High speed digital acoustic telemetry system

The increasing use of untethered underwater working platforms requires the ability to provide command, control, and data communication between the underwater platform and an operator control station for these systems to be effective. Remote under ice surveillance, military mine detection and classification, and diver communications are examples of work situations where reliable, secure communication must be available if these systems are to be used effectively. This paper describes a high data rate underwater acoustic telemetry system which will operate in a reverberant, multipath environment. Spread spectrum multifrequency pulsed transmission, coupled with appropriate use of dead zones and directional transmission are primary techniques used in a system designed to achieve a data rate of 4800 bits per second at ranges up to 1000 meters. The system employs a multi-channel high frequency directional transmitter for high data rate transmission, and a lower frequency 2- way omnidirectional channel for control commands. Control commands are used to adjust data rate, change power levels, and align the directional transducers as well as other necessary supervisory command and control functions.