Differences Between RTK and PPK in UAV Surveying

First, let’s outline the basics of RTK and PPK used in drone (UAV) surveying by organizing their differences in positioning methods and roles. Both utilize GNSS satellites such as GPS to determine position, but the major difference is whether corrections are applied in real time (RTK) or processed afterward (PPK).

​

What is RTK Positioning: In RTK (Real-Time Kinematic), the GNSS mobile unit mounted on the drone communicates in real time with a ground-based reference station (base station). By immediately applying the correction data continuously transmitted from the reference station during flight, the drone sequentially computes high-precision positional coordinates. For example, by receiving real-time error corrections from known points at the base station, the drone’s positional error can be reduced to just a few centimeters even while airborne. Because RTK instantly tags the images captured during flight with precise coordinates, it enables high-accuracy surveying through real-time correction.

​

What is PPK Positioning: In PPK (Post-Process Kinematic), the drone records GNSS data to an onboard log during flight and then, after landing, matches it against ground reference‐station data to correct its position. In other words, no real‐time communication occurs during the flight; corrections are applied later in post‐processing. Specialized software combines and analyzes the drone’s observation data with the base station’s observation data to compute highly accurate positional information. Because PPK does not rely on in-flight communications, it delivers stable accuracy even in mountainous or otherwise connectivity-challenged environments.

​

Which Is More Accurate?In general, both RTK and PPK, when properly operated, deliver very high precision—on the order of a few centimeters horizontally and a few to a dozen centimeters vertically. Theoretically, PPK has a slight edge because it can process all pre- and post-flight data comprehensively, whereas RTK carries a risk of temporarily degraded accuracy if its communication link is interrupted.

However, in environments with stable communications, RTK can consistently achieve a fixed solution (high-precision fix), so there is no significant difference in the accuracy of the final survey results. In short, under proper conditions both methods deliver equivalent high precision. What matters is understanding each approach’s advantages and disadvantages in terms of site conditions and operations, and choosing the one best suited to the situation.

​

Benefits and Application Scenarios of RTK Positioning
The greatest advantage of RTK positioning is that you can obtain high-precision, corrected coordinates on the spot in real time. Below, we explain how RTK works, its key benefits, and the types of field conditions where it is most effective.

In RTK, as described above, the reference station continuously transmits correction data to the rover (drone) via real-time communication. Concretely, you either set up your own base station and send corrections over radio or a mobile network, or you subscribe to a network-RTK service (e.g. VRS) provided by carriers such as NTT or SoftBank. With the latter approach, you don’t need to install a physical base station on site—you simply receive virtual reference-station data over the cellular network, assuming adequate coverage. In either case, once a stable communication link is secured, the drone can maintain centimeter-level accuracy throughout its flight. For example, RTK operates ideally in open terrain within a 2–3 km radius of the base station.

One major benefit of real-time correction is immediate results right after the flight. Because each photo is tagged on the fly with precise geocoordinates (geotags), you eliminate the need for post-flight coordinate adjustment and can begin analysis and application of the data at once. RTK is particularly valuable when you need to verify as-built conditions on site or jump straight into point-cloud processing and model generation immediately after capture. It is also indispensable for smart-construction or precision-agriculture use cases—such as automatically controlling heavy machinery or farm equipment in real time based on the drone’s RTK position data.

​

So, in what cases should you choose RTK? Below is a summary of examples where the RTK method is suitable.

• When you need immediate survey results:
  On sites where you want to verify accuracy and use the data immediately after flight, RTK provides high-precision coordinates at the moment of capture. For example, it’s ideal for daily progress surveys on construction sites with same-day reporting.

• When working in locations with reliable communications:
  RTK operations run smoothly on sites where radio links to the base station or mobile networks are stable. This includes earthwork on flat terrain or urban surveys where setting up a base station is easy.

• When you want to ensure high accuracy on short flights:
  In surveys of relatively small areas with brief flight times—where a fixed solution can be maintained throughout—RTK enables rapid, high-precision positioning. It’s also well-suited to projects that need to be completed within a limited timeframe.

