Estimating ultrasonic time of flight using envelope and quasi maximum likelihood method for damage detection and assessment

Online Time-Resolved Reconstruction Method for Acoustic Tomography System

“…Estimating the TOF through parametric approximation through envelope extraction [38,40,41] has been widely used in ultrasound ranging and nondestructive testing. The received signal is usually modelled as a delayed Gaussian echo signal, and the TOF can be estimated after its envelope is extracted [42]. However, this Gaussian echo model is based on the assumption that the received signal is a backscattered echo from a flat surface reflector.…”

Nonlinear Acoustic Shadow Method to Reduce Reverberation Artifact

“…Note that the linear acoustic shadow imaging corresponds to the conventional acoustic shadow method that utilizes primary waves. Finally, the two-dimensional acoustic shadow images were reconstructed by traversing the transducer and hydrophone across the square cylinder after detecting the envelope of each waves by Hilbert transformation [18]- [20]. These images were normalized by each maximum amplitude that corresponds to the direct wave.…”

Epoxy cure monitoring using ultrasonic spread spectrum binary signals

“…Technique is using global signal properties to establish the maximum likelihood between reference (transmitted) and received signals. Reference signal can be pre-recorded from some reference object (usually strong reflector with one interface) or produced using adaptive model [9,10]. Cross-correlation function (CCF):…”