5  Post-processing logs from the DJI D-RTK2 GNSS base station

The D-RTK2 base station from DJI is often used to provide RTK corrections to the Phantom 4 RTK and M300/350 DJI drones. Its main (and only) advantage over using a receiving station from another brand is its ‘plug-and-play’ connectivity with the DJI drones. However, it is supposed to operate like a black-box, with no expectations of post-processing from the user. Luckily, there are non-official ways to access the raw GNSS logs from the D-RTK2 station and post-processes them using PPK. This chapter will teach you the step-by-step procedures for doing so.

5.1 Downloading the raw GNSS logs

The D-RTK2 station automatically saves the raw GNSS logs every time it is powered up and starts receiving data. To access this data, you need to install the DJI Assstant 2 app on your computer. Both the ‘Enterprise’ and ‘Phantom’ versions will be able to pull data from the D-RTK2 station. Once you have it installed, power up the D-RTK2 station and connect it to your computer via USB. DJI Assistant will recognize it, and you will then be able to export ther logs under the options Log Export > RTCM Data > Save to Local rtcm_log dir > .DAT (binary) RTCM 3.2 raw data. Each log filw will have a long name ending in .DAT - for example, RTK124_202211011555_13ALH6W005005X.DAT. On this example, the number 124 is the log number, and 202211011555 means the log started on 2022-11-01 15:55:00.

This .DAT file is actually a GNSS log file in the RTCM 3.2 MSM5 format, which can be converted to a RINEX format using RTKlib. To convert it, first change the file extension frop, .DAT to .rtcm3. Then, use rtconv from RTKlib or EMLID Studio to convert it to a Rinex 2 file format. You will then have files with the same name ending in .obs and .nav. You can then use these files as the ‘Rover’ positions on rtkpost or EMLID studio, and correct the base position using a third-party reference station.