Study of evaluation method of wood quality using wavelet transform

The wavelet transform is effective in the processing of an unsteady signal like the tapping tone of wood. In this study, we try to develop a method for evaluating wood quality using a wavelet transform and the main obtained results can be shown as follows: 1) The Young´s modulus calculated by using the resonant frequency obtained from the wavelet transform, is compared with one measured. As for both the clear sample and the sample which includes a knot, Young´s modulus of the wood can be estimated by finding the resonant frequency in the wavelet transform. 2) The relation between the degradation of resonant frequency caused by the existence of a knot and the ratio of the knot and the diameter can be approximated in the second polynomial. Therefore, the analysis of the resonant frequencies of clear wood and wood which includes a knot leads to estimation of the amount of knots in the wood.