Acoustic Modem: December 20, 1989 Trip Report

An experiment was conducted on 20 December 1989 as part of a project investigating the design of an acoustic communication link between a Swallow float and a sonobuoy. The objective of the experiment was to measure the transmission characteristics of the acoustic channel at high frequency 10 to 20 kHz, including the nature of fading and multipath. A conclusion from the analysis results, shows that in the frequency range of 10-20 kHz, the ocean is a nonminimum phase, slowly time-varying, frequency selective fading channel. The fading amplitude characteristics changes between Rayliegh and Rayleigh-Rice distribution. The fading and the multipath phenomena are very strong in the ocean, and they must be considered in the design of an underwater acoustic communication system.