Acoustic signal propagation time measuring method uses intersection of tangent to maximum gradient point of first half wave with zero line as time reference point

摘要

Method has acoustic signals propagated between transmission and reception acoustic transducers on opposite sides of measuring path, with reception of acoustic signal as oscillating wave group. Maximum gradient point along front flank of first half wave (25) of wave group is determined and intersection of tangent to maximum gradient point with zero line (30) is used as reference time point for determining end of propagation time. An Independent claim for an acoustic signal propagation time measuring device is also included.