An Extension of Underwater Explosive Models to Include the High Frequency Transients Following Pulse Maxima

Direct arrival of signals produced from underwater explosions (having no reflective paths contributing to the first arrivals) exhibited high frequency pressure oscillations following the pulse maxima. Appearance is similar to the familiar ringing response of an underdamped linear system to an impulse, i.e., a decaying exponential multiplied by a sinusoid. Correlation equations for description of the main features of the pressure response to an underwater explosion are extensive in the literature. By combining these correlations with the concept of ringing, a simulation method of the pressure response of underwater explosions which includes these high frequency components has been developed for nearby explosions. An interesting method of estimating the ringing frequency from the quarter wave coincidence at the first bubble pulse maximum and a novel means of extending the number of bubble pulse oscillations into the noise level are also presented