Do You Need a Base Station for RTK? Own-Base vs Network RTK Compared

RTK surveying is a high-precision GNSS positioning technology required in civil engineering surveys and construction sites. For example, by using RTK (Real Time Kinematic), errors that were about 5-10 m (16.4-32.8 ft) with GPS standalone positioning can be reduced to a few centimeters (a few cm (a few in)), allowing the coordinates of the point to be measured to be determined on the spot. Replacing long-duration observations required by high-precision static GNSS surveys or optical surveys, RTK lets you bring a pole or GPS antenna to the site and obtain results in a short time. For this reason, RTK is used in a wide range of situations such as as-built surveys and batter-board (layout) work for civil engineering, guidance for autonomous tractors in agriculture, and improving the accuracy of drone surveys.

However, to realize RTK you need to either set up a base station (reference station) in-house or on-site, or use an external service to receive correction information. So, is a base station really necessary to start RTK surveying? This article explains the basic concept of RTK and the differences, advantages, and disadvantages between "own-base RTK" and "network RTK." It also considers which approach is easier to introduce and, at the end of the article, introduces a new simplified surveying method called LRTK.

Table of Contents

• What is RTK (Overview of Real Time Kinematic Positioning)

• Characteristics of Own-Base RTK

• Characteristics of Network RTK

• Is a Base Station Really Necessary? Which Is Easier?

• Simple Surveying with LRTK

• FAQ

What is RTK (Overview of Real Time Kinematic Positioning)

With general GPS standalone positioning, it is common to have horizontal errors of about 5-10 m (16.4-32.8 ft) and vertical errors of several meters or more due to satellite-originated errors. In contrast, RTK positioning achieves centimeter-level high precision by using two GNSS receivers to cancel out error factors. Of the two receivers, one is installed on-site as a "reference station (base station)" whose accurate coordinates are known, and this station compares the data it receives from satellites with the data from the "rover" whose position you want to measure. From the difference between the two, the theoretical error amount is calculated and the correction information is sent from the base station to the rover via communication. The rover applies this correction information quickly, enabling it to determine highly accurate coordinates that cannot be obtained by standalone positioning.

The advantage of RTK surveying is that it combines immediacy and high precision. Traditionally, obtaining precision coordinate values on the order of several centimeters required long-duration observations in GNSS static surveys or optical surveys, but with RTK you can bring equipment to the point to be measured and obtain results in a short time. For this reason, RTK is widely used in as-built surveys and batter-board work (grade-stake setting), guidance for autonomous tractors in agriculture, and improving the accuracy of drone surveys.

To implement RTK, correction data must be delivered from the base station to the rover via communication. There are two major communication methods: installing your own reference station and using radio communication, or receiving correction information via the internet from an existing reference-point network (network RTK). Below, we will look at the characteristics of own-base RTK and network RTK.

Characteristics of Own-Base RTK

The own-base station method involves installing and operating a GNSS receiver as a reference station on-site by yourself. An antenna is set up at a known point near the site (a point whose coordinates are already accurately known) to serve as the reference station, and correction information is sent from that base station by radio to correct the rover’s positioning. For example, in a construction site implementing own RTK, one GNSS receiver is fixed at a local control point or a fourth-order triangulation point, and surveyors carry the second receiver for surveying. If the base station and rover can communicate directly, cm level accuracy (half-inch accuracy) positioning can be achieved in real time even without an internet connection.

Advantages:

• Independent communication: Because the base station and rover are connected directly by radio, operation does not rely on cellular signals or external services. RTK surveying can continue as long as radio waves can reach the area, even in mountainous regions or locations without communications infrastructure. Using local radio (UHF band or specified low-power radio, etc.) can deliver stable correction data within a confined site.

• Low running costs: Although initial investment in base station equipment is required, once your company owns a base station you do not need to pay fees for external correction services (monthly subscriptions, etc.). For long-term, medium-to-high-frequency RTK surveying, self-operation can be more cost-effective than continuing to pay service fees. When multiple rovers are used simultaneously, one base station can distribute correction information to many units without additional service fees, allowing multiple people to survey at once.

• Manageable and stable accuracy: If you install your own base station on a known point, you can consistently achieve a certain level of accuracy within that site. Keeping the distance between the base station and rover (baseline length) short reduces the impact of atmospheric errors and yields stable high accuracy. By strictly managing the coordinates of your base station, you can guarantee the absolute accuracy (correctness relative to the geodetic datum) of positioning results according to your own standards.

Disadvantages:

• Initial setup hurdles: You need a full set of equipment for the base station, such as a GNSS receiver and antenna for the base station, radios, tripods and mounts, and battery power. High-performance GNSS receivers are expensive, and initial investment can be large. Also, if radio communication is used, license applications may be required depending on the frequency band used. Selection of equipment and licensing procedures require specialized knowledge and preparation, which can be a hurdle.

