【Complete Guide】What Is High-Precision Positioning Achievable with Only a Smartphone? Comprehensive Explanation of Mechanisms, Accuracy, and Use Cases

In recent years, technologies that enable centimeter-level high-precision positioning using only a smartphone have been attracting attention. Until now, position information typically had errors on the order of several meters, but nowadays it is becoming possible to perform high-precision positioning with a smartphone without relying on special surveying instruments. This article provides a comprehensive explanation of what high-precision positioning is, how it works, the accuracy that can be obtained, and concrete use cases. It also touches on key points for utilizing high-precision location information with just a smartphone and the latest solutions for easily performing surveying in the field, so please use this as a reference.

What is high-precision positioning?

High-precision positioning refers to positioning in which the errors in position information obtained from satellite positioning systems (GNSS) are reduced to very small values. With GPS positioning used in general smartphones and car navigation systems, errors of several meters to several tens of meters often occur. These arise from various factors such as atmospheric effects, satellite clock errors, and reflections from buildings (multipath). For example, ordinary GPS can commonly show deviations of ±5–10 m (±16.4–32.8 ft) even in open areas. In contrast, high-precision positioning can reduce errors to the order of a few centimeters. In some cases, horizontal positions can be accurate to a few centimeters, and with stationary measurements it is possible to achieve accuracy of less than 1 cm (0.4 in).

When high-precision positioning is realized, the “accuracy” of location information improves dramatically. Everyone has likely experienced the blue dot indicating your current location on a map being noticeably off the road. With high-precision positioning, you can expect accuracy sufficient to determine which lane of a road you are in. This has great value not just for car navigation, but also in fields where position accuracy is critical, such as surveying and construction, drones, and autonomous driving.

Background: why smartphones can now do high-precision positioning

In the past, achieving centimeter-level positioning required professional and expensive equipment such as high-performance GNSS receivers for surveying and base stations. However, advances in technology have significantly improved the performance of chips and sensors built into smartphones, and we have arrived at an era in which high-precision positioning is possible with a small device. The main factors behind this are the following.

• Support for multi-GNSS and multi-frequency: Recent smartphones are equipped with receivers that support not only GPS but also GLONASS (Russia), Galileo (Europe), and QZSS (Japan’s quasi-zenith satellite), among others. As the number of satellite systems increases, the number of signals that can be received increases, improving positioning accuracy and reducing interruptions in tunnels and shadowed areas near buildings. Furthermore, some of the latest smartphones can receive multiple-frequency satellite signals, not only GPS L1 but also L5. Supporting multi-frequency allows the effects of ionospheric delay to be mitigated, enabling more accurate distance measurements.

• Access to raw GNSS observables and advances in correction technologies: Since Android 7.0, access to GNSS raw data (carrier phase, Doppler, etc.) has been available. This allows dedicated apps and software to retrieve high-precision positioning information from the smartphone’s built-in GPS chip and perform error correction via post-processing or real-time processing. Additionally, the infrastructure for correction information that supports high-precision positioning (such as RTK, SBAS, PPP, described below) has been advancing. When a smartphone can receive reference station data via the Internet or use augmentation signals broadcast from satellites, it can achieve precision unattainable with standalone GPS.

• Emergence of compact, high-performance GNSS antennas and receivers: While improvements can be made with only the smartphone, the small antenna and signal noise issues make it difficult to stably achieve centimeter-level accuracy. Recently, attention has been focused on external high-precision GNSS receivers that can be attached to smartphones. Compact, low-power RTK-GNSS terminals weighing a few hundred grams or less have appeared, and by combining them with smartphones, high-precision positioning can be realized easily. The hybrid style of using the smartphone’s display and communication functions together with a dedicated GNSS antenna for precise positioning is the key to making high-precision positioning possible with “only a smartphone” without expensive dedicated equipment.

How high-precision positioning works

Whether on a smartphone or a dedicated device, error correction of the signals from GPS satellites is essential to obtain centimeter-level accuracy. Representative methods for high-precision positioning are RTK (Real Time Kinematic) and PPP (Precise Point Positioning).

• Improving accuracy with RTK: RTK, or Real Time Kinematic positioning, is a method that uses simultaneous GNSS signal reception at two locations: a reference station (fixed) and a rover (mobile). By using the difference between the two, errors can be canceled out to obtain a high-precision relative position. The reference station is a receiver with known precise coordinates, and the rover (the smartphone side) receives signals from the same satellites in its vicinity. By comparing the data received by both, atmospheric and satellite errors can be canceled, capturing millimeter-level changes. A key feature of RTK is the use of the carrier phase of the GPS signal. The carrier has a wavelength of a few tens of centimeters, and by precisely measuring the phase shift of this wave, distances can be measured to the order of millimeters to centimeters. However, the carrier phase measurement requires resolving the integer number of whole wavelengths, known as resolving the integer ambiguity. RTK uses advanced algorithms to resolve these integers rapidly, enabling real-time centimeter-level positioning.

