Does the AST measure distance from effectively the same point on the instrument as the pressure sensor? Nortek Support June 22, 2019 13:39 Updated Follow Yes, the pressure reading and the AST distance has been calibrated so that they both have the same distance. Related articles What is the difference between the raw and the processed AST time series? Do I need to calibrate Nortek instruments? Comments 0 comments Please sign in to leave a comment.