Differential GPS data processing

Hello all!
I am new to UAVs and this forum. I specialize in DGPS high-accurate positioning. I would love to start a topic which will share information on how to download and process GPS aerial data and mix it with a GPS station on land in order to differentially correct the onboard GPS coordinates and hence have a much more accurate geotagging at the end.

What we need is a means of recording continuos GPS observables (not coordinates). Only raw GPS data in RINEX format that we could import into a sophisticated geodetic software and combine with GPS land CORS to be able to obtain the geotagging of photos within a few centimeters of accuracy. Has anyone out there tried this out or is interested in developing this?

I am all ears…I mean eyes! :open_mouth:



since you obviously know a lot about GPS tech, what is the difference between “GPS Coordinate” and “GPS Observable”?



Hello Hector,
I’m really interested in post-processing the GPS data collected during my missions and I hope you can give me some help.
I’m using the 3DR UBlox GPS module together with APM 2.6 and I’ve written some scripts to get the GPS coordinates at the precise moment when the camera shoots (I’m using a TETRACAM ADC micro). With this images I’m trying to generate a high-accuracy map using Pix4D or AgiSoft softwares.
The problem is that, apparently, it isn’t possible to record GPS observables in the APM flash memory. All the information I can get from GPS is the following:

Status: 0 = no GPS, 1 = GPS but no fix, 2 = GPS with 2D fix, 3 = GPS with 3D fix
Time: the GPS reported time since epoch in milliseconds
NSats: the number of satellites current being used
HDop: a measure of gps precision (1.5 is good, >2.0 is not so good)
Lat: Lattitude according to the GPS
Lng: Longitude according to the GPS
RelAlt: Accelerometer + Baro altitude in meters
Alt: GPS reported altitude (not used by the flight controller)
SPD: horizontal ground speed in m/s
GCrs: ground course in degrees (0 = north)

Is there a way to do post-processing only with this information?