A detectable range is increased in a radar apparatus that measures a distance from a round-trip time of a sound wave. A transmitting unit transmits a plurality of sound waves including different frequency components in order. A receiving unit receives reflected waves obtained as the plurality of sound waves is reflected. An analyzing unit analyzes a frequency component of each of the reflected waves and identifies, for each reflected wave, the sound wave corresponding to the reflected wave among the plurality of sound waves on the basis of the analysis result. A ranging unit acquires a distance corresponding to a period of time from a transmission time of the sound wave corresponding to the reflected wave to a reception time of the reflected wave.

This disclosure describes presence-detection devices that detect movement of a person by emitting ultrasonic signals into an environment, and characterizing the change in the frequency, or the Doppler shift, of the reflections of the ultrasonic signals off the person caused by the movement of the person. The techniques include downsampling the audio signals from the carrier frequency range down to a frequency range with a center frequency around 0 Hz. A filter is applied to attenuate signals around 0 Hz and below (or above), such as the emitted signals. In addition to removing the emitted signals, the negative side (or positive side) of the audio signals are removed, but the Doppler shift is still represented in the remaining portion of the audio signals. By removing a portion of the audio signals, the amount of processing required to detect the Doppler shift in the reflections of the ultrasonic signals is reduced.

A method is accordingly provided for operating an ultrasonic sensor, a plurality of measuring cycles being successively carried out. In each measuring cycle—an electroacoustic transducer of the ultrasonic sensor is excited using an excitation pulse, causing it to mechanically oscillate, as a result of which a measuring signal is transmitted by the transducer, an echo signal is received by the transducer, and a piece of object information is ascertained from the echo signal. The frequency curve of the excitation pulse is differentiated into two measuring cycles successively carried out at least at the end of the frequency curve. The ascertained pieces of object information from at least two measuring cycles are compared with one another and an interference is identified as a function of the result of the comparison.

A pressure tolerant energy system may comprise a pressure tolerant cavity and an energy system enclosed in the pressure tolerant cavity configured to provide electrical power to the vehicle. The energy system may include one or more battery cells and a pressure tolerant, programmable management circuit. The pressure tolerant cavity may be filled with an electrically-inert liquid, such as mineral oil. In some embodiments, the electrically-inert liquid may be kept at a positive pressure relative to a pressure external to the pressure tolerant cavity. The energy system may further comprise a pressure venting system configured to maintain the pressure inside the pressure tolerant cavity within a range of pressures. The pressure tolerant cavity may be sealed to prevent water ingress.

An object detection device includes a signal generator configured to generate a drive signal including an identification signal for identifying ultrasonic waves, a transmitter configured to transmit an ultrasonic wave as a probe wave in response to the drive signal, a receiver configured to receive the ultrasonic wave to generate a reception signal, and a determiner configured to analyze frequencies of the reception signal to determine whether the received wave is a reflected wave of the probe wave, thereby detecting an object. The drive signal includes a ramp-up signal generated to be followed by the identification signal and is used to ramp up an amplitude of the probe wave. A frequency of the ramp-up signal is set to include a frequency at which a transmission/reception efficiency is higher than a transmission/reception efficiency at each of a maximum frequency of the identification signal and a minimum frequency of the identification signal.

Aspects of the subject technology relate to a method of correcting sensor position. The method comprises transmitting one or more first pulses of a first frequency range towards a first portion of a seabed and one or more second pulses of a second frequency range towards a second portion of the seabed, and receiving a first set and second set of backscattered data. The method further includes processing the first and second set of backscattered data to form a first and second set of image data and comparing the first set and second set of image data. The method further includes creating one or more error vectors between the first set and second set of image data, and updating the first set of backscattered data based on the one or more error vectors to produce an updated set of image data.

An acoustic dual-frequency phased array system with common beam angles is disclosed. In one aspect, the system includes a planar array of transducer elements and a multiplexing circuit for selecting between a first state and a second state during either transmit operation, receive operation or both transmit and receive operation. The multiplexer is configured to connect transducer elements to a plurality of connections different between the first state and second state. The system is configured to transmit and receive beams at a first frequency when the multiplexer is in the first state and transmit and receive beams at a second frequency when the multiplexer is in the second state. The angle of the beams from vertical in the first and second state are substantially similar.

A sonar system comprising a sonar transmitter, a very large array two dimensional sonar receiver, and a beamformer section transmits a series of sonar pings into an insonified volume of fluid at a rate greater than 5 pings per second, receives sonar signals reflected and scattered from objects in the insonified volume, and beamforms the reflected signals to provide a video presentation and/or to store the beamformed data for later use. The parameters controlling the sonar system are changed between pings to provide enhanced video imaging.

A sonar system comprising a sonar transmitter, a very large array two dimensional sonar receiver, and a beamformer section transmits a series of sonar pings into an ensonified volume of fluid at a rate greater than 5 pings per second, receives sonar signals reflected and scattered from objects in the ensonified volume, and beamforms the reflected signals to provide a video presentation and/or to store the beamformed data for later use. The parameters controlling the sonar system are changed so that the beamformer section treats the data from the receiver section with more than one set of parameters per ping and/or neighboring pings. The stream of data is treated either in parallel or in series by different beamforming methods so that at least one beam from the beamformer has more than one value.

A method of real time three dimensional (3D) sonar imaging is disclosed, where large array of sonar signal detectors images an underwater object and electromagnetic measuring means fixed in a known position with respect to the large array of sonar detectors measure the position of an above water object which has a known position with respect to the underwater object. The position of the sonar detector may be corrected to give a stable image of the underwater object from ping to ping of the sonar imaging system.