Investigation of deturbing methods for sonic boom signatures

Abstract

There is a desire to certify aircraft for supersonic flight using microphone measurements of the aircraft’s sonic boom signature on the ground. If the signature propagates through the planetary boundary layer before it reaches the ground, the signature becomes distorted because of atmospheric turbulence, corrupting the measurement. Methods to remove the turbulence effect, or deturbing methods, currently exist but are restricted to typical N-wave shapes or knowledge of the turbulence structure beforehand. This work investigates methods of deturbing sonic boom signatures independent of the N-wave shape and not requiring prior knowledge of turbulence. Improvements are made to the averaging method and subtraction method of deturbing, and a new method is investigated which uses audio fingerprinting, an audio identification algorithm used by music identification apps such as Shazam. The effects of each deturbing method are described using a wide set of physical and subjective metrics. [Work supported by the FAA. The opinions, findings, conclusions, and recommendations expressed in this material are those of the authors and do not necessarily reflect the views of ASCENT FAA Center of Excellence sponsor organizations.]