An acoustic transponder provides information related to the transponder when the transponder is receiving an acoustic interrogating signal. The transponder includes a power supply, an electronic circuit connected to the power supply, and one or more transducers receiving and emitting the acoustic signal. The electronic circuit includes a sequence generator. The transponder further includes an amplification and modulation unit, an extraction filter, and a suppression filter. The extraction filter is adapted to extract the received acoustic interrogating signal and suppress other signals prior to being input to the amplification and modulation unit which are configured to modulate the received acoustic signal according to a sequence generated by the sequence generator and to amplify the modulated signal. The suppression filter is adapted to suppress the received acoustic interrogating signal from the amplified and modulated signal. The amplified modulated signal is transferred through the one or more transducers of the transponder and/or through other transducer(s).

Techniques for calibrating presence-detection devices to account for various factors that can affect the presence-detection devices' ability to detect movement. Presence-detection devices may detect movement of a person in an environment by emitting ultrasonic signals into the 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. However, factors such as environmental acoustic conditions, noise sources, etc., may affect the ability of the presence-detection devices to detect movement. To calibrate for these factors, the presence-detection devices may use a loudspeaker to emit an ultrasonic sweep signal that spans different frequencies in an ultrasonic frequency range. The presence-detection devices may generate audio data using a microphone that represents the ultrasonic sweep signal, and analyze that audio data to determine an optimal frequency range and/or transmission power for subsequent ultrasonic signal transmissions.

Techniques for calibrating presence-detection devices to account for various factors that can affect the presence-detection devices' ability to detect movement. Presence-detection devices may detect movement of a person in an environment by emitting ultrasonic signals into the 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. However, factors such as environmental acoustic conditions, noise sources, etc., may affect the ability of the presence-detection devices to detect movement. To calibrate for these factors, the presence-detection devices may use a loudspeaker to emit an ultrasonic sweep signal that spans different frequencies in an ultrasonic frequency range. The presence-detection devices may generate audio data using a microphone that represents the ultrasonic sweep signal, and analyze that audio data to determine an optimal frequency range and/or transmission power for subsequent ultrasonic signal transmissions.

A learning SONAR system and method including receiving, at an input, mission parameters including one or more of mission accuracy, mission covertness, learning rate, and training matrix dependency; transmitting pulsed signals; receiving return pulsed signals, for instance, using a tunable acoustic receiver having controllable receiver elements; and determining a number of the controllable receiver elements to generate estimates of altitude and 3D velocity based on a combination of transmit power, signal-to-noise ratio, and altitude range using an adaptive spatial sampler of a learning controller.

This method includes emitting, by an emitter at an emitting depth, moved along an axis, at least one incident sound wave at an emitting frequency, receiving a first sound wave reflected by a first reflective object at a first depth and a second sound wave reflected by a second reflective object at a second depth, greater than the first depth, providing a first velocity at the first depth, and determining a second velocity of the sound waves at the second depth, from the frequencies of the first and second reflected sound waves, the emitting frequency and the first velocity.

A method for controlling a sound box, includes: in response to the sound box being in a standby state, emitting an ultrasonic signal, and receiving a reflected ultrasonic signal reflected by an external object; acquiring a moving trajectory of the external object according to the reflected ultrasonic signal; and determining a target operation instruction to be executed according to the moving trajectory of the external object.

Techniques are disclosed for systems and methods to provide speed through medium (STM) sensor calibration for mobile structures. An STM sensor calibration system includes a logic device configured to communicate with an STM sensor, an orientation sensor, and a position sensor for a mobile structure. The logic device determines a time series of estimated STM velocities and a time series of speed over ground (SOG) velocities during a dynamic maneuver of the mobile structure. The logic device determines an STM sensor calibration associated with the STM sensor based, at least in part, on the estimated STM velocities and the SOG velocities.

The invention is based on speed changes of sound/ultrasound pulses and a fixed detecting depth between a transducer and sampling points to collect information of the detecting depth and/or a velocity of motionless and/or moving objects from the sampling points to construct two-dimension or three-dimension images of the sampling points. By taking advantages of a pulse ultrasound and a continuous ultrasound, a method of coded sound pulses can simultaneously collect the information of the detecting depth and the velocity from the sampling points, which improves imaging quality. Calculating a speed of the moving objects by simultaneously detecting time-of-flight (TOF) and TOF shift at same site from two separated piezoelectric (PZT) elements improves testing results with accuracy, simplification and reproducibility. An aliasing can be rectified based on the TOF and the TOF shift.

The invention is based on speed changes of sound/ultrasound pulses and a fixed detecting depth between a transducer and sampling points to collect information of the detecting depth and/or a velocity of motionless and/or moving objects from the sampling points to construct two-dimension or three-dimension images of the sampling points. By taking advantages of a pulse ultrasound and a continuous ultrasound, a method of coded sound pulses can simultaneously collect the information of the detecting depth and the velocity from the sampling points, which improves imaging quality. Calculating a speed of the moving objects by simultaneously detecting time-of-flight (TOF) and TOF shift at same site from two separated piezoelectric (PZT) elements improves testing results with accuracy, simplification and reproducibility. An aliasing can be rectified based on the TOF and the TOF shift.

A method for determining the elevation angle and/or azimuth angle of a signal received by an ultrasound sensor includes: providing an ultrasound sensor with a frequency-dependent radiation pattern; transmitting a first ultrasound wave at a first frequency; transmitting a second ultrasound wave at a second frequency different from the first frequency; receiving reflections of the first and second waves, the reflections being caused by an object; and determining the elevation angle of the first and second reflected waves based on amplitudes of the reflections of the first and second waves. Determining the elevation angle (and/or azimuth angle includes calculating a ratio between the amplitudes of received reflections of the first and second waves and mapping a calculated ratio to an elevation angle and/or azimuth angle. The mapping is based on a predetermined ratio curve or ratio dataset which associates a certain amplitude ratio to an elevation angle and/or azimuth angle.