RE: What The.... Noooooooo!
Intrim, why would DFI bother to publish a TI calibration procedure if it weren't necessary? Why would they stress to hold the DF "away from your body heat"? And why would they want you to set "thermal level" while standing a good 10 to 15 feet away from the DF?
Although the ground is warmer than the sky, the ground here may be the same temperature as the sky there, hence the calibration requirement. During calibration (if you're following the directions), the DF is being held in a known orientation, with the front sensors pointing toward the sky and the rear sensors pointing toward the ground. The program saves these sample temperature readings--which are now correct for the local conditions--and uses them when trying to self-level. But in order for it to work, it needs to be able to make an assumption about the position it's in when it's armed, hence the instructions to hold it "eyes up."
(Anyone else want to jump in here?)
Will