History shows wondering/drifting location

[New user]

Installed new tracker on fathers car (84 years old).
Looked at history for yesterday and he didn't go anywhere outside the first geofence, but the history shows the tracker was all over his yard, the street and neighbors yards.
It is covertly installed, so in two days I doubt he knows its there and he is walking around in the yard with it.

What causes the wondering or drifting location?

[ATSupport]

This is normal GPS drifting. We have an article regarding this: http://support.accutracking.com/kb/article/000043