A method and downhole tool is provided that uses beamforming to localize acoustic energy at a desired zone-of-interest within a wellbore traversing a subterranean formation. The tool has an array of transmitter elements configured to emit guided mode acoustic signals at variable amplitude and variable time delay, which are individually controlled by an amplitude factor and time delay assigned to respective transmitter elements. A set of amplitude factors and time delays can be assigned to the transmitter elements of the transmitter array such that the transmitter elements produce a focused acoustic beam at the desired zone-of-interest by combination of guided mode acoustic signals transmitted by the transmitter elements.

A digital transmit beamformer for an ultrasound system has a waveform sample memory which stores sequences of samples of different pulse transmit waveforms of differing pulse widths. The memory is shared by a plurality of transmit channels, each of which can access its own selected sample sequence, independent of the selections by other channels. Waveform sample readout by the channels occurs substantially simultaneously during a transmit event, producing a transmit beam from a transmit aperture with different pulse waveforms applied to different elements of the transmit aperture. Higher energy waveforms with wider pulse widths are applied to central elements of the aperture and lower energy waveforms with narrower pulse widths are applied to lateral elements of the aperture to produce an apodized transmit beam.

In one aspect, a system of active noise cancellation includes a signal processing apparatus in operative communication with at least one input device and at least one output device disposed within or proximate to a cabin of a work vehicle. Generally, the signal processing apparatus can be configured to perform a method of active noise cancellation. The method can include receiving an audio input signal from the at least one input device, the audio input signal comprising audio perceptible from within the cabin. The method can also include processing the audio input signal to separate ambient noise in the audio input signal from equipment noise in the audio input signal and generating an output waveform based on the ambient noise, and outputting the output waveform through the at least one audio output device. The output waveform can be configured to at least partially cancel out the ambient noise.

An apparatus and method for generating high quality, high frame rate images in a handheld or hand-carried ultrasound imaging machine. The apparatus includes a time-multiplexed beamformer coefficient generator that supplies the necessary delay and weight coefficients to process multiple beams in parallel via a beamforming coefficient bus. This approach reduces the required hardware and power consumption to satisfy the physical space and power requirements of a handheld probe. The ultrasound machine may optionally turn off or operate beamformers in a standby mode. The ultrasound machine may also use pulse inversion harmonics to improve image quality by improving signal-to-noise ratio.

A downhole tool including at least one transmitter, a receiver array, and a controller. Each receiver element of the receiver array is configured to apply variable amplification and a variable time delay to detected acoustic waveforms, wherein the variable amplification is controlled by an amplification factor assigned to the given receiver element, and wherein the variable time delay is controlled by a time delay assigned to the given receiver element. The controller assigns a set of amplification factors and time delays to the receiver elements of the receiver array and combines signals resulting from the application of the variable amplification and the variable time delay to the detected acoustic waveforms such that sensitivity of the receiver elements of the receiver array is focused at a desired zone-of-interest in a wellbore corresponding to the set of amplification factors and time delays assigned to the receiver elements of the receiver array.

An apparatus and method for generating high quality, high frame rate images in a handheld or hand-carried ultrasound imaging machine. The apparatus includes a time-multiplexed beamformer coefficient generator that supplies the necessary delay and weight coefficients to process multiple beams in parallel via a beamforming coefficient bus. This approach reduces the required hardware and power consumption to satisfy the physical space and power requirements of a handheld probe. To improve image quality, the ultrasound machine may optionally use synthetic aperture to improve penetration and resolution. The ultrasound machine may also use pulse inversion harmonics to improve image quality by improving signal-to-noise ratio.

The invention provides methods and systems for generating an ultrasound image. In a method, the generation of an ultrasound image comprises: obtaining channel data, the channel data defining a set of imaged points; for each imaged point: isolating the channel data; performing a spectral estimation on the isolated channel data; and selectively attenuating the spectral estimation channel data, thereby generating filtered channel data; and summing the filtered channel data, thereby forming a filtered ultrasound image. In some examples, the method comprises aperture extrapolation. The aperture extrapolation improves the lateral resolution of the ultrasound image. In other examples, the method comprises transmit extrapolation. The transmit extrapolation improves the contrast of the image. In addition, the transmit extrapolation improves the frame rate and reduces the motion artifacts in the ultrasound image. In further examples, the aperture and transmit extrapolations may be combined.

A programmable metasurface and method is described having a plurality of parallel slits in an elastic substrate plate defining a plurality of unit cells, each having an actuator beam and a sensing beam with a slit therebetween. Each sensing beam has a pair of sensors for sensing flexural waves in the substrate. The actuator beam has a piezoelectric actuator that is controlled by a control circuit where the control circuit generates an actuator signal and where the control circuit compares the preceding actuator signal to the difference between the sensors and an electrical transfer function to result in the metasurface being able to perform a desired function.

Producing multiple independent fields from many phased acoustic transducers represents a difficult computational problem. By first dividing up each field to its own group of transducers and then treating each group as an element with adjustable phase, one can minimize the field-to-field interference through a power iteration solution. These solutions can be further refined by including tracking information from users in the space and how they shadow or reflect the acoustic fields.

Systems and methods are disclosed for performing ultrasound imaging using biphasic driving and/or reception for ferroelectric ultrasound elements having propagation and lateral electrode pairs. Electrode pairs are driven using biphasic drive signals, where the drive signals applied to the respective pairs of electrodes are provided with a phase difference therebetween, and where a time delay may be added between the drive signals to further increase the power of the emitted ultrasound. In some example embodiments, passive determination of the direction and/or location of an acoustic source relative to a multiaxial ultrasound transducer is determined based on the voltages detected at the propagation electrodes and the lateral electrodes the multiaxial transducer, according to a pre-determined relationship between the electrode voltages and one or more directional angles. A plurality of multiaxial ultrasound transducers may be employed to improve the accuracy of the estimated direction and/or location of the acoustic source.