or public institution, and enter the provided NTRIP server connection information (URL, port, user ID, etc.) into your receiver or positioning app. Then, at the site, connect the receiver to the internet via smartphone tethering or an embedded SIM, and you can start receiving real-time correction data and begin high-precision positioning.

Q: How far apart can the base station and rover be for RTK positioning to work? A: In general, the farther the rover is from the base station, the more accuracy gradually degrades. Typical RTK maintains centimeter-level accuracy within about 10–20 km (6.2–12.4 mi) of the base station, but errors tend to increase beyond that. Networked RTK, which uses data from multiple base stations, can sometimes maintain centimeter-level accuracy even at points 50 km (31.1 mi) away. Still, keep in mind that getting an immediate high-precision Fix becomes more difficult at very large distances.

Q: Is RTK positioning impossible in areas without mobile coverage? A: RTK positioning is possible in communication-free areas depending on the method. If you set up a private base station and exchange correction data with rovers via radio, real-time positioning is possible without the Internet. In Japan, satellite-based augmentation systems such as Michibiki’s CLAS can also provide correction information directly from satellites (a compatible receiver is required). For example, LRTK terminals support CLAS, so they can maintain positioning accuracy via satellite augmentation even in mountainous areas.

Q: What is LRTK? A: LRTK is the name of a series of compact RTK positioning devices developed by Refixia Co. These ultra-light GNSS receivers attach to a smartphone and enable centimeter-level positioning (cm level accuracy (half-inch accuracy)) by using network RTK services and satellite augmentation. LRTK makes it easy to obtain and share high-precision coordinates without specialized surveying equipment, offering a solution that can significantly change simple surveying and construction management practices.