Abstract: Aiming at the problem of finding weak reflection signal from the bottom of the anchor, we carried out test on anchor model in accordance with current technique specification, and extracted three instantaneous information, i.e. instantaneous frequency, instantaneous amplitude, and instantaneous phase by the Hilbert transform. Result of the test indicates that the three instantaneous information is effective at picking up the reflection wave information, especially the instantaneous frequency can effectively extract the arrival time of reflection wave, which remarkably enhances the accuracy of anchor length evaluation.              

Key words: anchor, non-destructive test, three instantaneous information, reflection wave