Abstract: An acoustic array transducer capable of forming narrow dispersion, broadband or narrowband acoustic beam sets in two dimensions with a minimum aperture size. Concurrent yet independent electrical interfacing with array transducer elements allows simultaneous formation of multiple transmit and receive beams inclined within two planar orientations normal to the array face, while requiring a minimum amount of supporting circuitry. A method of economically and accurately fabricating the aforementioned transducer array by incrementally dicing bonded layers of solid discs of transducer materials being rigidly held together is also disclosed.

Abstract: An electronic heading and attitude sensing subsystem which is fully integrated with the existing hardware of an acoustic Doppler current profiler (ADCP) oceanographic sonar suite to reduce the size and complexity of the apparatus. The subsystem uses a tri-state drive signal with relaxation periods and integration windows to synchronously drive the fluxgate magnetic sensors while reducing the effects of non-linearities and higher order harmonics which may result in heading errors. The present invention includes an electrolytic tilt sensor device and driving circuit which allow measurement of system vertical orientation without the effects of electrolyte conductivity are described. The present invention further includes methods of system calibration, magnetic perturbation modeling, and heading calculation.

Abstract: A system and method for measuring current velocities using coded-pulse broadband acoustic signals. Autocorrelation of two phase coded pulses which are in the water during a single transmission cycle is used to calculate a Doppler frequency. The effective result is current profilers having improved profiling range and spatio-temporal resolution.

Abstract: In a correlation device, a system and method for measuring velocities using a single coded pulse generator. The correlation device may also include maximum likelihood estimation techniques for processing the echo signals received from a plurality of transducers. The presently preferred embodiment of the device is as a current profiler having a bottom tracking capability for providing vessel velocity.

Abstract: A system and method for measuring current velocities using coded-pulse broadband acoustic signals. Autocorrelation of two phase coded pulses which are in the water during a single transmission cycle is used to calculate a Doppler frequency. The effective result is current profilers having improved profiling range and spatio-temporal resolution.

Abstract: A system and method for bottom tracking in a sonar system. The present invention provides for convolving the received signal with the second derivative, or an approximation thereof, of the matched transmitted pulse. In another aspect of the invention, the received signal is convolved with the matching transmitter pulse and the result is evaluated by summing the differences between a central peak and its neighboring left and right values. The filtering of the present invention removes the effect of water absorption on signal amplitude. The invention also includes compensating for spreading loss in the received signal.

Abstract: A system and method for measuring current velocities using coded-pulse broadband acoustic signals. Autocorrelation of two phase coded pulses which are in the water during a single transmission cycle is used to calculate a Doppler frequency. The effective result is current profilers having improved profiling range and spatio-temporal resolution.