Abstract:

The expansion of modal wave numbers about a center frequency is considered for the efficient synthesis of low-frequency time series of acoustic pulses propagated at long ranges in the ocean. For absolutely bandlimited signals, the complex envelope is obtained directly in terms of the Fresnel integral, allowing very rapid computation of time series at long range. The quality of the approximation is evaluated for both shallow and deep water scenarios as a function of center frequency and bandwidth. Results show that time series with bandwidths of up to approximately half the center frequency may be reliably synthesized using these types of techniques for center frequencies above 20 Hz.