Reporting this from the field. This is the new PV2+ fourth flight. I was flying safely above grass lands with no houses, trees or even telephone poles in non restricted airspace. Had 11 GPS links, batteries good, and strong signal. I was the highest I have ever been, 650 ft when "Control Signal Lost" came on the screen. 3 seconds later "Coming Home". The aircraft was directly above me if that makes any difference. But the Phantom did as designed and started a slow decent towards me. I was in GPS, not NAZA mode. I'm calm and cool and them switched S1 to mid position and back to top position at about 400 ft. This then let me regain control and about 4 more minutes of low altitude speed tests. Any thoughts on why loss of signal occurred would me greatly appreciated. Regards, J.