In the boot state of input: *#15963#*
Open the GPS to accept
Enter the "EngineerMode" interface ,slide to the "Location" and choose "YGPS" to access to the test
Put the phone on the window to have a test and see if there is the satellite to receive
If star turns to the green ,it shows that the phone has been located
Whether the singal is good or not ,it depends on the quantity of the star data
Normally it takes 5-10 minutes when phone locates  on the status of cold start
If still can't be located ,you only need to optimize the phone via the hardware