An underwater ultrasonic device includes at least one first ultrasonic transducer and at least one second ultrasonic transducer. The first ultrasonic transducer is configured to transmit a plurality of ultrasonic signals and the second ultrasonic transducer is configured to receive a plurality of reflected signals of the ultrasonic signals. The first ultrasonic transducer and the second ultrasonic transducer are disposed with respect to each other. One of the first ultrasonic transducer and the second ultrasonic transducer is curvilinear and another one of the first ultrasonic transducer and the second ultrasonic transducer is curvilinear or straight linear.

An underwater ultrasonic device includes at least one first ultrasonic transducer and at least one second ultrasonic transducer. The first ultrasonic transducer is configured to transmit a plurality of ultrasonic signals and the second ultrasonic transducer is configured to receive a plurality of reflected signals of the ultrasonic signals. The first ultrasonic transducer and the second ultrasonic transducer are disposed with respect to each other. One of the first ultrasonic transducer and the second ultrasonic transducer is curvilinear and another one of the first ultrasonic transducer and the second ultrasonic transducer is curvilinear or straight linear.

Techniques for determining the directional frequency response of an arrangement of transducer elements are disclosed. In an example, a method includes providing a simulation of locations of the transducer elements, in the spatial domain; providing a beamforming direction and a frequency range; converting the simulation of locations from the spatial domain into corresponding frequency response values in a spatial frequency domain, such that, for each frequency of a plurality of frequencies in the frequency range, a spatial frequency contour is defined, each of the spatial frequency contours intersecting at the origin; determining the frequency response by applying a transformation to the frequency response values for the provided beamforming direction and frequency range and translating the spatial frequency domain into a modified frequency domain; and outputting the frequency response.

Techniques for determining the directional frequency response of an arrangement of transducer elements are disclosed. In an example, a method includes providing a simulation of locations of the transducer elements, in the spatial domain; providing a beamforming direction and a frequency range; converting the simulation of locations from the spatial domain into corresponding frequency response values in a spatial frequency domain, such that, for each frequency of a plurality of frequencies in the frequency range, a spatial frequency contour is defined, each of the spatial frequency contours intersecting at the origin; determining the frequency response by applying a transformation to the frequency response values for the provided beamforming direction and frequency range and translating the spatial frequency domain into a modified frequency domain; and outputting the frequency response.

A direction of arrival estimation apparatus includes at least first and second sub-arrays to receive a reflected wave of a transmission waveform from a target; first and second phasing parts that perform phasing of reception signals at the first and second sub-arrays to generate first and second sub-array beams; an arrival time difference calculation part that calculates first and second correlations of the reception signals of the first and second sub-array beams at first and second time points to find an arrival time difference between times of the reflected wave arriving at the first and second sub-arrays, based on a result of a predetermined operation on the first and second correlations and a time difference between the first time point and the second time point; and a direction of arrival calculation part that finds a direction of arrival of the target based on the arrival time difference.

A survey system and method to improve one or more of survey quality, efficiency, and utility for example by utilizing a vessel mounted MBES and a selected survey plan to check sound speed(s) via eliciting echoes from reflectors in colocated groups of reflectors using multi-perspective ensonification.

A survey system and method to improve one or more of survey quality, efficiency, and utility for example by utilizing a vessel mounted MBES and a selected survey plan to check sound speed(s) via eliciting echoes from reflectors in colocated groups of reflectors using multi-perspective ensonification.

A 1D ultrasonic transducer unit for area monitoring, having a housing having a securing device for securing to a surface and having at least three discrete ultrasonic transducers designed to decouple sound waves with a consistent operating frequency between 20 kHz and 400 kHz in a gaseous medium, and a control unit designed to control each ultrasonic transducer individually, wherein two ultrasonic transducers, directly adjacent to one another, are spaced apart by a distance, the 1D ultrasonic transducer unit has a sound channel per ultrasonic transducer with an input opening, associated with exactly one respective ultrasonic transducer, and an output opening, the output openings are arranged along a straight line, a distance from the directly adjacent output opening corresponds at most to the full or half the wavelength in the gaseous medium and is smaller than the corresponding distance.

A 1D ultrasonic transducer unit for area monitoring, having a housing having a securing device for securing to a surface and having at least three discrete ultrasonic transducers designed to decouple sound waves with a consistent operating frequency between 20 kHz and 400 kHz in a gaseous medium, and a control unit designed to control each ultrasonic transducer individually, wherein two ultrasonic transducers, directly adjacent to one another, are spaced apart by a distance, the 1D ultrasonic transducer unit has a sound channel per ultrasonic transducer with an input opening, associated with exactly one respective ultrasonic transducer, and an output opening, the output openings are arranged along a straight line, a distance from the directly adjacent output opening corresponds at most to the full or half the wavelength in the gaseous medium and is smaller than the corresponding distance.

A method of stereoscopic mapping an underwater location includes determining a relative position and relative distance between two separate sensors on separate underwater platforms. Each of the two separate sensors scans a same underwater feature from its respective determined relative position. A stereoscopic image of the underwater feature is created from the two scanned images.