Mobile RTK vs Conventional RTK: Differences in Field Work

Table of Contents

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

• Characteristics of Base Station RTK (Conventional RTK)

• Characteristics of Mobile RTK

• Base Station RTK vs Mobile RTK: Which is more convenient in the field?

• Simple surveying with LRTK

• FAQ

RTK (Real Time Kinematic) is a technology that uses satellite positioning to perform high-precision position measurement in real time. Standalone GPS positioning typically has errors of several meters (several ft), but with RTK those errors can be reduced to within a few centimeters (a few in). In recent years, the use of RTK positioning has expanded across a wide range of field operations, including civil engineering surveys and construction sites, autonomous agricultural machinery, and drone surveying, and it has become an indispensable technology for efficient and accurate surveying. This article compares the main methods for implementing RTK in the field—the “base station RTK (own-reference-station method)” and “mobile RTK (network RTK method)”—explaining the advantages and disadvantages of each and the differences in fieldwork effort. We also consider which method is easier to use on site, and at the end introduce a new simple surveying method called LRTK.

What is RTK (Overview of Real Time Kinematic positioning)

RTK is a GNSS positioning method that uses error correction information transmitted from a reference station (base station) to improve the positioning accuracy of a rover in real time. Ordinary GNSS positioning can have position deviations of about 5–10 m (16.4–32.8 ft) due to ionospheric and atmospheric effects. With RTK, two GNSS receivers—the reference station installed at a point with known accurate coordinates and the rover placed where positioning is desired—are operated simultaneously, and the difference (error) between their observation data is calculated as correction information. This correction information is sent to the rover in real time and applied on the rover side, cancelling out positioning errors that would otherwise be on the order of several meters (several ft) down to the order of a few centimeters (a few in), allowing immediate acquisition of high-precision position coordinates.

A major advantage of RTK surveying is that it can provide “real-time” and “high-precision” positioning. Traditionally, obtaining centimeter-level accuracy required long-duration static GNSS observations or measurements with a total station. With RTK, however, you can bring the receiver to the point to be measured, perform a short observation, and get results on the spot. Because of this convenience, RTK technology is used in many situations such as as-built surveys and layout work in civil engineering, guidance for automatic tractors in agriculture, and improving the accuracy of aerial surveys by drones.

To use RTK positioning in the field, a communication method is required to deliver the correction data computed at the reference station to the rover in real time. There are broadly two communication methods: (1) installing your own reference station on site and transmitting correction information by radio (base station RTK, the conventional method), and (2) receiving correction information over the Internet using a pre-established network of reference points (mobile RTK, network RTK). The next chapter looks at the characteristics of base station RTK and mobile RTK.

Characteristics of Base Station RTK (Conventional RTK)

Base station RTK (own-reference-station method) is a method in which you install and operate your own GNSS receiver as a reference station on site. If there is a known point nearby with accurately known coordinates (such as a public control point or triangulation point), you can set up an antenna-equipped receiver there as the reference station and transmit correction information by radio from that reference station to correct the positioning of the rover. For example, at a construction site using base station RTK, you fix the first receiver (the reference station) at a known local point and the surveyor carries the second receiver (the rover) to perform field work. If the reference station and rover can communicate directly by radio, it is possible to achieve centimeter-level positioning in real time even at sites without Internet connectivity.

Advantages:

• Autonomous and stable communication: Because the reference station and rover are connected directly by local radio, operation does not depend on mobile phone signals or external services. RTK positioning can continue in mountainous or remote island locations where communication infrastructure is lacking, as long as radio coverage is available. Specific low-power radios or UHF radios are often used for on-site communication, and for relatively small work areas stable transmission of correction data can be maintained.

• Low running costs: Although initial investment is required to assemble the equipment for a reference station, once you operate your own reference station you do not incur ongoing monthly fees for correction information. If you perform RTK surveying frequently over a long period, self-operation can be more cost-effective than continuously paying an external service. Also, one reference station can send correction information to multiple rovers simultaneously, so using multiple receivers in parallel does not incur per-unit additional fees, allowing efficient team surveying.

