Originally Posted by docbert

I use an Android app called "GPS Test" (there are dozens of similar ones available) that will show you the status of the GPS on the phone, including how good a signal it's getting and the location of the satellites.

Once it confirms that I've got a signal, then I jump over to Google Maps.

Also keep in mind that GPS's don't work well (or basically, at all) on 787's. On other aircraft they will work fine near the window, but likely not all that well elsewhere.