DJI trademark reveals plan for RTK GNSS
DJI has added a trademark for D-RTK which the name suggests is a DJI implementation of a Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS), such systems provide centimeter level accuracy, using either GPS, Glonass or other satellite systems whilst using a second mobile receiver.
The trademark application can be read here:
To achieve centimeter level accuracy two GPS units are used with one of them being stationary (a base station) and another one in the drone. The base station sends corrections to the drone via radio.
RTK systems have been available on other systems for example Arducopter for a number of years, one being Piksi.
An example of the accuracy of RTK can be seen here: