Abstract: In one aspect, an acoustic full-duplex communication system includes a transmitter array having at least two transmitters. The transmitters are positioned along an axis of maximum transmission and are separated by about half of a wavelength of a transmission frequency band. The transmitters transmit waveforms of opposing polarity that mutually interfere in a plane orthogonal to the transmission axis. The system includes a receiver array having at least one receiver in the orthogonal plane. In a second aspect, an underwater acoustic full-duplex communication system includes a transmitter and two receivers. The receivers are symmetrically positioned about an axis, separated by about half of a wavelength of a transmission frequency band, and equidistant from the transmitter. The receivers are connected in opposing polarity. Either aspect may include an adaptive filter to improve cancellation of transmitter originated near field transmissions received by the one or more receivers.

Abstract: In one aspect, an acoustic full-duplex communication system includes a transmitter array having at least two transmitters. The transmitters are positioned along an axis of maximum transmission and are separated by about half of a wavelength of a transmission frequency band. The transmitters transmit waveforms of opposing polarity that mutually interfere in a plane orthogonal to the transmission axis. The system includes a receiver array having at least one receiver in the orthogonal plane. In a second aspect, an underwater acoustic full-duplex communication system includes a transmitter and two receivers. The receivers are symmetrically positioned about an axis, separated by about half of a wavelength of a transmission frequency band, and equidistant from the transmitter. The receivers are connected in opposing polarity. Either aspect may include an adaptive filter to improve cancellation of transmitter originated near field transmissions received by the one or more receivers.

Abstract: A method and apparatus for determining the geophysical position of an autonomous underwater system utilizing underwater acoustic modems that exchange broadband underwater acoustic signals. The method of the invention includes the steps of initiating an exchange of broadband acoustic signals between the autonomous system of unknown geophysical position and a base system of known geophysical position wherein the depths of both systems is known. A bearing calculation is made on one of the signals transmitted between the systems, preferably through the use of an array of hydrophones placed closely together at predetermined locations on either the autonomous or base system. Also, the range between the two systems is determined by measuring the time of travel of at least one signal.

Abstract: A data communications and underwater release management system for acquiring data from remote positively buoyant instrumentation packages moored underwater through the use of an intervening mechanical release coupled at one end to the buoyant instrumentation package and at the other to the mooring. A topside modem system provides bidirectional communication with an undersea modem commonly housed with the release to permit data generated from the instrumentation to be conveyed topside and/or send command signals to release the instrumentation package so that it can ascend to the surface for recovery, repair, or refitting. Power is supplied via an on-board battery whose energy level is monitored and directed when below a threshold value to operate only the mechanical release.

Abstract: Apparatus and methods for in-line testing of the internal pressure of flexible containers traveling along a production line at high speeds. The apparatus inspects semi-rigid plastic and thin-walled liquid filled containers by analyzing the output from a load cell that indirectly measures the reaction force applied to a container through the intermediary of a load cell roller that, in turn, supports a flexible belt that directly contacts containers while moving them through an inspection station without interrupting the flow of the production line. Containers are contacted only by a flexible portion of a conveyor belt to minimize structural and aesthetic damage to them that might otherwise occur during the inspection process.

Abstract: Apparatus and methods for in-line testing of the internal pressure of flexible containers traveling along a production line at high speeds. The apparatus inspects semi-rigid plastic and thin-walled liquid filled containers by analyzing the output from a load cell that indirectly measures the reaction force applied to a container through the intermediary of a load cell roller that, in turn, supports a flexible belt that directly contacts containers while moving them through an inspection station without interrupting the flow of the production line. Containers are contacted only by a flexible portion of a conveyor belt to minimize structural and aesthetic damage to them that might otherwise occur during the inspection process.