I was rudely woken up at 5:30 this morning by a pulsating aeroplane noise, coming and going quite nearby. I turned on FR24 to see a Cessna Titan, out of EMA, vaguely wandering back and forth over the Isle of Purbeck at 4800'. It didn't show the regular, straight lines of most survey aircraft I have seen and his props were definitely out of sync, at least some of the time. Judging from the irritating noise, from an aircraft which was at least 5 - 10 miles away from me, the props were also in fine pitch. It could have been in trouble I suppose.