Abstract: Lots of uncertain factors affect the time delay estimation precision of time-difference location method in rock acoustic estimation(AE) experiments. Aiming at this problem, the all phase phase-difference time delay estimation method is proposed. Time delay of AE signal is deduced through the phase-difference obtained by combining wavelet decomposition and all phase frequency analysis. AE sub-band signals with the same dominant frequency from different sensors are found with wavelet decomposition. Then the phases of middle sample of every sub-band signal are obtained with all phase frequency analysis method for those chosen sub-band signals, and the time-differences of AE signals’ reaching different sensors are computed according to the relationship between phase-difference and time-difference. Finally, the AE source is located by the method of time-difference location. Experiments are conducted on a 50 mm×100 mm×50 mm granite stone, and AE source is generated by broken lead at ten different points. Under the lab environment, the results from the proposed AE location method indicate that using phase-difference based on wavelet transform and all phase frequency analysis can effectively improve the accuracy of location of AE source. Compared to the results obtained by the PCI-2 acoustic emission instrument, the absolute error reduces by about 3 mm, so as to provide an effective way for AE source inversion.

Key words: acoustic emission (AE), wavelet transform, all phase spectrum analysis, phase difference, source location