• Accuracy control under your own standards: If the reference station is installed on a known accurate point, you can achieve consistent accuracy within that site. Keeping the baseline (distance between reference station and rover) short reduces error factors such as atmospheric signal delay, providing stable high accuracy. Managing the reference station’s coordinates internally also makes it easier to guarantee positioning results according to your own standards. Conformance to public coordinate systems (for example, Japan’s geodetic systems) is also ensured if you set the reference station’s coordinates yourself.

Disadvantages:

• High initial setup hurdles: You need to prepare a full set of equipment such as a high-performance GNSS receiver for the reference station, antenna, radio, tripod and mounts, and battery power, which tends to raise initial costs. Depending on the radio frequency used, a radio station license application may also be required. Equipment selection and licensing procedures require specialized knowledge, so this method can be difficult for beginners to adopt.

• Operation is time-consuming and labor-intensive: Each time you start surveying you must set up and configure the reference station on site. The reference station needs to be placed in a stable location with a clear sky; if the coordinates are known you input them, but if only unknown points exist you must perform observations for a certain period so coordinates can be post-processed. Because equipment setup and establishing the reference station position take time, you cannot begin measuring instantly. For short inspections where you want to finish quickly, preparation time can reduce operational efficiency.

• Limited applicable area (measurement area): Positioning accuracy degrades if the reference station and rover are too far apart, so base station RTK is generally suitable for surveys within a radius of several kilometers (several mi) from the reference station. If the rover moves tens of kilometers (tens of mi) away within a large site, errors accumulate and obtaining a fixed RTK solution becomes difficult. For wide areas you may need to move the reference station sequentially or set up relay stations, complicating operations. Also, when surveying separate distant sites you must re-establish the reference station each time, reducing mobility.

Characteristics of Mobile RTK

Mobile RTK (network RTK method) receives correction information over the Internet from a pre-established regional network of reference points. Users do not need to prepare a physical reference station themselves; they can utilize reference station data placed nationwide, such as the Geospatial Information Authority of Japan’s continuously operating reference stations. In practice, the rover GNSS receiver connects to the Internet via a mobile phone line or mobile router and accesses a correction data distribution service using the Ntrip protocol. The service’s server sets up a virtual reference station (VRS) near the user’s current position and generates correction data for that virtual point in real time. This allows positioning as if you had your own nearby reference station, enabling high accuracy even though the actual reference stations are remote.

Advantages:

• Easy and simple to introduce: There is no need to prepare additional reference station equipment as with the own-reference method; you only need one GNSS rover and a smartphone or tablet for communication to get started. Since you don’t have to set up a base station on site, preparation time before surveying is greatly reduced. Even without specialized knowledge, you can start operating by entering connection IDs and coordinate system settings provided by the service provider into the receiver or dedicated app, making it easy for beginners to adopt. With minimal equipment and simple procedures, first-time RTK users face a low barrier.

• High-precision positioning over wide areas: Because mobile RTK uses a wide-area network of reference points, it maintains accuracy even far from any single reference station. The issue of increasing error with distance is mitigated by the service combining data from multiple reference stations to generate correction information. Except in extremely remote mountain interiors or underground spaces, centimeter-level (half-inch accuracy) positioning is possible nationwide wherever mobile phone signals are available. It is suitable for surveys that involve moving around large sites or sequentially surveying multiple dispersed sites. Since the rover continuously receives optimal correction data while moving, it is easier to maintain accuracy over wide-area fieldwork.

• Direct conformity to public coordinate systems: Correction information distributed by network RTK services is based on official geodetic systems (in Japan, for example, JGD2011 or the newer JGD2022). Therefore, the positioning results directly correspond to Japan’s public coordinate systems. Unlike own-reference-station methods, post-hoc coordinate adjustments to match local known points are generally unnecessary. Always having coordinates aligned with global standards makes comparing data between sites or checking against coordinates on design drawings smoother.