• Improving accuracy with PPP: PPP, or Precise Point Positioning, operates with a single receiver and differs from RTK. It computes a high-precision global solution by integrating observations from multiple GNSS satellites with correction information for satellite orbit and clock errors, ionospheric and tropospheric delays, and other error terms. Because PPP models and corrects all error terms, its initial convergence time can be long (several minutes to tens of minutes). However, once converged, PPP can provide absolute positioning with centimeter-level accuracy. Recently, technologies such as PPP-RTK, which deliver correction information from satellites in real time, have emerged to shorten convergence times.

By using the correction information obtained via RTK or PPP on the smartphone side, high-precision positioning becomes achievable. Specifically, when a smartphone can connect to the Internet, it can receive RTK correction data via electronic reference station networks provided by organizations like the Geospatial Information Authority of Japan or private companies. In Japan, receivers compatible with QZSS’s centimeter-level augmentation service (CLAS) can receive correction signals directly from satellites without Internet when paired with a smartphone. In this way, accuracies unattainable by a standalone GPS can be overcome by incorporating external correction information.

How to perform high-precision positioning with a smartphone

So what is needed to actually perform high-precision positioning with a smartphone? Key points are both “hardware that supports high precision” and “software that utilizes correction information.”

On the hardware side, as mentioned above, smartphones equipped with dual-frequency GNSS chips are advantageous. Specifically, some high-end Android models (for example, those with high-sensitivity GNSS modules) can receive dual-frequency L1 and L5. Recent iPhone models have also begun to support L5 in addition to L1. However, the smartphone’s built-in antenna is small and has limits in sensitivity and noise immunity. For robust centimeter accuracy, using an external high-precision GNSS receiver that can be connected to the smartphone is practical. By using an external receiver that links via wireless (Bluetooth) or via the smartphone’s connector, you can leverage both the smartphone’s display and processing power and the high-precision antenna.

On the software and service side, you need apps or systems that can obtain and apply GNSS correction information. For smartphone-based RTK, it is common to receive reference station data over the Internet using the Ntrip protocol. Connect the app on your smartphone to a reference station service provided by prefectures or surveying companies, or to a private cloud-based RTK correction service, and receive correction data appropriate to your location (such as virtual reference station methods). Based on that data, the smartphone can compute the RTK solution and obtain high-precision coordinates in real time. Also, if you have a device capable of receiving the CLAS signals from the QZSS, you can configure the supporting app to utilize augmentation information directly from the satellites.

A typical procedure might follow these steps:

• Install a smartphone app that supports high-precision positioning and, if necessary, connect an external GNSS receiver to the smartphone (Bluetooth pairing or cable connection).

• Before starting positioning, set the method for obtaining GNSS correction information in the app settings. If you have Internet access, connect to your contracted RTK reference station service; if not, select using augmentation signals from satellites.

• Start the positioning mode in the app and wait until an RTK “fixed solution” (Integer Fix) is obtained. Typically, centimeter-level fixes stabilize in a few seconds to tens of seconds.

• Once you confirm high-precision positioning, record survey points with a button in the app. You can also use features such as distance calculations between measured points or on-screen guidance to target points on the map.

Accuracy obtainable with high-precision positioning and precautions

Whether using a smartphone or dedicated equipment, the actual accuracy achievable with high-precision positioning varies depending on the environment and measurement conditions. Theoretically, with an RTK fixed solution, horizontal position errors are expected to be within a few centimeters, and vertical errors typically within a few centimeters to at most about 10 cm (3.9 in). In practice, with sufficient static observations, cases have been reported where smartphone-based measurements achieved errors below 1 cm (0.4 in). However, caution is required in dynamic positioning or challenging environments. Keep the following points in mind.

• Reception environment effects: For high-precision positioning, an unobstructed sky view is ideal. In forests or urban canyons, satellite signal strength weakens and reflections from buildings can produce false signals (multipath errors). In such conditions, it may take longer to obtain a fixed solution or the solution may become unstable. Although smartphones are highly portable, they have less multipath resistance than professional large antennas, so achieving centimeter-level positioning in urban areas remains challenging. That said, improvements in positioning algorithms and multi-GNSS support have reduced these issues compared to the past.

• Stability of positioning and initialization time: In RTK, high precision is not guaranteed until the integer ambiguities are resolved and a “fixed solution” is obtained (the intermediate stage is called a float solution). Achieving a fixed solution usually takes from a few seconds to several tens of seconds, and even after fixing, moving a large distance or losing the signal may require reinitialization. When performing high-precision positioning with a smartphone, maintaining centimeter-level accuracy while moving is difficult; it may be necessary to stop at required points and wait a few seconds. PPP generally requires a longer convergence time but offers stable accuracy over wide areas. Depending on the use case, consider switching between RTK and PPP.

• Remaining errors and reliability: Even with high-precision positioning, errors are not completely eliminated. Vertical errors tend to be larger than horizontal errors. Positioning results are accompanied by confidence intervals such as “within X cm at 99% confidence.” For example, if a specification states "horizontal error 2 cm (2σ)", it means there is about a 5% chance the actual error will exceed 2 cm (0.8 in). Therefore, when using smartphone high-precision positioning for critical applications, exercise caution—take multiple measurements and average them or verify accuracy at known points as needed.

