I've been looking at some performance tests and the GPS and OBD2 data is not identical, and can differ quite a bit.
The GPS seems to be "faster" by almost a second at high speed tests, while the OBD2 is faster on everything from standing start (understandable) but also 80-120km/h.
So to get my head around this I started looking at altitudes, exact speed correlation between OBD2 and GPS and more.
My question is (finally!), what are these "DOP" units used for satelite precision? Is a lower figure better, and what can be considered "good" for accurate testing?
Also what's "3d precision"? I can understand coordinate and altitude, is 3d some kind of combination of these?
Is the number of satelites important at all or are these DOP values all that matters for precision?