Abstract: A system and a method for determining one or more wave characteristics from a moving platform are disclosed. A sonar system, such as an Acoustic Doppler Current Profiler, can profile the water motion relative to the platform, and an earth reference can determine a measure of the platform motion relative to a fixed earth reference. Both water profile and earth reference measurements can be synergistically employed to compensate for motion of the platform. Directional wave spectra and non-directional wave spectrum can be computed and translated via linear wave theory to surface height spectra and used to calculate characteristics, such as significant wave height, peak period, and peak direction.

Abstract: A sonar system and method of operating a sonar system are disclosed. In one embodiment, the sonar system comprises an array of transducers and a multiplexer configurable into a plurality of states. In one embodiment, the multiplexer, when in a first state, electrically couples a plurality of connections with the plurality of transducers via a first mapping and, in a second state, electrically couples the plurality of connections with the plurality of transducers via a second mapping.

Abstract: A system and a method for determining one or more wave characteristics from a moving platform are disclosed. A sonar system, such as an Acoustic Doppler Current Profiler, can profile the water motion relative to the platform, and an earth reference can determine a measure of the platform motion relative to a fixed earth reference. Both water profile and earth reference measurements can be synergistically employed to compensate for motion of the platform. Directional wave spectra and non-directional wave spectrum can be computed and translated via linear wave theory to surface height spectra and used to calculate characteristics, such as significant wave height, peak period, and peak direction.

Abstract: A system and method of remote sound speed measurement are disclosed. In one embodiment, a system for estimating a sound speed comprises a plurality of transducers configured to i) transmit a first acoustic signal from a first location, ii) receive a first scattered signal at a second location, iii) receive a second scattered signal at a third location, and iv) receive a third scattered signal at a fourth location; and a microprocessor configured to i) estimate a travel time based on at least one of the first, second, or third scattered signals, ii) generate a cross-correlation signal comprising a product of at least two of the first, second, and third scattered signals, iii) estimate a travel time difference based on at least the cross-correlation signal, and iv) estimate a sound speed based on at least the estimated travel time and the estimated travel time difference.

Abstract: A system and method of determining a magnetic field and magnetic compass calibration is disclosed. One embodiment is a method of determining a magnetic field vector, the method comprising storing, for each of a plurality of sensor orientations, one or more calibration components, determining, for a sensor orientation not included in the plurality of sensor orientations, a magnetic field vector and a gravity vector, iteratively estimating one or more calibration coefficients based on the stored components, the determined magnetic field vector, and the determined gravity vector, wherein the calibration coefficients are updated during each of a plurality of iterations, and determining a sensor-orientation-independent magnetic field vector based on at least one of the calibration coefficients.

Abstract: A system and method of range estimation are disclosed. In one embodiment, the method comprises transmitting beams through a medium towards a surface, receiving reflected signals from the surface, and estimating range to the surfaced based on the reflected signals and an estimate of sidelobe coupling of the beams.

Abstract: A sonar system and method of operating a sonar system are disclosed. In one embodiment, the sonar system comprises an array of transducers and a multiplexer configurable into a plurality of states. In one embodiment, the multiplexer, when in a first state, electrically couples a plurality of connections with the plurality of transducers via a first mapping and, in a second state, electrically couples the plurality of connections with the plurality of transducers via a second mapping.

Abstract: A system and method of remote sound speed measurement are disclosed. In one embodiment, a system for estimating a sound speed comprises a plurality of transducers configured to i) transmit a first acoustic signal from a first location, ii) transmit a second acoustic signal at a second location, iii) receive a first reflected signal at a third location, and iv) receive a second reflected signal at a fourth location, the reflected signals comprising at least one echo from at least one of the acoustic signals; and a microprocessor configured to i) estimate a travel time based on at least the first or second reflected signals, ii) estimate a travel time difference based on at least the first and second reflected signals, and iii) estimate a sound speed based on at least the estimated travel time and estimated travel time difference.

Abstract: A system and method of range estimation are disclosed. In one embodiment, the method comprises transmitting beams through a medium towards a surface, receiving reflected signals from the surface, and estimating range to the surfaced based on the reflected signals and an estimate of sidelobe coupling of the beams.

Abstract: A sonar system and method of operating a sonar system are disclosed. In one embodiment, the sonar system comprises an array of transducers and a multiplexer configurable into a plurality of states. In one embodiment, the multiplexer, when in a first state, electrically couples a plurality of connections with the plurality of transducers via a first mapping and, in a second state, electrically couples the plurality of connections with the plurality of transducers via a second mapping.