Use cases for high-precision positioning

When smartphones can easily measure positions to centimeter-level accuracy, many fields can benefit. Here are some examples.

• Civil surveying and construction management: On construction sites, high-precision position checks are essential for tasks such as establishing reference points and as-built control. Tasks that traditionally used total stations or expensive GNSS survey equipment can in some cases be replaced or simplified with smartphone high-precision positioning. For example, by using a smartphone and a simple GNSS device, workers can quickly measure heights and positions or check as-built conditions for small-scale earthworks or site development. “Staking out” positions from design drawings can also be guided via app screen navigation, enabling on-site staff to perform some surveying without calling in specialized teams, improving productivity.

• Mapping and GIS data collection: High-precision positioning is useful when collecting georeferenced data in the field. For instance, municipal staff who survey road signs, street trees, or fire hydrants and register them in a geographic information system (GIS) can do so more easily with a smartphone. Ordinary GPS may require later correction, but centimeter-level recording dramatically improves coordinate data quality. Additionally, when photographing objects, embedding highly accurate coordinates as metadata enables precise location tagging at centimeter accuracy, improving data management for infrastructure inspections or ecological surveys.

• Disaster response and field surveys: Rapid situation assessment and recording are required at earthquake or landslide sites. Smartphones with high-precision positioning can quickly measure ground displacement or map debris extents. For example, during the 2023 Noto Peninsula earthquake, smartphone-connected high-precision GNSS receivers were useful in mountain areas where communications were down. Because such devices can receive augmentation signals directly from satellites without relying on the Internet, they can record site conditions to centimeter accuracy even in harsh post-disaster environments. The portability of small equipment makes smartphone-based positioning a powerful tool in disaster response.

• Drones and autonomous navigation: High-precision position information is also key for drone aerial photography and autonomous mobile robots. While more consumer drones now support RTK, in the future smartphones paired with drones could enable real-time precise self-positioning for route guidance and accurate navigation to targets. RTK-GNSS is already used in agriculture for tractor auto-steering, enabling straight cultivation at centimeter accuracy. If smartphone high-precision positioning becomes widespread, small robots and unmanned delivery vehicles can incorporate this accuracy affordably, lowering the barrier to various automation technologies.

• AR/MR (augmented reality / mixed reality): The appeal of smartphone AR apps lies in blending virtual objects with real-world geography, but poor position accuracy can break the illusion. High-precision positioning allows digital content to be placed pinpoint-accurately in the real world. For example, at tourist sites, holding up a smartphone could project a historically accurate CG reconstruction of a building at the correct position and scale. With centimeter-level self-positioning, outdoor AR experiences become far more convincing, enabling new services and entertainment.

Toward an era of easy surveying with LRTK

As described, high-precision positioning achievable with just a smartphone or a smartphone plus a small receiver is expanding possibilities across many fields. In construction and surveying, this is attracting attention as an “easy surveying tool anyone can use.” A representative solution is [LRTK（ElRTeKa）](https://www.lrtk.lefixea.com/). LRTK is an ultra-compact RTK-GNSS receiver device that can be attached to a smartphone and provides centimeter-level accuracy comparable to traditional dedicated surveying equipment. It weighs about the size of a smartphone case (approximately 125 g) and has an internal battery, making it easy to carry on site.

Attach LRTK to your smartphone and launch the dedicated app, and with a single button you can measure and record your current position. The obtained coordinates are automatically converted to Japan Plane Rectangular coordinates or the global geodetic system (WGS84) and can be uploaded to the cloud for sharing immediately. By using the included monopod when necessary, you can stably place the device on a specific ground point for measurement, and height offset corrections can be easily set in the app. Instead of writing in a paper field notebook, you can digitally record survey point information with a smartphone + LRTK.

In terms of accuracy, LRTK demonstrates practically sufficient performance. For example, by taking multiple stationary measurements and averaging, errors can be reduced to the millimeter level. In experiments, averaging about 60 measurements reduced horizontal error to around 8 mm (0.31 in). Even a single-shot measurement without averaging has confirmed accuracy slightly over 1 cm—about 10–12 mm (0.39–0.47 in)—which already rivals conventional high-end GNSS survey instruments. Despite this, LRTK can be introduced at a fraction of the cost of traditional equipment, making it a groundbreaking tool that points toward an era of “one device per person.”

LRTK also supports CLAS signals broadcast by Japan’s QZSS (Michibiki), allowing high-precision positioning even in mountainous or disaster-affected areas where cellular networks are not available. While Ntrip-based RTK can be used where network connections exist, the ability to continue positioning with only satellite augmentation signals when communications are down provides on-site reassurance.

High-precision positioning achievable with only a smartphone has become more accessible thanks to devices and services like LRTK. Designed to be easy for field managers and surveying beginners to use, and with intuitive operation, these pocket-sized, affordably priced tools will enable non-specialists to take on part of the surveying work traditionally left to experts. Smartphone-based high-precision positioning technology will continue to evolve and deliver new value to our lives and industries. Why not take this opportunity to experience the world of high-precision positioning achievable with your smartphone?