• Operational effort: Before surveying starts, you must set up and configure the base station each time. You must choose a stable location with an open sky for the base station, input coordinates for a known point if available, or conduct observations to enable later offset correction if it is an unknown point. Equipment setup and coordinate referencing can take time, so surveying cannot begin immediately. For short-duration tasks or spot inspections, the preparation time can reduce efficiency.

• Limited applicable range: Because accuracy degrades if the base station and rover are too far apart, the own-base station method is basically suitable for surveying in the vicinity of the base station. Generally, high accuracy can be maintained within a range of a few kilometers, but if a site is vast and tens of kilometers away from the base station, errors accumulate and it becomes difficult to obtain an RTK fixed solution. Covering a wide area thus requires moving the base station sequentially or arranging relay stations, complicating operations. When surveying remote separate sites, the base station must be re-established each time, reducing mobility.

Characteristics of Network RTK

The network RTK method receives correction information over the Internet from an established regional network of reference points. Also called network RTK, users do not need to set up a reference station themselves; they can use correction data from permanent stations deployed nationwide, such as the Geospatial Information Authority of Japan’s Continuously Operating Reference Stations (CORS). In practice, the rover connects to the internet via a cellular line or mobile router, and accesses correction data distribution services using the Ntrip protocol. The service provider’s server sets up a virtual reference station (VRS) near the user’s position and generates and sends back correction information for that point in real time. This allows positioning accuracy as if a nearby base station were present.

Advantages:

• Easy initial setup: There is no need to prepare additional base station equipment as with the own-base method; you can start with just a GNSS receiver for the rover and a communication device (smartphone or tablet). Because there is no need to install a base station on-site, preparation time before starting surveying is short. Even without specialized knowledge, you can relatively easily begin operation by setting the receiver according to configuration information provided by the service (connection IDs, coordinate system settings, etc.).

• Usable over a wide area: Network RTK uses a reference-point network covering a region, so accuracy can be maintained even far from any single base station. The network mitigates long-distance error growth by interpolating data from multiple reference stations to produce correction information. Except in extremely remote mountainous areas, cm level accuracy (half-inch accuracy) positioning can be achieved anywhere cellular coverage is available. Because appropriate correction data are received as you move, network RTK is suitable for surveying tasks with wide movement ranges or for teams that frequently move between sites.

• Positioning results tied to public coordinate systems: Corrections distributed by network RTK are based on official coordinate datums (in Japan, JGD2011/JGD2022, etc.). Therefore, the obtained positioning results correspond directly to global geodetic coordinates. Unlike own-base methods where you might need to later tie results to known points for coordinate correction, this is generally unnecessary. Always working in a public coordinate system makes it easier to compare data among multiple sites and to check against design coordinates.

Disadvantages:

• Dependence on communications: Internet connectivity is essential, so in areas with poor signal you cannot receive correction data and RTK positioning will not work. This is a major limitation when working in mountainous areas, underground, or outside cellular coverage. Also, if there are communication failures, server maintenance, or other service-side problems, users cannot handle it themselves and work may be interrupted. The risk from factors you cannot control is greater than with an own base station.

• Ongoing usage costs: Using network RTK services usually requires a contract with a correction service provider and payment of fees for access to correction information. Fee structures vary by service, but monthly or annual subscriptions or pay-per-use arrangements are common. Frequent long-term use can result in high total costs. When multiple GNSS units are used simultaneously, contracts or licenses may be needed for each unit, increasing costs as the number of devices grows.

• Service area constraints: The availability of reference-station networks differs by country and region, so some services may not cover every area. In Japan, VRS services using the Geospatial Information Authority’s CORS are available nationwide, but overseas or on remote islands, available network RTK services may be limited. Also, service providers may adopt different geodetic datums or height systems, so coordinate transformations or height corrections may be required depending on the application.

Is a Base Station Really Necessary? Which Is Easier?

So far we've looked at the characteristics of own-base RTK and network RTK, but which is actually easier in operation? In short, for those introducing RTK for the first time or without detailed knowledge of the equipment, network RTK is generally easier. Network RTK requires minimal equipment and the on-site setup is simple. The own-base station method requires equipment preparation and prior knowledge, making the initial entry hurdles feel higher. Especially for short tasks or spot surveying, the convenience of network RTK—where correction information is available as soon as a signal is received—is clear.

On the other hand, in some operational scenarios the own-base station method can be more appropriate and may feel easier. For example, when surveying deep in mountains with no communications infrastructure, preparing your own base station is the only realistic approach and can be the simplest solution. Also, for projects that survey the same site repeatedly, once a base station is installed and fixed in place, you can maintain stable accuracy and efficiency improves with repeated use. Which method feels easier thus depends on the operating environment and purpose.

Overall, network RTK wins on "ease of initial setup and configuration," while own-base RTK has the advantage of "the freedom to use it anywhere regardless of communications." Which feels easier for your company will vary depending on site conditions, operating costs, and the level of accuracy management required. Below are cases suited to each method.