Abstract: A system and method of remote sound speed measurement are disclosed. In one embodiment, a system for estimating a sound speed comprises a plurality of transducers configured to i) transmit a first acoustic signal from a first location, ii) transmit a second acoustic signal at a second location, iii) receive a first reflected signal at a third location, and iv) receive a second reflected signal at a fourth location, the reflected signals comprising at least one echo from at least one of the acoustic signals; and a microprocessor configured to i) estimate a travel time based on at least the first or second reflected signals, ii) estimate a travel time difference based on at least the first and second reflected signals, and iii) estimate a sound speed based on at least the estimated travel time and estimated travel time difference.

Abstract: A sonar system and method of operating a sonar system are disclosed. In one embodiment, the sonar system comprises an array of transducers and a multiplexer configurable into a plurality of states. In one embodiment, the multiplexer, when in a first state, electrically couples a plurality of connections with the plurality of transducers via a first mapping and, in a second state, electrically couples the plurality of connections with the plurality of transducers via a second mapping.

Abstract: A system and method of range estimation are disclosed. In one embodiment, the method comprises transmitting beams through a medium towards a surface, receiving reflected signals from the surface, and estimating range to the surfaced based on the reflected signals and an estimate of sidelobe coupling of the beams.

Abstract: A system and method of range estimation are disclosed. In one embodiment, the method comprises transmitting beams through a medium towards a surface, receiving reflected signals from the surface, and estimating range to the surfaced based on the reflected signals and an estimate of sidelobe coupling of the beams.

Abstract: A system and method of determining a magnetic field and magnetic compass calibration is disclosed. One embodiment is a method of determining a magnetic field vector, the method comprising storing, for each of a plurality of sensor orientations, one or more calibration components, determining, for a sensor orientation not included in the plurality of sensor orientations, a magnetic field vector and a gravity vector, iteratively estimating one or more calibration coefficients based on the stored components, the determined magnetic field vector, and the determined gravity vector, wherein the calibration coefficients are updated during each of a plurality of iterations, and determining a sensor-orientation-independent magnetic field vector based on at least one of the calibration coefficients.

Abstract: A system and method for forming acoustic beams is disclosed. One embodiment is an acoustic system configured to generate a plurality of beams non-orthogonal to a transducer array simultaneously with a vertical acoustic beam orthogonal to the array. The acoustic system includes a plurality of transducer elements arranged to form a two-dimensional array and electrically connected into rows in a first dimension and columns in a second dimension.

Abstract: A system and method of remote sound speed measurement are disclosed. In one embodiment, a system for estimating a sound speed comprises a plurality of transducers configured to i) transmit a first acoustic signal from a first location, ii) transmit a second acoustic signal at a second location, iii) receive a first reflected signal at a third location, and iv) receive a second reflected signal at a fourth location, the reflected signals comprising at least one echo from at least one of the acoustic signals; and a microprocessor configured to i) estimate a travel time based on at least the first or second reflected signals, ii) estimate a travel time difference based on at least the first and second reflected signals, and iii) estimate a sound speed based on at least the estimated travel time and estimated travel time difference.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a transducer are disclosed. In one aspect, the method comprises transmitting an acoustic signal comprising N (where N is integer and N>1) pings for each of a plurality of beams, receiving echoes from each ping, obtaining a velocity estimate for each of the N pings based on echoes of the ping, and calculating a velocity based on the sum of the N velocity estimates such that the velocity is substantially free from error caused by cross-coupling between the beams.

Abstract: An improved acoustic Doppler flow measurement system which employs multiple acoustic frequencies to acquire multiple independent backscatter data from the flow channel, combining the data to enable survey measurement of channel flow properties beyond what can be achieved with either a single frequency system or multiple independent single frequency systems. The system is installed on small moving channel survey boats, remotely measuring vertical profiles of river currents, achieving accurate surveys of channel flow velocity structure and bottom topography, enabling accurate (approximately 1% resolution) survey measurement of channel flow discharge. Significant synergistic improvements are realized from both physical and functional integrations of the multi-frequency operational capability into a single integrated flow survey system. Use of phased array transducer techniques further reduces flow disturbance and transducer size, enabling use on even smaller survey boats.

Abstract: A system and method for forming acoustic beams is disclosed. One embodiment is an acoustic system configured to generate a plurality of beams non-orthogonal to a transducer array simultaneously with a vertical acoustic beam orthogonal to the array. The acoustic system includes a plurality of transducer elements arranged to form a two-dimensional array and electrically connected into rows in a first dimension and columns in a second dimension.