Abstract: An underwater communication system comprises a plurality of network nodes for sending and receiving ultrasonic energy through water. In accordance with one aspect, each of the network nodes includes an array of two ultrasonic transducers positioned so as to define a line segment. Each node also includes a transceiver adapted to generate a code element, generate a data element, generate a modulation element, and combine the code element, the data element and the modulation element into an analog waveform. The system is further adapted to transmit the analog waveform through each of the ultrasonic transducers and receive the analog waveform generated by at least one of the network nodes.

Abstract: An underwater communication system comprises a plurality of location and messaging units for sending and receiving ultrasonic energy through water. In accordance with one aspect, each of the location and messaging units comprising an array of transducers, a transceiver adapted to generate a code element, generate a data element, generate a modulation element, and combine the code element, the data element and the modulation element into an analog wave form. The system is further adapted to transmit the analog wave form through one of the ultrasonic transducers and receive the analog wave-form generated by at least one of the location and messaging units.

Abstract: An underwater communication system comprises a plurality of location and messaging units for sending and receiving ultrasonic energy through water. In accordance with one aspect, each of the location and messaging units comprising an array of four ultrasonic transducers positioned such that they define a generally tetrahedral shape, a transceiver adapted to generate a code element, generate a data element, generate a modulation element, and combine the code element, the data element and the modulation element into an analog wave form. The system is further adapted to transmit the analog wave form through each of the four ultrasonic transducers and receive the analog wave-form generated by at least one of the location and messaging units.