The application relates to bi-static or multi-static holographic navigation systems, including methods of localizing an emitter or receiver with high precision relative to the sea floor. The system and methods can be used with a fully active sonar or radar system using well synchronized transmitters and receivers. The system and methods can be used with a passive sonar or radar system localizing a transmitter or a receiver based on poorly timed received signals.

An underwater imaging system is disclosed. A boat sonar transducer is configured to transmit and receive sonar signals and generate an image of water and surfaces using received sonar signals. An active echo system is configured to be positioned within the water to remotely communicate with the boat sonar transducer. The active echo system includes an ultrasound transducer configured to detect sonar signals transmitted by the boat sonar transducer and transmit an active echo pulse, or a series of active echo pulses, back to the boat sonar transducer. A microprocessor is configured to drive the ultrasound transducer to transmit the active echo pulse, or series of active echo pulses, back to the boat sonar transducer in response to the ultrasound transducer detecting sonar signals transmitted by the boat sonar transducer.

An underwater vehicle includes a propeller able to propel the vehicle, the vehicle comprising a synthetic aperture sonar comprising a set of at least one physical antenna for receiving acoustic waves, the underwater vehicle comprising a connector able to mechanically couple removably a cable to the vehicle so as to allow the underwater vehicle to be towed by a surface vehicle. The physical receiving antenna comprises a plurality of acoustic sensors, the underwater vehicle comprising an electrical network able to convey electrical power to the receiving antenna, the electrical network being configured so as to have a plurality of states wherein it conveys electrical power to different sets of acoustic sensors containing different respective numbers of acoustic sensors.

A synthetic aperture sonar (SAS) system utilizes a novel timing and pointing method to illuminate and process data from multiple receive channels over one or more elevation swaths. The system further utilizes cross-track interferometry to improve accuracy of three-dimensional mapping.

An echo measuring apparatus has: a transmission signal forming unit for forming a transmission signal by a pseudo noise sequence signal; a transmitting unit for transmitting the transmission signal as an ultrasonic wave into the water; a receiving unit for receiving an echo of the ultrasonic wave; and a correlator for discriminating the echo corresponding to the transmission signal by executing a correlating process to the echo by the pseudo noise sequence signal and measuring a distance to a measurement target on the basis of a time difference between the transmission signal and the echo, wherein assuming that a velocity of a sound wave in the water is equal to Vu and the distance to the measurement target is equal to D, a period of the transmission signal includes a case where it is equal to or less than (2D/Vu).

An interferometric synthetic aperture acoustic imager is disclosed. Specifically, an acoustic imaging system includes an acoustic transmitter, an acoustic receiver array, a signal processing system, a navigation data system, and a meteorological data system. The acoustic transmitter and the acoustic receiver array are mounted on transceiver array. The navigation data system includes a Position and Orientation System for Land Vehicles system which receives data from two Global Positioning System antennas, an inertial measurement unit, and a wheel encoder mounted on a vehicle wheel. The system also includes meteorological data system that records temperature, relative humidity, and barometric pressure. The meteorological data may be used to adjust the received acoustic data based on atmospheric conditions.

Encoded transmit signals are provided to an ultrasound array such diverging ultrasound waves are sequentially transmitted. Each diverging ultrasound wave is generated by a respective set of encoded transmit signals, where each set of encoded transmit signals is encoded by a respective row of an NN invertible orthogonal matrix. Only a selected subset of M rows, with N<M, is employed to encode the transmit signals. Sets of receive signals detected in response to the transmitted diverging ultrasound waves are decoded via a transposed matrix generated based on the invertible orthogonal matrix, with each set of decoded receive signals being associated with insonification via a subset of the ultrasound array elements in the fixed aperture. Synthetic aperture beamforming is performed on the decoded receive signals to generate an ultrasound image.

A signal processing device includes: a data receiver configured to transmit a transmission wave a position of which changes in a first direction and which spreads in a second direction orthogonal to the first direction, and generate a matrix of acquired observation data in the first and second directions, as a reception signal matrix, with a value of a position in the reception signal depending on a signal strength; a range processor configured to specify a range in the second direction in an imaging matrix, and set a sparse vector including a component in the first direction of the specified range; a reconstruction processor configured to perform reconstruction processing using the reception signal matrix and the sparse vector to calculate a component of the sparse vector; and a synthesis processor configured to synthesize the resulting sparse vector while moving the range, to generate an imaging matrix.

A synthetic aperture sonar (SAS) system utilizes a novel timing and pointing method to illuminate and process data from multiple receive channels over one or more elevation swaths. The system further utilizes cross-track interferometry to improve accuracy of three-dimensional mapping.

In the ultrasound diagnosis, a probe performs transmission of an ultrasonic beam a plurality of times so as to form predetermined transmission focus points, the analog reception data output by the probe is A/D converted to turn into a first element data, a plurality of first element data is used to generate a second element data corresponding to any one of the plurality of first element data, and a sound velocity is determined using the first element data in a case where the position for determining the sound velocity is in a vicinity of the transmission focus point and using the second element data in a case where the position is not in a vicinity of the transmission focus point. In this manner, the sound velocity of the ultrasound waves in an inspection object can be accurately determined without decreasing the frame rate.