US5327894A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wall filter using circular convolution for a color flow imaging system
Assignee: General Electric Co
•
Filing: 1993-03-01
•
Granted: 1994-07-12
•
Expires: 2013-03-01
Abstract
Abstract An ultrasonic imaging system includes a receiver which demodulates the echo signals received by a transducer array and dynamically focuses the baseband echo signals, and a color flow processor which includes an adaptive wall filter in the form of a circular convolution filter that enables a narrow band of wall signals to be removed without loss of data samples. The mean frequency of the resulting filtered baseband echo signals is used to indicate the velocity of flowing reflectors and to control color of the displayed image.
Inventors
- 👤 Lewis J. Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:53
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/52; G01S7/52017; G01S7/52053; G01S7/52057; G01S7/52071; G01S15/00; G01S15/88; G01S15/89; G01S15/8906; G01S15/8979; G01S15/8981
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
144 words
In an ultrasonic imaging system which includes a receiver for demodulating an ultrasonic echo signal received from an ultrasonic transducer to produce a set of baseband echo signal samples, and further includes a display system, a color flow processor comprising: a mixer for shifting frequency of the set of baseband echo signal samples produced by said receiver such that wall signal components in said set of baseband echo signal samples are at essentially D.C.; a circular convolution filter for filtering out signal components in the set of shifted baseband echo signal samples from said mixer which have a frequency near D.C.; an autocorrelation estimator for indicating the mean frequency of the set of filtered, shifted baseband echo signal samples provided by the circular convolution filter; and chrominance control means responsive to the autocorrelation estimator for controlling color of a display on said display system.
Claim 2
Dependent Claim
144 words
In an ultrasonic imaging system which includes a receiver for demodulating an ultrasonic echo signal received from an ultrasonic transducer to produce a set of baseband echo signal samples, and further includes a display system, a color flow processor comprising: a mixer for shifting frequency of the set of baseband echo signal samples produced by said receiver such that wall signal components in said set of baseband echo signal samples are at essentially D.C.; a circular convolution filter for filtering out signal components in the set of shifted baseband echo signal samples from said mixer which have a frequency near D.C.; an autocorrelation estimator for indicating the mean frequency of the set of filtered, shifted baseband echo signal samples provided by the circular convolution filter; and chrominance control means responsive to the autocorrelation estimator for controlling color of a display on said display system.
Claim 3
Dependent Claim
55 words
The apparatus of claim 1 wherein the circular convolution filter includes memory means for storing the set of shifted baseband echo signal samples, and a convolution circuit for repeatedly receiving the shifted baseband echo signal samples sequentially from said memory means so as to produce an equal number of filtered, shifted baseband echo signal samples.
Claim 4
Dependent Claim
37 words
The apparatus of claim 2 including a look-up table for providing the convolution circuit with a kernel having filter coefficients equal in number to the number of samples in said set of shifted baseband echo signal samples.
Claim 5
Dependent Claim
32 words
The apparatus of claim 3 including means coupled to said look-up table for providing the variance of the set of baseband echo signal samples produced by said receiver to said look-up table.
Claim 6
Dependent Claim
71 words
The apparatus of claim 1 in which the circular convolution filter includes memory means for storing the set of shifted baseband echo signal samples, means responsive to said memory means for calculating the average value of said set of shifted baseband echo signal samples, and means for producing the filtered shifted baseband echo signal samples by subtracting the calculated average value from respective ones of the shifted baseband echo signal samples.
Claim 7
Dependent Claim
17 words
The apparatus of claim 1 wherein said circular convolution filter has a stop band centered at D.C.
Claim 8
Dependent Claim
47 words
The apparatus of claim 1 including an additional autocorrelation estimator responsive to the set of received baseband echo signal samples for providing to said mixer an output signal representing the mean value of the frequency of the set of baseband echo signal samples produced by said receiver.
Claim 9
Dependent Claim
68 words
The apparatus of claim 5 wherein said means for calculating the average value of said set of shifted baseband echo signal samples comprises accumulator means coupled to said memory means for summing the values of each frequency shifted sample stored in said memory means, and divider means coupled to said accumulator means for dividing the sum in said accumulator means by the number of samples in said set.
Claim 10
Dependent Claim
142 words
A color flow processor for use in an ultrasonic imaging system wherein a received ultrasonic echo signal is converted to a set of baseband echo signal samples, said color flow processor comprising: mixer means for shifting frequency of the set of baseband echo signal samples such that wall signal components therein are at essentially D.C.; means for filtering out signal components in the set of shifted baseband echo signal samples from said mixer means which have a frequency near D.C.; an autocorrelation estimator for indicating the mean frequency of the set of filtered, shifted baseband echo signal samples provided by the filtering means; display means for generating images in which a line is produced in response to each separate echo signal, respectively; and chrominance control means responsive to the autocorrelation estimator for controlling color of said images presented on said display means.
