A Real-time Method for Underwater Noise Time Series Generating

Fourier synthesis is the most commonly used method for broadband simulation in underwater acoustics. The receiver time series could be obtained via Fast Fourier Transform, where the time window should be long enough to avoid the aliasing in time domain. Therefore, it is optimal for solving the non-real time pulse propagation problem. A new filter method is presented to generate the underwater noise time series real-time by using normal mode propagation model. The simulation process is realized by two FIR filters. The first one has a frequency response approximates to that computed by normal mode selection. The second one is a time-delay filter to achieve the propagating delay. Convolutions in time domain are applying to the source signal with a short time window, which is very suitable for Digital Signal Processor. The ship radiated noise time series emulated by the filter method above is compared with that by Fourier synthesis. The results show that the filter method could generate receiver time series accurately and effectively.