​

As noted above, RTK truly excels in scenarios where achieving “on-the-spot” accuracy is critical. However, because it cannot perform effectively in environments where real-time communication cannot be maintained, the PPK method described next may be more suitable in such cases.

​

Benefits and Application Scenarios of PPK Positioning
The key advantage of PPK positioning is that it does not require real‐time communication on site. The drone simply logs GNSS data during flight and then you can perform high‐precision processing at your leisure back in the office. This method is therefore far less constrained by communication infrastructure or flight‐time limitations. Below, we explain the merits of PPK and the situations in which it excels.

In PPK, the drone’s onboard GNSS data are later matched with the base‐station GNSS records to achieve precise positioning. During flight, only satellite data are recorded—no real‐time error corrections occur. As a result, you can still obtain accurate positions even in mountainous or densely forested areas where radio signals struggle to reach. For example, in regions outside cellular coverage or at the entrances of tunnels and underground spaces, the drone records data in flight and you apply the corrections afterward on the ground. Unlike RTK, you don’t need to set up on‐site communication equipment (radios or internet connections), and the distance between the aircraft and base station is not a limiting factor. In practice, RTK accuracy degrades beyond approximately 2–3 km from the base station, but PPK can support long‐range flights and BVLOS (beyond‐visual‐line‐of‐sight) operations.

PPK also tends to deliver more stable precision. Even if satellite reception temporarily degrades during flight, the logged data can be interpolated and analyzed in sequence, often reconstructing a continuous, high‐accuracy trajectory. By contrast, RTK can fall back to a “float solution” or standalone GNSS fix when communication is lost in flight, causing a significant drop in precision—whereas PPK allows you to re‐process the data later to restore full accuracy.

The main drawbacks of PPK are that you don’t get immediate results and you incur extra time and effort for post‐processing. Specialized software and technical expertise are required, making PPK less suitable when you need real‐time, on-site decision-making.

​

In what situations should you choose PPK? Here are the main examples.

• Wide‐Area Surveys and Long‐Range Missions:
  For surveys of roads, railways, or rivers spanning several kilometers, or when capturing multiple remote areas in one flight—distances beyond the reach of RTK corrections—PPK remains effective. It is especially valuable for infrastructure inspections involving BVLOS (Beyond Visual Line of Sight) operations.

• In locations lacking established communication infrastructure:
  In mountainous regions, remote islands, forest-harvesting sites, and other areas where communication with a base station is difficult, PPK is the only choice. Because you don’t need to worry about real-time communications, you can focus on the flight itself, which also provides safety advantages.

• When pursuing the highest level of accuracy:
  For tasks such as monitoring minute terrain changes or measurements that cannot tolerate even centimeter-level errors, it is reassuring to analyze and validate the entire flight dataset using PPK. With RTK, you might not notice if accuracy degrades mid-flight, but PPK allows you to detect any problematic data segments during post-processing and make an informed decision about re-flying.

​

Thus, PPK excels in situations where on-site conditions are constrained or accuracy is paramount. It is the ideal method when you are willing to invest extra time in post-flight processing to ensure reliable results.

​

How to Choose Between RTK and PPK (Cost, Accuracy, and Task Time)
Now that we’ve organized the characteristics of RTK and PPK, let’s compare them in terms of cost, accuracy, task time, and operational considerations to guide your selection based on actual field needs.

​

・RTK (Real-Time Kinematic)

Positioning method: The rover (drone) and reference station communicate continuously in real time, applying corrections on the fly to compute high-precision positions during flight.

Required equipment & communications: A reference-station GNSS unit (or VRS service) plus a communication link or radio. Operation is limited to within the coverage area—typically a few kilometers of the base station.

Positioning accuracy: Centimeter-level (very high precision as long as the communication link is maintained and a fixed solution is held). Because errors are corrected in real time, accuracy remains high, but there is a risk of temporary degradation if the link is lost.

Work efficiency: No post-processing is required, so you can use results immediately. Data can be delivered or analyzed right after flight, enabling rapid decision-making on site.

Ease of operation: Preparation is somewhat involved—you must set up the base station and configure communications before flight, and manage link maintenance during operation. However, the overall workflow is simple (“capture and you’re done”).

