Wall filter using circular convolution for a color flow imaging system
AssigneeGeneral Electric Company
InventorLewis J. Thomas
Life of this patent
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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.
Claims20
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.
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.
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.
Dependencies are inferred from the claim text.