I think this line in GPS info
Satellites in use x/y
is y satellites are received in the moment
and x satellites are currently used for the calculation of the position.
The appearance of a number x >= 4 (the more the better) leads to a valid position fix. This must be satellites of the same system, e.g. GPS. Receiving e.g. 2 US GPS sat’s and 2 Galileo sat’s (=4 in sum) does not work.