Whats the secrect on how the unit works?

[Goldenhour]

With the HC3a I would find a hover for 10 seconds or whatever and hit an assigned switch that would lock the hover in.
With the HC3sx there is the level surface the unit is on in the copter. There is the level surface it takes off from but from there does it sense gravity like a bubble level. Is this basically an Apple iphone bubble level?
Or is it something proprietary and none of the above?