Claim 11
Dependent Claim
142 words
A color flow processor for use in an ultrasonic imaging system wherein a received ultrasonic echo signal is converted to a set of baseband echo signal samples, said color flow processor comprising: mixer means for shifting frequency of the set of baseband echo signal samples such that wall signal components therein are at essentially D.C.; means for filtering out signal components in the set of shifted baseband echo signal samples from said mixer means which have a frequency near D.C.; an autocorrelation estimator for indicating the mean frequency of the set of filtered, shifted baseband echo signal samples provided by the filtering means; display means for generating images in which a line is produced in response to each separate echo signal, respectively; and chrominance control means responsive to the autocorrelation estimator for controlling color of said images presented on said display means.
Claim 12
Dependent Claim
16 words
The color flow processor of claim 9 wherein the filtering means comprises a circular convolution filter.
Claim 13
Dependent Claim
52 words
The color flow processor of claim 10 wherein the circular convolution filter includes memory means for storing the set of shifted baseband echo signal samples, and a convolution circuit for repeatedly receiving the shifted baseband echo signals sequentially so as to produce an equal number of filtered, shifted baseband echo signal samples.
Claim 14
Dependent Claim
39 words
The color flow processor of claim 11 including a look-up table for providing the convolution circuit with a kernel having filter coefficients equal in number to the number of samples in said set of shifted baseband echo signal samples.
Claim 15
Dependent Claim
34 words
The color flow processor of claim 12 including means coupled to said look-up table for providing the variance of the set of baseband echo signal samples produced by said receiver to said look-up table.
Claim 16
Dependent Claim
68 words
The color flow processor of claim 10 in which the circular convolution filter includes memory means for storing the set of shifted baseband echo signal samples, means for calculating the average value of said set of shifted baseband echo signal samples, and means for producing the filtered shifted baseband echo signal samples by subtracting the calculated average value from respective ones of the shifted baseband echo signal samples.
Claim 17
Dependent Claim
70 words
The color flow processor of claim 14 wherein said means for calculating the average value of said set of shifted baseband echo signal samples comprises accumulator means coupled to said memory means for summing the values of each frequency shifted sample stored in said memory means, and divider means coupled to said accumulator means for dividing the sum in said accumulator means by the number of samples in said set.
Claim 18
Dependent Claim
19 words
The color flow processor of claim 10 wherein said circular convolution filter has a stop band centered at D.C.
Claim 19
Dependent Claim
46 words
The color flow processor of claim 9 including an additional autocorrelation estimator responsive to the set of received baseband echo signal samples for providing to said mixer means an output signal representing the mean value of the frequency of the set of baseband echo signal samples
Claim 20
Independent Claim
124 words
A method of operating a color flow processor in an ultrasonic imaging system which includes a receiver for demodulating an ultrasonic echo signal received from an ultrasonic transducer to produce a set of baseband echo signal samples and a display system, comprising the steps of: shifting frequency of the set of baseband echo signal samples produced by said receiver such that wall signal components in said set of baseband echo signal samples are at essentially D.C.; filtering out signal components in the set of shifted baseband echo signal samples which have a frequency near D.C.; determining the mean frequency of the set of filtered, shifted, baseband echo signals; and controlling color of a display on said display system in accordance with said mean frequency.
Claim 21
Independent Claim
124 words
A method of operating a color flow processor in an ultrasonic imaging system which includes a receiver for demodulating an ultrasonic echo signal received from an ultrasonic transducer to produce a set of baseband echo signal samples and a display system, comprising the steps of: shifting frequency of the set of baseband echo signal samples produced by said receiver such that wall signal components in said set of baseband echo signal samples are at essentially D.C.; filtering out signal components in the set of shifted baseband echo signal samples which have a frequency near D.C.; determining the mean frequency of the set of filtered, shifted, baseband echo signals; and controlling color of a display on said display system in accordance with said mean frequency.
Claim 22
Dependent Claim
50 words
The method of claim 18 wherein the step of filtering out signal components comprises storing the set of shifted baseband echo signal samples, and producing a number of filtered, shifted baseband echo signal samples equal to the number of stored shifted baseband echo signal samples repeatedly provided sequentially from storage.
Claim 23
Dependent Claim
65 words
The method of claim 18 wherein the step of filtering out signal components comprises storing the set of shifted baseband echo signal samples, determining the average value of the stored set of shifted baseband echo signal samples, and subtracting the average value of the stored set of shifted baseband echo signal samples from respective ones of the stored set of shifted baseband echo signal samples.
References Cited (Backward Citations)
US4839652A
Cited
US4926872A
Cited
US4983970A
Cited
US5123417A
Cited
US5058593A
Cited
US5228009A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-07-11 | 1998-01-10 | 1998-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-07-11 | 2002-01-10 | 2002-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-07-11 | 2006-01-10 | 2006-07-12 | $7700.00 | Window Closed / Lapsed |