Techniques and apparatuses are described that implement face authentication anti-spoofing using ultrasound. In particular, a face-authentication system uses ultrasound to distinguish between a real human face and a presentation attack that uses instruments to present a version of a human face. The face-authentication system includes or communicates with an ultrasonic sensor, which can detect a presentation attack and notify the face-authentication system. In general, the ultrasonic sensor analyzes characteristics of a presented object and determines whether the object represents a human face or a presentation attack instrument. In this way, the ultrasonic sensor can prevent unauthorized actors from using the presentation attack to gain access to a user's account or information.

Techniques and apparatuses are described that implement face authentication anti-spoofing using interferometry-based coherence. In particular, a face-authentication system uses ultrasound to distinguish between a real human face and a presentation attack that uses instruments to present a version of a human face. The face-authentication system includes or communicates with an ultrasonic sensor, which can detect a presentation attack and notify the face-authentication system. In general, the ultrasonic sensor uses interferometry to evaluate an amount of coherence (or similarity) between reflections observed by two or more transducers. In this way, the ultrasonic sensor can prevent unauthorized actors from using the presentation attack to gain access to a user's account or information.

Techniques and apparatuses are described that implement face authentication anti-spoofing using ultrasound. In particular, a face-authentication system uses ultrasound to distinguish between a real human face and a presentation attack that uses instruments to present a version of a human face. The face-authentication system includes or communicates with an ultrasonic sensor, which can detect a presentation attack and notify the face-authentication system. In general, the ultrasonic sensor uses power-spectra to evaluate an amount of variance observed over time within at least one receive channel. In this way, the ultrasonic sensor can prevent unauthorized actors from using the presentation attack to gain access to a user's account or information.

Techniques are described herein for displacing liquid away from a signal path of sonic signals in a signal anemometer. A sonic anemometer may include a membrane positioned between a sonic transducer and the open environment. The membrane may be formed of a hydrophobic material that repels the liquid. The membrane may also include a plurality of pores that impede the flow of liquid through the membrane but enables sonic signals to pass through the membrane. The sonic anemometer may also include a reflector that displaces liquid away from the signal path of the sonic anemometer. The reflector may include one or more pores that wick liquid away from the signal path.

An ultrasound flow measurement device has a vessel through which a fluid to be measured flows. An ultrasound measurement configuration with an ultrasound transducer is provided for measuring a propagation time of an ultrasound signal containing a plurality of periods along a measurement section that runs partly in a direction of flow. A controller determines a fluid flow on a basis of a propagation time measurement. The controller contains a memory, a first evaluator for determining a period duration of at least one of the periods of an ultrasound signal received after passing through the measurement section, a second evaluator for determining a spread value of a predetermined number of last received ultrasound signals, a comparator for comparing the spread value with a threshold value, and an actioning device for initiating a control action, assigned to the threshold value that has been exceeded, for the ultrasound flow measurement device.

A method, performed by an electronic device, of determining a location of an external device includes: receiving a trigger signal, which is output at a first location; receiving, after the trigger signal is received, a first chirp signal transmitted from a first external device among at least one external device present at a different location from a location of the electronic device, the first chirp signal being transmitted according to the trigger signal being received by the first external device; obtaining, based on a time point at which the first chirp signal is received, a difference value between a time point at which the trigger signal is received by the electronic device and a time point at which the trigger signal is received by the first external device; and determining a location of the first external device based on the difference value.

A wave generator for an ultrasonic air data system can be configured to collect data derived from a flow of air in a downstream direction. The wave generator can include an ultrasonic wave source configured to output ultrasonic waves from a first end and a wave shaper connected to the first end of the ultrasonic wave source. The wave shaper can be configured to focus the ultrasonic waves into an area downstream from the ultrasonic wave source bounded by a first plane parallel to the downstream direction and a second plane orthogonal to the first plane.

A method for locating an object underwater may involve using a sound transmitter to transmit a sound pulse. The sound pulse may be reflected by the object to be located and then received by a sound receiver. The sound receiver may be spatially distant from the sound transmitter, meaning that the sound receiver is spaced apart from the sound transmitter by an amount that is of a similar order of magnitude as a distance between the sound transmitter and the object or between the sound transmitter and the seafloor. The sound pulse may contain encoded information relating to a time of transmission of the sound pulse and a transmission position of the sound transmitter. The encoded information may then be decoded by the sound receiver to determine the position of the object.

A determining method for obstacles includes determining whether an ultrasonic noise exists in TOF of an ultrasonic wave reflected by an object and received; generating a virtual object on an outline of a parking path that a vehicle is to move on based on the received ultrasonic wave TOF; generating virtual indirect wave TOF using the virtual object; and determining whether the object is located inside or outside the outline of the parking path by comparing real indirect wave TOF, which is indirect wave TOF among the received ultrasonic wave TOFs, with the virtual indirect wave TOF.

The present disclosure provides systems and methods associated with determining velocity and/or acceleration information using ultrasound. A system may include one or more ultrasonic transmitters and/or receivers. An ultrasonic transmitter may be configured to transmit ultrasound into a region bounded by one or more surfaces. The ultrasonic receiver may detect a Doppler shift of reflected ultrasound to determine an acceleration and/or velocity associated with an object. The velocity and/or acceleration information may be utilized to modify the state of a gaming system, entertainment system, infotainment system, and/or other device. The velocity and/or acceleration date may be used in combination with a mapping or positioning system that generates positional data associated with the objects.