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.

This invention relates to a method of improving performance of a SODAR system adapted to locate discontinuities in the atmosphere by transmitting pulse compression signals such as a plurality of acoustic chirps, the method comprising: transmitting one or more acoustic chirps; receiving one or more acoustic echoes of the transmitted chirps; processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere, thereby providing a wind shear profile; processing the wind shear profile to correct systematic Doppler errors associated with the acoustic echoes by: subtracting a first measured wind speed from the wind shear profile; and adding a second measured wind speed to the wind shear profile.

A wind speed specification system according to the present disclosure includes an optical fiber (10) laid around a power transmission line (40), a reception unit (20) that receives an optical signal including information indicating a sound generated when an airflow hits the optical fiber (10), from the optical fiber (10), and a specification unit (32) that specifies a wind speed around the optical fiber (10), based on information indicating a sound that is included in the optical signal.

A Doppler device including a transducer and processing circuitry is provided. The transducer transmits underwater ultrasonic wave and receives a reflected wave of the ultrasonic wave. The Doppler device generates a first echo signal from the reflected wave in a first direction making a depression angle θ with a receiving surface of the transducer, generates a second echo signal from the reflected wave in a second direction making the depression angle θ with the receiving surface, the second direction being different from the first direction, and generates a third echo signal in a third direction perpendicular to the receiving surface. The processing circuitry further calculates a first Doppler frequency of the first echo signal, a second Doppler frequency of the second echo signal, and a third Doppler frequency of the third echo signal. The processing circuitry further calculates the depression angle θ from the first, second and third Doppler frequencies.

Apparatus and methods for velocity scanning in, e.g., bodies of water. In one embodiment, a scanned one-dimensional transducer array Doppler sonar arrangement is used to remotely measure both vertical and horizontal profiles of a river or channel along-stream water velocities within a cross-section of the river/channel from a single side-mounted sonar.

A survey system including a multibeam echo sounder having a projector array and a hydrophone array in a Mills Cross arrangement uses a multicomponent message to ensonify one or more fans to estimate a Doppler velocity.

Devices and methods are provided for determining frequency spectra, as well as the polarity of frequency, of energy in quadrature signals. In Doppler detection systems, found in sonar, radar, lidar, optical velocimeters using interferometers, and ultrasonics applications, for example, this information can be used to determine target speed and direction. Embodiments obtain a quadrature signal and determine a sine transform of a cross correlation between the I and Q components of the quadrature signal, and can provide an output comprising a signed frequency spectrum. A sign of a sample of the signed frequency spectrum can correspond to a polarity of frequency. The signed frequency spectrum can be rapidly determined over a unipolar frequency span that may be only approximately half the baseband sampling frequency. The signed frequency spectrum may be impervious to imaging under severe conditions of uncorrected quadrature amplitude imbalance.

A system and a method for determining one or more wave characteristics from a moving platform are disclosed. A sonar system, such as an Acoustic Doppler Current Profiler, can profile the water motion relative to the platform, and an earth reference can determine a measure of the platform motion relative to a fixed earth reference. Both water profile and earth reference measurements can be synergistically employed to compensate for motion of the platform. Directional wave spectra and non-directional wave spectrum can be computed and translated via linear wave theory to surface height spectra and used to calculate characteristics, such as significant wave height, peak period, and peak direction.

Ultrasonic ranging systems and methods that emit coded bursts and correlate transduced acoustical echoes of the bursts with a receive template characterizing a burst code to determine time-of-flight information use receive templates of time-variable length to improve short-range object detection. The template length is based on a time index measured from the start of the burst emission. The detection can account for a dead zone of transducer ringing following a burst. A time-variable gain that is also based on the time index can be applied to the correlated signal. The length and gain can be adjusted with reduced temporal frequency to reduce computation cost.

An in-vehicle object determining apparatus cooperates with an obstacle sensor unit, which detects an obstacle at a first time. An estimated detected state is calculated as a detected state of the obstacle estimated to be detected by the obstacle sensor unit at a second time after a lapse of a predetermined time period from the first time, on condition that the obstacle is assumed to be under stationary state, based on (i) a vehicle-relative position of the obstacle detected at the first time, (ii) a sensor position of the obstacle sensor unit, and (iii) a vehicle position change during a period from the first time to the second time. It is determined that the obstacle is a moving object based on a discrepancy between the estimated detected state of the obstacle and a real detected state of the obstacle actually detected by the obstacle sensor unit at the second time.