Phased array ultrasonic beam forming using oversampled A/D converters
First Claim
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1. In a vibratory energy imaging system which includes a vibratory energy transducer having a set of N elements that produce N separate echo signals, a beam former for separately delaying and summing the N echo signals to produce a digital beam signal, comprising:
- a set of N oversampled analog-to-digital converters, each one of said converters being coupled to receive a respective one of the N echo signals and each being operable to produce a digitized representation of its respective echo signal at a sample rate in excess of the sample rate required to meet the Nyquist criterion;
delay means for separately delaying each digitized representation of an echo signal in increments corresponding to said sample rate;
summing means for arithmetically adding together the digitized and delayed representations of the N echo signals; and
decimator means for reducing the sample rate of said digitized representation of said N echo signals to the rate required to meet the Nyquist criterion.
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Abstract
A beam former in a PASS ultrasonic imaging system includes a set of sigma-delta modulators which operate to separately digitize the received echo signal from each transducer element. The oversampled one-bit digital representations of each echo signal are delayed as required for beam steering and focusing, and are summed together. A decimator filter reduces the sample rate of the digitized receive beam prior to display of the image resulting from the receive beam.
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Citations
12 Claims
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1. In a vibratory energy imaging system which includes a vibratory energy transducer having a set of N elements that produce N separate echo signals, a beam former for separately delaying and summing the N echo signals to produce a digital beam signal, comprising:
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a set of N oversampled analog-to-digital converters, each one of said converters being coupled to receive a respective one of the N echo signals and each being operable to produce a digitized representation of its respective echo signal at a sample rate in excess of the sample rate required to meet the Nyquist criterion; delay means for separately delaying each digitized representation of an echo signal in increments corresponding to said sample rate; summing means for arithmetically adding together the digitized and delayed representations of the N echo signals; and decimator means for reducing the sample rate of said digitized representation of said N echo signals to the rate required to meet the Nyquist criterion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 12)
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8. In a vibratory energy imaging system which includes a vibratory energy transducer having a set of N elements that produce N separate echo signals, a beam former for separately delaying and summing the N echo signals to produce a digital beam signal, comprising:
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a set of N single-bit analog-to-digital converters, each one of said converters being coupled to receive a respective one of the N echo signals and being operable to produce a digitized representation of its respective echo signal at a high sample rate; a set of delay register means, each one of said delay register means being operable to receive at an input a digitized representation of an echo signal at the high sample rate, and being operable to produce at an output a delayed digitized representation of an echo signal previously applied to its input; a set of summing means interconnected with the set of delay register means to form a chain in which one input of each summing means is coupled to an output of a respective one of the delay register means, an output of said each summing means is coupled to the input of the next respective one of the delay register means in the chain, and a second input of said each summing means is coupled to receive the digitized representation of an echo signal from a respective one of said single-bit analog-to-digital converters, wherein said each summing means is operable to arithmetically add a delayed digitized representation of an echo signal applied to its one input to the digitized representation of an echo signal applied to its second input and produce a resulting digitized representation of an echo signal at its output; and decimator means coupled to the output of the delay register means at an end of said chain to receive a delayed digitized representation of an echo signal at said high sample rate and being operable to produce at an output a digital beam signal at a lower sample rate. - View Dependent Claims (9, 10, 11)
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Specification