Aloka Co., Ltd.

North American Philips Corporation

Hitachi Aloka Medical, Ltd.

Radu Alexandru

A finite impulse response filter is implemented as a sum of individual component, running-sum filters. The sum of all of the component filters required for a desired filter response is calculated in an accumulator and only the component filters' update terms, which are the difference between a new and an old discarded sample, is calculated for each component filter. A desired impulse response is decomposed into a sum of rectangular impulse responses of equal height, each of which implemented as a running sum requiring a subtraction and an addition. Using circuits running at a multiple of the sampling clock, multiple running sums may be implemented on the same hardware. A whole filter of arbitrary impulse response shapes and lengths may be implemented using memory and two arithmetic units. Two or more such filters may be cascaded to obtain a better approximation of the desired frequency characteristic. The invention saves significant chip resources and manufacturing costs.

Method and apparatus for implementing finite impulse response filters without the use of multipliers

An ultrasound system includes an ultrasound transducer having an array of elements and a beam origin located between two adjacent elements, each of the elements for converting received energy into an echo signal; and a beamformer that includes an initialization controller having initialization controller circuitry for calculating initialization parameters according to a process for calculating initialization parameters from a reduced table; at least one channel having a delay circuit and a delay controller; and a summer for summing phase-aligned signals to form a beamformed signal.

Delay controller for ultrasound receive beamformer

In an ultrasound receive beamformer signals from two or more aperture elements are multiplexed at the input of each beamformer channel, stored in different portions of a delay memory, delayed and apodized in a time-multiplexed fashion, demultiplexed at the output of the channel, and summed in different summation units running at an upsampled rate. The partial sums are then time-aligned, summed to produce the total upsampled beam sum, filtered and decimated in an interpolation filter to produce the beamformed signal.

Ultrasound receive beamformer

A system for connecting an transducer matrix array to a beamformer via a multiplexer where the multiplexer includes a plurality of numbered switches, the array including a plurality of rows and columns where the rows include plural center rows the elements of which are uniquely associated with a numbered switch portion and a top row associated with first and second numbered switches offset by L in first and second differing directions with respect to one of the center row elements, and a bottom row associated with third and fourth numbered switches offset by L in first and second differing directions with respect to the one of the center row elements.

Multiplexer for connecting a multi-row ultrasound transducer array to a beamformer

A parallel, frequency domain filter ( ) for providing frequency-dependent phase delay for real data includes a fast Fourier transform (FFT) device ( ), a complex multiplier ( ), a filter memory ( ) and an inverse fast Fourier transform (IFFT) device ( ). The FFT and IFFT devices ( ) and ( ) are shown with two inputs and two outputs each. The filter ( ) of the present invention allows for increased throughput by filtering two real signals in parallel, one being applied to the real input of FFT device ( ) and the other being applied to the imaginary input of FFT device ( ). The filter memory of FIG. is provided with sufficient capacity to store several filter frequency characteristics. The appropriate filter frequency characteristic for the particular digitized rf signal being processed can be selected based on factors such as beam focus depth. The parallel, frequency domain filter ( ) allows the use of coded waveforms to improve signal to noise ratio in ultrasound images.

Apparatus and method for improving the signal to noise ratio on ultrasound images using coded waveforms

An apparatus ( ) for the real-time calculation of local variance in an array of digital signals includes a first squaring device ( ) arranged to receive an input signal, the input signal being one of a plurality of signals within a window defined in the array. The first squaring device ( ) squares the value indicated by the input signal and provides a signal indicative of the squared value to a first recursive sum device ( ). The first recursive sum device ( ) uses a recursive sum method to calculate the sum of the squares of a plurality of values indicated by the plurality of digital signals. The input signal is also received by a second recursive sum device ( ). The second recursive sum device ( ) uses a recursive sum method to calculate the sum of the plurality of values. The second recursive sum device ( ) outputs a signal indicative of this sum to a second squaring device ( ), which, in turn, provides a signal to a first dividing device ( ). The signal output from the first dividing device ( ) is indicative of the square of the sum of the plurality of values in the window, divided by the number of digital signals in the window. In the first subtracting device ( ), this value is subtracted from the value indicated by the signal from the first recursive sum device ( ). Finally, in the second dividing device ( ), the value indicated by the signal from the first subtracting device ( ) is divided by the number of digital signals in the window. The resulting value is the variance for the plurality of values. A signal indicative of this value is output from the second dividing device ( ).

Apparatus and method for the real-time calculation of local variance in images

An ultrasound imaging system provides for depth-variable elevational and azimuthal focusing by combining electronic beamforming and fixed mechanical lens (or element shaping). The imaging system includes a plurality of beamformer channels that are selectively allocated to the imaging elements of an array. For phased arrays, a switching circuit controls the allocation of the beamformers, while a linear/convex array also requires an aperture shifting circuit for shifting the aperture along the array. The elevational focusing is achieved using a small number of beamformer channels by sharing the beamformer channels assigned to azimuthal elements for far field imaging and to elevational elements for near field imaging. A portion of the beamformer channels are connected to elevational elements (elements in the off-center rows) during near-field imaging. During far-field imaging, these channels connected to the elevational elements are allocated to the lateral elements for azimuthal focusing, and the elevational elements are allocated directly to the center-row elements of their column. The mechanical focus depth is chosen to be in the far field to provide improved elevation focusing in the far field without the need for electronic beamforming delays. In addition, since the f-number is large in the far field, the depth of focus will be large.

Elevation focusing by beamformer channel sharing

A bus structure for an image processing system connecting a plurality of devices capable of transmitting and receiving packets of N data words serially on N sub-buses wherein the data sub-buses are spatially multiplexed and an address bus is time multiplexed.

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Cheshire, CT, United States of America

Radu Alexandru