Disadvantages:

• Dependent on communication environment: Internet connection is essential, so in areas with poor signal you cannot receive correction data and RTK positioning cannot be established. It is difficult to use in mountainous or island locations outside mobile coverage, and large underground facilities where signals do not reach are also unsuitable. Service-side problems such as communication failures or server maintenance can interrupt work and cannot be handled by the user. Compared with a private base station, there is risk due to external factors beyond your control.

• Ongoing usage costs: Using mobile RTK requires contracting with a company or organization that provides high-precision correction information and paying for the service. Pricing models vary, but monthly/annual subscription fees or usage-based charges by connection time are common. Frequent long-term use tends to accumulate high total costs. Also, if you operate multiple GNSS receivers simultaneously, you may need accounts or licenses for each unit, increasing costs proportional to the number of devices. Unlike self-operated reference stations, the more you use the service the more you pay to an external provider.

• Service area and datum constraints: The availability of reference station networks varies by country and region, and network RTK services may not be available everywhere. In Japan, VRS services using the Geospatial Information Authority’s reference stations are available nationwide, but overseas or on remote islands suitable services may be limited. Additionally, providers may use different geodetic datums (horizontal coordinate systems) or height references (geoids, etc.), so coordinate transformation or height corrections may be necessary depending on the application.

Base Station RTK vs Mobile RTK: Which is more convenient in the field?

So far we have reviewed the characteristics of base station RTK and mobile RTK. Which is actually easier to use in the field? In conclusion, for first-time RTK adopters or those inexperienced with equipment handling, mobile RTK is generally easier to use. It requires minimal equipment and on-site setup is simple. Base station RTK requires equipment preparation and prior knowledge, making the initial adoption feel more challenging. Especially for short surveys or spot high-precision measurements, the convenience of mobile RTK—where you can receive correction data as soon as you power on—stands out. With less preparation time on site and the ability for a single person to start working immediately, mobile RTK offers a major advantage.

On the other hand, depending on the operational scenario, base station RTK can be more appropriate and in some cases “ultimately easier.” For example, in a mountain site with no communication infrastructure, preparing your own reference station is the only solution, making base station RTK the sole option. Also, if you survey the same site almost every day over a long period, installing and fixing a reference station once can thereafter provide stable accuracy under your own standards, and repeated use can actually make operations more efficient. Thus, which method is “easier to use” depends on the field environment and purpose.

Overall, mobile RTK excels in “ease of introduction and setup,” while base station RTK wins on “reliability to use anywhere regardless of communication environment.” Which feels “easier” will vary based on site conditions, operating costs, and the required level of accuracy control. Recently, a phased approach is becoming mainstream: “start easily with mobile RTK, and consider a private reference station later if needed.” Initially using network RTK services to build know-how and, if usage frequency increases and self-operation becomes cost-effective, adding a reference station later forms an effective two-stage strategy.

Cases suited to base station RTK:

• Surveying in environments where Internet connection cannot be expected, such as mountainous areas outside mobile coverage.

• Large-scale projects where you repeatedly survey the same area over long periods and want stable accuracy management under your own reference.

• When operating multiple surveying instruments and it is economically more sensible to provide your own reference station than to pay per-device external service fees.

• When the company has in-house surveying expertise to manage equipment and reference points, enabling full advantage from self-operation.

Cases suited to mobile RTK:

• Mobile surveying in urban or plain areas with mobile phone coverage, where you want quick, agile operation and can receive correction while moving.

• When you want to keep surveying equipment minimal and quickly adopt RTK positioning even as a first-time user.

• Short-term tasks or spot inspections where you cannot afford time to set up reference points each site.

• Operations that sequentially survey many dispersed sites over a wide area where a single reference station cannot cover everything.

Both methods have pros and cons, but the practical approach is often to start easily with mobile RTK and combine private reference station use as needed. Choose the method that fits site conditions and objectives to maximize the benefits of RTK positioning.

Simple surveying with LRTK

As described above, using RTK positioning typically involves installing your own base station or contracting with an external network correction service. However, recently a new approach has emerged that further reduces that effort and makes high-precision positioning even easier. One such system is called LRTK. LRTK is a smartphone-integrated GNSS positioning solution that aims to minimize specialized surveying equipment and complicated settings so that “anyone can easily handle centimeter-level positioning.”