Typical application scenarios: Small- to medium-scale site surveys and progress tracking where same-day results are needed; routine surveys at infrastructure construction sites; drone-guided construction or precision agriculture requiring real-time control.

Implementation cost: RTK-capable drones and base-station equipment tend to be expensive. You may also incur ongoing costs for communication hardware or subscription-based GNSS correction services.

​

・PPK (Post-Process Kinematic)

Positioning method: The drone and the reference station each record GNSS data, and those logs are matched after flight to compute precise positions. No corrections are applied in real time; all accuracy improvements come from post-processing.

Required equipment & communications: A reference-station GNSS receiver is required (for later data use), but no communication link is needed during flight. Long-range missions are possible. Base-station data can be retrieved afterward via on-site logs or electronic reference-point downloads.

Positioning accuracy: Centimeter-level accuracy (stable, high precision achieved through time-intensive office analysis). Unaffected by in-flight communication conditions, allowing thorough error correction in post-processing. Can match or even exceed RTK precision under optimal circumstances.

Work efficiency: Post-processing time is required, introducing a delay before results are available. Although you must perform analysis back in the office after flight, you can multitask by running other operations during processing.

Ease of operation: In-flight operation is simple—just log data. The base station only needs to be placed on site; no active communications are necessary. Post-processing expertise and a capable PC environment are required, but field procedures remain minimal.

Typical application scenarios: Wide-area surveys and aerial mapping in communication-challenged environments such as mountainous regions and remote islands. Areas with heavy signal obstruction, such as around structures or dense forests. Projects requiring rigorous accuracy validation. Survey plans with ample time.

Implementation cost: No special communication equipment is required for PPK itself, and it can be operated with non-RTK drones. However, high-precision GNSS receivers and post-processing software are necessary, and depending on the equipment configuration, costs can be comparable to those of an RTK system.

* The above reflects general comparative tendencies. In actual operations, it’s common to combine both methods—for example, even with RTK equipment you can save flight logs for later PPK processing. By flying an RTK drone while recording data as a safeguard against communication failures and applying post-flight corrections as needed, you can hedge your risks. Rather than being opposing choices, RTK and PPK complement each other depending on the situation.

​

Introduction to LRTK
Finally, we’d like to introduce LRTK, a compact device that makes RTK/PPK far more accessible. LRTK is a next-generation RTK-GNSS system developed with the vision of “anytime, anywhere, anyone can use RTK.” Its standout feature is its small, lightweight form factor. Traditionally, RTK setups required bulky base-station equipment mounted on large tripods or poles, plus radios and batteries, making them cumbersome to transport. By contrast, LRTK fits in the palm of your hand and is available in a range of models—from versions that clip onto a dedicated helmet for hands-free, on-foot surveying to smartphone-integrated units. For example, by attaching the pocket-sized LRTK Phone to your smartphone, you can achieve centimeter-level positioning anytime, anywhere.

​

From a technical standpoint, it also incorporates the latest GNSS solutions, offering both high accuracy and ease of use. The LRTK devices support multi-GNSS reception across constellations such as GPS, GLONASS, and Galileo, and by operating on multiple frequency bands (L1, L2, and L6), they reduce ionospheric errors and multipath effects. Furthermore, they are compatible with Japan’s Quasi-Zenith Satellite System “Michibiki” centimeter-class augmentation service (CLAS), enabling high-precision positioning using only satellite augmentation signals even in mountainous or offshore areas outside cellular coverage. As a result, in sites where RTK radio signals cannot reach, the LRTK device alone can receive corrections—effectively delivering on-site, PPK-like high precision in real time.

​

Thanks to these innovations, LRTK has evolved into an RTK/PPK terminal that any field engineer can operate with ease. In UAV surveying, you can mount an LRTK device on a drone to perform RTK positioning or record logs for PPK processing. For example, by deploying two LRTK units—one as a makeshift base station and the other on the drone—you can achieve centimeter‐level accuracy in real time over a proprietary radio link, even in areas without any communication infrastructure. Alternatively, you can run in PPK mode by simply mounting a single LRTK on the drone, making it ideal for retrofitting existing airframes to attain high‐precision positioning.