Self contained and calibrated??
It would be nice to have a unit that was self contained and calibrated. I'm sure with modern technology it would be possible to build one that can be removed and replaced by a pilot or mechanical lame? They can make portable GPS's that work very well so why not an adsb that does not require a specialist to screw it in and calibrate it?
We have "throw away" gps's now. No real maintenance problems.