Why drones mapping now does not prefer to GPS RTK, but GPS PPK?

Comparison with GPS RTK and GPS PPK

* Common points between GPS RTK and GPS PPK

1. The work mode is the same. Both techniques use same work mode, ground base station and rover station.

2. Two techniques need to be initialized before work.

3. Both can reach cm level accuracy.

*Difference between GPS RTK and GPS PPK

1. The communication method is different.

GPS RTK technology requires a radio or network, transmitting differential data;

GPS PPK technology does not require communication real time, recording static data.

2. Difference for positioning way

Real-time positioning techniques adopted by GPS RTK can see the coordinates and accuracy of the survey point at rover station;

GPS PPK positioning belongs to the post-processing positioning, can't see the coordinates at field,  need to post-process data.

3. Difference for working radius

The GPS RTK job is restricted by the communication station, and the work distance is generally not more than 10 km, and the network mode requires a full coverage of network signals;

Using  GPS PPK technology work, general work radii can reach 50 km.

4. Different from the extent of satellite signals.

When the RTK work, if it is very easy to unlock if near the obstacle like the big tree;

When the PPK work, after initialization, it is generally not easy to lose signal.

5. The positioning accuracy is different.

RTK horizontal accuracy 8mm + 1ppm, vertical accuracy 15mm + 1ppm

PPK horizontal  accuracy is 2.5mm + 0.5 ppm, vertical  accuracy 5mm + 0.5 ppm.

6. The positioning frequency is different.

The RTK base station transmits differential data and the frequency received by the rover station  is generally 1-2 Hz.

The PPK positioning frequency is up to 50Hz.

*Comparative and  Analysis:

1. The speed of the drone is very fast, it takes a high positioning frequency, and it is difficult to achieve this condition if with GPS RTK technology. While GPS PPK supports 50Hz positioning frequency, fully meets the demand.

2, RTK Real-time is only providing location information, PPK can solve the calendar data within one cycle by the post-processing method not only increase the fixed rate, but also more accurate.

3, RTK needs to use the radio or network communication module, PPK does not need communication module , thus  reduce the load of the drone, increase the aircraft life.

4, RTK's work distance is short, PPK work distance can reach 50km, in a wide range of jobs, especially strip areas, such as transmission lines, roads, railways, oil and gas pipelines, and PPK will be the best choice.

*Summarize

Although RTK can provide high-precision location information in real time,but there is currently a big technical problem in the application of drones. The maximum benefit of PPK relative to RTK is to process afterwards, reverse Kalman Filter, which can solve some of the satellite unlock problems, and improve the positioning accuracy through the FORWARD & Reverse.

GPS PPK technology is a more suitable spatial positioning technology equipped on drones with technology development. UAV technology has become more mature, a wide range of work  is much more efficient than traditional RTK.

GPS PPK technology has significantly has a broader development prospects in drone.