A Comparison of Wavelet, Quadrature, and Peak-to-Peak Methods for Determining Shock Velocity from Microwave Interferometer Data

摘要

Microwave interferometry (MI) is used to measure shock and detonation velocities in explosives. To achieve greater spatial resolution, modern systems employ a quadrature mixer to continuously measure the phase advancement of the output signal over time. However, quadrature analysis is difficult to implement on data having a low signal to noise ratio, variable amplitude, and harmonic frequencies. In this work, a continuous wavelet transform (CWT) based on the Gabor mother wavelet was used to analyze velocity data. The wavelet-based method is compared with the previous techniques of quadrature and peak-to-peak analysis using real and manufactured data from a small-scale explosives characterization experiment. Results show that the wavelet-based analysis has multiple advantages over peak-to-peak and quadrature, including a greater robustness for handling signal noise, increased velocity-time resolution, and a single tunable parameter that may be optimized for different types of signals. In addition, the wavelet-based technique was used to show the effect of density variations in the explosive triaminotrinitrobenzene (TATB). This technique also has the potential to distinguish multiple independent frequencies, and should be considered to study the decoupling of shock and reaction zones. Overall, a wavelet-based technique is suggested as an improved addition to the analysis tools used in the field of explosives research and in particular to microwave interferometry. This analysis approach could also be applied to other experimental data.