LRTK combines a dedicated small GNSS receiver and a smartphone app to achieve RTK-like high-precision positioning with simple procedures. For example, a small receiver attached to a smartphone can be held in one hand, and by pressing a single button at the point to be measured you can obtain high-precision coordinates of that point. Height measurement, which is difficult with standalone GPS, is also possible; horizontal accuracy reaches about ±1–2 cm (±0.4–0.8 in) and vertical accuracy is also within a few centimeters (a few in), achieving professional surveying levels. Operation is intuitive, and unlike conventional RTK equipment there is no need for complex base station setup or radio frequency adjustments.

Unlike conventional RTK methods, LRTK users do not need to provide their own base stations or individually contract with external correction services. Proprietary algorithms that utilize cloud-based correction data and positioning information from multiple points enable high precision with a single small receiver. Acquired positioning data is automatically converted to Japan’s geodetic coordinates (JGD) and can be plotted on maps for verification, greatly reducing post-processing and coordinate correction work. In short, even non-specialist users with only a smartphone and an LRTK device can perform precise surveying—a revolutionary system.

Compared to base station RTK and mobile RTK, LRTK can be seen as a third option that eliminates many of their inconveniences. Required equipment fits in a pocket, there is no need to worry about communication environment, and one-touch results provide a level of convenience not found in traditional methods. Of course, the optimal positioning method depends on site conditions and required accuracy, but for those who want to try high-precision surveying more casually, LRTK is a compelling solution. Detailed materials on LRTK implementation and use cases are available, so interested readers are encouraged to consult them. Using the latest technology will make high-precision surveying more accessible.

FAQ

Q: What is the difference between RTK and ordinary GPS positioning? A: Standalone GPS (GNSS) positioning calculates position only from signals from multiple satellites, resulting in errors of about 5–10 m (16.4–32.8 ft). RTK uses correction information from a reference station to cancel these error factors and determine position with centimeter-level accuracy. In other words, RTK provides a dramatic improvement in positioning accuracy compared to ordinary GPS.

Q: What accuracy can be obtained with RTK surveying? A: When properly operated, RTK surveying can achieve horizontal positions on the order of ±1–3 cm (±0.4–1.2 in) and elevation (height) on the order of ±3–5 cm (±1.2–2.0 in). However, accuracy depends on the distance to the reference station and satellite signal reception conditions. As baseline distance increases, errors gradually grow, and in environments with many obstructions it may be difficult to obtain a fixed solution and accuracy may decrease. In open-sky environments and when operated close to the reference station, errors generally remain around 2 cm (0.8 in).

Q: What is required to use network RTK? A: To use network RTK (mobile RTK), you need an RTK-capable GNSS receiver (the rover) and its antenna, and a communication means to access the correction service (a SIM-enabled communication module or smartphone). You must contract with a high-precision positioning service provider in advance and register login IDs/passwords, the correction data server address, and coordinate system settings on the receiver or dedicated app. On site, power on the GNSS receiver and connect to the service via a smartphone or similar device to start receiving real-time correction data and enable high-precision positioning.

Q: Are there advantages to installing your own reference station? A: Yes. Depending on conditions, installing your own reference station can be advantageous. For example, it enables RTK positioning in locations without communication infrastructure, can reduce long-term costs by avoiding external service fees, and allows you to manage the reference station coordinates and operation internally for stable accuracy guarantees. However, owning a reference station requires equipment costs and operational effort, so it is not recommended lightly for everyone. Consider site conditions and usage frequency and adopt self-operation when its benefits outweigh the drawbacks.

Q: What kind of positioning method is LRTK? A: LRTK is a new positioning system that, unlike conventional RTK, achieves centimeter-level accuracy with a single small receiver and a smartphone. Users do not need to own a base station or deal with special communication settings. Proprietary algorithms and cloud technology enable RTK-like accuracy with simple operation—pressing a button on a smartphone—making it a user-friendly RTK-style positioning service. Because LRTK reduces setup and operational burdens compared to traditional RTK, it is accessible even to those outside the surveying profession.