To acquire a beat frequency necessary for target extraction, target speed estimation, and Doppler influence detection by preventing the necessary beat frequency from overlapping unnecessary frequencies in a heterodyne processing result, an apparatus includes a wave receiver that receives a reflected wave of a chirp wave reflected from a target, and outputs a reception wave signal, a dual-sweep signal generator that generates a dual-sweep signal of the chirp wave, having a frequency which does not overlap that of the chirp wave, and a heterodyne processor that generates a beat frequency by multiplying the reception wave signal and the dual-sweep signal as a heterodyne signal.

A method for measuring, using a radar or sonar, the velocity with respect to the ground of a carrier moving parallel to the ground, includes the following steps: a) orienting the line of sight of the radar or sonar toward the ground; b) emitting a plurality of radar or sonar signals (P.sub.1-P.sub.N) that are directed toward the ground, and acquiring respective echo signals (E.sub.1-E.sub.N); c) processing the acquired echo signals so as to obtain, for one or more echo delay values, a corresponding Doppler spectrum; d) for the or at least one the echo delay value, determining a high cut-off frequency of the corresponding Doppler spectrum; and e) computing the velocity of the carrier with respect to the ground on the basis of the one or more high cut-off frequencies. A system allowing such a method to be implemented.

In one form, an acoustic distance measuring circuit includes a frequency generator, a transmitter amplifier, an acoustic transducer, and a sensing circuit. The sensing circuit includes an input adapted to be coupled to the acoustic transducer, for receiving an input signal. The sensing circuit provides an in-phase portion and a quadrature portion of the input signal to a filter. The sensing circuit filters the in-phase portion and the quadrature portion and calculates a phase of the input signal in response to the filtered in-phase and quadrature portions. The sensing circuit determines a frequency slope of the input signal in response to calculating the phase and provides the frequency slope of the input signal to an output.

A driving support apparatus according to the present disclosure includes a memory and a hardware processor coupled to the memory and a sound wave sensor. The hardware processor is configured to select, as a transmission and reception scheme, either a pulse scheme or a spread spectrum modulation scheme, and control the sound wave sensor with the selected transmission and reception scheme. When the spread spectrum modulation scheme is selected as the transmission and reception scheme, the hardware processor causes the sound wave sensor to successively transmit and receive sound waves by using the spread spectrum modulation scheme.

An electronic device (1) such as a cell phone, or a proximity detector for an electronic device (1), has an ultrasound transmitter (5), an ultrasound receiver (6), and a processing system. It transmits an ultrasonic sine-wave signal from the transmitter (5), and receives the ultrasonic sine-wave signal, through air, at the receiver (6). It detects when the frequency of the transmitted signal and a frequency of the received signal satisfy a predetermined difference criterion, and uses this to determine whether to disable or enable a touch or touchless input (2) on the device (1).

An electronic device (1) such as a cell phone, or a proximity detector for an electronic device (1), has an ultrasound transmitter (5), an ultrasound receiver (6), and a processing system. It transmits an ultrasonic sine-wave signal from the transmitter (5), and receives the ultrasonic sine-wave signal, through air, at the receiver (6). It detects when the frequency of the transmitted signal and a frequency of the received signal satisfy a predetermined difference criterion, and uses this to determine whether to disable or enable a touch or touchless input (2) on the device (1).

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.

An air-coupled ultrasonic interferometric method is disclosed. An air-coupled ultrasonic transducer, as a probe, is placed directly facing the surface of a workpiece, and an ultrasonic wave is reflected back and forth between the ultrasonic transducer and the surface of the workpiece; the phase difference of the first echo reflected from the surface of the workpiece and reaching the air-coupled ultrasonic transducer is measured; based on the change of the ultrasonic frequency and wavelength, the measured distance is transformed into the rate of change of the acoustic phase with respect to the acoustic angular frequency, wherein the change in the acoustic angular frequency is a product obtained by multiplying 2 by the difference between the highest frequency F2 and the lowest frequency F1 within the bandwidth fB of the air-coupled ultrasonic transducer.

An air-coupled ultrasonic interferometric method is disclosed. An air-coupled ultrasonic transducer, as a probe, is placed directly facing the surface of a workpiece, and an ultrasonic wave is reflected back and forth between the ultrasonic transducer and the surface of the workpiece; the phase difference of the first echo reflected from the surface of the workpiece and reaching the air-coupled ultrasonic transducer is measured; based on the change of the ultrasonic frequency and wavelength, the measured distance is transformed into the rate of change of the acoustic phase with respect to the acoustic angular frequency, wherein the change in the acoustic angular frequency is a product obtained by multiplying 2 by the difference between the highest frequency F2 and the lowest frequency F1 within the bandwidth fB of the air-coupled ultrasonic transducer.

A Continuous Transmission Frequency Modulated (CTFM) detection apparatus is provided. The apparatus includes a projector, a sensor, and a hardware processor. The projector is configured to transmit a frequency modulated transmission wave at a given transmission period. The sensor is configured to receive a reflected wave, the reflected wave comprising a reflection of the transmission wave on a target object. The hardware processor is programmed to at least generate a beat signal based at least in part on the transmission wave and the reflected wave, extract asynchronously from the transmission period a processing signal from the beat signal, and generate information related to the target object based on the processing signal.