I usually get 8-10 satellite on the status bar of the DJI go but still telling me no gps. I read somewhere that the minimum needed is, but even at 10 it seems not enough.
can someone explain please?

Same thing here, sometimes it needs 15 satellites before its satisfied and the GPS signal is enough

Technically you need only 3 sats for a 2D fix and 4 sats for a 3D fix. I always wait till the home point has been recorded (takes usually up to ten seconds). Then you can check your position on the map but with the current app version this isn't possible anymore. Hope they will fix that. Most of the time I have a quick fix with 9 to 12 sats.

ernieken Posted at 2017-7-17 04:04
Technically you need only 3 sats for a 2D fix and 4 sats for a 3D fix. I always wait till the home point has been recorded (takes usually up to ten seconds). Then you can check your position on the map but with the current app version this isn't possible anymore. Hope they will fix that. Most of the time I have a quick fix with 9 to 12 sats.

Mine takes longer, it could take something around 5 minutes to get ready to fly, 5 minutes showing 8, 9 or 10 satellites.

Will also depend on the environment where you fly. Here at home it's quite flat and rural (no tall buildings) and there a GPS fix is obtained quickly. Last week I was in the mountains (Andorra) and less sats could be found and time to fix was increased with a few seconds. Flew there more than ten times without issues.

Number of sats is no index for the quality of the position it would be better to use and display the hdop value - but maybe that would be too technical for the Spark user
I usually get a good fix within 20 seconds and >15 sats

I usually don't fly outdoors without 8