Cases suited to own-base station method:

• Surveying in areas without expected internet connectivity, such as sites outside cellular range or in mountain areas

• Large-scale projects where the same area is surveyed repeatedly over a long term and you want to manage accuracy with your own stable reference

• Operating multiple surveying machines where providing an in-house base station is more economical than paying per-device service fees

• Having in-house surveying expertise that can manage equipment and reference points autonomously

Cases suited to network RTK method:

• Wanting to perform mobile surveys in urban or plain areas where cellular signals are available (can receive corrections while moving)

• Keeping surveying equipment as simple as possible and quickly adopting RTK for the first time

• Short-term tasks or spot inspections where time to set up a reference station is limited

• Surveying multiple distant sites sequentially where moving a single base station cannot cover all locations

Both methods have pros and cons, but the current trend is "start easily with network RTK, and consider your own base station later if needed." Using services at first lets you accumulate know-how, and if usage frequency increases and in-house operation becomes cost-effective, introducing your own base station as a second phase can be effective.

Simple Surveying with LRTK

As described above, RTK traditionally required either setting up your own base station or contracting an external network service, but recently new approaches have appeared to further reduce that effort and enable simplified high-precision positioning. One of these is a system called LRTK. LRTK is a smartphone-linked positioning solution that aims to remove special surveying equipment and complex settings as much as possible so that "anyone can easily handle cm-level positioning."

LRTK achieves RTK-level high-precision positioning through a combination of a dedicated small GNSS receiver and a smartphone app with simple procedures. For example, attaching a receiver to a smartphone and holding it in one hand, you can press a button at the point to be measured and acquire highly accurate coordinates for that point. It can also realize vertical positioning that normal GPS cannot achieve, with errors of about ±1-2 cm horizontally (vertical within a few cm) — achieving practical surveying precision — while keeping the operation intuitive and without the complicated setup of traditional RTK equipment.

Unlike conventional RTK, LRTK users do not need to provide their own base station or contract external correction services. The technology behind LRTK uses cloud-based correction data and algorithms that leverage positioning information from multiple points to enhance accuracy, enabling high precision even with a single receiver. Acquired coordinate data can be converted on the spot to the Japanese geodetic coordinate system and displayed on a map, automating post-processing. In short, even non-specialist users can perform precision surveying with just a smartphone and an LRTK device.

We compared which of the own-base and network RTK methods feels easier, and LRTK can be seen as a third option that eliminates the hassles of both. Minimizing equipment to carry, removing concerns about communications, and obtaining results by simply pressing a measurement button are conveniences not found in conventional methods. Of course, the optimal solution varies with application and site conditions, but for those who want to try high-precision surveying more casually, LRTK is a promising solution. Detailed implementation guides and case studies of LRTK are now available, so interested readers should consult those resources. With the help of the latest technologies, high-precision surveying should become more accessible.

FAQ

Q: What is the difference between RTK and regular GPS positioning? A: Regular GPS (GNSS) standalone positioning derives position solely from satellite signals and typically has errors on the order of 5-10 m (16.4-32.8 ft). RTK uses correction information from a base station to cancel out error factors and pinpoint position with centimeter-level accuracy. In short, RTK is dramatically more accurate than standard GPS.

Q: What level of accuracy can RTK surveying achieve? A: When properly operated, RTK surveying typically achieves horizontal accuracy of about ±1-3 cm (±0.4-1.2 in) and vertical accuracy of about ±3-5 cm (±1.2-2.0 in). Accuracy is affected by the distance to the base station and satellite reception conditions; errors tend to increase at long distances. In environments with an open sky and short baselines, you can generally expect errors to be within about 2 cm (about 0.8 in).

Q: What is needed to use network RTK? A: To use network RTK you need an RTK-capable GNSS receiver (rover) and a means of internet connection. Specifically, prepare a GNSS receiver and antenna for the rover, and a communication device (SIM-enabled device or smartphone) to connect to correction services. You also need a contract with a network RTK provider in advance and input login IDs, server information, and coordinate system settings into the receiver or app. Then start the receiver on-site and connect via a smartphone or similar device to begin receiving correction data.

Q: Are there benefits to installing a base station yourself? A: Yes. Under certain conditions, installing your own base station has advantages: enabling RTK in areas without communications infrastructure, reducing long-term service fees, and allowing you to manage base station coordinates and operations internally for stable accuracy guarantees. However, self-installation also incurs equipment costs and operational effort, so it is not always recommended for everyone. Consider site conditions and usage frequency to determine whether benefits outweigh drawbacks.

Q: What kind of positioning method is LRTK? A: LRTK is a new positioning system that, unlike conventional RTK, achieves cm-level accuracy with only a small standalone receiver and a smartphone. Users do not need to possess a base station or worry about complex communication settings. Through proprietary algorithms and cloud technology, LRTK provides RTK-level precision with the simple operation of pressing a button on a smartphone. It is essentially an "RTK service anyone can use," simplifying field surveying and making RTK easier to adopt even for non-specialists.