Identification of the acoustic ocean transfer function in the Tyrrhenian Sea. I: Statistical considerations

Abstract

In the process of statistical analysis of signature/response pairs collected in the Tyrrhenian Sea during the Napoli 85 Trial, a novel method has been developed for identifying the ocean transfer function (OTF). This method allows for the first-order diffraction effects, multipath propagation, and the signal bandwidth narrow compared to the bandwidth of the OTF. It is based on deconvolution of the received pulse with the signature of the emitted broadband pulse. The deconvolution is carried out under several physically reasonable constraints. One of them restricts the method to situations when no phase reversal takes place along any of the paths or, alternatively, when all the paths deliver the signal with a reversed phase. When applied to the Napoli 85 data, the method appears to indicate the presence of two direct (deep sea) paths between the experimental source and receiver with quite distinct times of propagation. In this paper, exploratory statistical data analysis is used to validate both the method and the underlying constraints.