I’m doing some experiments with the RTK GPS (Hero+).
It is working quite well, but I have a few quesitons on how the data is used and how to retrieve some data from the logs of MAVlink.
So, the general idea with RTK is that there is a relative information, i.e. the lat,lon calculated by the rover are given by the lat,lon of the base plus the distance between the two. This was confirmed because if I move the base, the copter moves (follows) accordingly in the same direction and the same distance I moved the base.
My questions are:
- the LAT and LON field I can find on the log under GPS are the ones computed with RTK (i.e. base + relative) or the pure NMEA messages arriving at the rover GPS or they are somehow manipulated?
- the data coming from MAVlink GPS_RAW_INT message are the ones corrected by RTK or the raw from the rover module? If I don’t have a precise base position or the base is moving do I still have the global lat and lon here?
- the data coming from MAVlink GLOBAL_POSITION_INT message are the estimation with the RTK correction? If the base position is not correct or moving do I get a wrong global coordinate but good local coordinate?