Acoustic transfer function of the ocean for a motional source

The motional-source transfer characteristics of long-range acoustic propagations are derived based on the discrete multipath propagation model predicted by geometrical acoustics. Parameters are those associated with the characteristic solutions of the eikonal equation. A modified transfer function is formulated which relates the received signal to a particularly useful transformation of the source signal. The modified transfer function shows that a remotely received signal consists of the weighted superposition of a number of modified source signals both slightly compressed (or expanded) and translated in time. The time variable compression factor is a stochastic process which reflects the fluctuations inherent in both the medium and the source motion. Application of the model transfer function to a specific ocean profile exemplifies the ocean filter characteristics and the complex nature of the received signal from a CW source in motion. It is concluded that the model transfer function will be a useful tool for signal processing applications in underwater acoustics.