High-resolution minimum variance ultrasonic imaging method based on frequency domain segmentation

Abstract

The invention relates to a high-resolution minimum variance ultrasonic imaging method based on frequency domain segmentation and belongs to the acoustic imaging field. The method comprises the following steps of firstly, carrying out delay processing on a sampling signal received by an array element to obtain echo data required by ultrasonic focusing; secondly, selecting a frequency domain segmentation optimal window function according to a maximum concentration measurement criterion of an adaptive window function in STFT; converting an ultrasonic echo signal into a narrow-band sub-signal by using STFT; carrying out conjugate symmetry processing on a first half of narrow-band sub-signal to generate the other half of narrow-band signal by using conjugate symmetry; successively dividing a receiving array into sub-arrays with overlapped array elements, and carrying out forward and backward smoothing and diagonal loading processing on a frequency domain signal to obtain a sample covariancematrix; and finally, processing a frequency domain segmented minimum variance beam forming weight by using inverse fast Fourier transform to obtain a final time domain adaptive beam forming signal. By using the method, an ultrasonic imaging resolution can be remarkably improved, a contrast ratio is increased, and ultrasonic imaging quality can be integrally improved.

Description

technical field

[0001] The invention belongs to the technical field of ultrasonic imaging, and relates to a high-resolution minimum variance ultrasonic imaging method based on frequency domain segmentation. Background technique

[0002] Ultrasonic imaging is widely used in the field of nondestructive testing and diagnosis due to its advantages of safety, non-invasiveness, real-time and low cost. Beamforming technology is the key technology of ultrasonic imaging, which directly determines the image quality of ultrasonic imaging. DelayAnd Sum (DAS) is the most widely used and simplest beamforming technique in ultrasound imaging. It calculates the delay amount of the received echo signal according to the geometric position relationship of the array element channel, and then aligns and superimposes the delayed data. The traditional DAS algorithm has low complexity, good robustness, and fast imaging speed, but because it uses a fixed window function weighting to increase the wid...

Examples

Embodiment Construction

[0073] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0074] figure 1 It is a flowchart of the method of the present invention, figure 2 It is a schematic diagram of forward and backward spatial smoothing algorithm. As shown in the figure, the present invention provides a high-resolution minimum variance ultrasonic imaging method based on time-frequency segmentation, which specifically includes the following steps:

[0075] Step S1: Perform amplification, AD conversion and delay processing on the echo signal received by the ultrasonic array element to obtain ultrasonic echo data; obtain the signal x(τ)=[x 1 (τ),x 2 (τ),...x N (τ)], x 1 (τ)...x N (τ) respectively represent the echo signals received by each array element, N represents the number of ultrasonic array elements, and τ represents the sampling time corresponding to the depth;

[0076] Step S2: According to the maximum concentra...

technical field

[0001] The invention belongs to the technical field of ultrasonic imaging, and relates to a high-resolution minimum variance ultrasonic imaging method based on frequency domain segmentation. Background technique

[0002] Ultrasonic imaging is widely used in the field of nondestructive testing and diagnosis due to its advantages of safety, non-invasiveness, real-time and low cost. Beamforming technology is the key technology of ultrasonic imaging, which directly determines the image quality of ultrasonic imaging. DelayAnd Sum (DAS) is the most widely used and simplest beamforming technique in ultrasound imaging. It calculates the delay amount of the received echo signal according to the geometric position relationship of the array element channel, and then aligns and superimposes the delayed data. The traditional DAS algorithm has low complexity, good robustness, and fast imaging speed, but because it uses a fixed window function weighting to increase the wid...

Examples

Embodiment Construction

[0073] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0074] figure 1 It is a flowchart of the method of the present invention, figure 2 It is a schematic diagram of forward and backward spatial smoothing algorithm. As shown in the figure, the present invention provides a high-resolution minimum variance ultrasonic imaging method based on time-frequency segmentation, which specifically includes the following steps:

[0075] Step S1: Perform amplification, AD conversion and delay processing on the echo signal received by the ultrasonic array element to obtain ultrasonic echo data; obtain the signal x(τ)=[x 1 (τ),x 2 (τ),...x N (τ)], x 1 (τ)...x N (τ) respectively represent the echo signals received by each array element, N represents the number of ultrasonic array elements, and τ represents the sampling time corresponding to the depth;

[0076] Step S2: According to the maximum concentra...

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