In the SparkFun_Ublox_Arduino_Library there are multiple functions to get the location accuracy. How should these numbers be interpreted?
Is it: position +/- accuracy, i.e. accuracy specifies the maximum distance away from the reported position,
or is it: position +/- (accuracy / 2), i.e. accuracy specifies the maximum diameter around the reported position?
In both of the above cases I’m assuming that accuracy specifies the maximum deviation from the reported position, but is that assumption correct? Does it report the maximum or is it some percentile of the confidence interval?
I’m guessing these questions apply more to the ZED-F9P module than the library, but I’ll first check anyone here knows the answer. Thanks!
Hi Scott.
As far as GPS accuracy goes, if you’re seeing 1 meter accuracy, you could be within 1 meters distance of where the GPS indicates you are. (You would be within 1 meter north, south, east or west of the stated position.) You could draw that as a 2 meter circle and you’re somewhere inside that circle.
I might be wrong about this, if anyone knows for sure, please comment.
The best way to get a feeling for those numbers is to do tests yourself. Make sure that the RTK solution has stabilized at a fixed outdoor location with a clear view of the sky, collect rover position data for several hours, and look at the spread. Calculate the standard deviation from the mean.
Move the rover unit by 1.000 meters in a known direction and repeat.