M.Tigelaar said:The barometric sensor in the Phantom sees rising temperature as an increase in altitude. There is a lot of heat generated inside the body just sitting there.
Mine always thinks it's 10 feet up after 3 minutes on the ground the first time it's powered on. If you've been messing around setting waypoints for much longer than that I wouldn't be surprised if the bird thinks it's already at 15 feet when you hit "Go". Just watch your camera screen for a few minutes on the ground at first power-on to see what I'm talking about.
Interesting! I wonder if better ventilation is necessary for more accurate height determination? I would want to terminally alter the vents on the bird just to find out I was wrong (although a temporary mod might be feasible - not sure how at the moment). An opening top and bottom letting prop wash through could help I suppose (but again, that sounds fairly permanent). The only real value in that kind of surgery of course is having the altitude accuracy to fly very close to the ground without crashing - not sure if that is worth it.
And by the way, any drift that you guys see like this could either be gain or offset error because both types of affected electronic parts (resistors or op amps) have temperature coefficients, and the barometric sensors are probably much worse (but would cause only offset error).