An Expanded Characterization of the Information Capacity of a Short Range Underwater Communications Channel

摘要

The report considers theoretical limits in transmitting information through an underwater communications channel. Acoustic energy is the vehicle for information transfer since virtually no other form of energy propagates usefully in sea water. Short range near surface transmissions between computer bearing ocean vessels in the mid North Atlantic are evaluated. The characterization conducted provides valuable guidance needed for designing optimum signal generation and detection systems. The fundamental mechanism involved in undersea transmissions is analyzed to develop a channel model. Major channel characteristics are high energy absorption and the severe time varying multipath environment. It is shown that directive transmitting and receiving transducers mitigate the multipath problems and allow a frequency dispersive, time selective model to be employed. (Author)